Red Exam 3

Question 1

Sunlight absorbed by chlorophyll is used to energize electrons, which are passed from high energy electron acceptors, thought the electron transport system, and is eventually used to reduce NADPH. From what molecules were the electrons obtained

Answer 1

Water

Question 2

Both chloroplasts and mitochondria use chemiosmosis to phosphorylate ADP. Where are the ATP synthase located in chloroplasts

Answer 2

thylakoid membranes

Question 3

photosynthesis is a process that captures light energy and converts it into chemical energy that can be used to make sugars. What happens when a plant cell is placed in the dark?

Answer 3

the plant metabolize glucose using glycolysis and oxidative phosphorylation

Question 4

RUBISCO is an important enzyme in chloroplasts. What does RRUBISCO do?

Answer 4

it is a calvin cycle enzyme that captures carbon dioxide and fixed it on ribulose bis phosphate

Question 5

most of the ATP produced in chloroplasts during photosynthesis is used

Answer 5

to assemble sugar

Question 6

bacteria that associate with Hawaiian bobtail squid can produce light but inly under certain conditions. What are the conditions?

Answer 6

bacteria must grow to a certain concentration that promotes their signaling to each other to put out light

Question 7

GLUT4 is a channel in muscle and liver cells that can allow facilitated diffusion of glucose across the plasma membrane. GLUT4 normally is located in the membranes of secretory vesicles int eh cytoplasm. The display of GLUT4 is stimulated when the cells are exposed to insulin. What would you predict would happen if GLUT4 proteins lacked ER signal sequence?

Answer 7

The cell would be unable to take up glucose even if insulin is present

Question 8

what do protein kinases do in a cell

Answer 8

protein kinases add phosphate groups to proteins

Question 9

How is cyclic AMP produced in a cell

Answer 9

when activated adenylyl cyclades produce cAMP from ATP

Question 10

protein phophatases are a family of enzymes that specifically remove phosphate groups from proteins that were added by protein kinases. Vandate is an inhibitor of phosphatases in eukaryotic cells. What effect would vanadate have on the response of cells to signal received by receptor kinases?

Answer 10

the response of the cell would last longer than it normally would

Question 11

How does a G-protein become inactivated?

Answer 11

G-proteins hydrolyze the GTP to form DDP and release phosphate. The G-proteins with GDP bound can no longer bind and activate the downstream molecule

Question 12

where would you expect to find a receptor for a protein hormone like insulin?

Answer 12

on the plasma membrane

Question 13

Caffeine is an inhibitor of phosphodiesterase. Therefore, the cell of a person who has recently consumed coffee weill have increased levels of

Answer 13

cAMP

Question 14

Cholera is caused by a toxin that prevent s GTP hydrolysis by G-proteins. How can this cause diarrhea

Answer 14

Cholera toxin prevents GTP hydrolysis by a G protein that activates adenylyl cyclase, cAMP continues to be produces, which activates a protein kinase that activates a CFTR channel, which allows CL- to diffuse into the intestine. Water follows osmosis

Question 15

Where are CL- channels associated with cholera located in a cell

Answer 15

on the plasma membrane that faces the lumen of the intestine

Question 16

Photoreceptors in a human retina don’t divide after they have differentiated. In what stage of the cell cycle are rod cells in your eye?

Answer 16

G0

Question 17

There are about 6 billion nucleotide base pairs in a human cell but only 1.5% of those nucleotides are expressed. What is meant by gene expression

Answer 17

genes that are transcribed by RNA polymerase to make mRNA that is translated to assemble proteins

Question 18

During which stage of cell division do sister chromatids separate?

Answer 18

meiosis 2 and mitosis

Question 19

Soppose you observe a mouse cell with 40 chromosomes during metaphase of mitosis. If you stain the DNA molecules with a fluorescent stain, how many DNA molecules would you expect to find in this mitotic mouse cell

Answer 19

80

Question 20

Consider a dog intestinal cell with 78 chromosomes. As the cell goes through mitosis to produce more intestinal cells, how many centromeres would you expect to be present?

Answer 20

78

Question 21

What might tell an individual human cell that it should divide

Answer 21

growth factors that bind cellular receptor molecules

Question 22

Ras is a G-protein that when mutated is associated with causing cancer. What is a function of a non cancer causing Das protein

Answer 22

replaying a signal from a growth factor receptor

Question 23

SNA polymerase is an enzyme that is responsible for replicating DNA. During which stage in the cell cycle would you expect to find DNA polymerase being most active

Answer 23

G2

Question 24

Cyclins activate cyclin-dependent protein kinases that phosphorylate other proteins important for the progression of the cell cycle. Why don’t cyclins continuously stimulate cell division

Answer 24

Cyclins are only synthesized at or just prior to the time that they are needed in the cell cycle an d are degrading after the cell completes that portion of the cell cycle

Question 25

Which of the following is not true regarding the protein CDK

Answer 25

the levels of CDK change with the cell cycle

Question 26

Suppose a cell has a gene that codes for a tumor suppressor X. What would happen to a diploid celll if one of the allies for that gene was mutated and could not produce the tumor suppressor protein

Answer 26

the cell would not be affected

Question 27

location of the lowest pH in the light

Answer 27

in the lumen of a thylakoid membrane

Question 28

ATP synthase enzymes

Answer 28

on the surface of a thylakoid membrane

Question 29

RUBISCO and CO2 fixation

Answer 29

in the stroma

Question 30

Where in a plant cell would you expect to find ATPsynthase molecules

Answer 30

thylakoid membran and on the cristae of the plant mitochondria

Question 31

Defects in a cystic fibrosis chloride ion channel are associated with cystic fibrosis, daises in which patients have which mucus that cannot be transported out of the lungs. What kind of transmembrane protein is a CFTR

Answer 31

Ligand-gated ion channel

Question 32

Colon cancer are caused by defects in proteins produced by specific genes. Is it reasonable to state that there is one gene that is responsible for any particular cancer?

Answer 32

no

1) loss of tumor suppressor genes
2) actuation of res oncogene
3) loss of two more tumor suppressor genes
4) additional mutations

Question 33

Suppose you have a patient whose pancreas secretes plenty of insulin in response to sugar levels in the bloodstream but you also find the patient has high glucose levels in their bloodstream. Propose a hypothesis to explain why the insulin is not stimulating sugar uptake

Answer 33

insulin receptor on cells that take up glucose may not be displayed, synthesized, or might be mutated and bind insulin

Question 34

How is a G-protein activated?

Answer 34

G=protein coupled receptor removes the GDP from an inactive F protein and replaces it with GTP

Question 35

How is a G-protein inactivates?

Answer 35

GTP is hydrolyzed and leaved only GDP bound to the G-protein

Question 36

What happens to the adenylyl cyclase if the G-protein cannot be inactivated?

Answer 36

adenylyl cyclase that is activated by a GTP-G protein will continue to produce cyclin AMP from ATP

Question 37

How can this cause the diarrhea associated with cholera

Answer 37

Continued production of cAMP will continue to activate protein kinase A. The protein kinase A will continue to phosphorylate the CFTR channel and cells will continue to release chloride ions into the intestine. The increased concentration of chloride ions will draw water from cells and tissue spaces and fill the intestinal lumen with water. The increased water will produce diarrhea, tissues will dehydrate, and an infected persona may die

Question 38

what is the best and least expensive way to treat cholera patients and prevent cholera from reading in a community

Answer 38

provide a good sewage/waste treatment to prevent spread of cholera-producing bacteria and provide clean, bacteria free water for drinking washing and cooking to prevent infection instate first place

Question 39

Why can a fertilized egg in a mule undergo mitotic division to produce all of the cells of a mule but the mule cannot produce eggs or sperm to mate with another mule?

Answer 39

cells are required to separate homologous chromosomes and since the horse and donkey have different numbers of chromosomes they don’t have sets of homologous chromosomes that can be separated