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Biochemistry > Exam 3: Glycolysis > Flashcards

Exam 3: Glycolysis Flashcards

1
Q

What is a catabolic reaction

A

break down large molecules to smaller

extracts energy

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2
Q

anabolic reaction

A

small molecules into larger molecules, require energy input

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3
Q

Is glycolysis anaerobic or aerobic

A

anaerobic

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4
Q

What are the 2 stages of glycolysis

A

stage 1 energy input (2ATP used)

stage 2 energy output (use 2 ATP, produces 4ATP)

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5
Q

What kind of reaction is reaction 2 in glycolysis

glucose-6-phosphate –>

A

isomerization reaction

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6
Q

What is the first energy OUTPUT reaction in glycolysis (use diagram)

A

reaction 7:

glycerate 1,3 bisphosphate –>

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7
Q

What kind of reaction is ADP–>ATP

A

substrate level phosphorylation, a phosphate is taken from a substrate and transferred to ADP to produce ATP

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8
Q

What are the anaerobic and aerobic fates of pyruvate

A

anaerobic: fermentation
aerobic: CAC–>ETC

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9
Q

What is a better way to get energy from pyruvate? Fermentation or anaerobic glycolysis

A

anaerobic glycolysis

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10
Q

What is homolactic fermentation and when does it happen

A

pyruvate is transformed into lactate. Can be done during intense exercise

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11
Q

What is the purpose of fermentation

A

to regenerate NAD from NADH without using O2 allowing glycolysis to continue

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12
Q

Why does intense exercise cause muscle cramping?

A

because you build up lactate during homolactic fermentation making the pH levels go down and causing proteins to denature in muscles

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13
Q

What enzyme catalyzes homolactic fermentation

A

LDH lactate dehydrogenase

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14
Q

When does alcohol fermentation happen?

A

in bacteria, yeast.

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15
Q

What enzyme catalyzes alcohol fermentation

A

PDC pyruvate decarboxylase

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16
Q

Why can’t humans ferment alcohol?

A

We dont have the PDC enzyme encoded in our DNA.

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17
Q

What enzyme do humans have to break down alcohol when drinking, where is it what does it do

A

ADH1 alcohol dehydrogenase 1, in our gut, converts ethanol into acetyl aldehyde and regenerates NAD+ from it, NADH–> NAD+

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18
Q

what are the 3 places energy is -delta G in glycolysis in RBCs

A

hexokinase, PFK-1, pyruvate kinase.

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19
Q

Where are hexokinases 1-3 located

A

in the mitochondrial membrane

20
Q

Talk about the affinity and inhibitors of hexokinase 1-3

A

small km, higher affinity for glucose

all inhibited by G-6-p

21
Q

Where is hexokinase 4 located

A

liver, pancreas, intestine, brain

22
Q

Talk about the affinity and inhibitors of hexokinase 4

A

larger km, less affinity for glucose, no inhibited by G-6-p, needs higher glucose concentration to be activated

23
Q

what happens to glucose in pancreas and liver

A

liver: stores excess glucose
pancreas: acts as glucose monitor to signal insulin secretion

24
Q

What does glucokinase or GK do

A

initiated by higher levels of glucose, binds to glucokinase regulatory protein GKRP, complex goes into nucleus and dissociated or separates, signals insulin secretion.

25
Q

When and why is glucagon secreted

A

produced by alpha cells in pancreas, secreted when glucose levels are low

26
Q

How does glucagon affect glycolysis and gluconeogenesis

A

causes glycolysis to slow down and gluconeogenesis to speed up. binds to receptor causing adenylate cyclase in membrane to activate it, catalyzes ATP–> CAMP. CAMP binds to PKA and activates it

27
Q

When and why is insulin secreted

A

secreted by pancreatic beta cells when glucose levels are high

28
Q

How does insulin affect glycolysis and gluconeogensis

A

binds to a receptor, activates ppp, increases glycolysis and decreases gluconeogenesis

29
Q

Where does gluconeogenesis occur in the body

A

only in the liver

30
Q

Where in the cell does gluconeogenesis occur

A

1st step in mitochondrial matrix, the rest in cytosol

31
Q

What are the non carbohydrate progenitors of gluconeogenesis

A

pyruvate, lactate, glycerol and some AAs

32
Q

What are the 3 places gluconeogenesis is different from glycolysis

A

hexokinase, PFK-1, pyruvate kinase

33
Q

Explain the OAA oxaloacetate/ malate shuttle

A

a transport system to move OAA in the mitochondria to the cytosol to be converted into PEP, malate is a protein transporter that carries it across. NAD+–> NADH to bind in mitochondria. Vice versa to separate once crossed to cytosol.

34
Q

What does the Cori cycle do

A

transports lactate from muscle to liver to go through gluconeogenesis

35
Q

What is cortisol, when is it released, what does it do

A

steroid hormone that is released in response to stress, causes increase in gluconeogenesis enzyme. a type of longer term control

36
Q

What are the 2 enzymes used in glycogen synthesis

A

phosphoglucomutase and glycogen synthase

37
Q

Is glycogen synthesis creating any energy? Why?

A

no, a delta G=0 reaction because ultimately UDP is given back,

38
Q

What enzyme is needed for glycogen degradation

A

glycogen phosphorylase

39
Q

Describe glycogen degradation

A

glucose is taken off of non reducing end of glycogen chain by glycogen phosphorylase, bond is replaced by phosphate (not from ATP), glycogen is converted into G-1-P

40
Q

How are glucagon and glycogen degradation/synthesis related

A

glucagon is released when blood glucose levels are low, causes more glycogen breakdown, producing more glucose

41
Q

How are Insulin and glycogen degradation/synthesis related

A

insulin is released at high glucose levels, causes less glycogen breakdown and more glycogen synthesis

42
Q

Who does epinephrine act like and what does it do to the glycogen synthesis/degradation process

A

acts like glucagon, activates adenyl cyclase and increases glycogen breakdown, decreases glycogen synthesis

43
Q

In glycolysis __ moles of ATP are produced per mole of glucose

A

2 ATP

44
Q

In anaerobic organisms pyruvate is used to regenerate cellular

A

NAD+

45
Q

In animals excess glucose is stored as

A

glycogen

Biochemistry (7 decks)

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