How is osmosis different from simple diffusion? |
Water movement is driven by the concentration of solutes rather than its own concentration. |
Nonspecific permeases |
allow a variety of molecules to cross the cytoplasm membrane |
What will happen to a cell that is placed in a solution containing a high concentration of sugar, a molecule that cannot pass across the cell membrane? |
the cell will lose its interior water, causing it to shrivel up and possibly die |
How is simple diffusion different from other types of passive transport? |
Simple diffusion does not require a permease |
Why is no energy required in passive transport? |
The concentration gradient drives the movement |
Once equilibrium is reached, |
molecules move, but there is no net movement in a particular direction |
Which of the following would not move freely across the cytoplasmic membrane? |
positively charged hydrogen ions |
What makes phospholipid membranes good at keeping some molecules out and allowing others to freely pass? |
They have both hydrophilic ad hydrophobic regions |
Integral proteins are mostly involved in |
transport function |
How does water enter and exit a cell? |
By simple diffusion or by use of an integral transport protein |
A glycoprotein |
is a type of peripheral protein above that can be used as a receptor or in enzymatic functions |
Molecules would be blocked by a cell membrane |
ions |
Hydrophobic molecules would enter a cell |
through integral transport proteins |
What is a hallmark of passive transport across a cell membrane? |
It occurs along an electrochemical gradient, and may involve the use of transport proteins |
A positively charged sodium ion |
would require the use of integral protein channels to pass through a cell membrane |
Active Transport |
-requires ATP -requires the use of transport proteins |
Active transport type that employs diffusion |
symport |
What type of transport uses two transport proteins? |
Symport |
Sodium and potassium ions need to be pumped simultaneously against their concentration gradients. Which one of the transport proteins would be most effective at this? |
Antiport |
Why are ATPases associated w/active transport proteins? |
They provide transport proteins w/the energy needed to pump molecules against their concentration gradients |
Efflux pumps can be used to pump antibiotics out of a cell once they enter to protect the cell. This will be done against the concentration gradient of the antibiotic. Which of the active transports would most likely be used? |
Uniport b/c a uniport would pump the antibiotic out w/out needing to bring additional molecules into the cell, and would not allow the antibiotic to diffuse back in |
Why is a ATP necessary for active transport? |
ATP provides energy to transfer material against its concentration gradient |
Which type of active transport protein moves two molecules into the cell at the same time? |
Symport |
Which transport protein employs transporters that move molecules only in one direction? |
uniport and symport |
Which type of active transport protein uses one protein to pump two different molecules? |
Antiport and Symport |
Where is the genetic information of the cell stored? |
nucleus |
The structural framework in a cell is the |
cytoskeleton |
Where in a cell is ATP made? |
Mitochondria |
What carries instructions for making proteins from the nucleus into the cytoplasm? |
mRNA |
One of the ways smooth ER differs from rough ER is that rough ER is covered by |
ribosomes |
What is part of the endomembrane system |
Golgi apparatus, ER, lysosomes and vesicles; it manufactures, processes and transports lipids and proteins. The Golgi apparats processes and packages proteins |
What organelles break down worn-out organelles? |
Lysosomes |
Where are lipids made in the cell? |
smooth ER |
What structure acts as a selective barrier, regulating the traffic of materials into and out of the cell? |
plasma membrane |
What is the mechanism of action of penicillin in a prokaryotic cell? |
Penicillin weakens the cell wall |
Plasmids |
Prokaryotic plasmids may carry genes that provide antibiotic resistance to the cell |
Difference between Gram-Positive and Gram-Negative cells |
only gram-negative cells have a lipopolysaccharide layer |
Which type os solution would cause a bacterium w/a week or damaged cell wall to burst as water moves into the cell? |
Hypotonic solution |
Structure or function of ribosomes |
In eukaryotes, the ribosomes found in the chloroplasts and mitochondria are 70S ribosomes, which are similar to he size of the prokaryotic ribosome |
Evidence of the endosymbiotic theory |
-ribosomes contain w/in mitochondria and chloroplasts are very similar to prokaryotic ribosomes -mitochondria and chloroplasts contain circular DNA, similar to the DNA in prokaryotes -The same antibiotics that inhibit protein synthesis in prokaryotes also inhibit protein synthesis w/in mitochondria and chloroplasts |
Distinguishing characteristics of Prokaryotic cells |
-Their DNA is not associated w/histones -Their DNA is not enclosed w/in a membrane -They have cell walls containing peptidoglycan -They lack membrane-enclosed organelles |
What happens when a bacterial cell is placed in a solution containing 5% NaCl? |
Water will move out of the cell |
Which organelle most closely resembles a prokaryotic cell? |
mitochondrion |
What structures are found in prokaryotic cells? |
Flagellum, axial filament, pilus, peritrichous flagella |
Glycocalyx |
-is used to adhere to surfaces -may be composed of polypeptide -may be composed of polysaccharide -may be responsible for virulence |
Chemical components of a bacterial cell wall |
N-acetylmuramic acid peptidoglycan teichoic acids peptide chains |
The difference between simple diffusion and facilitated diffusion is that facilitated diffusion |
requires transporter proteins |
Where are phospholipids most like found in a prokaryotic cell? |
Plasma membrane? |
Energy reserves |
sulfur granules lipid inclusions polysaccharide granules metachromatic granules |
Considered to be microorganisms |
-bacteria and viruses -microscopic algae -fungi (including yeasts and molds) |
Which microorganisms are acellular and contain a nucleic acid core surrounded by a protein coat? |
viruses |
In the scientific name, Escherichia coli, Escherichia is the |
genus |
How did Pasteur’s 1861 experiment disprove the theory of spontaneous generation? |
Pasteur used open-ended, long-necked flasks w/necks bent into curves; other did not |
Which of the following is the concept, proposed by the German scientists Virchow in 1858, that challenged the hypothetical process called "spontaneous generation"? |
Biogenesis |
Which scientist, in 1876, established a sequence of experimental steps for directly linking a scientific microbe to a specific disease? |
Koch |
Example of bioremediation |
use of bacterial enzymes in drain cleaners to remove clogs |
Human diseases can be caused by a complex aggregation of microbes known as a "biofilm"? |
Endocarditis |
Emerging Infectious disease that is a spongiform encephalopathy caused by a prion |
Creutzfeldt-Jakob disease |
The presence of several types of bacteria on the surface of the tongue indicates the presence of |
normal microbiota |
Statement regarding the experiments that "proved" spontaneous generation |
microorganisms were already present |
Regarding Pasteur’s experiment w/the S-neck flask |
-there was air involved -all microorganisms were killed before beginning -there was a food source involved -any possibility of contamination was removed |
Insect control by microorganisms |
The microorganisms are specific for the insect pest |
Who proved that microorganisms cause disease? |
Koch |
Findings that were essential of Jenner’s vaccination process? |
a weakened microorganism may produce immunity |
An agent that reproduces in cells but is Not composed of cells and contain RNA as its genetic material is a |
virus |
Fungi differ from bacteria in that fungi |
have a nucleus |
Bacteria differ from viruses in that bacteria |
-are composed of cells -can live without a host -have DNA and RNA |
Biofilms |
-on rocks provide food for animals -in pipes black the flow of water -on medical implants cause infections -in your body protect mucous membranes from harmful microbes |
Regular use of antibacterial cleaning products |
promotes survival of bacteria that are resistant |
A multicellular organism that has a mouth and lives in an animal host is a |
helminth |
What is the type of bond holding hydrogen and oxygen atoms in the H2O molecule? |
covalent bond |
glucose+fructose => sucrose + water |
dehydration synthesis reaction |
What type of bond between molecules of water in a beaker of water? |
hydrogen bond |
What type of bond is holding K+ and I- ions in Kl? |
Ionic bond |
Lactose + H2O=> Glucose + Galactose |
hydrolysis reaction |
Which type of molecule contains the alcohol glycerol? |
lipid |
Which type of molecule is composed of (CH2O) units? |
carbohydrate |
Which type of molecule contains -NH2 groups? |
protein |
What is the type of bond between carbon, hydrogen, and oxygen atoms in organic molecules? |
covalent bond |
Structurally, ATP is most like which type of molecule? |
nucleic acid |
What do genes consist of? |
nucleic acids |
Which molecule is composed of a chain of amino acids? |
protein |
Primary making up plasma membranes in cells |
lipids |
starch, dextran, glycogen, and cellulose are polymers of |
glucose |
Oil-degrading bacteria are naturally present in the environment but cannot degrade an oil spill fast enough to avoid ecological damage. How can the actions of these bacteria be sped up? |
Provide nitrogen and phosphorus |
Why do electron microscopes have higher resolving power than light microscopes? |
electrons have a smaller wavelength than visible light, leading to higher resolution |
Which of the lenses are found on electron microscopes but not on light microscopes? |
projector lens |
Which type of microscope would allow the viewer to see ribosomes inside a cell? |
a transmission electron microscope |
Characteristic shared by both electron and light microscopes? |
both employ the use of objective lenses |
What is the fate of the electrons that interact w/a specimen in an electron microscope? |
they may be absorbed, reflected, or refracted by the specimen |
Why is a specimen smaller than 200 nm not visible w/a light microscope? |
Anything smaller than 200 nm cannot interact w/visible light |
What happens to the light rays wen they hit the specimen? |
they are reflected, refracted, or absorbed by the specimen |
What is the role of the ocular lens? |
to recreate the image in the viewer’s eye |
What is meant by light rays being divergent? |
it is spreading out |
In a typical bright field microscope, which point does magnification begun? |
the objective lens |
What is the role of lenses in microscopy? |
lenses focus either light or electrons to create a magnified image of a specimen |
What is the resolution limit of the human eye, unaided by the instruments of microscopy? |
200 x 10-6 |
Physical Requirements for Growth |
-temperature -pH -Osmotic Pressure |
Bacterial Growth is defined as |
increase in bacterial cell population |
In which phase is the rate of cell death equal to the rate of cell growth? |
lag and stationary phase |
Why is cell growth typically graphed logarithmically? |
Cell growth is rapid, and plotting the log of the number of cells versus the generation on a logarithmic graph produces a linear graph |
Why might cells begin to die at a faster rate than new cells are made? |
Lack of nutrients and an increase in cellular waste products |
Bacterial Growth |
When the log of the number of cells is plotted versus the generation, the graph is linear |
What results when a single bacterium reproduces? |
Two genetically identical daughter cells |
If you begin with six cells, how many cells would you have after three rounds of division? |
forty-eight cells |
A step in bacterial cell division |
disappearance of nuclear envelope |
Which step of binary fission is the reason for genetically identical daughter cells? |
replication of the bacterial chromosome |
What enables the copied chromosomes to separate during binary fission? |
The chromosomes are attached to different parts of cell membrane, which elongates and thus separates the chromosomes |
How long does it take for the daughter cells from one round of replication to replicate themselves? |
no time is required-they are fully mature and ready to divide immediately after separation if conditions are right |
Steps of bacterial replication in the correct order, starting from a parent cell |
1.chromosome replication 2.cell elongation 3.septum formation 4.separation of daughter cells |
What would happen if the septum did not form during binary fission? |
The parent cell would now have two copies of the chromosome |
Starting with 3 cells, how many cells would result from three rounds of replication? |
24 |
Aerobic bacteria that have developed (or retain) the ability to continue growing in the absence of molecular oxygen are called |
facultative anaerobes |
Which type of culture media is best for the growth of most chemoheterotrophic organisms? |
complex media |
Which process is best for the short-term storage of bacterial cultures/ |
refrigeration |
Lag phase |
intense activity preparing for population growth, but no increase in population |
Log phase |
logarithmic, or exponential, increase in population |
Stationary phase |
period of equilibrium; microbial deaths balance production of new cells |
Death phase |
population is decreasing at a logarithmic rate |
During which phases of the bacterial growth curve are there no changes in the number of living cells |
lag phase and stationary phase |
Intense activity preparing of population growth occurs in which phase of the bacterial growth curve? |
Lag phase |
What does a spectrophotometer directly measure? |
absorbance of light |
Represents an ideal number of colony-forming units for effective enumeration using the direct method? |
100 |
Salts and sugars work to preserve foods by creating a |
hypertonic environment |
An advantage of the standard plate count? |
determines the number of viable cells |
An advantage of the direct microscopic count |
requires no incubation time |
A culture medium on which only gram-positive organisms grow and a yellow halo surrounds Staphylococcus aureus colonies is call a |
selective medium and differential medium |
A culture medium consisting of agar, human blood, and beef hear is a |
complex medium |
During which growth phase will gram-positive bacteria be most susceptible to penicillin? |
log phase |
Which group of microorganisms is most likely to spoil a freshwater trout preserved with salt? |
Facultative halophiles |
Patients with indwelling catheters are susceptible to infections because |
biofilms develop on catheters |
Microorganisms |
bacteria viruses microscopic algae fungi (including yeast and molds) |
Microorganisms that are acellular and contain a nucleic acid core surrounded by a protein coat |
virus |
In metabolism, energy that is not used |
is given off as heat |
The reactions involved in producing larger compounds from smaller compounds is called |
anabolism |
Where does the energy required for anabolic reactions come from? |
catabolic reactions |
The use of amino acids to make proteins |
is an example of anabolism |
How does noncompetitive inhibitor reduce an enzyme’s activity? |
The inhibitor binds to the enzyme in a location other than the active site, changing the shape of the active site |
What would be the likely outcome if you increased the concentration of substrate for an enzyme in the presence of a noncompetitive inhibitor? |
no change in enzyme activity would be observed |
How is nevirapine used to treat HIV infections? |
It alters the active site of reverse transcriptase, decreasing that enzyme’s activity |
How does a competitive inhibitor slow enzyme catalysis? |
They compete w/the substrate for the enzyme’s active site |
What enables competitive inhibitors to bind to a specific enzyme? |
competitive inhibitors have structures that resemble the enzyme’s substrate |
If high amounts of sulfanilamide are in the presence of an enzyme whose substrate is PABA, what outcome is expected? |
The enzyme will stop functioning |
competitive inhibitors |
decrease the rate of enzyme activity |
Why do all enzymatic reactions need activation energy? |
Energy is required to disrupt a substrate’s stable electron configuration |
What is meant by the statement "Enzymes are biological catalysts"? |
Enzymes speed up the chemical reactions in living cells |
Why are enzymes important biological systems? |
Enzymes decrease the amount of activation energy required for chemical reactions to occur |
What is the fate of an enzyme after it dissociates from the products of the reaction? |
The enzyme returns to its original configuration, ready to bind more substrate |
features of a substrate that can be accommodated by an enzyme’s active site? |
shape size and electron configuration of the substrate |
The first step of any enzymatic reaction is |
binding of the substrate by the enzymes |
The amino acids in an enzyme can facilitate the reaction by |
accepting or donating electrons |
A reaction that involves the transfer of electrons from one molecule to another is referred to as |
a redox reaction |
During an oxidation reaction |
the donor molecule loses an electron and becomes oxidized |
Why is a reduction the term used to describe the gain of an electron? |
The electron acceptor’s net charge decreases |
Redox reactions |
redox reactions involve an oxidation reaction coupled with a reduction reaction |
Where would you expect to find electron transport chains in a prokaryote? |
along the plasma membrane |
Which compounds provide electrons to the electron transport system? |
NADH & FADH2 |
What does oxygen get reduced to at the end of the electron transport chain? |
water |
What does the electron transport chain do to the concentration of hydrogen ions (protons)? |
The concentration of protons is higher outside the membrane than inside |
The process of generating ATP using a proton gradient is referred to as |
chemiosmosis |
Why does lack of oxygen result in the halt of ATP synthesis? |
The chain shuts down and can no longer pump hydrogen ions across the membrane, and the proton gradient cannot be maintained. |
Why might some cells uncouple the electron transport chain? |
Cells can use the energy from the proton gradient for functions other than producing ATP, such as heat generation |
How does cyanide poisoning result in the decrease of ATP production? |
Cyanide permanently reduces cytochrome a3, preventing other components to change into the oxidized state. This causes the proton gradient to break down, stopping ATP synthesis. |
Result in the breakdown of the proton gradient |
oxygen deprivation cyanide poisoning |
Fermentation |
it is an alternative way to return electron carriers to their oxidized state |
What is he role of pyruvic acid in fermentation? |
It takes the electrons from NADH, oxidizing it back into NAD+ |
What is the fate of the NAD+ newly regenerated by fermentation? |
It returns to glycolysis to pick up more electrons. |
An acid produced by fermentation |
Lactic acid and propionic acid |
What is the intermediate product formed by pyruvic acid during alcoholic fermentation? |
Acetaldehyde |
Why is ATP required for glycolysis? |
ATP makes it easier to break apart glucose into two three-carbon molecules. |
Glycolysis literally means |
sugar splitting |
How many net ATPs can be made from one molecule of glucose in glycolysis? |
2 |
What carbon molecule remain at the end of glycolysis? |
pyruvic acid |
Glycolysis |
is also called the Embden-Meyerhof pathway |
What occurs at the bridge step? |
Decarboxylation of pyruvic acid |
How many electrons carriers are reduced in the Krebs cycle only? |
Four |
What is he function of GTP? |
An energy carrier |
What is the fate of metabolites during respiration? |
They are oxidized completely to carbon dioxide and water |
Lipases break down |
lipids |
The Pentose Phosphate Pathway |
is an example of anabolism |
Oxidative phosphorylation |
is a catabolic process |
The reactions that occur between glucose and pyruvic acid |
can either be anabolic or catabolic |
How food fuels cellular respiration |
1.eating food provides fuel and building blocks for your body 2.after food is broken down the digestive system, it is transported to cells via the circulatory system 3.fuel molecules are broken down further in glycolysis and the citric acid cycle 4.ATP is produced with the help of the ETC |
Microbiology Exam 1#
Share This
Unfinished tasks keep piling up?
Let us complete them for you. Quickly and professionally.
Check Price