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Biomolecular Mechanisms > Week 12: Glycolysis > Flashcards

Week 12: Glycolysis Flashcards

1
Q

What cell types require glucose?

A

erythrocytes, retina, renal, brain

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2
Q

What is the straight chain structure of glucose called?

A

hexose

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3
Q

What 2 carbons link to make a ring structure?

A

Carbon 1 (on the aldehyde) & Carbon 5

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4
Q

beta-D-glucose structure?

A

OH points up on carbon 1

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5
Q

alpha-D-gluose structure?

A

OH points down on carbon 1

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6
Q

When 2 glucose form a linkage, what is the biproduct?

A

H2O, Carbon 1 gives the H and the other structure gives the OH.

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7
Q

How to make surcose?

A

alpha glucose and fructose

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8
Q

How to make maltose?

A

alpha glucose + beta glucose

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9
Q

How to make cellabiose?

A

beta and beta glucose

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10
Q

How to make polysaccharides?

A

many glucose molecules

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11
Q

What do proteins, lipids and carbohydrates breakdown to form?

A

amino acids, fatty acids, glucose

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12
Q

What needs to happen before the stages of glucose catabolism can occur?

A

Glucose transport into cells via Na+/glucose symporters

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13
Q

where are the Na+/glucose symporters located?

A

gut

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14
Q

What is the Na+ concentration outside the cell?

A

high Na+

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15
Q

What is the Na+ concentration inside the cell?

A

low Na+

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16
Q

What pump is used to push Na+ out of cell, against its concentration gradient?

A

Na+/K+ antiport/pump

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17
Q

What substance is needed to drive glucose into cell?

A

Na+

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18
Q

what tissue is GLUT 1&3 receptors?

A

brain

19
Q

Does the brain GLUT receptors operate at low Km

A

Yes, continue to operate at high affinity even when low glucose. even when energy supply is low
keeps you alive.

20
Q

What tissue are GLUT 2 receptors located?

A

Liver & pancreatic beta cells

21
Q

Do GLUT 2 receptors operate at low Km?

A

no, really sensitive to changes in glucose conc.

Drop in glucose conc, drop activity of receptor.

22
Q

What cells produce insulin?

A

pancreatic beta cells

23
Q

What receptors/cells do insulin bind to?

A

GLUT 4 on the muscle and adipose tissue (where it is stored)

24
Q

what does the GLUT 5 receptor do?

A

Gut
fructose transport
transports glucose

25
Q

How does the GLUT 1 receptor work?

A

glucose binds outside
confo change and binding site moves inside cell
low conc of glucose inside so very little probability of binding to receptor on the inside
receptor is unoccupied, confo change and regenerates binding site to outside

26
Q

catabolism of glucose to 2Xpyruvate equation?

A

glucose+2ADP+2Pi+2NAD+–>

2Xpyruvate+ 2ATP + 2H20 +2NADH +2H+

27
Q

What is the first intermediate product of glucose?

A

fructose 1,6biphosphate

conversion of 2ATP–>2ADP

28
Q

What does fructose 1,6 biphosphate change to in the glucose pathway?

A

2 triose phosphates G3P

29
Q

what does 2 triose phosphates change to in the glucose pathway?

A

2X pyruvate
conversion of 4ADP–>4ATP
2NAD+ –> 2NADH + 2H+

30
Q

What is the first control point in glycolysis?

A

enzyme hexokinase
glucose to glucose-6-phosphate
not reversible, big energy diff

31
Q

What is the second control point in glycolysis?

A

phosphofructokinase
fructose-6-phosphate to fructose-1,6-biphosphate
not reversible, big energy diff

32
Q

What is the third control point in glycolysis?

A

pyruvate kinase
phosphoenolpyruvate to pyruvate
not reversible, big energy gap

33
Q

what are the 2 cellular needs for control points in glycolysis?

A
  1. production of ATP
  2. provision of building blocks for synthetic reactions
    >don’t need to breakdown pathway, breakdown precursors if needed
34
Q

What is stage 1 called in glycolysis?

A

energy investing reactions

35
Q

what stage 3 called in glycolysis?

A

energy harvesting reactions

36
Q

If you have enough energy do you need to proceed at control points?

A

don’t need to proceed

no need to source more energy in the body

37
Q

what are negative modulators of phosphofructokinase?

A

ATP, H+ & citrate (citric acid)

38
Q

How does citric acid work as a negative modulator of phosphofructokinase in glycolysis?

A

early intermediate in the citric acid cycle
biosynthetic precursors are abundant
no need to breakdown glucose

39
Q

How does H+ work as a negative modulator of phosphofructokinase in glycolysis?

A

Low pH inside cell
Under anaerobic conditions, breakdown of glucose = lactic acid slowly poisoning itself
doesn’t want to metabolise glucose at the detriment to itself
slow down glycolysis, lactic acid will clear –>
allow glucose metabolism to continue

40
Q

what are positive modulators of phosphofructokinase?

A

AMP & fructose-2,6-biphosphate (FBP)

41
Q

what is the ATP/AMP ratio called?

A

energy charge

42
Q

When is a cell fully charged/uncharged?

A

all adenalate nucleotides are in ATP form = fully charged

cell contains only AMP+P = uncharged

43
Q

What does energy charge in a cell tell us?

A

2ADP–>ATP+AMP.
depleted enough ATP, need to start converting
2ADP–>ATP+AMP

Biomolecular Mechanisms (34 decks)

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