If a biological reaction results in an increase in free energy (G), then:

Choose one answer.

	a. it will spontaneously proceed.
	b. it will always remain at equilibrium.
	c. it will only proceed if coupled with a reaction that results in a greater decrease in G.
	d. it will only proceed if the resultant increase in G is immediately used by the cell.

Question 2

If you wanted to find a hydrophobic molecule, in which of these groups would you look?

Choose one answer.

	a. Polar molecules
	b. Nonpolar molecules
	c. Ions
	d. Inorganic molecules

Question 3

If you were an active organism (for example, an animal) and wanted to store energy efficiently, what type of molecule would be best suited for this purpose?

Choose one answer.

	a. Carbohydrates
	b. Lipids
	c. Inorganic ions
	d. Nucleic Acids

Question 4

The following describes the functions and roles of members of which of the four major classes of organic molecules? They are the primary form of informational molecules in the cell.

Choose one answer.

	a. Carbohydrates
	b. Lipids
	c. Proteins
	d. Nucleic Acids

Question 5

The following describes the functions and roles of members of which of the four major classes of organic molecules? They function as a form of energy storage for plant and animal cells and structure for plant cells, and they are cell-surface markers and cell-signaling molecules.

Choose one answer.

	a. Carbohydrates
	b. Lipids
	c. Proteins
	d. Nucleic Acids

Question 6

The following describes the functions and roles of members of which of the four major classes of organic molecules? They function as a highly efficient form of energy storage; they are a major component of cell membranes; they are cell-signaling molecules.

Choose one answer.

	a. Carbohydrates
	b. Lipids
	c. Proteins
	d. Nucleic Acids

Question 7

The following protein example describes which level of its structure? A glucose transporter is made up of many α helices.

Choose one answer.

	a. Primary
	b. Secondary
	c. Tertiary
	d. Quaternary

Question 8

The following protein example describes which level of its structure? Hemoglobin is a "heterotetramer" because it has four polypeptide chains that do not interact symmetrically.

Choose one answer.

	a. Primary
	b. Secondary
	c. Tertiary
	d. Quaternary

Question 9

The following protein example describes which level of its structure? This protein's sequence of amino acids is argenine-argenine-lysine-glycine-valine-serine.

Choose one answer.

	a. Primary
	b. Secondary
	c. Tertiary
	d. Quaternary

Question 10

A molecule that is not membrane permeable binds to a membrane protein on the outside of a cell. This changes the conformation of the protein, causing the binding site to face the inside of the cell. The molecule is then released into the cell and the conformation of the binding site changes again so that it is outside the cell. This is a description of what type of transport(er)?

Choose one answer.

	a. A membrane channel
	b. A membrane carrier
	c. A membrane pump
	d. A peripheral protein

Question 11

If the magnitude of the sodium gradient were to decline, which of the following would not be likely to happen, given what you know about sodium's role in linked active transport?

Choose one answer.

	a. Calcium-triggered muscle contraction, particularly in cardiac muscle, would be facilitated.
	b. Glucose concentrations outside of cells would decline.
	c. Cells would become more acidic.
	d. Glucose concentrations inside of cells would decline.

Question 12

The viscosity of membranes depends on temperature and on aspects of their lipid components. If you increased the temperature of a bacterial culture, which of the following would need to happen in order to maintain the original viscosity of the bacteria's membranes?

Choose one answer.

	a. Enzymes that regulate the double bonds in membrane fatty acids would increase the number of double bonds.
	b. Enzymes that regulate the chain length of membrane fatty acids would make longer-chain fatty acids.
	c. Enzymes that regulate the chain length of membrane fatty acids would make shorter-chain fatty acids.
	d. Enzymes that regulate the incorporation of cholesterol in membranes would add more cholesterol to membranes.

Question 13

Which major membrane component includes molecules that span the membrane, remaining fixed in it, as well as molecules that are indirectly associated with the membrane?

Choose one answer.

	a. Membrane ion channels
	b. Membrane lipids
	c. Membrane proteins
	d. Membrane glycogens

Question 14

Which of the following is an example of symport?

Choose one answer.

	a. A molecule of glucose is transported into the cell via a membrane carrier.
	b. To remove calcium from the cell, the expulsion of one molecule of calcium is coupled with the intake of three molecules of sodium.
	c. Epithelial cells in the intestine are able to take up glucose by coupling this reaction with the uptake of two molecules of sodium.
	d. To prevent acidification of the cytoplasm, the expulsion of one proton is coupled with the intake of one molecule of sodium.

Question 15

Which of the following is an example of uniport?

Choose one answer.

	a. A molecule of glucose is transported into the cell via a membrane carrier.
	b. To remove calcium from the cell, the expulsion of one molecule of calcium is coupled with the intake of three molecules of sodium.
	c. Epithelial cells in the intestine are able to take up glucose by coupling this reaction with the uptake of two molecules of sodium.
	d. To prevent acidification of the cytoplasm, the expulsion of one proton is coupled with the intake of one molecule of sodium.

Question 16

Which of the following is true of cholesterol?

Choose one answer.

	a. In human cell membranes, it makes membranes more rigid (viscous) at higher temperatures but more fluid at lower temperatures.
	b. In human cell membranes, it makes the transition from lower to higher viscosity (phase transition) more steep and abrupt.
	c. In human cell membranes, it makes membranes more rigid.
	d. Cholesterol only functions as a membrane-structuring component in bacterial cells.

Question 17

Which of the following statements is false in regards to membranes and their components?

Choose one answer.

	a. Membranes are composed primarily of phospholipids and proteins.
	b. Some trans-membrane proteins have many membrane-spanning regions.
	c. The lipid and/or protein composition of membranes varies, depending on the type of membrane.
	d. The lipid composition of membranes is always 50%.

Question 18

Which of these methods of membrane transport is always active (that is, always transports molecules against their concentration gradients)?

Choose one answer.

	a. A ligand-gated ion channel
	b. A voltage-gated ion channel
	c. A membrane carrier
	d. A membrane pump

Question 19

Identify the type of receptor based on its description: one of the most common receptors in eukaryotic cells, they have seven membrane-spanning domains.

Choose one answer.

	a. G-protein-coupled receptors
	b. Receptor tyrosine kinases
	c. Cytokine receptors
	d. Receptor serine/threonine kinases

Question 20

Identify the type of receptor based on its description: these receptors are monomeric, and their cytosolic domains do not have any catalytic properties.

Choose one answer.

	a. G-protein-coupled receptors
	b. Receptor tyrosine kinases
	c. Cytokine receptors
	d. Guanalyl cyclase receptors

Question 21

Suppose the concentration of GTP in a cell were dramatically reduced so that it was much less abundant than GDP. Which of the following represents the most direct effect this would have on the G-protein-coupled-receptor process?

Choose one answer.

	a. There would be no conformational change in the receptor, and it would not bind to the Gα subunit.
	b. The Gα subunit's GTP would never be hydrolyzed.
	c. There would be no activation of the Gα subunit, and it would not bind to its effector.
	d. The Gα subunit would not undergo a conformational change, so it would not disassociate from its GDP.

Question 22

Suppose the Gα subunit of a G-protein-coupled receptor could not hydrolyze GTP. Which of the following represents the most direct effect this would have on the G-protein-coupled-receptor process?

Choose one answer.

	a. There would be no conformational change in the Gα subunit, so it would never disassociate from the β and γ subunits.
	b. The Gα subunit would always be active, so it would perpetually activate its effector.
	c. There would be no activation of the Gα subunit, and it would not bind to its effector.
	d. The Gα subunit would not undergo a conformational change, so it would not disassociate from its GDP.

Question 23

Which of the following best defines endocrine signaling?

Choose one answer.

	a. Cells produce signaling molecules of which they themselves are the targets.
	b. The ligand on a cell's surface binds to the receptor of a cell directly adjacent to it.
	c. Molecules released elsewhere in the body are transported by the circulatory system to target cells.
	d. Cells release a signal molecule that reaches nearby target cells.

Question 24

Which of the following is true of guanalyl cyclase receptors?

Choose one answer.

	a. They are involved in a signaling cascade whose result is induced cell death.
	b. They are also known as members of the TGF-β family.
	c. They are the primary receptors involved in activating growth factors.
	d. They catalyze the formation of GMP, a secondary messenger.

Question 25

Which of the following statements is false in regards to Ras proteins?

Choose one answer.

	a. They are involved in nuclear protein transport and vesicle trafficking.
	b. They behave in a manner analogous to that of the Gα subunit of G proteins but are not associated with βγ subunits.
	c. Mutations in these proteins often lead to excessive cell growth and proliferation in cancer cells.
	d. Typical mutations in these proteins prevent them from hydrolyzing the GTP to which they have bound.

Question 26

Which of these best defines juxtacrine signaling?

Choose one answer.

	a. Cells produce signaling molecules of which they themselves are the targets.
	b. The ligand on a cell
	c. Molecules released elsewhere in the body are transported by the circulatory system to target cells.
	d. Cells release a signal molecule that reaches nearby target cells.

Question 27

You suspect that growth-factor signaling is impaired in the cells you are studying. Which type of receptors might not be functioning properly in these cells?

Choose one answer.

	a. G-protein-coupled receptors
	b. Receptor tyrosine kinases
	c. Cytokine receptors
	d. Guanalyl cyclase receptors

Question 28

A researcher observes that her patient does not have an appropriate physiological response to inflammation; his leukocytes do not appear to interact properly with endothelial cells at the sites of inflammation. The patient may have a problem with what cell-adhesion molecules?

Choose one answer.

	a. Selectins
	b. Integrins
	c. Immunoblogins (Ig-CAMs)
	d. All of these

Question 29

A researcher's tissue culture is falling apart; cells within it no longer form stable junctions linked by their cytoskeletons. She suspects that the lab tech accidentally introduced a solution that interferes with which cell-adhesion molecules?

Choose one answer.

	a. Cadherins
	b. Integrins
	c. Immunoblogins (Ig-CAMs)
	d. All of these

Question 30

Cardiac-muscle cells that must communicate with adjacent cells using electric impulses most likely have what kind of junctions between them?

Choose one answer.

	a. Gap junctions
	b. Tight junctions
	c. Desmosomes
	d. Adherens junctions

Question 31

Epithelial cells that must control the movement of ions and molecules between adjacent cells most likely have what kind of junctions between them?

Choose one answer.

	a. Gap junctions
	b. Tight junctions
	c. Desmosomes
	d. Adherens junctions

Question 32

In the extracellular matrix of bone cells, you would expect to find:

Choose one answer.

	a. a higher proportion of fibrous proteins.
	b. a matrix hardened with calcium-phosphate crystals.
	c. a high number of elastin fibers.
	d. a higher proportion of polysaccharides forming a firm, supportive gel.

Question 33

In the extracellular matrix of cartilage cells, you would expect to find:

Choose one answer.

	a. a higher proportion of fibrous proteins.
	b. a matrix hardened with calcium-phosphate crystals.
	c. a high number of elastin fibers.
	d. a higher proportion of polysaccharides forming a firm, supportive gel.

Question 34

In the extracellular matrix of lung cells, you would expect to find:

Choose one answer.

	a. a higher proportion of fibrous proteins.
	b. a matrix hardened with calcium-phosphate crystals.
	c. a high number of elastin fibers.
	d. a higher proportion of polysaccharides forming a firm, supportive gel.

Question 35

In the extracellular matrix of tendon cells, you would expect to find:

Choose one answer.

	a. a higher proportion of fibrous proteins.
	b. a matrix hardened with calcium-phosphate crystals.
	c. a high number of elastin fibers.
	d. a higher proportion of polysaccharides forming a firm, supportive gel.

Question 36

The primary component of the plant cell wall is:

Choose one answer.

	a. hemicellulose.
	b. pectin.
	c. glycogen.
	d. cellulose.

Question 37

Which macromolecules include portions that, because of their negative charge, can bind positive ions and water molecules to form supportive gels?

Choose one answer.

	a. Collagens
	b. Elastins
	c. Proteoglycans
	d. Adhesive proteins

Question 38

A cell's vesicles are not being transported throughout the cytoplasm, its Golgi apparatus is disassembled, and its endoplasmic reticulum is not extended in its normal position. What could cause this?

Choose one answer.

	a. Disruption of actin-filament formation
	b. Disruption of microtubule formation
	c. Disruption of intermediate-filament formation
	d. None of these

Question 39

A sperm is amotile (non-moving), because its flagellum does not function properly. What could cause this?

Choose one answer.

	a. Disruption of actin-filament formation
	b. Disruption of microtubule formation
	c. Disruption of intermediate-filament formation
	d. None of these

Question 40

Because uncontrolled cell proliferation is a characteristic of cancer cells, drugs used in cancer treatment often try to inhibit mitosis. What is one way in which such a drug could function?

Choose one answer.

	a. It could increase the concentration of GTP in the cell.
	b. It could prevent microtubule polymerization.
	c. It could prevent MAP activity.
	d. It could do all of these.

Question 41

If you were to fluorescently label the actin in a cell and then bleach a line through the florescent actin filaments (using the FRAP technique described in one of the course lectures), what would you see over time?

Choose one answer.

	a. The bleached zone would move from the plus end toward the minus end of the filaments, indicating that actin filaments are in a continual state of assembly/disassembly.
	b. The bleached zone would quickly disappear, indicating that actin-binding proteins quickly repair damaged portions of actin filaments.
	c. The bleached zone would remain steady within the filaments, indicating that actin filaments are in a continual state of assembly/disassembly.
	d. The bleached zone would remain in the same place within the filaments, indicating that actin filaments are very stable.

Question 42

If you were to lower the concentration of calcium within muscle cells, what would happen and why?

Choose one answer.

	a. Muscle contraction would be promoted, because calcium increases the speed at which ATP binds to the myosin head.
	b. Muscle contraction would be inhibited, because calcium triggers the conformation change in the shape of the myosin head.
	c. Muscle contraction would be inhibited, because calcium shifts the proteins bound to actin to a different position, allowing actin to contract.
	d. Muscle contraction would be promoted, because calcium triggers the binding of proteins to actin, preventing it from contracting.

Question 43

In order for a cell to crawl, what must occur?

Choose one answer.

	a. Actin filaments must be polymerized and cross-linked, so the front of the cell can extend forward.
	b. Focal adhesions or other attachments must be made between the back end of the cell and its substrate.
	c. Protrusions, for example lamellipodia, must be pulled back into the cell so that they will not block its movement.
	d. Sarcomeres must contract to bring the cell forward.

Question 44

In which of the following ways are intermediate filaments similar to actin and actin filaments?

Choose one answer.

	a. Both are involved in cell movement.
	b. Both are involved in anchoring cells to substrates.
	c. Both are polymers of single types of proteins.
	d. Both are nonpolar molecules.

Question 45

In which of the following ways are microtubules similar to actin and actin filaments?

Choose one answer.

	a. The assembly of both is polymerized by ATP.
	b. Both are highly stable molecules.
	c. Both exhibit dynamic instability.
	d. Both are nonpolar molecules.

Question 46

What property of actin assembly leads to its very high turnover in cells that is, causing it to rapidly assemble and disassemble?

Choose one answer.

	a. Once it has formed large filaments, those filaments have a binding site with a very high affinity for actin-disassembly proteins.
	b. Actin does not have a high turnover in cells; it is very stable.
	c. Its assembly with ATP triggers the hydrolysis of ATP, which in turns makes the ADP-bound actin more likely to disassemble.
	d. Its loose cross-linkage makes its filament connections fragile and easily disrupted.

Question 47

A researcher discovers that some of the mice she studies show gene-expression problems; more research reveals that they are expressing both copies of imprinted genes of which only one copy (either the maternal or paternal) should be expressed. What regulatory process is most likely in error in these mice?

Choose one answer.

	a. DNA methylation
	b. Chromatin condensation
	c. Binding of transcription factors to enhancers
	d. Binding of repressors to activator proteins

Question 48

How is heterochromatin during interphase similar to all chromatin during metaphase?

Choose one answer.

	a. Both are transcribed at very rapid rates.
	b. Both have been moved out of the nuclear envelope.
	c. Both are no longer in association with proteins.
	d. Both are highly condensed so that transcription is impossible.

Question 49

Identify the portion of the nuclear envelope described: the area of selective traffic of transcription factors from the cytoplasm into the nucleus.

Choose one answer.

	a. The inner nuclear membrane
	b. The nucleolus
	c. The nuclear lamina
	d. The nuclear pore complex

Question 50

Identify the portion of the nuclear envelope described: it is the site of structural support and chromatin attachment.

Choose one answer.

	a. The inner nuclear membrane
	b. The nucleolus
	c. The nuclear lamina
	d. The nuclear pore complex

Question 51

Some genes that are present in all cells are only active in certain cells or tissues. What is the best and most likely way through which this selective expression occurs?

Choose one answer.

	a. DNA Methylation
	b. Chromatin condensation
	c. Transcriptional activation
	d. Transcriptional repression

Question 52

When metaphase chromosomes are stained with dye, they show a pattern of dark and light bands; each chromosome's band pattern is unique but consistent to that chromosome, and each gene within a chromosome is regularly located within the same band. Which of the following indicates what this tells us about chromosome organization?

Choose one answer.

	a. The way chromosomes take up dye is consistent and predictable regardless of where genes appear within them.
	b. Genes have an affinity for certain dyes, so they aggregate in such areas during chromosome condensation.
	c. The way that chromosomes organize DNA is predictable and reproducible each time they condense during metaphase.
	d. The way that chromosomes condense repeats the formation of heterochromatin.

Question 53

Which of the following is an example of a repressor of transcription?

Choose one answer.

	a. Histone acetyltransferases, which acetylate histones
	b. Histone deacetylases, which de-acetylate histones
	c. Nucleosome remodeling factors, which change the structure of nucleosomes
	d. A and C are both examples of transcriptional repressors.

Question 54

Which of the following statements is false?

Choose one answer.

	a. Enhancers can stimulate transcription from more than one promoter.
	b. Enhancers can stimulate transcription from an upstream or downstream location.
	c. Enhancers can stimulate transcription, even when located a long distance from a promoter.
	d. Enhancers can stimulate transcription when in a forward orientation and suppress transcription when in a backward orientation.

Question 55

Which of these does not provide suggestive evidence of rRNA's catalytic action in ribosomes?

Choose one answer.

	a. The small subunit of eukaryotic ribosomes is composed of one type of rRNA and approximately 30 proteins.
	b. The self-assembly of ribosomes in vitro does not occur effectively in the absence of rRNAs, even with all ribosomal proteins present.
	c. Ribosomes created by self-assembly in vitro continue to function in the absence of many ribosomal proteins when rRNAs are present.
	d. The ribosomal subunit is able to form peptide bonds if rRNAs are present, even when the vast majority of ribosomal proteins are absent.

Question 56

At which stage of the mitotic cycle would you be unable to observe tightly condensed chromosomes under the microscope?

Choose one answer.

	a. Prometaphase
	b. Metaphase
	c. Anaphase
	d. Telophase

Question 57

During which phase of mitosis would you first be able to distinguish the difference between a cell undergoing closed vs. open mitosis?

Choose one answer.

	a. Prophase
	b. Prometaphase
	c. Metaphase
	d. Telophase

Question 58

Identify the mitotic phase or cell behavior during which the following occurs in animal cells: chromosomes de-condense.

Choose one answer.

	a. Cytokinesis
	b. Prophase
	c. Anaphase
	d. Telophase

Question 59

Identify the mitotic phase or cell behavior during which the following occurs in animal cells: a contractile ring of actin and myosin filaments pinch the plasma membrane inward.

Choose one answer.

	a. Cytokinesis
	b. Prophase
	c. Anaphase
	d. Telophase

Question 60

Identify the mitotic phase or cell behavior during which the following occurs in animal cells: chromosomes are lined up along the mitotic spindle.

Choose one answer.

	a. Prophase
	b. Prometaphase
	c. Metaphase
	d. Telophase

Question 61

Identify the mitotic phase or cell behavior during which the following occurs in animal cells: the microtubules of the spindle attach to chromosomes' kinetochores.

Choose one answer.

	a. Prophase
	b. Prometaphase
	c. Metaphase
	d. Telophase

Question 62

Which of the following occurs in bacterial cells during mitosis and cell division?

Choose one answer.

	a. Vesicles with cell-wall components fuse at the site of the metaphase plate, and the resultant disc eventually expands to fuse with the original plasma membrane and cell wall, forming two separate cells.
	b. An outgrowth of the cell wall and plasma membrane, the "septum," grows from opposite sides of the membrane toward the middle of the cell, where the two septa meet and fuse, creating two separate cells.
	c. A ring of actin and myosin filaments contracts the plasma membrane, eventually pinching the cell and dividing it in two.
	d. None of these occurs in bacterial cells.

Question 63

You want to be able to observe a cell during specific points in mitosis. You expose the cell to a drug that prevents sister chromatids from separating. At which step of the mitotic cycle have you arrested the cell?

Choose one answer.

	a. Prometaphase
	b. Metaphase
	c. Anaphase
	d. Telophase

Question 64

You want to be able to observe a cell during specific points in mitosis. You expose the cell to a drug that prevents sister chromatids from separating. Which cell behavior or step of the mitotic cycle have you blocked?

Choose one answer.

	a. Cytokinesis
	b. Prophase
	c. Anaphase
	d. Telophase

Question 65

Identify the stage of meiosis I prophase during which Recombination occurs.

Choose one answer.

	a. Leptotene
	b. Zygotene
	c. Pachytene
	d. Diplotene

Question 66

Identify the stage of meiosis I prophase during which the following occurs: homologous chromosomes are tightly "zippered" together into a synaptonemal complex.

Choose one answer.

	a. Leptotene
	b. Zygotene
	c. Pachytene
	d. Diakinesis

Question 67

Identify the stage of meiosis I prophase during which the following occurs: the spindle forms and nuclear envelope breaks down.

Choose one answer.

	a. Leptotene
	b. Zygotene
	c. Pachytene
	d. Diakinesis

Question 68

The process of oocyte formation is different from that of sperm formation. At what point in gametogenesis does this difference first become apparent?

Choose one answer.

	a. The first meiotic division
	b. The second meiotic division
	c. Mitosis
	d. Differentiation and maturation

Question 69

Which of the following events occurs during the anaphase of meiosis I?

Choose one answer.

	a. Homologous chromosomes separate.
	b. Sister chromatids separate.
	c. Bivalent chromosomes align on the spindle.
	d. Chromosomes decondense.

Question 70

Which of the following events occurs during the anaphase of meiosis II?

Choose one answer.

	a. Homologous chromosomes separate.
	b. Sister chromatids separate.
	c. Bivalent chromosomes align on the spindle.
	d. Chromosomes decondense.

Question 71

Which of the following is not one of the ways in which meiosis is different from mitosis?

Choose one answer.

	a. Homologous chromosomes pair.
	b. At metaphase, both kinetochores of one homologue face the same pole.
	c. Chiasmata link homologous chromosomes.
	d. DNA replication occurs prior to initiation of the process.

Question 72

Why are chiasmata important once the desynapsis of homologous chromosomes has occurred?

Choose one answer.

	a. They do not have an important role once desynapsis has occurred.
	b. They hold the chromosomes together, ensuring their alignment at metaphase.
	c. They orient the chromosomes
	d. They allow recombination to occur at recombination nodules.

Question 73

Why are sexual reproduction and meiosis considered beneficial to species in terms of evolutionary forces and selection?

Choose one answer.

	a. Meiosis is the most common type of cell division and occurs at a much higher rate than mitosis.
	b. The re-assortment of alleles during meiosis guarantees that only the best allelic combinations will be present in the next generation.
	c. The reshuffling of alleles and recombination in meiosis lead to phenotypic variation, which is better for a species' survival in a changing environment.
	d. Sexual reproduction and meiosis are not considered evolutionarily beneficial, but once they are present in a species they are too hard to select against.

Question 74

Cells with DNA contents of 2n are most likely in which cell phase?

Choose one answer.

	a. G1
	b. G2
	c. S
	d. M

Question 75

In mammals, a DNA damage signal will lead a cell to arrest the cell cycle. In what way will it accomplish this?

Choose one answer.

	a. CKIs, such as p27, bind to CDK and cyclin, and through conformational changes, CKIs lock them in the inactive state.
	b. Cyclins, which activate CDK-cyclins and are rapidly produced and broken down, are allowed to degrade naturally without more molecules being produced.
	c. CAKs phosphorylate a residue on the CDK
	d. Cyclins are actively degraded within the nucleus, so they are not present at a high enough volume to activate CDK-cyclins.

Question 76

In which cell-cycle phase(s) would you expect the human nerve cell to be?

Choose one answer.

	a. Primarily in G2
	b. Primarily in G0
	c. In phases in M and S
	d. In phases M, G1, S, and G2

Question 77

In which cell-cycle phase(s) would you expect the early embryonic cell to be?

Choose one answer.

	a. Primarily in G2
	b. Primarily in G0
	c. In phases in M and S
	d. In phases M, G1, S, and G2

Question 78

In which cell-cycle phase(s) would you expect the yeast cell to be?

Choose one answer.

	a. Primarily in G2
	b. Primarily in G0
	c. In phases in M and S
	d. In phases M, G1, S, and G2

Question 79

Rb is a protein that plays different roles during the cell cycle depending on its level of phosphorylation. In M phase, what would its state and its role be?

Choose one answer.

	a. Unphosphorylated, repressing E2F
	b. Hypophosphorylated, repressing E2F
	c. Hyperphosphorylated, unable to repress E2F
	d. Hyperphosphorylated, repressing E2F

Question 80

Rb is a protein that plays different roles during the cell cycle depending on its level of phosphorylation. In G0 phase, what would its state and its role be?

Choose one answer.

	a. Unphosphorylated, repressing E2F
	b. Hypophosphorylated, repressing E2F
	c. Hyperphosphorylated, unable to repress E2F
	d. Hyperphosphorylated, repressing E2F

Question 81

You inject cells with a growth factor to take them into G1. After 10 hours, you inject one group of cells with an antibody against cyclin D (inhibiting its function). After 14 hours, you inject a second group of cells with this antibody. After 16 hours, you inject a third group. The fourth group of cells, a control group, is not injected with antibodies. You label these cells in order to see whether DNA synthesis (i.e. growth) has occurred in them. You find that the cells injected with anti-cyclin D after 10 hours show no DNA synthesis; those injected after 14 hours show about half as much synthesis as the control group; those injected after 16 hours show the same amount of synthesis as the control group. From these results, what can you conclude about the presence or absence of a restriction point related to the G1 phase?

Choose one answer.

	a. There is a restriction point for G1, and it occurs around 10 hours after growth factors are added to cells.
	b. There is a restriction point for G1, and it occurs around 14 hours after growth factors are added to cells.
	c. There is a restriction point for G1, and it occurs around 16 hours after growth factors are added to cells.
	d. There is no restriction point for G1 once growth factors have been added to cells.

Question 82

You inject cells with a growth factor to take them into G1. After 10 hours, you inject one group of cells with an antibody against cyclin D (inhibiting its function). After 14 hours, you inject a second group of cells with this antibody. After 16 hours, you inject a third group. The fourth group of cells, a control group, is not injected with antibodies against cyclin D. You label these cells in order to see whether DNA synthesis (i.e. growth) has occurred in them. You find that the cells injected with anti-cyclin D after 10 hours show no DNA synthesis; those injected after 14 hours show about half as much synthesis as the control group; those injected after 16 hours show the same amount of synthesis as the control group. From these results, what can you conclude about the role of cyclin D on cell growth during G1?

Choose one answer.

	a. Because there is a clear restriction point during G1 to initiate cell growth, cyclin D is not needed during this phase.
	b. Cyclin D is required only at the very beginning of the G1 phase.
	c. Cyclin D is required at every point within the G1 phase.
	d. Cyclin D is required to get cells past the restriction point in G1, after which cell growth will continue regardless.

Question 83

Answer the following question about the nuclear pore complex. If there were an error in the α subunit of importin that prevented it from binding, which of the following would happen?

Choose one answer.

	a. Proteins that were brought into the nucleus would remain bound to importin indefinitely.
	b. Proteins that were destined for the nucleus would never be bound to importin and would remain outside it indefinitely.
	c. Proteins that were destined for the nucleus would never be brought, by importin, to the nuclear pore.
	d. This change in the function of the α subunit would not affect proteins destined for the nucleus.

Question 84

Answer the following question about the nuclear pore complex. If there were an error in the β subunit of importin that prevented it from being bound to Ran/GTP, which of the following would happen?

Choose one answer.

	a. Proteins that were brought into the nucleus would remain bound to importin indefinitely.
	b. Proteins that were destined for the nucleus would never be bound to importin and would remain outside it indefinitely.
	c. Proteins that were destined for the nucleus would never be brought, by importin, to the nuclear pore.
	d. This change in the function of the α subunit would not affect proteins destined for the nucleus.

Question 85

Answer the following question about the nuclear pore complex. If the enzymes responsible for hydrolyzing GTP were localized to the cytoplasmic side of the nuclear envelope, which of the following would happen?

Choose one answer.

	a. Proteins that were brought into the nucleus would remain bound to importin indefinitely.
	b. Proteins that were destined for the nucleus would never be bound to importin and would remain outside it indefinitely.
	c. Proteins that were destined for the nucleus would never be brought, by importin, to the nuclear pore.
	d. Protein transport would continue normally, as this is the normal location for these enzymes.

Question 86

If you wanted a molecule to be brought into the cell via receptor-mediated endocytosis, but the formation of clathrin-coated pits had been inhibited, what type of vesicle would you want?

Choose one answer.

	a. COP I coated vesicle
	b. Dynamin vesicle
	c. COP II coated vesicle
	d. Caveolin-coated vesicle

Question 87

If you wanted a protein to remain in or return to the ER after processing, which of these types of vesicle would you want?

Choose one answer.

	a. COP I coated vesicle
	b. Clathrin-coated vesicle
	c. COP II coated vesicle
	d. Caveolin-coated vesicle

Question 88

SRPs are involved in what cellular process?

Choose one answer.

	a. Protein translocation
	b. Protein folding
	c. Glycosylation
	d. Protein degradation

Question 89

Where would you most likely expect to find the occurrence of protein folding?

Choose one answer.

	a. Rough ER lumen
	b. Mitochondrial matrix
	c. Chloroplast stroma
	d. Nucleus

Question 90

Which of the following is false in regards to mitochondrial and chloroplast protein transport?

Choose one answer.

	a. Transport of proteins to chloroplasts is even more difficult than to mitochondria, because chloroplasts have three membranes, not two.
	b. While proteins targeted to mitochondria have positively charged presequences, the transit peptides of chloroplasts are not charged.
	c. While protein transport in mitochondria requires chaperone proteins on the outside and inside of the organelle, protein transport in chloroplasts only requires outside chaperones.
	d. As with mitochondria, specific proteins from the cytosol must be transferred to the chloroplast.

Question 91

Which of the following is false in regards to proteins and mitochondria?

Choose one answer.

	a. The proteins involved in oxidative metabolism must be transferred from the cytosol to mitochondria.
	b. The proteins involved in expressing mitochondrial DNA must be transferred from the cytosol to mitochondria.
	c. Protein transport to mitochondria is made more difficult because of the double membrane of mitochondria.
	d. Proteins that are brought into mitochondria by Hsp70 chaperones enter the matrix in a pre-folded state.

Question 92

A plant seed would need which of the following organelles for energy, as it converts fatty acids to carbohydrates?

Choose one answer.

	a. Glyoxysome
	b. Peroxysome
	c. Lysosome
	d. Golgi apparatus

Question 93

Consider a fur seal in the arctic: in winter, when the seal still needs to be active without freezing, which type of organelles will be particularly useful?

Choose one answer.

	a. Peroxisome
	b. White-fat mitochondria
	c. Smooth ER
	d. Brown-fat mitochondria

Question 94

Lysosomes contain acid hydrolases that degrade any number of molecules. If a lysosome's membrane were to break, what, if anything, would prevent these hydrolases from degrading everything in the cell's cytoplasm?

Choose one answer.

	a. There is nothing to prevent these enzymes from degrading cytoplasmic elements, which is why the membrane of the lysosome is designed so that it can be immediately repaired of damage.
	b. These hydrolases only function at a lower pH than is present in the cytoplasm, so they would not be able to work outside the lysosome.
	c. There are repressor-proteins present in the cytoplasm that bind to these hydrolases and inactivate them.
	d. Hydrolases only bind to and degrade aging molecules and organelles that have a specific amino-acid sequence; they would not degrade healthy cytoplasmic elements.

Question 95

What organelle is the site at which cholesterol is made?

Choose one answer.

	a. Golgi apparatus
	b. Chloroplast
	c. Smooth ER
	d. Mitochondria

Question 96

What organelle is the site at which proteins' oligosaccharides are added or changed?

Choose one answer.

	a. Glyoxysome
	b. Peroxysome
	c. Lysosome
	d. Golgi apparatus

Question 97

What organelle would be used to degrade bacteria taken in by the cell via phagocytosis?

Choose one answer.

	a. Glyoxysome
	b. Peroxysome
	c. Lysosome
	d. Golgi apparatus

Question 98

What organelle's stroma contains its genetic material and metabolic enzymes?

Choose one answer.

	a. Golgi apparatus
	b. Chloroplast
	c. Smooth ER
	d. Mitochondria

Question 99

Which of the following types of organelles would you expect to see in abundance in liver cells?

Choose one answer.

	a. Peroxisome
	b. White-fat mitochondria
	c. Smooth ER
	d. Brown-fat mitochondria

Question 100

Which of the following types of organelles would you expect to see in abundance in ovarian cells?

Choose one answer.

	a. Peroxisome
	b. White-fat mitochondria
	c. Smooth ER
	d. Brown-fat mitochondria

Question 101

Which of these is false in regards to mitochondria and chloroplasts?

Choose one answer.

	a. The inner membrane of each is responsible for oxidative phosphorylation.
	b. Both contain their own genetic material.
	c. Both contain inner and outer membranes.
	d. Both contain metabolic enzymes responsible for oxidative metabolism.

Question 102

The apoptotic pathway triggered by intracellular signals that cause release of proteins from the mitochondrial intermembrane space into the cytosol is known as the:

Choose one answer.

	a. extrinsic pathway.
	b. intrinsic pathway.
	c. death-inducing signaling pathway.
	d. necrotic pathway.

Question 103

Which of the following is an example of an initiator caspase?

Choose one answer.

	a. Caspase -7
	b. Caspase-6
	c. Caspase-1
	d. Caspase-8

Question 104

Which of the following is not a characteristic of apoptosis?

Choose one answer.

	a. DNA fragmentation
	b. Shrinkage of the cytoplasm
	c. Lysis or damage to neighboring cells
	d. Membrane changes

Question 105

Which of the following is the phospholipid that is no longer restricted to the cytosolic part of the membrane when a cell undergoes apoptosis?

Choose one answer.

	a. Phosphatidylserine
	b. Phosphatidylcholine
	c. Phosphatidylinositsol
	d. Diacylglycerol