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My MCAT Sets > Biochem Class 2 > Flashcards

Biochem Class 2 Flashcards

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MCAT flashcards
1
Q

animals are ______ aerobic _____-trophs

A

obligate heterotrophs

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2
Q

the lipid/fat soluble vitamins are

A

ADEK

the rest are water soluble

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3
Q

most water soluble vitamins are converted into

A

coenzymes

*except for Vitamin K, which is fat soluble yet is converted into coenzyme

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4
Q

reactants, intermediates, and products of metabolic pathways are all referred to as

A

metabolites

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5
Q

acetyl-CoA is a common _________ in metabolic pathways

A

intermediate

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6
Q

enzymatic reactions in metabolic pathways fall into which 4 major classes?

A
  1. oxidations and reductions (catalyzed by oxidoreductases),
  2. group-transfer reactions (catalyzed by transferases and hydrolases),
  3. eliminations, isomerizations, and rearrangements (catalyzed by isomerases and mutases),
  4. reactions that make or break carbon–carbon bonds (catalyzed by hydrolases, lyases, and ligases).
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7
Q

the end products of aerobic glycolysis are

A

2pyruvate + 2NADH + 2ATP

^this is the net end products. the total ATP output is 4 but since 2 ATP are initially used, the net ATP produced is 2

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8
Q

equation for aerobic glycolysis

A

Glucose+2NAD++2ADP+2Pi → 2pyruvate+2NADH + 2ATP + 2H2O +4H+

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9
Q

the step in glycolysis responsible for reducing NAD+ into NADH does so by oxidizing a _________ into a _________

A

aldehyde into a carboxilic acid

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10
Q

T/F: glycolisis does not require or use oxygen

A

true

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11
Q

Glyceraldehyde 3 phosphate in glycolysis represents

A

abbreviated GAP.. it is the first product of glucose in which it is split into 2 and is no longer cyclic

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12
Q

the step immediately following the cleavage of cyclic fructose (F-1,6-bP) into 2 Glyceraldehydes is significant how?

A

it is the one step in which 2 NAD+ are converted into 2 NADH

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13
Q

T/F: hexokinase is inhibited by it’s product

A

true

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14
Q

phosphofructokinase is inhibited by _____

A

ATP

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15
Q

what type of enzymatic reactions do both phosphofructokinase and hexokinase accomplish

A

phosophorylation (adding a phosphate)

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16
Q

how would you characterize the reversibility of the reaction from fructose-6-phosphate to fructose 1, 6 biphosphate?

A

nearly irreversible because it has a delta G much less than zero

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17
Q

the activity of _______________is the key regulatory step in glycolysis due to its thermodynamic favorability and from it’s strong mechanism of regulation: it is allosterically regulated by ATP

What enzyme is described?

A

PFK (phosphofructokinase)

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18
Q

what would be the effect of increased ATP concentration in glycolysis

A

cell will slow glycolysis (d/t the allosteric inhibition by ATP on PFK)

19
Q

product of PDC (Pyruvate dehydrogenase complex)

A

Acetyl-CoA

20
Q

1 NADH inputted into the electron transport chain produces # ____

A

3 ATPs

21
Q

the citric acid cycle is the entry point for what molecules:

A

fats and proteins that are converted into Acetyl CoA

22
Q

Is any Co2 produced during the stage 1 reaction of the Krebs cycle

*Stage 1 is the reaction of oxaloacetate and acetyl-CoA to make citric acid

A

no

23
Q

what are the stages of the Krebs Cycle

A
  1. Acetyl CoA + Oxaloacetate→ Citric Acid (6 Carbons)
  2. Citric acid → → succinyl CoA (5 carbons) 2NADH + 2CO2
  3. Succinyl CoA (4 carbons*) → succinate + GTP→→→oxaloacetate +NADH +FADH2

*not including the CoA part

24
Q

enzymes of the electron transport train/oxidative phosphorylation are bound to what structure?

A

the inner mitochondrial membrane

25
Q

T/F: Succinate dehydrogenase (Complex 2 in electron transport chain) is the only membrane-bound enzyme in the Citric acid cycle

A

True

26
Q

______ is the final electron acceptor in the electron transport chain

A

Oxygen (to form water)

27
Q

how many hydrogens moving throught ATP synthase can create 1 ATP

A

4

28
Q

How many NADH are produced from the citric acid cycle per glucose

A

6

Products of the first turn of the cycle are one GTP (or ATP), three NADH, one QH2, and two CO2. Because two acetyl-CoA molecules are produced from each glucose molecule, two cycles are required per glucose molecule. Therefore, at the end of two cycles, the products are:two GTP, six NADH, two QH2, and four CO2

29
Q

eukaryotes make 30 ATP from glucose, prokaryotes make

A

32

30
Q

enzyme activity normally increases with increasing temperature, extreme high temperature does what?

A

denatures the enzyme and renders it inactive.

31
Q

at what concentrations are the equivalence points?

A

1 and 2

33
Q

pH + pOH = ?

A

14

sample calculation: given: pH of 7.6. Since pH + pOH = 14, that means the pOH of the solution should be 7.6 + pOH = 14, or 6.4

34
Q

Based on the Figure, which of the following is least supported?

A. The OCA2 proteins in the eight species studies would be considered homologous.

B. The OCA2 protein is conserved across eukaryotes.

C. Zebrafish and Japanese killifish have a OCA2 common ancestor protein which is more related that that between horse and human.

D. Humans and chimpanzees are more closely related than fission yeast and the wild boar.

topic: interpreting phylogenetic trees

A

D. Humans and chimpanzees are more closely related than fission yeast and the wild boar.

Explanation: OCA2 in zebrafish and Japanese killifish share a common ancestor which is not far away in evolutionary terms (i.e., is not very far down the diagram). In contrast, the common ancestor protein between human and horse OCA2 protein is the point at the bottom of the diagram; this is farther away in evolutionary terms (choice C is supported and can be eliminated).

35
Q

what does the process of PDC use and produce?

A
36
Q

T/F: the citric acid cycle oxidizes acetyl groups from many sources, not just pyruvate.

A

True

37
Q

During fermentation, pyruvate is reduced/oxidized to lactate

A

reduced

38
Q

What is the best description for the energetics of glycolysis?

A

Overall under typical cellular conditions, glycolysis has a negative free-energy change, though there are steps of both positive and negative free-energy change

39
Q

Which glycolytic reaction cannot be directly reversed in gluconeogenesis?

Glucose → glucose-6-phosphate

Glyceraldehyde 3-phosphate → 1,3-bisphosphoglycerate

1,3-bisphosphoglycerate → 3-phosphoglycerate

Glucose-6-phosphate → fructose-6-phosphate

A

The three most favorable steps (and therefore most difficult to reverse) of glycolysis are: glucose→ G-6-P, fructose-6-phosphate→ fructose 1,6-bisphosphate, and phosphoenolpyruvate (PEP)→ pyruvate.

So the answer is Glucose → glucose-6-phosphate

40
Q

What carbohydrates are reactants in glycolysis?

Neither glucose or sucrose directly participate in glycolysis

Glucose and sucrose

Sucrose only

Glucose only

A

Glucose only

41
Q

Will an agent that acts as an inhibitor of the electron transport chain kill a mammalian cell?

A

Yes

42
Q

fermentation has evolved to regenerate _____in anaerobic conditions, thereby allowing glycolysis to continue in the absence of oxygen

A

NAD+

43
Q

What is the role of fructose-2,6-bisphosphate

A

Fructose 2,6-bisphosphate allosterically affects the activity of the enzymes phosphofructokinase 1 (PFK-1) and fructose 1,6-bisphosphatase (FBPase-1) to regulate glycolysis and gluconeogenesis. [1]Fru-2,6-P2 itself is synthesized and broken down by the bifunctional enzyme phosphofructokinase 2/fructose-2,6-bisphosphatase.

*don’t confuse with fructose-1,6-bisphosphate, which is an intermediate in glycolysis

44
Q

which intermediate product in glycolysis can be shuttled to the pentose phosphate pathway?

A

only Glucose-6-phosphate (product #2) is shuttled from glycolysis to the pentose phosphate pathway

Order of products:

0-1-1-2-1-2-1-1-1-0 (numbers indicate number of phosphate present)

45
Q
A

My MCAT Sets (24 decks)

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