Cell Bio Exam 2 :(

How many enzymatic steps are involved in converting glucose to pyruvate?

10

Glycolysis uses ___ ATPs to generate ___ATPs => net ___ ATPs per glucose molecule, ___ NADHs made

2, 4 net 2, 2NADH

) Gluconeogenesis uses ___ ATPs and __ GTPs (__ ATPs total) to generate __ glucose molecule, __ NADHs used

4, 2, 6 total 1 glucose 2NADH

How many photons must be absorbed to generate two NADPH and a molecule of O2?

8 photons. 4 in Photosystem II and 4 in Photosystem I.

Glucose is transported in the bloodstream to cells in all parts of your body. In cells, glucose has four main fates. Which of the following is not one of those fates? A) Glucose is transformed into sucrose. B) Glucose is catabolized to carbon dioxide and water. C) Glucose is converted to lactate. D) Glucose is used to synthesize glycogen. E) Glucose is converted to acetyl CoA to make body fat.

A

Kinases and phosphatases are essential in the cell because they A) help turn proteins "on and off" through changes in phosphorylation status. B) are enzymes that destroy damaged proteins. C) sense short poly-A tails in mRNA as a signal to degrade the mRNA. D) destroy second messengers, thereby turning off a signal transduction pathway. E) all of the above

A

NADP+ is the coenzyme of choice in ________ reactions, while NAD+ is the coenzyme of choice in ________ reactions. A) anabolic; catabolic B) catabolic; anabolic C) metabolic; anabolic D) anabolic; both catabolic and anabolic

A

Which of the following products cannot be used in the Calvin cycle? A) phosphoglycolate B) NADPH C) 3-phosphoglycerate D) CO2 E) ribulose-1, 5-bisphosphate

A

You have recently identified a molecule that you believe to be a ligand associated with a signal transduction mechanism. All you know about this ligand is that chemically it is hydrophilic. As a result, you expect it to interact with its receptor A) at the outer cell surface. B) within the cytoplasm of the cell. C) within the nucleus of the cell. D) on the cytoplasmic side of the plasma membrane. E) all of the above

A

We cannot synthesize Niacin, Vitamin B3 on our own. Based on what we learned in these chapters, what might be the cellular process that can be impede dramatically when you don't obtain enough Vitamin B3?

Any cellular processes requiring NAD+ as coenzyme to carry electrons (glycolysis, TCA cycle etc..)

In electron transport, which respiratory complex is not involved in the flow of electrons from NADH? A) complex I B) complex II C) complex III D) complex IV E) all of the above

B

In the Calvin cycle, the enzyme that catalyzes the capture of carbon dioxide and the formation of 3-phosphoglycerate is A) phosphoglycerokinase. B) ribulose bisphosphate carboxylase/oxygenase (rubisco). C) triose phosphate isomerase. D) phosphoribulokinase. E) glyceraldehyde-3-phosphate dehydrogenase.

B

Pyruvate is converted to acetyl CoA by a unique enzyme known as A) pyruvate decarboxylase. B) pyruvate dehydrogenase complex. C) transitionase system. D) multiplex enzyme system. E) pyruvate CoA transferase.

B

What is the advantage to having various types of chlorophylls and accessory pigments for the photosynthetic process? A) It allows for a variation in color amongst plants. B) It allows for light in many wavelengths to be utilized for photosynthesis. C) It allows light to be harvested specifically in a step-wise manner. D) It shifts the equilibrium of photosynthesis toward the formation of products. E) both choices C and D

B

3) Some herbicides, such as paraquat, work by causing the oxidation of NADPH to NADP. Although this is a potent herbicide, it also is toxic to humans, particularly when inhaled. How does paraquat interfere with photosynthesis and thus act as an herbicide? How might paraquat be causing toxicity for human cells?

By oxidizing NADPH to NADP directly, the amount of NADPH available for the Calvin cycle is minimized, and the plant literally starves to death. In human cells, any of the anabolic pathways that utilize NAPDH are compromised

) Of the following electron carriers of the electron transport system, which transfers protons in addition to electrons? A) cytochrome a B) cytochrome b C) coenzyme Q D) iron-sulfur proteins E) iron-copper proteins

C

G protein-adenyl cyclase activity has been shown, in some cases, to be associated with certain diseases. In the case of cholera, which of the following is not correct? A) Vibrio cholera bacteria colonize the gut. B) Cholera toxin is secreted by Vibrio cholera bacteria. C) The cholera toxin causes the cells of the gut to take in salts and fluids. D) Cholera toxin alters Gs so that it no longer hydrolyzes GTP. E) The toxin, by altering Gs, keeps intracellular cAMP levels high and doesn't allow them to decrease.

C

The endosymbiotic theory states that mitochondria originated from A) a routine step in evolution. B) the fusion of several prokaryotes. C) purple bacteria entering and remaining in the cytoplasm of another cell. D) the slow evolution of various organelles over millions of years, particularly during the time of the dinosaurs. E) a long, intense period of lightning.

C

The relationship between photosystem I (PSI) and photosystem II (PSII) is correctly described by which of the following statements? A) PSI absorbs only short wavelengths of light. B) Electrons are excited by PSI or PSII, but not both. C) PSI is designated P700, whereas PSII is designated P680. D) The absorption maximum of PSII is 700 nm. E) The absorption

C

Which of the following is not an essential feature of electron transfer from water to NADP+? A) photosystem II complex B) photosystem I complex C) coenzyme Q D) plastocyanin (PC) E) cytochrome b6/f complex

C

Which of the following statements regarding the Ras protein is false? A) Ras is monomeric. B) It is regulated by GTPase activating proteins. C) The ligands are largely steroid hormones. D) It is regulated by Sos, a guanine nucleotide exchange factor. E) Ras activates a cascade of phosphorylation events.

C

Why are mitochondria so prevalent in skeletal muscle? A) They give the muscle enough elasticity to contract. B) They are needed to repair damaged tissue that accumulates during exercise. C) They are needed to provide energy for muscle contraction. D) Bones and muscles require a great deal of energy to prevent them from separating. E) The flow of blood is greatest in skeletal muscle.

C

) All of the following are directly used as alternative substrates for glycolysis except A) galactose. B) mannose. C) ribose. D) fructose. E) both choices A and C

C ribose

) During strenuous exercise, you may notice that your muscles burn. Which of the following statements best explains this phenomenon?

C) Without oxygen, pyruvate is being converted to lactic acid.

NADPH contains the pentose sugar ________ and the nitrogenous base ________. A) glucose; thymine B) deoxyribose; cytosine C) deoxyribose; nicotinamide D) ribose; adenine E) ribose; nicotinamide

D

Which of the numbered respiratory complexes is not correctly paired with its name? A) complex I: NADH dehydrogenase complex B) complex II: succinate-coenzyme Q oxidoreductase complex C) complex III: coenzyme Q-cytochrome c oxidoreductase complex D) complex IV: cytochrome c reductase complex E) none of the above

D

Which three organelles are involved in the glycolate pathway? A) lysosome, chloroplast, rough endoplasmic reticulum B) mitochondrion, nucleus, lysosome C) peroxisome, smooth endoplasmic reticulum, chloroplast D) peroxisome, chloroplast, mitochondrion E) Golgi complex, peroxisome, lysosome

D

Which of the following is not a product of the TCA cycle? A) CO2 B) ATP C) NADH D) acetyl CoA E) FADH2

D) acetyl CoA

The process by which photosynthetic organisms use light energy for ATP production is known as

D) photophosphorylation.

How is it that different cells can respond in different ways to exactly the same signaling molecules even when they have identical receptors?

Depends on the target tissues and downstream molecule, availability of precursor molecules, different gene expression profiles etc.. cells can respond in different ways to the same same signaling molecules.

) Blood pressure is regulated by the second messenger A) cAMP. B) Ca2+. C) IP3. D) CO. E) NO.

E

) Which of the following statements accurately describes the Calvin cycle? A) It is a carbon assimilation process. B) In this process, carbon dioxide is reduced to organic sugars. C) It occurs in the chloroplast stroma. D) The Calvin cycle is a means of carbon fixation. E) all of the above

E

A key regulator of both glycolysis and gluconeogenesis is A) hexokinase. B) glyceraldehyde-3-phosphate. C) alanine. D) coenzyme (CoA). E) fructose-2, 6-biophosphate.

E

All of the following are second messengers except A) calcium ions. B) IP3. C) DAG. D) cAMP. E) epinephrine. F) cGMP

E

In a chloroplast, the stroma is the A) cytochromes associated with the thylakoids. B) stack of thylakoids. C) region between in the inner and outer membranes. D) connection between the grana. E) central semifluid region.

E

NADH concentrations serve to regulate oxidative decarboxylation and the TCA cycle. Which of the following enzymes is not regulated by NADH? A) pyruvate dehydrogenase B) isocitrate dehydrogenase C) α-ketoglutarate dehydrogenase D) malate dehydrogenase E) succinate dehydrogenase

E

Synthetic compounds that inhibit receptors by preventing the natural messenger from binding are known as A) agonists. B) receptor upregulators. C) specific proteoglycans. D) syndecans. E) antagonists.

E

When nitric oxide is used in the dilation of smooth muscle cells, which of the following would interfere with the relaxation of the smooth muscle cells? Inhibitors of A) calcium release by the ER. B) nitric oxide. C) guanylyl cyclase. D) calmodulin. E) all of the above

E

Why is ATP yield clarified with "maximum"?

Energy may be used for other purposes. The energy of the proton gradient may be used to transport ions, substrates, intermediates, and metabolites across the membrane.

Protruding from the inner membrane of the mitochondria into the matrix are knoblike spheres called _ ____ complexes, which are attached by a short protein stalk to a(n) _____ complex. Together these complexes are referred to as the ______ _ complex.

F1, Fo, FoF1

The α-subunit of a heterotrimeric G protein is active when bound to

GTP

Pertussis toxin causes a whooping cough by inactivating _____, which lead to sustained activity of _________.

Gi and adenylyl cyclase

Although the brain is an obligatory aerobic organ, it still depends on glycolysis because...

Glycolysis is the 1st stage in aerobic energy metabolism for any cell that depends on glucose as its energy source, as brain cells do

Rubisco is an important enzyme in the Calvin cycle. It catalyzes the addition of carbon dioxide and water to ribulose-1,5-bisphosphate, which then forms two molecules of 3-phosphoglycerate. Rubisco acts as a carboxylase and is essential for carbon fixation. a. Rubisco has an additional function. It can also function as an oxygenase. Why is this a problem for plants?

If rubisco functioned solely as an oxygenase, carbon fixation would cease.

Galactosemia is often a problem in infants. Why would infants be more likely to develop galactosemia?

Infants solely depends on milk (Lactose therefore galactose) therefore more prone to develop such condition.

Viagra

Inhibitor for Phosphodiesterase (PDE-5) that degrades cGMP into GMP in smooth muscle cells

Human cancers consume larger amounts of glucose compared to normal tissues with most being converted and excreted as lactate(fermentation) despite abundant oxygen availability (Warburg effect). The underlying higher rate of glycolysis is therefore at the root of tumor formation and growth. Considering aerobic respiration is the complete oxidation of carbohydrate into CO2 and H2O during which ATP is generated, what would be the potential reason for cancer cells to prefer glycolysis instead of aerobic respiration?

Intermediate molecules generated during glycolysis can be used as precursors that are needed for cells to divide and survive (amino acid, nucleotide etc..). As cancer cells are constantly dividing with faster rate, these cells need contact supplies of such biomolecules.

) Ethanol intoxication and methanol toxicity. The enzyme alcohol dehydrogenase (ADH) was mentioned in chapter 9 because of its role in the final step of alcoholic fermentation. However, the enzyme also occurs commonly in aerobic organisms, including humans. The ability of the human body to catabolize the ethanol in alcoholic beverages depends on the presence of alcohol dehydrogenase in the liver. One effect of ethanol intoxication is a dramatic decrease in the NAD+ concentration in liver cells, which decreases the aerobic utilization of glucose. Methanol, on the other hand, is not just an intoxicant; it is a deadly poison due to the toxic effect of the formaldehyde to which it is converted in the liver. (a) Why does ethanol consumption lead to a reduction in NAD+ concentration and to a decrease in aerobic respiration?

Liver cells convert ethanol to acetaldehyde using alcohol dehydrogenase (ADH), reverse reaction of alcohol fermentation process, during which process, NAD+ is converted to NADH(reduced). Therefore, not enough amount of NAD+ is available for aerobic respiration process

The medical treatment for methanol poisoning usually involves administration of large doses of ethanol. Why is this treatment effective?

Methanol is converted to the formaldehyde also through alcohol dehydrogenase (ADH). By administering a large dose of ethanol, forcing ADH to work on ethanol rather than methanol. Therefore reducing accumulation of formaldehyde.

G-protein-coupled receptors activate G proteins by reducing the strength of GDP binding, allowing GDP to dissociate and GTP, which is present at much higher concentration, to bind. How do you supposed the activity of a G protein would be affected by a mutation that caused its affinity for GDP to be reduced without significantly changing its affinity for GTP?

Mutant G protein will constantly release GDP due to decreased binding affinity therefore, it can get activated (bind to GTP) without engagement of G-protein-coupled receptors activation. Resulting in constitutive active status of G protein.

The yield of ATP varies in eukaryotes from 36 to 38 ATP. Why is there a variation?

NADH does not have a carrier protein in the mitochondrial membrane. The movement of the electrons and protons through the membrane will require a shuttle. This shuttle may be an active or passive process. The concentration of cytoplasmic NADH may be higher or lower than mitochondrial NADH concentrations. If the NADH concentration is higher in the cytoplasm, a molecule of NADH will be generated in the mitochondria as electrons and protons are shuttled. If the NADH concentration is lower in the cytoplasm, a molecule of FADH2 will be generated. This difference may decrease the yield by 2 ATP per glucose (since 2 NADH are generated from glycolysis).

During photosynthesis, light reactions use light energy to create chemical energy (_______ and ___) whereas dark reactions use chemical energy to produce sugar from _______.

NADPH and ATP

The energy transduction reactions of photosynthesis convert solar energy into chemical energy in the form of ______ and ________.

NADPH and ATP

Most of the unpleasant effects of hangovers result from an accumulation of acetaldehyde and its metabolites. Where does the acetaldehyde come from?

Oxidation of ethanol through ADH

Propose specific types of mutations in the gene for the regulatory subunit of PKA that could lead to either a permanently active PKA or a permanently inactive PKA.

Permanently active PKA: mutation causing regulatory subunit to be active without binding to cAMP leads to constant activation of catalytic units (detached from regulatory units). Mutation preventing regulatory units to bind to catalytic units. Etc... Permanently inactive PKA: mutation in binding sites for cAMP, mutation that prevent conformational changes of regulatory units upon cAMP binding. Etc..

What is (are) the product(s) of the reaction when rubisco acts as an oxygenase?

Phosphoglycolate and 3-phosphoglycerate are the products rather than two molecules of 3-phosphoglycerate.

The maximum yield of ATP per molecule of glucose in eukaryotic cells is 36 or 38 ATP. In prokaryotic cells, the maximum yield is 38 ATP. a. From what you know about prokaryotes and eukaryotes, suggest why there is a difference in maximum ATP production.

Prokaryotes do not have inner membranes. In eukaryotes, the NADH produced in the cytoplasm by glycolysis must be transported into the mitochondrion. The transport of the electrons may be active and require energy. The result is a loss of 2 ATP.

Both mitochondria and chloroplasts use electron transport to pump protons, creating an electrochemical proton gradient, which derives ATP synthesis. Are protons pumped across the same (analogous) membranes in the two organelles? Is ATP synthesized in the analogous compartment? Explain your answers.

Protons are pumped across the inner membrane into the intermembrane space in mitochondria whereas they are pumped across the thylakoid membrane into the thylakoid space in chloroplasts. ATP is synthesized in the corresponding compartments in the two organelles: in the matrix in mitochondria and in the stroma in chloroplasts.

Lactic acidosis is a medical condition characterized by the buildup of lactate in the body, which results in an excessively low pH in the bloodstream. It is known that a genetic mutation on the several enzymes are involved in such condition. Based on what we learned in the class, list names of two enzymes that can cause Lactic acidosis when they are mutated and explain why.

Pyruvate carboxylase: In liver, lactate is re-oxidized and converted to pyruvate and enter gluconeogenesis. During this process, if PC is mutated cells are not able to convert pyruvate to oxaloacetate therefore accumulating lactate. Pyruvate dehydrogenase (PDH) : even in the presence of O2, if pyruvate is not converted to Acetly CoA by Pyruvate dehydrogenase (PDH), the only destination of pyruvate is to go through fermentation therefore accumulating lactate. Can be many other enzymes, Fructose 1,6-bisphosphatase deficiency, Glucose-6-phosphatase deficiency

Why do tree leaves turn colors in autumn?

The colder weather causes breakdown of chlorophyll molecules. As a result, the decrease in the amount of chlorophyll allows the accessory pigments to become visible. Because these pigments are species specific, we see the range of colors characteristic for the fall season.

Rubisco has a much lower affinity for oxygen than for carbon dioxide. Why is the oxygenase activity still a problem for plants?

The earth's atmosphere contains much higher concentrations of oxygen.

How does the plant deal with the product of the oxygenase reaction?

The glycolate pathway is used to transform phosphoglycolate into 3-phosphoglycerate.

From what you know about the metabolism of galactose can you suggest why galactosemia is more common than fructosemia

There are more enzymes involved in a process to convert galactose to glucose -1-phosphate than a process converting fructose to fructose 6-phosphate. Therefore more chance to accumulate mutations on the enzymes.

The synthesis of ATP as a result of the electron transport system is dependent on the delivery of electrons and hydrogen ions by NADH and FADH2 to the inner membrane of the mitochondria in eukaryotic cells or the cell membrane of prokaryotic cells. For each of the situations below, give the maximum number of ATP generated.

a. one molecule of FADH2 produced during the TCA cycle : 2 b. one molecule of NADH produced during the TCA cycle :3 c. one molecule of NADH produced by glycolysis in a muscle cell that has a very low cytoplasmic level of NADH (therefore retained in cytoplasm) : 2 d. one molecule of FADH2 produced during the TCA cycle in a prokaryotic cell :2 e. one molecule of NADH produced by glycolysis in a prokaryotic cell :3

F2,6BP ___ glycolysis, ____________ gluconeogenesis

activates, inhibits

catalyzes formation of cAMP from ATP

adenylate cyclase

Fructose-1,6-biphosphate

aldolase

) Galactosemia is a genetic defect in which an individual is unable to correctly metabolize galactose. This results in high galactose levels in the blood and galactose-1-phosphate in the tissues. a. If you were a physician treating a person with this genetic disorder, what suggestions would you make to avoid high galactose levels in the blood?

avoid all foods with lactose and galactose. All milk and milk products must be replaced with formula that contains no lactose.

Which two triose phosphates are produced during the Calvin cycle and are the starting points for starch and sucrose synthesis? A) 3-phosphoglycerate and glyceraldehyde-3-phosphate B) dihydroxyacetone phosphate and glyceraldehyde-3-phosphate C) ribulose-1,5-bisphosphate and glycerol phosphate D) dihydroxyacetone phosphate and glycerate-1,3-bisphosphate E) 3-phosphoglycerate and ribulose-1,5-bisphosphate

b

A strain of Drosophila known as dunce produces one-half the amount of cAMP phosphodiesterase than the wild type flies. Using your knowledge of cell signaling based upon cAMP, what effects would you expect in the dunce flies?

cAMP will remain longer in the cell, resulting in prolonged cAMP levels within the cell.

_______________ is the link between glycolysis in muscle cells and gluconeogenesis.

cori cycle

When there is an immediate demand for ATP, the cells will proceed for ______- photophosphorylation within the Thylakoid Membrane.

cyclic

sucrose synthesis

cytoplasm

Ca2+ is involved in variety of cellular functions, and it can bind to _____ such as ______ to mediate calcium-activated cellular processes.

effector proteins such as calmodulin

2-phosphoglycerate

enolase

describes an organism that can function in an aerobic or anaerobic environment.

faculative

GNG fructose-1,6-biphosphate

fructose-1,6-biphosphatase

glyceraldehyde-3-phosphate

glyceraldehyde-3-phosphate dehydrogenase

High ATP would inhibit ___________, Acetyl CoA would activate __________________.

glycolysis, gluconeogenesis

Glucose

hexokinase

Which glycolytic enzyme uses ATP as a substrate?

hexokinase

endocrine hormones

hormones acting over long distances

Which of the following is true of NAD+?

it is a conenzyme

Two organs in your body that can use lactate are....

liver and heart muscle

Pyruvate passes freely across some intracellular membranes. The membranes of the ___________ must be crossed by pyruvate prior to its oxidation during respiration.

mitochondria

Ras

monomeric G protein

GTP

necessary for the activation of heterotrimeric G proteins

GNG oxaloacetate

oxaloacetate kinase

ATP synthesis that involves phosphorylation events linked to oxygen-dependent electron transport is called

oxidative phosphorylation

inhibition of Gi

pertussis toxin

fructose-6-phosphate

phosphofructokinase-1

glucose-6-phosphate

phosphoglucoseisomerase

1,3-bipohosphoglycerate

phosphoglycerokinase

3-phosphoglycerate

phosphoglyceromutase

GNG 2-phosphoglycerate

phosphoglyceromutase

catalyzes formation of second messenger diacylglycerol (DAG)

phospholipase C

produces the second messenger diacylglycerol (DAG).

phospholipdase C

The glycolate pathway is also called ____________, because CO2 is released and oxygen is consumed in a light-dependent manner.

photorespiration

Cyanobacteria carry out photosynthesis in specialized _ ___________ ___ in the _ ________.

photosynthetic membranes, cytoplasm

The outer membrane of the mitochondrion is not a significant permeability barrier because it contains transmembrane proteins called

porins

IP3

precursor of diacyglycerol

calmodulin

protein that, when bound with calcium, can be a second messenger

GNG pyruvate

pyruvate carboxylase

phosphoenol pyruvate (pep)

pyruvate kinase

The ultimate, coordinated response of cells to a vast array of signals from the environment is known as

signal integration

Oxygen is toxic to

strict anaerobes

starch synthesis and calvin cycle

stroma

is the direct transfer of a phosphate to ADP, forming ATP.

substrate level phosphorylation

DAG activate protein kinase C (PKC) at

the membrane

Although one of its reactions is an oxidation, glycolysis can proceed in the absence of oxygen because...

the oxidation that occurs at one step is balanced by the reduction that occurs when pyruvate is converted to lactate or ethanol and carbon dioxide.

If you bake bread or brew beer, you depend on glycolysis for

the pyruvate that is then reductively decarboxylated to generate the ethanol present in the beer and the carbon dioxide that causes the bread to rise

concentration of protons

thylakoid lumen

electron transport location

thylakoid membrane

split to two after aldolase to make two identical needs

triose phosphate isomerase

What happens to the pyruvate generated by the glycolytic pathway depends on...

whether an external electron acceptor is available, which in most cases means whether oxygen is available (ex. whether the cell is functioning under aerobic conditions)

Draw a chloroplast review 2

yep

draw g protein

yep

fill in blanks found in first review answers

yep