Midterm 2 Review Flashcards
Ricin is a potential chemical warfare agent that kills by disabling the ribosomes. The most direct effect the of ricin poisoning, then, would be that a cell would no longer be able to make ________.
a
DNA
b
phospholipids
c
proteins
d
carbohydrates
e
None of the above - ribosomes are not involved in the production of any of the above
c
proteins
Because you inherit your ______ almost exclusively from your mother, you have more DNA from your mother than from your father.
a
nuclei
b
ribosomes
c
mitochondria
d
endomembrane system
e
lysosomes
c
mitochondria
A patient was involved in a serious accident and lost a large quantity of blood. An inexperienced observer suggests replenishing body fluids by adding distilled water to the blood directly via one of their veins. What would be the most probable result of this transfusion?
a
The patient’s red blood cells will swell and possibly burst because the blood has become hypotonic compared to the cells.
b
The patient’s red blood cells will burst because the blood has become hypertonic compared to the cells.
c
The patient’s red blood cells will shrivel up because the blood has become hypotonic compared to the cells.
d
It will have no unfavorable effect as long as the water is free of viruses and bacteria.
e
The patient’s red blood cells will shrivel up because the blood has become hypertonic compared to the cells.
a
The patient’s red blood cells will swell and possibly burst because the blood has become hypotonic compared to the cells.
Glucose diffuses slowly through artificial phospholipid bilayers. The cells lining the small intestine, however, rapidly move large quantities of glucose from the glucose-rich food into their glucose-poor cytoplasm. Using this information, which transport mechanism is most probably functioning in the intestinal cells?
a
facilitated diffusion
b
exocytosis
c
phagocytosis
d
simple diffusion
e
active transport
a
facilitated diffusion
Archaean species are classified as prokaryotes along with bacteria because:
a
Unlike all eukaryotes, archaea are unicellular
b
Like bacteria, they lack many organelles found in eukaryotes, such as mitochondria and a nucleus
c
Like bacteria, many of them are pathogenic
d
That is false, archaea are actually a domain of eukaryotes
e
All of the above are false
b
Like bacteria, they lack many organelles found in eukaryotes, such as mitochondria and a nucleus
Which of the following statements about the nucleus is false?
a
The nuclear envelope is composed of two membranes
b
Some proteins require a nuclear localization signal in order to be transported into the nucleus
c
Though nucleotides, RNA, and proteins regularly move in and out of nucleus, DNA does not normally leave the nucleus
d
Molecules pass into and out of the nucleus through nuclear pores.
e
all of the above are false
e
all of the above are false
Which of the following is true comparing endocytosis and exocytosis? (select all that apply)
a
Both are often used to transport molecules that are too large to fit through normal transport proteins in the plasma membrane
b
Endocytosis slightly decreases the size of the plasma membrane, whereas exocytosis slightly increases it
c
Exocytosis is often used to transport proteins that were made and modified by the endomembrane system to the outside of the cell
d
Endocytosis involves vesicles merging with the plasma membrane whereas exocytosis involves vesicles pinching off from the plasma membrane
a
Both are often used to transport molecules that are too large to fit through normal transport proteins in the plasma membrane
b
Endocytosis slightly decreases the size of the plasma membrane, whereas exocytosis slightly increases it
c
Exocytosis is often used to transport proteins that were made and modified by the endomembrane system to the outside of the cell
The blood-brain barrier is an important structure that regulates what is in the liquid surrounding the brain, the cerebrospinal fluid. It prevents most viruses and bacteria, for example, from getting from the blood stream into the cerebrospinal fluid and being able to infect the brain. The blood-brain barrier’s ability to regulate what gets from the blood into cerebrospinal fluid is largely due to the connections between the cells of this barrier, which form a seal and prevent passage of fluid in between the cells of this barrier. Out of the different cell-cell attachment structures that we learned about in this course (desmosomes, gap junctions, tight junctions, plasmodesmata), which of these structures is most likely important in preventing the flow of ions/liquids/pathogens in between the cells of the blood-brain barrier? Why?
Tight junctions are likely important here. Tight junctions are able to form a water-tight seal, preventing the passage of molecules in between two cells. Desmosomes would anchor the cells together but they act more like pop rivets - strong, but not forming a seal. Gap junctions and plasmodesmata are both ways to link the cytoplasm of adjacent cells to coordinate cellular activities
You study viral infections in cows. You discover a new virus that we’ll call cowvirus1 . Cowvirus1 has an RNA genome, but you notice that cells infected by the virus have DNA in their nuclei that is complementary to sequences in the viral genome. These sequences were not part of the genome of the cow cells until after cowvirus1 infection. Based on this information, what can you likely say about cowvirus1?
a
It can infect almost any living organism, not just cows
b
It is a retrovirus
c
It can reproduce outside of cow cells
d
It is a bacteriophage
e
It is transmitted by plasmids
b
It is a retrovirus
You have discovered a new pathogen that creates a disease in humans. Which of the following, if true, would indicate to you that the pathogen you are studying cannot be a virus?
a
The pathogen contains an enzyme that converts RNA into DNA
b
The pathogen only contains RNA and proteins
c
The pathogen does not require human cells in order to reproduce
d
The pathogen recognizes certain cell types based on molecules on the surface of those cells
e
Any of the above would indicate that the pathogen is not a virus
c
The pathogen does not require human cells in order to reproduce
Which of the following is false concerning antibiotics?
a
Antibiotics are medicines that kill bacteria or inhibit their growth
b
Antibiotics usually target structures found in prokaryotic cells, but not eukaryotic cells, such as prokaryotic ribosomes
c
Several common practices have contributed to the spread of antibiotic bacteria, including patients not finishing their full course of antibiotics and the overuse of antibiotics in agriculture
d
Antibiotics are more effective at treating some viral infections, such as the flu, than they are at treating most common bacterial infections, due to the increase in antibiotic resistance in bacteria
e
All of the above are true
d
Antibiotics are more effective at treating some viral infections, such as the flu, than they are at treating most common bacterial infections, due to the increase in antibiotic resistance in bacteria
Luteinizing hormone (LH) is a hormone secreted by a specific part of your brain, the hypothalamus. LH has direct effects on the gonads (testes and ovaries), but it does not affect most other parts of the body (for example, muscle cells). Based solely on this information, what can you say about LH?
a
There are cells with receptors for LH in the gonads, but muscle cells do not have receptors for LH
b
LH is a steroid hormone
c
LH will activate phosphatases in the gonads
d
LH will reach the gonads via the bloodstream, but it will not get anywhere near muscle cells
e
LH is used in quorum sensing
a
There are cells with receptors for LH in the gonads, but muscle cells do not have receptors for LH
Kinases and phosphatases are two important enzymes involved in the same cellular process. Compare and contrast the two. Make sure to mention at least one similarity and one difference in your answer and be reasonably specific (that is, your similarity can’t just be that they are both enzymes, since that is mentioned in the question)
Similarity: they are both enzymes involved in phosphorylation cascades that activate/deactivate other enzymes during cell signaling. Difference: kinases add phosphate groups and generally amplify the signal; phosphatases turn off the signal by removing phosphates
You have isolated a previously unstudied protein, identified its complete structure in detail, and determined that it catalyzes the breakdown of a large substrate. You notice it has two binding sites. One of these is large, apparently the bonding site for the large substrate; the other is small, possibly a binding site for a regulatory molecule. What do these findings suggest about the mechanism of this protein?
a
It is probably a structural protein found in the extracellular matrix.
b
It is probably an enzyme that is regulated through allosteric regulation.
c
It is probably a cell membrane transport protein–like an ion channel.
d
It is probably a protein that makes up part of the cytoskeleton
e
It is probably an enzyme that is regulated through competitive inhibition.
b
It is probably an enzyme that is regulated through allosteric regulation.
Which of the following statements concerning energy and chemical reactions is true?
a
The first law of thermodynamics states that energy transformations are always at least somewhat inefficient and increase entropy
b
Chemical reactions are less likely to happen at higher temperatures because when molecules are moving around faster they are less likely to collide in the correct orientation for a reaction to occur
c
Though the cells and bodies of living things are very organized, they do not break the laws of thermodynamics because they increase entropy in the environment around them
d
An example of a type of potential energy is electromagnetic radiation from the sun
e
All of the above are false
c
Though the cells and bodies of living things are very organized, they do not break the laws of thermodynamics because they increase entropy in the environment around them
