exam 5 bio

This is an image of a _____.

phage

Who demonstrated that DNA is the genetic material of the T2 phage?

Hershey and Chase

The radioactive isotope 32P labels the T2 phage’s _____.

DNA

Hershey and Chase used _____ to radioactively label the T2 phage’s proteins.

35S

After allowing phages grown with bacteria in a medium that contained 32P and 35S, Hershey and Chase used a centrifuge to separate the phage ghosts from the infected cell. They then examined the infected cells and found that they contained _____, which demonstrated that _____ is the phage’s genetic material.

labeled DNA … DNA

In the accompanying image, a nucleotide is indicated by the letter _____.

B

Which of these is a difference between a DNA and an RNA molecule?

DNA is usually double-stranded, whereas RNA is usually single-stranded.

This is an image of a(n) _____.

nucleotide

The letter A indicates a _____.

phosphate group

A nitrogenous base is indicated by the letter _____.

C

You can tell that this is an image of a DNA nucleotide and not an RNA nucleotide because you see a _____.

sugar with two, and not three, oxygen atoms

Which of these nitrogenous bases is found in DNA but not in RNA?

thymine

Which of these is(are) pyrimidines?

C, D, and E

In a nucleotide, the nitrogenous base is attached to the sugar’s _____ carbon and the phosphate group is attached to the sugar’s _____ carbon.

1′ … 5′

Nucleic acids are assembled in the _____ direction.

5′ to 3′

In a DNA double helix an adenine of one strand always pairs with a(n) _____ of the complementary strand, and a guanine of one strand always pairs with a(n) _____ of the complementary strand.

thymine … cytosine

In the 1950s, when Watson and Crick were working on their model of DNA, which concepts were well accepted by the scientific community?

Chromosomes are found in the nucleus. Genes are located on chromosomes. Chromosomes are made up of protein and nucleic acid.

What are the chemical components of a DNA molecule?

phosphate groups sugars nitrogenous bases

In the early 1950s, many researchers were racing to describe the structure of DNA using different approaches. Which of the following statements is true?

Jim Watson and Francis Crick built theoretical models, incorporating current knowledge about chemical bonding and X-ray data.

Early, flawed DNA models proposed by Watson and Crick and by Linus Pauling correctly described which property of DNA?

DNA is composed of sugars, phosphates, and bases.

What did Rosalind Franklin’s famous photo 51 show?

DNA is a helix.

Erwin Chargaff observed that the proportions of adenine (A) and thymine (T) bases were always equal, as were the proportion of guanine (G) and cytosine (C). Chargaff’s observation suggests which of the following statements?

The data suggest that A would always pair with T and G would always pair with C in a DNA molecule.

What did the structure of DNA’s double helix suggest about DNA’s properties?

DNA can be replicated by making complementary copies of each strand. DNA stores genetic information in the sequence of its bases DNA can change. Errors in copying can result in changes in the DNA sequence that could be inherited by future generations.

The enzyme that can replicate DNA is called….. DNA polymerase.
2. Okazaki fragmentsare…….. the short sections of DNA that are synthesized on the lagging strand of the replicating DNA.
3. The new DNA strand that grows continuously in the 5′ to 3′ direction is called the……. leading strand.
4. After replication is complete, the new DNAs, called……. daughter DNA, are identical to each other.
5. During DNA replication, an open section of DNA, in which a DNA polymerase can replicate DNA, is called a…….. replication fork.

…

Which of the following choices describes the function of DNA polymerase?

Catalyzes the linking of dATP, dCTP, dGTP, and dTTP in a specific order, using single-stranded DNA as a template

Short segments of newly synthesized DNA are joined into a continuous strand by _____.

ligase

After DNA replication is completed, _____.

each new DNA double helix consists of one old DNA strand and one new DNA strand

The action of helicase creates _____.

replication forks and replication bubbles

Why is the new DNA strand complementary to the 3′ to 5′ strands assembled in short segments?

DNA polymerase can assemble DNA only in the 5′ to 3′ direction

An old DNA strand is used as a _____ for the assembly of a new DNA strand.

template

The first step in the replication of DNA is catalyzed by _____.

helicase

The synthesis of a new strand begins with the synthesis of a(n) _____.

RNA primer complementary to a preexisting DNA strand

Which of these is responsible for catalyzing the formation of an RNA primer?

D

Which statement explains why 14N-DNA and 15N-DNA form bands at different positions after density-gradient centrifugation?

14N has 7 protons and 7 neutrons, whereas 15N has 7 protons and 8 neutrons. Therefore, 15N has a greater atomic mass, making 15N-DNA denser than 14N-DNA.

1. DNA possesses many negative charges because of the presence of phosphate groups, which also help form the backbone of each DNA strand.
2. DNA contains deoxyribose sugars, which distinguish DNA from RNA and help form the backbone of each DNA strand.
3. Adenine and thymine are examples of nitrogenous bases, which pair with each other in the double helix.
4. The complementary DNA strands of a double helix are held together by hydrogen bonds between their nitrogenous bases.

…

. During DNA replication, if the next base on the template strand is A (adenine), the next nucleotide added to the new strand will contain T (thymine) as a base.
2. In the DNA double helix, the base G (guanine) forms a hydrogen bond with C (cytosine).

…

Which of the following statements correctly describes the formation of the bond between a new nucleotide and the primer?

The newly added nucleotide forms a bond with the hydroxyl (-OH) group on the 3′ end of the primer.

helicase

binds at the replication forkbreaks H-bonds between bases

topoisomerase

binds ahead of the replication forkbreaks covalent bonds in DNA backbone

single-strand binding protein

binds after the replication forkprevents H-bonds between bases

Remembering that the new (daughter) DNA strands will run antiparallel to the parental strands, which of the following statements correctly describes the direction in which the two strands will elongate?

Polymerase 1 elongates its strand toward the replication fork, but polymerase 2 elongates its strand away from the replication fork.

leading strand

daughter strand elongates toward replication fork only one primer needed made continuously

lagging strand

made in segments multiple primers needed daughter strand elongates away from replication fork

both strands

synthesized 5′ to 3′

On either side of the replication bubble, the most recently added RNA primer on the lagging strand will be located

closest to the replication fork.

How does DNA polymerase I function in lagging strand synthesis?
In bacteria, the three primary enzymes involved in lagging strand synthesis are DNA polymerase III, DNA polymerase I, and DNA ligase.
Select the two phrases that correctly describe the functions of DNA polymerase I

replaces the RNA nucleotides of primers with DNA nucleotides leaves a gap in the sugar-phosphate backbone after replacing the last RNA nucleotide of a primer

What catalyzes DNA synthesis?
Which of the following is an enzyme?

DNA polymerase

Which of the following statements about DNA synthesis is true?
What requirements must be met for DNA synthesis to occur?

Primers are short sequences that allow the initiation of DNA synthesis.

Which part of a deoxynucleoside triphosphate (dNTP) molecule provides the energy for DNA synthesis?
Where is the potential energy in a DNA molecule found?

Phosphate groups

Which of the following enzymes creates a primer for DNA polymerase?
DNA synthesis requires an RNA primer to be bound to the template strand before DNA polymerase can start its work.

Primase

Which of the following statements about Okazaki fragments in E. coli is true?
Remember that DNA synthesis proceeds on both strands of a replication bubble.

They are formed on the lagging strand of DNA.

Which of the following enzymes is important for relieving the tension in a helix as it unwinds during DNA synthesis?
This enzyme nicks the DNA and untwists the coils that occur as it is being unwound.

Topoisomerase

True or false? Single-stranded DNA molecules are said to be antiparallel when they are lined up next to each other but oriented in opposite directions.
Consider the orientation of the leading and lagging strands of a DNA template.

True

What is the mechanism by which DNA is replicated?
The following statements describe three alternative models of DNA replication. Select the one statement that correctly describes how DNA is replicated.

Semiconservative replication: Each daughter DNA molecule contains one original parental strand and one complementary, newly synthesized strand.

Which of the following problems during DNA replication is being illustrated with the kids in the video?

Nucleotides at the ends of the DNA strands are lost when DNA replicates.

What are telomeres?

regions of DNA at the end of chromosomes which do not code for making proteins

Many enzymes are named for the substrate on which they work, either to build or disassemble molecules. Also, enzyme names often end in "-ase." For example, lactase is the enzyme that breaks down lactose. With a name like "telomerase," we can deduce that telomerase is probably:

an enzyme that regulates the assembly of DNA at the ends of chromosomes

How is the aging process linked to telomeres?

Cells with short telomeres can no longer divide, so damaged tissues cannot be repaired.

Which cells are most likely to have the gene for making telomerase switched on?

The cells in a developing embryo.

Which of the following is NOT true about naked mole rats?

Their cells do not produce telomerase.

Which of the following has the greatest potential as a cancer treatment?

Find a way to turn off the gene for making telomerase in cancer cells, since the cells would stop dividing when the telomeres were gone.

Many of the first responders at the Chernobyl accident died within hours or days of working at the explosion site. What were they most likely to die from, and why?

acute radiation sickness due to exposure to ionizing radiation

We may never know how many people became ill or died as a result of the Chernobyl accident. What is the main reason why this is so difficult to determine?

Cancer might not occur for many years after exposure to ionizing radiation.

Why is ionizing radiation damaging to cells?

It knocks the electrons from the cell’s molecules, forming ions and breaking bonds.

Although the forest is growing quickly around Chernobyl, and some of the wildlife is thriving, studies show that biodiversity around Chernobyl has been reduced by over 50% since the accident. Why?

The ionizing radiation affects the DNA of the wildlife, just as it affects the DNA of humans.

The concrete sarcophagus enclosing the damaged reactor is crumbling, allowing radiation to leak out into the environment. An animation of a new protective cover is shown in the video. Why hasn’t the construction of this cover been completed?

It will be extremely expensive to build.

Why is the town of Pripyat uninhabited?

The radiation levels in the town are still unsafe.

In addition to the risk of accidents, which of the following is a problem when nuclear power is used as a method of generating electrical power?

storage and disposal of spent fuel rods

The letter A indicates _____.

a DNA double helix

Where would RNA polymerase attach?

A

The letter C indicates _____.

histones

What is this an image of?

supercoils

What is this an image of?

loops

The unpaired nucleotides produced by the action of restriction enzymes are referred to as _____.

sticky ends

The sticky end of the DNA restriction fragment shown here will pair with a DNA restriction fragment with the sticky end _____.

ACGT

Which of these DNA molecules is the shortest?

E

In gel electrophoresis DNA molecules migrate from _____ to _____ ends of the gel.

negative … positive

In this example the marker DNA includes fragments that have 23,130, 9,416, 6,557, 4,361, 2,322, 2,027, and 564 base pairs. Approximately how many base pairs are in the DNA fragment indicated by the letter A?

6,557

In this example the marker DNA includes fragments that have 23,130, 9,416, 6,557, 4,361, 2,322, 2,027, and 564 base pairs. Approximately how many base pairs are in the DNA fragment indicated by the letter B?

between 6,557 and 4,361 base pairs

DNA fragment B consists of _____ base pairs.

1,405

What information can not be obtained from the sequence of a gene?
What information cannot be derived from the sequence of bases in a gene?

Whether the gene is methylated.

What is the polymerase chain reaction (PCR)?
What can be accomplished by doing PCR?

A method to amplify a fragment of DNA.

True or false? Comparison of the sequences of the same gene across species can give some insight into the existence of a common ancestor with that gene.
What conclusions can be drawn if a gene is found in several different species?

T

True or false? The Taq enzyme is a type of DNA polymerase that allows researchers to separate the DNA strands during the annealing step of the PCR cycle without destroying the polymerase.
Consider which step of PCR takes place at the highest temperature.

F

How many DNA molecules would there be after four rounds of PCR if the initial reaction mixture contained two molecules?

32

During which step in the PCR cycle are nucleotides used?

Extension.

During which step in the PCR cycle do primers form bonds with a single-stranded template?
Primers are short, single-stranded DNA molecules.

Annealing.

For the first time, the U.S. Food and Drug Administration is considering whether to allow the sale of _____.

food from a genetically altered animal

The fish in the video have been genetically engineered to _____.

grow faster

The modified salmon were created by _____.

adding genetic material from a Pacific salmon and an eel-like fish

According to the producers of the genetically modified salmon, the meat _____.

looks and tastes the same as unmodified salmon

What concerns do some consumer groups have about genetically modified fish?

all

How does the company raising these fish claim to prevent the genetically modified fish from breeding with wild fish?

The genetically modified fish are sterile.

Which enzyme(s) will produce a DNA fragment that contains the entire vgp gene (shown in red) and has "sticky ends"?

BamHI HindIII x and y

To produce a DNA fragment that contains the whole gene and has two sticky ends, where must the enzyme’s restriction sites be located?

outside the gene on both sides, but not inside the gene

Suppose that a restriction enzyme cut the plasmid within the ampR gene and that an additional piece of DNA were inserted into the gene’s base sequence. How would that affect the mRNA and ultimately the protein encoded by the ampR gene?

Both the mRNA and the protein would be abnormal.

What is bacterial transformation?
Which of the following correctly describes a transformed bacterium?

a bacterium that has taken up external DNA, such as a plasmid

How do ampicillin-sensitive bacteria become resistant to ampicillin?
The third step in the cloning procedure involves incubating ampicillin-sensitive bacteria with plasmids, some of which contain the vgp gene. How do some of these bacteria become resistant to ampicillin?

by being transformed

How can you identify the template strand of a gene?
The template strand is complementary to the mRNA, which begins with the start codon. What is the sequence of the start codon?

AUG

This is a DNA fingerprint exhibiting samples from a victim, two suspects, and the crime scene. Which of these DNA fragments is common to both the victim and Suspect 1?

B

This is a DNA fingerprint exhibiting samples from a victim, two suspects, and the crime scene. Which of these DNA fragments is common to both the victim and Suspect 2?

C

Why is Suspect 1 considered more likely to have committed the crime than Suspect 2?

The crime scene sample contains DNA fragments from both the victim and Suspect 1.

In order to insert a human gene into a plasmid, both must _____

be cut by the same restriction enzyme

What enzyme forms covalent bonds between restriction fragments?

DNA ligase

DNA is a self-replicating molecule. What accounts for this important property of DNA?

The nitrogenous bases of the double helix are paired in specific combinations: A with T and G with C.

During DNA replication, the leading strand is synthesized continuously, whereas the lagging strand is synthesized as Okazaki fragments. Why is this so?

DNA synthesis can take place only in the 5′ to 3′ direction.

Nucleotides are added to a growing DNA strand as nucleoside triphosphates. What is the significance of this fact?

Hydrolysis of the two phosphate groups (P-Pi) and DNA polymerization are a coupled exergonic reaction.

Meselson and Stahl cultured E. coli for several generations in a medium with a heavy isotope of nitrogen, 15N. They transferred the bacteria to a medium with a light isotope of nitrogen, 14 N. After two rounds of DNA replication, half the DNA molecules were light (both strands had 14N) and half were hybrids (15N-14N). What did the researchers conclude from these results?

DNA replication is semiconservative.

Select the most accurate statement describing DNA replication complexes.

DNA replication complexes are grouped into factories, which are anchored to the nuclear matrix.

A researcher is preparing to insert a human gene of interest into a bacterial plasmid in order to clone the human gene. She has genetically engineered the plasmid to carry a gene amp R , which confers resistance to the antibiotic ampicillin. She will include ampicillin in the plating medium when she grows the recombinant bacteria. Why has she engineered the plasmid to include an antibiotic resistance gene? Choose the best answer.

Recombinant bacteria that have taken up the plasmid can be recognized because they are able to survive in the presence of ampicillin.

Cold case detectives are investigating a homicide that took place 30 years ago. In reexamining the evidence, they find a tiny spot of blood on the victim’s clothing that was likely left by the murderer. The DNA in the blood has partially degraded over time. What technique(s) would the blood lab technicians use in their examination of this tiny, degraded blood sample?

They would use PCR to amplify the DNA.

Which of the following is a concern expressed by opponents of the use of genetically modified (GM) food crops?

The protein products of transgenes in GM food crops might lead to allergic reactions in human consumers. GM food crops might pass their new genes to close relatives in nearby wild areas.

The average length of a transcription unit along a eukaryotic DNA molecule is about 27,000 nucleotide pairs, whereas an averaged-sized protein is about 400 amino acids long. What is the best explanation for this fact?

Most eukaryotic genes and their RNA transcripts have long noncoding stretches of nucleotides that are not translated.

Which of the following mutations would likely be most dangerous to a cell?

Deletion of one nucleotide

Which of the following molecules are produced by transcription?

Ribozymes Messenger RNA

Which of the following molecules is/are produced by translation? Include molecules that are subject to further modification after initial synthesis.

RNA polymerase Aminoacyl-tRNA synthetase

Which of the following statements about ribozymes is/are correct?

In some genes, intron RNA functions as a ribozyme and catalyzes its own excision. A ribosome can be regarded as one large ribozyme. Ribozymes are RNA molecules that function as enzymes.

Which of the following is most likely in a fetus lacking adequate amounts of the protein REST?

Neurons will develop improperly.

You are a neurologist. A patient presents to you with amyloid plaques. Which of the following is true?

The patient may or may not exhibit symptoms of Alzheimer’s.

Which of the following people is most likely to have the highest levels of REST?

A healthy 91 year old man.

You are a neurologist doing research on Parkinson’s disease. You discover something very similar to REST that impacts people with Parkinson’s. What have you discovered?

a protein

Which of the following is true?

REST is found in a wide variety of animals.

If what is happening with rape kits in Detroit and Cleveland holds true around the country, which of the following will happen?

Numerous people will be arrested and indicted after analysis of stored rape kits.

Prior to DNA analysis, why were rape kits typically collected for biological analysis?

blood typing

You work for the government agency in charge of Codis, helping to analyze rape kits. Who do you work for?

Federal Bureau of Investigation

You are an attorney in Ohio. Why should you focus on rape cases from rape kits that are 18-20 years old?

Because of the statute of limitations on rape in Ohio.

Which of the following is the biggest reason so many rape kits are not analyzed in the United States?

cost

Assuming all other numbers of interest fall into the normal range, which of the following people is most likely to be successfully treated with the statin drug Lipitor?

A 57 year old man with high LDL.

You have a blood panel done and your triglyceride level is 107. Which of the following is true?

Your level is below that of the average American.

Which of the following is true?

LDL is a type of cholesterol.

Which of the following appears to be true?

Both LDL and triglycerides play a role in heart disease.

You have a normal APOC3 gene. You eat a very fatty meal. Which of the following is most likely to happen?

Your triglycerides will spike.

You are a genetic engineer and discover a gene sequence that works in a similar fashion as CRISPR-Cas9 and can be isolated from the same organism as CRISPR-Cas9. What do you isolate this sequence from?

Bacterium

What is the goal of CRISPR-Cas9 technology?

Correct genetic errors.

Which of the following proved key to allowing CRISPR-Cas9 to cross the cell membrane safely?

The use of nanoparticles.

Based on this research, which of the following is true?

Delivering Cas9 and sgRNA are more successful than editing efficiency.

You study adoptive therapy for a pharmaceutical company. What are you researching?

The use of CRISPR to remove a diseased cell from a patient, repair it, and put it back.

What name is given to the process in which a strand of DNA is used as a template for the manufacture of a strand of pre-mRNA?

transcription

What name is given to the process in which the information encoded in a strand of mRNA is used to construct a protein?

translation

What name is given to the process in which pre-mRNA is edited into mRNA?

RNA processing

Polypeptides are assembled from _____.

amino acids

RNA processing converts the RNA transcript into _____.

mRNA

A codon is a group of three bases that can specify more than one amino acid.
What is a codon?

FALSE

Which of the following statements about mutations is false?
What types of mutation can occur in a gene sequence?

A knock-out mutation results in a total absence of the mutated protein.

If a DNA sequence is altered from TAGCTGA to TAGTGA, what kind of mutation has occurred?

Determine how the two sequences differ.

deletion

Which mutation(s) would not change the remainder of the reading frame of a gene sequence that follows the mutation(s)?

Think about how the genetic code is organized into "words."

One addition and one deletion mutation.

In the diagram below, the gray unit represents _____.

RNA polymerase

In the diagram below, the green unit represents _____.

the promoter

In the diagram below, the two blue strands represent _____.

DNA

Which of these correctly illustrates the pairing of DNA and RNA nucleotides?

GTTACG CAAUGC

The direction of synthesis of an RNA transcript is _____.

5′ —> 3′

What is the process called that converts the genetic information stored in DNA to an RNA copy?

Most of these terms describe part of the gene expression process. One describes the process of making two identical copies of DNA from one parental DNA molecule.

Transcription

DNA does not store the information to synthesize which of the following?
DNA contains the code to make specific types of products, including copies of itself.

organelles

Transcription begins at a promoter. What is a promoter?

A promoter is an essential part of a gene.

A site in DNA that recruits the RNA Polymerase

Which of the following statements best describes the promoter of a protein-coding gene?

Transcription of a gene is initiated by its promoter.

The promoter is a nontranscribed region of a gene.

Which of the following terms associated with transcription describe regions of nucleic acid?

gene promoter terminator

Which two statements correctly describe the template and/or coding strands?

During transcription, the DNA bases on the template strand are paired with their complementary RNA bases to form the RNA transcript. The template and coding strands are always antiparallel; that is, if one strand has its 3′ end on the left and its 5′ end on the right, the other strand has the opposite orientation.

Does RNA polymerase move in a set direction along a strand of DNA during transcription?

Yes, the RNA polymerase moves in a direction that reads the bases of the DNA sequence from the 3′ end toward the 5′ end.

Which three statements correctly describe the processing that takes place before a mature mRNA exits the nucleus?

A poly-A tail (50-250 adenine nucleotides) is added to the 3′ end of the pre-mRNA. Noncoding sequences called introns are spliced out by molecular complexes called spliceosomes. A cap consisting of a modified guanine nucleotide is added to the 5′ end of the pre-mRNA.

During RNA processing a(n) _____ is added to the 5′ end of the RNA.

modified guanine nucleotide

During RNA processing a(n) _____ is added to the 3′ end of the RNA.

a long string of adenine nucleotides

Spliceosomes are composed of _____.

snRNPs and other proteins

The RNA segments joined to one another by spliceosomes are _____.

exons

Translation occurs in the _____.

cytoplasm

What is the the function of tRNA?

It recognizes and binds a specific codon on mRNA during translation.

What is the function of aminoacyl-tRNA synthetase?

It attaches amino acids to a specific tRNA.

1. The process, performed by the ribosome, of reading mRNA and synthesizing a protein is called translation.
2. The RNA that has an amino acid attached to it, and that binds to the codon on the mRNA, is called atRNA.
3. Terminationof translation happens when the ribosome hits a stop codon on the mRNA.
4. Initiationof translation always happens at the start codon of the mRNA.
5. Amino acids are attached to tRNA by enzymes called aminoacyl-tRNA synthetase.

…

What are the properties of tRNA?
Which of the following statements accurately describe(s) tRNA?

It is often drawn as a cloverleaf shape. It carries amino acids to the ribosome. It recognizes the codons in mRNA.

Which of the following statements accurately describe(s) rRNA?

It is a primary component of ribosomes. It is involved in protein synthesis. It is the most abundant form of RNA.

Which of the following statements accurately describe(s) mRNA?

It carries the genetic information needed to specify a protein. It is produced in the nucleus. It contains codons.

Which type of RNA is either created during or participates in replication?

Neither tRNA, nor rRNA, nor mRNA is created during or participates in replication.

Which statement correctly describes where cytoplasmic and secreted proteins are synthesized?

Cytoplasmic proteins are synthesized on free ribosomes, whereas secreted proteins are synthesized on ribosomes bound to the rough ER.

Which two statements correctly describe the roles of tRNA and rRNA in protein synthesis?

rRNA is the major structural component of ribosomes and is involved in binding both mRNA and tRNAs. tRNAs implement the genetic code, translating information from a sequence of nucleotides to the sequence of amino acids that make up a protein.

Which three statements correctly describe the role that mRNA plays in protein synthesis in eukaryotes?

mRNA is produced only after the steps of RNA processing. mRNA carries genetic information from the nucleus to the cytoplasm. mRNA is the template for protein synthesis in translation.

Which of these is a tRNA?

B

What enzyme catalyzes the attachment of an amino acid to tRNA?

aminoacyl-tRNA synthetase

The tRNA anticodon, GAC, is complementary to the mRNA codon with the sequence _____.

CUG

What is the name of the process shown in the diagram?

initiation (of translation)

The initiator tRNA attaches at the ribosome’s _____ site.

P

Where does translation take place?

Consider the processes that occur at each organelle.

Ribosome

Which nucleic acid is translated to make a protein?

Which nucleic acid serves as the message that is decoded into a series of amino acids to make a protein?

mRNA

Which of the following processes is an example of a post-translational modification?

Which process occurs after a protein is synthesized on the ribosome?

Phosphorylation

Which of the following steps occurs last in the initiation phase of translation?

The initiation phase involves both the recognition of the start codon in the mRNA molecule and the formation of a ribosomal complex.

The large ribosomal subunit joins the complex.

At which site do new aminoacyl tRNAs enter the ribosome during elongation?

Think about how tRNAs move through the different positions of the ribosome during elongation.

A-site

What is meant by translocation?

Translocation occurs during the elongation phase of translation.

The ribosome slides one codon down the mRNA.

rue or false. A tRNA with an anticodon complementary to the stop codon catalyzes the reaction by which translation is terminated.

Release factors are involved in translation termination.

F

What is the codon sequence that the anticodon 5′-CUA-3′ recognizes?

5′-UAG-3′

In the sequence alignment (Figure 1), count the number of each base at position -9. Order them from most frequent to least frequent.

7 G, 2 A, 1 C, 0 T

In the sequence alignment (Figure 1), count the number of each base at position 0. Order them from most frequent to least frequent.

8 A, 1 G, 1 T, 0 C

In the sequence alignment (Figure 1), count the number of each base at position 1. Order them from most frequent to least frequent.

10 T, 0 A, 0 C, 0 G

Which two positions in the logo sequence have the most predictable bases, and which bases would you predict at those two positions in a newly sequenced gene?

position 1 (T) and position 2 (G)

Which positions in the logo have the least predictable bases? How can you tell?

The 12 positions showing no bases have the lowest predictive power (-18, -17, -16, -12, -11, -6, -5, -4, -2, 5, 6, and 8).

Which three positions in the sequence logo in Figure 3 have the most predictable bases? Name the most frequent base at each position.

position 0 (A); position 1 (T); position 2 (G)

What gene feature is represented by the bases in positions 0-2?

the translation start codon AUG

Based on the logo, what five adjacent base positions in the 5′ UTR region (the untranslated region at the 5′ end of the mRNA) are most likely involved in ribosome binding? Explain.

Positions -12 to -8 have the tallest stacks in the 5′ UTR region; therefore, they represent the most likely sequence for the ribosome binding site.

How many bases are in each mutated segment?
The correct DNA sequence contains nine bases. Which of the mutated sequences also contain(s) nine bases?

5′ – ACTAAGTGA – 3′ 5′ – ACTACGTGT – 3′

Of the mutations listed below, which one will likely change the amino acid sequence of the protein coded by the gene the least?

a base substitution at the end of the gene

Generally speaking, which of the following mutations would most severely affect the protein coded for by a gene?

a frameshift deletion at the beginning of the gene

Why is it ineffective to treat viral disease with antibiotics?

Antibiotics inhibit enzymes specific to bacteria and have no effect on virally encoded enzymes.

All of the statements below are true. Select the statement that best supports the view of most biologists that viruses are nonliving.

An isolated virus is unable to replicate its genes or regenerate ATP.

How does a virus differ from a bacterium?

Viruses, unlike bacteria, lack metabolic enzymes.

Identify all correct statements about how viroids differ from viruses.

Unlike viruses, viroids do not encode proteins.

How do prions differ from viruses?

Unlike viruses, prions do not include any nucleic acids. Unlike viruses, prions are infectious proteins. Unlike a virus, a prion is a single molecule.

You inhale the virus for the common cold. What sentinel cells does your immune system send out to determine the location of the infection?

CD4

You are an epidemiologist for the Centers for Disease Control, specializing in schistosomiasis. Your goal is to reduce or eliminate this disease by focusing on the intermediate host. What are you researching?

freshwater snail

In areas where schistosomiasis is rampant, having people do which of the following would be most likely to decrease the frequency of this illness?

Avoid getting into lakes and ponds.

You are a doctor in Egypt. Which of the following patients are you most likely to diagnose with schistosomiasis?

A patient with anemia and blood in the urine.

Which of the following would currently be the most effective way to eliminate schistosomiasis in Africa?

deworming pill distribution

Which of the following is NOT a characteristic of living things?

creating energy

Homeostasis is a living organism’s

ability to maintain constant internal conditions even when environmental conditions change.

Which of the following can be found in bacteria, but not viruses?

a cell membrane

Viruses are

not alive because they are not made of cells and require a host cell for reproduction.

Which of the following statements about viruses is FALSE?

The widespread use of antibiotics has led to resistant strains of viruses.

Why is combination drug therapy for HIV/AIDS less likely to lead to resistance than single drug therapy?

The likelihood of one virus spontaneously mutating to be resistant to several different drugs at the same time is extremely small.

know it. Which one of the following tests would be the best to use in this situation?

a test for the presence of cells that contain DNA

You work for the Centers for Disease Control and Prevention and have been sent to the country where this recent Ebola outbreak was first identified. Where do you go?

Guinea

You agree with the Centers for Disease Control and Prevention concerning the new plans to combat Ebola in Sierra Leone. What do you think?

Ebola patients should not be cared for at home.

Why aren’t antibiotics typically given to Ebola patients?

Ebola is a virus, so antibiotics will be ineffective.

You are a doctor working at a clinic in Liberia. Which of the following patients are you most likely to diagnose with Ebola?

A man with a high fever, diarrhea and vomiting.

How is Ebola spread?

By person to person contact.

According to the CDC regarding the recent bird flu outbreak, which of the following people should be treated with Tamiflu?

A trucker that transports live chickens.

Which of the following is currently most likely to be fatal to a human?

H5N1

You are an epidemiologist. You wish to visit the origin of the H5N1 that is frequently in the headlines. Where should you go?

hong kong

When and where are new flu gene mixes most likely to emerge?

Summer in the Arctic.

Your cousin is an Iowa egg producer and H5N2 is found in his flock. Which of the following will he have to do?

Destroy the entire flock.

Which of the following is true?

Ebola and Lassa are both caused by viruses.

You are a doctor working in Sierra Leone. A patient presents with fever, vomiting, bleeding and a brain infection. Which would be best to diagnose?

Lassa

Controlling populations of which of the following would likely cause a decline in cases of Lassa?

mice

Based on what happened in Nigeria, what is most likely to occur in Sierra Leone?

Over time, the number of people with the LARGE mutation will increase.

Why have so many people with Lassa been turned away from hospitals in Sierra Leone?

It was unknown as to what the patients had.

Which of the following is key to eradicating polio?

vaccinations

Which of the following countries would be best to study to understand why polio has the ability to continue coming back?

Nigeria

Which of the following is polio best known for causing?

paralysis

Where are doctors most likely to find new polio patients to treat?

Pakistan

You work for the World Health Organization and are sent to the last known place where polio was found in Africa to help ensure it does not return. Where do you go?

Somalia

You are a doctor. A patient presents with hepatitis C. Which of the following organs is/are likely to be most affected?

liver

Contact with which of the following is most likely to cause hepatitis C?

infected blood

Your aunt likely came in contact with hepatitis C while in Egypt 7 years ago. Which of the following is true?

If she had contracted hepatitis C, she may not be symptomatic yet.

Which of the following is most similar to the agent that causes hepatitis C?

HIV, caused by a virus.

Somalia wants to emulate Egypt’s hepatitis C treatment program. Which of the following would be best for them to do?

Have the government set official drug prices.

If using these genetically modified mosquitoes is a success, which of the following will happen in Brazil?

Cases of Zika and dengue fever will decrease.

Which of the following natural methods would likely work the best to decrease the mosquito population around your home?

Eliminate all standing water.

You are a genetic engineer interested in using the same technique used in this method to control the Anopheles mosquito which transmits malaria. Which of the following do you release in malaria-riddled regions?

Engineered males.

Which of the following is the key to this project being a success?

Following the release of the engineered mosquitoes, the offspring born in the wild will live, but will die before reproducing.

If these mosquitoes are released in Florida and something goes wrong, which of the following agencies will be held responsible?

Food and Drug Administration

A person travelling to which of the following should be most concerned about contracting Zika?

Caribbean

You are a genetic engineer working to control Zika by altering the organism that transmits it. Which of the following are you working on?

mosquitoes

Assuming a recent discovery is shown to be true, which of the following appears to be true?

Sexual transmission of Zika can occur from a man to a woman or from a woman to a man.

If Zika follows recent trends of the top three sexually transmitted diseases in the United States, which of the following will happen?

There will be an increase in the number of Zika cases resulting from sexual contact.

Which of the following is currently a problem regarding Zika?

It is unknown as to how long Zika can survive in semen.

A new giant virus is discovered. How is it different from a regular virus?

It has genes that code for protein synthesis.

You discover a new giant virus similar to Mimiviruses and Klosneuviruses. Where did this new virus metagenome originate?

From a viral source.

If this research proves correct, where is the best place to locate Klosneuvirus?

Protists

Scientists are interested in studying the translation system genes of Klosneuvirus. Which of the following will they need in order to do this?

The host(s) that the translation system gene sequences came from.

Can giant viruses synthesize proteins?

nah

What genetic material has not been found in any virus?

a combination of DNA and RNA (single- or double-stranded)

Which statements about viruses are true?
Select the four statements that are true.

A retrovirus contains RNA. HIV contains reverse transcriptase. Enveloped viruses bud from the host cell. The capsid enters the host cell if the virus is enveloped.

The pointer is indicating the virus’s _____.

genome

Viral DNA makes mRNA by the process of _____.

transcription

The lytic cycle of bacteriophage infection ends with the _____.

rupture of the bacterium

The pointer is indicating the _____.

viral protein coat

As a result of the lytic cycle, _____.

the host cell’s DNA is destroyed

In the lysogenic cycle _____.

viral DNA is replicated along with host DNA

Cycle A is the _____ cycle and cycle B is the _____ cycle.

lytic … lysogenic

The genetic material of HIV consists of _____.

single-stranded RNA

Which of these binds to receptor molecules on the host cell membrane?

A

What is the function of reverse transcriptase?

It catalyzes the formation of DNA from an RNA template.

What is the source of a viral envelope?

host cell membrane

Which of these is reverse transcriptase?

C

Which of these is the viral genome?

E

Click on the diagram to start the animation. What enzyme is responsible for the process seen here?

reverse transcriptase

Double-stranded viral DNA is incorporated into a host cell as a _____.

provirus

How does HIV cause disease?

What system of the body is most affected by HIV?

HIV kills cells that defend the body against disease.

–

–

Which replicative cycle describes a virus that can integrate its genome into the host cell’s genome?

What mechanisms do viruses use to infect their host cells?

Lysogenic

Which enzyme inserts viral DNA into the host’s chromosomal DNA?

This HIV enzyme enters the cell cytoplasm when the virus fuses with the host cell.

Integrase

How does HIV bind to a host cell?
Several proteins must interact for viral entry into the cell.

The viral envelope proteins interact with CD4 and a co-receptor on the cell membrane.

Which of the following events stimulates the production of viral particles in a host cell?
This event triggers the production of new virus particles.

Activation of the host cell by cytokines, growth factors, or antigens.

True or false? The human immunodeficiency virus (HIV) uses reverse transcriptase to make double-stranded RNA copies of its DNA genome.

Remember that HIV is a retrovirus.

F

What happened in the soapberry bug population in central Florida when the bugs began to feed on smaller goldenrain tree fruits?

Bugs with shorter beaks had more access to food, allowing them to produce more offspring.

What is the meaning of Darwin’s expression "descent with modification"?

Descent with modification refers to evolutionary change over time.

In 1959, doctors began using the powerful antibiotic methicillin to treat infections of Staphylococcus aureus, but within two years, methicillin-resistant strains of S. aureus (MRSA) appeared. How did the resistant strains of S. aureus emerge?

Staphylococcus aureus bacteria that were able to synthesize cell walls using a protein that was not affected by methicillin survived the methicillin treatments and reproduced at higher rates than did other individuals. Over time, these resistant individuals became increasingly common.

Soapberry bugs use needlelike "beaks" to feed on seeds within the fruits of various plants. Bugs feed most successfully when their beak length matches the size of the fruit on which they are feeding. For 25 years, populations of soapberry bugs in central Florida have been feeding on small goldenrain tree fruits that were introduced to the area, rather than on the larger native balloon vine fruits that serve as food for other soapberry bug populations. Beak lengths of soapberry bugs are variable, but the average beak length is shorter in soapberry bug populations that feed on goldenrain tree fruits than in populations that feed on balloon vine fruits, as shown in the graph. How does natural selection act on beak length in soapberry bug populations?

The action of natural selection on beak length in soapberry bug populations varies with the environment.

Identify the pair of homologous structures.

Maple leaf and oak leaf

The wing of a bat is homologous to the _____ of a whale.
Which of the following is(are) homologous to the bones in this image?

flipper tiny brown

Which of the following statements about natural selection is true?

What conditions must be met for natural selection to occur?

Natural selection favors individuals that reproduce more than others.

Which term describes a trait that increases an individual’s ability to survive in a particular environment?
.
How do individuals change to accommodate their environment?

Adaptation

Which term describes the ability of a trait to be passed on to offspring?

How do offspring obtain traits from their parents?

Heritability

Which of the following organisms could be produced by artificial selection?

Remember that artificial selection only works for heritable traits.

A cow that produces a large quantity of milk.

Which pair of chickens should a farmer breed to produce larger chickens?

Consider which parental animals have the traits desired in the offspring.

Large hen, large rooster

Which of the following crosses would produce the highest corn yield with the highest resistance to drought?

Determine the average yield and drought resistance expected from each cross.

A and E

Identify the four postulates of natural selection.

Consider the four steps in the process of natural selection.

Survival and reproductive success are variable among individuals in a population. Individuals in a population vary in the traits they possess. Some trait differences are heritable. Individuals with certain traits are more likely to survive and reproduce.

Which of the following statements is an accurate combination of postulates 1 and 2 of natural selection?

Both of these postulates are required for natural selection to occur. Pick the statement that would enable evolution by natural selection.

Heritable variation exists for traits among individuals in a population.

Which of the following statements is an accurate combination of postulates 3 and 4 of natural selection?

Both of these postulates are required for natural selection to occur. Pick the statement that is a prerequisite for evolution by natural selection.

Individuals experience differential success in their ability to survive or reproduce due to differences in certain traits.

Does the ability of a Mycobacterium tuberculosis cell to infect a new host depend on its drug-resistant phenotype?

Think about how tuberculosis is spread.

No, drug-susceptible cells and drug-resistant cells are equally likely to infect a new host.

Which of the following statements describes the evolution by natural selection of Mycobacterium tuberculosis bacteria in their new environment?

The bacteria have evolved by natural selection to better "fit" their environment.

The drug-resistance trait is an adaptation to the environment in which human hosts are medicated with the antibiotic rifampin.

In the United States today, about half of the corn crop is genetically engineered with a protein that is toxic to corn borers, an insect pest of corn. Which of the following conditions would be necessary for evolution of resistance to the toxic protein to occur in the corn borer?

Consider the four postulates of natural selection.

The corn borer must have or generate (by mutation) heritable variation in resistance to the toxic protein. The resistant corn borers must survive better or reproduce more than nonresistant corn borers.

True or false? It would be difficult to assess whether the drug-susceptible or drug-resistant phenotype in a population of Mycobacterium tuberculosis was more fit in an environment without antibiotics.

Consider the Darwinian fitness of these bacterial cells.

T

When Charles Darwin set sail on the HMS Beagle, what did he and most of his contemporary scientists think about the origin of species?

Most scientists, including Darwin, thought each species was specially created by God in its present form and did not change over time.

Which observations led Darwin to establish a relationship between extinct and living animals?

The bony shells of armadillos resembled the shells of ancient Glyptodon fossils. The fossilized remains of giant sloths were found in places where smaller sloths now live.

After his journey on the HMS Beagle, Darwin made this now-famous sketch in his notebook. Which ideas does it represent?

All species are connected to one another in a "family tree." Species descend from other species just as naturally as children come from parents. All species are linked to one another by common ancestry.

Darwin and Wallace independently arrived at the same conclusion that species change over time. Which observations supported their conclusions?

all

What did Wallace conclude from observing that the bones in manatee flippers look similar to the bones in a human arm and hand?

Manatees’ arm and finger bones are evidence that manatees share a common ancestor with land mammals.

As Wallace traveled the Malay Archipelago, he noticed that western islands had placental mammals, like monkeys. Eastern islands had marsupial mammals, like kangaroos. How did Wallace explain this distribution?

The western islands were once connected to Asia and the eastern islands had been connected to Australia. The islands had never been connected to each other.

Darwin and Wallace made independent observations in different parts of the world. Which statements are true?

Both witnessed nature up close and realized it was a battlefield with massive casualties. Both observed slightly different species on nearby islands and concluded that species could change over time. Both collected huge numbers of specimens and realized that individuals vary within species.

Which of the following statements best describes the promoter of a protein-coding gene?

The promoter is a nontranscribed region of a gene.

The lytic cycle of bacteriophage infection ends with the _____.

rupture of the bacterium

How do enveloped viruses differ from nonenveloped viruses?

They have a membrane-like outer covering.

Different finch species have beaks of different shapes and sizes. What do these beak differences tell us?

Different finch beak shapes are evidence that finch species adapted to different environments over many generations.