Bio Exam 3

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

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

You can tell that an image of a DNA nucleotide apart from an RNA nucleotide because you see a _____.

sugar with two, and not three, oxygen atoms

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

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.

Sulfate 35

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

_____ are the short sections of
DNA that are synthesized on the lagging strand of the relicating DNA.

Okazaki fragments

The new DNA strand that grows continuously in the 5′ to 3′ direction is called the ________.

leading strand

After replication is complete, the new DNAs, called ________ , are identical to each other.

daughter DNA

During DNA replication, an open section of DNA, in which a DNA polymerase can replicate DNA, is called a _________.

replication fork

The enzyme that can replicate DNA is called _________.

DNA polymerase

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

After DNA replication is completed, _____.

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

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

helicase

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

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

RNA primer complementary to a preexisting DNA strand

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

template

What catalyzes DNA synthesis?

DNA polymerase

Which of the following statements about DNA synthesis is true?

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?

Phosphate groups

Which of the following enzymes creates a primer for DNA polymerase?

Primase

Which of the following statements about Okazaki fragments in E. coli is true?

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?

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.

TRUE

Where would RNA polymerase
attach?

DNA

In his work with pneumonia-causing bacteria and mice, Griffith found that

some substance from pathogenic cells was transferred to nonpathogenic cells, making them pathogenic.

E. coli cells grown on 15N medium are transferred to 14N medium and allowed to grow for two more generations (two rounds of DNA replication). DNA extracted from these cells is centrifuged. What density distribution of DNA would you expect in this experiment?

one low-density and one intermediate-density band

A biochemist isolates and purifies various molecules needed for DNA replication. When she adds some DNA, replication occurs, but each DNA molecule consists of a normal strand paired with numerous segments of DNA a few hundred nucleotides long. What has she probably left out of the mixture?

DNA ligase

In analyzing the number of different bases in a DNA sample, which result would be consistent with the base-pairing rules?

A + G = C + T

The elongation of the leading strand during DNA synthesis

depends on the action of DNA polymerase.

The spontaneous loss of amino groups from adenine results in hypoxanthine, an uncommon base, opposite thymine in DNA. What combination of molecules could repair such damage?

nuclease, DNA polymerase, DNA ligase

In a nucleosome, the DNA is wrapped around

histones

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

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

Transcription

DNA does not store the information to synthesize which of the following?

Organelles

Transcription begins at a promoter. What is a promoter?

A site in DNA that recruits the RNA Polymerase

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

The promoter is a nontranscribed region of a gene.

What determines which base is to be added to an RNA strand during transcription?

Base pairing between the DNA template strand and the RNA nucleotides

Which of the following terms best describes the relationship between the newly synthesized RNA molecule and the DNA template strand?

Complementary

What happens to RNA polymerase II after it has completed transcription of a gene?

It is free to bind to another promoter and begin transcription.

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′

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