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Biochemistry - Block 2 > Glycolysis > Flashcards

Glycolysis Flashcards

1
Q

Hexose ring has how many carbons?

A

Six

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2
Q

Pentose ring has how many carbons?

A

five

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3
Q

What are some 6 carbon Hexose rings?

A

First, theyre referred to as monosaccharides. Examples include : glucose, fructose, mannose, galactose

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4
Q

What are some 5 carbon pentose ring examples?

A

Example: Ribose which is in DNA, RNA and NADH

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5
Q

Most sugars in mammals are what kind of sugars?

A

D-sugars!

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6
Q

Enantiomers are?

A

mirror images

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7
Q

Disaccharides are used for what and composed of?

A

used for storage and are composed of two sugars

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8
Q

Lactose :

A

Galactose and Glucose

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9
Q

Sucrose :

A

Fructose and Glucose

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10
Q

Polysaccharides are used for ?

A

Structural sugars and for storage. 2 + sugars.

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11
Q

Glycogen is found in and made of?

A

Animals, and made of Glucose alpha linked

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12
Q

Starch is found in and made of?

A

Plants, and made of glucose alpha linked

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13
Q

dextran is found in and made of?

A

yeast, and alpha linked

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14
Q

Cellulose is found in and composed of?

A

plants, and glucose is beta linked

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15
Q

Chitin is found in and composed of?

A

insects, crustacean, exoskeleton, and its composed of N-Acetyl Glucosamine Beta linked.

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16
Q

Fxn of glycolysis?

A

to convert glucose to three carbon compounds with the formation of ATP

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17
Q

Glycolysis occurs in which cells and the enzymes are located in?

A

ALL CELLS in the body and in the cytosol.

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18
Q

How many rxns is glycolysis made up of? and what is glucose converted into?

A

10 rxns, glucose is converted into pyruvate!

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19
Q

The intial req of ATP in glycolysis is? and the NET production is?

A

intial req is 2 ATP, and net total production is 2 ATP!

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20
Q

What is the oxidative step in glycolysis where NAD+ is reduced to NADH?

A

Glyceraldehyde 3 phosphate to 1,3 biphosphoglycerate

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21
Q

How are NAD+ replenished?

A

Through aerobic respiration or anerobic fermentation : Lactate dehydrogenase

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22
Q

two substrate level phosphorylations. What are they?

A

phosphoglycerate kinase and pyruvate kinase

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23
Q

Formation of ATP from 1,3 biphosphoglycerate. Enzyme involved? Substrate? Products?

A

Enzyme : Phosphoglycerate kinase Substrate : ADP, 1,3 biphosphoglycerate Product: 3 phosphoglycerate, ATP

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24
Q

Formation of ATP from phosphoenolpyruvate. Enzyme? Substrate? Products?

A

Substrate : Phosphoenolpurvate, ADP Enzyme : Pyruvate Kinase Products : ATP, Pyruvate

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25
Q

Irreversible rxns :

A

Phosphofructokinase Hexokinase Pyruvate Kinase

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26
Q

How does Phosphofructokinase responds to changes in ATP. High ATP does what?

A

Inhibit phosphofructokinase

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27
Q

High lactate, High H+ does what to phosphofructokinase?

A

Inhibit

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28
Q

Alternate fuels available to phospfructokinase? high citrate?

A

Inhibit

29
Q

Insulin/glucagon ration

High fructose 2,6 biphosphate levels on phosphofructokinase?

A

activate

30
Q

Fructose 2,6 biphosphate is?

A

an allosteric activator on phosphofructokinase!

31
Q

Pyruvate Kinase has an allosteric regulator

What are they?

A

Fructose 1,6 Biphosphate –>

it upregulates the dephosphorylation of pyruvate kinase

32
Q

Phosphorylated pyruvate kinase ?

A

inactive

33
Q

Dephosphorylated pyruvate kinase?

A

active

34
Q

High Blood Sugar

A

up regulate dephosphorylated pyruvate kinase

35
Q

low Blood Sugar

A

up regulate phosphorylated pyruvate kinase

36
Q

Glycolysis is critical for what body parts?

A

brain and erythrocytes metabolism and excercising muscle.

37
Q

Phosphofructokinase is regulate by?

A

fructose 2, 6 biphosphate and is the rate limiting step

38
Q

pyruvate kinase has secondary regulation? how?

A

it undergoes phosphorylation-dephosphorylation

39
Q

glucose homeostasis relies critically on detection of variations in blood glucose concentrations by what cells and for a release of what?

A

pacreatic beta cells and the release of the appropriate amount of insulin.

40
Q

whats the rate controlling step in glucose stimulated insulin secretion ?

A

the glucokinase!

41
Q

glucokinase mutation causes early onset of?

A

type 2 diabetes

42
Q

Glut 2 has what affinity for glucose?

A

LOW affinity, thus needs ALOT of glucose to be recognized

43
Q

in Pancreas, where are hormones produced?

A

Islets of Langerhans!

44
Q

Elevated Blood glucose trips an ATP dependent switch in beta cells leading to ?

A

insulin release

45
Q

How is insulin released?

A

A rise in the [ATP]/[ADP] ratio in the cell serves to inhibit the

ATP-sensitive K+ channels (KATP) at the cell surface

–> causing the membrane to depolarize

Opening of voltage-dependent Ca2+ channels (VDCC) results in a rise in intracellular [Ca2+]

–> stimulates insulin secretion

46
Q

Type 2 Diabetes :

A

mutation in glucokinase thus leading to decreased levels of insulin release.

47
Q

Treatment of type 2 diabetes?

A

Sulfoyfurea and Repaglinide

This blocks the K channels regardless of glucose levels

and thus

depolarizes the membrane and turns on Calcium voltage channels signaling for insulin to be released

48
Q

What causes insulin to rise before we eat food?

A

from vagus nerve activation by the brain in response to input from sensory organs, including those of the oral cavity and the visual and olfactory systems

Acetylcholine (ACh) is released from intrapancreatic nerve endings and stimulates insulin secretion

49
Q

After we eat, insulin rises how?

A

Glucose is high

the vagus nerve stimulates AcH release of second messengers

and thats what triggers the release of insulin

50
Q

Recycling the carbon skeleton anaerobically

What happens to lactate in RBC or muscles?

A

Lactate is converted to glucose through the Cori cycle by

being shuttled back into the liver via gluconeogenesis

51
Q

Recycling of the carbon skeleton in the muscle cells to the liver?

A

Alanine Cycle shuttled into the liver

this is better because not acidic like lactate

its converted back into glycolysis via gluconeogenesis

52
Q

pyruvate kinase deficiency

A

Autosomal dominant or recessive disease,

resulting in spiny red blood cells (echinocytes)

  • Second most common cause of enzyme deficient hemolytic anemia
53
Q

Cancer

A

High glycolytic rate up to 200 fold higher than normal cells

  • overexpression of plasma membrane glucose transporters of the GLUT family
  • allowing for higher glucose uptake rates
54
Q

Why is PET and imagining used in oncology?

A

Bc of the high glycolytic rate of tumor cells thus using the uptake of 2-18F deoxyglucose FDG substrate.

55
Q

A patient comes into the ER and has a __________________ deficiency. This can lead to chronic hemolytic anemia and deformed spiny red blood cells, called “echinocytes”.

Glycokinase

PFK

Phosphoglycerate Kinase

Pyruvate Kinase

A

Pyruvate Kinase

56
Q

In the Alanine cycle, Alanine is recycled from muscle cells to the kidney.

True

False

A

False

to the LIVER

57
Q

Which of the following is NOT a hexose?

Glucose

Fructose

Ribose

Galactose

A

Ribose

58
Q

The following are polysaccharides that are (glucose)n alpha-linked EXCEPT:

Glycogen

Cellulose

Starch

Dextran

A

Cellulose

59
Q

Glycolysis occurs in all cells of the body and enzymes are located exclusively in the ________.

Inner membrane

Matrix

Cytosol

2 answers are correct.

A

Cytosol

60
Q

There is an initial requirement for ATP but glycolysis results in the net production of ______ ATP.

4

3

1

2

A

2

61
Q

What occurs in step 7 of glycolysis during substrate-level phosphorylation?

A. 1,3 Biphosphoglycerate catalyzed to 3 phosphoglycerate by phosphoglycerate kinase

B. 1,3 Biphosphoglycerate catalyzed to phosphoenolpyruvate by phosphoglycerate kinase

C. phosphoenolpyruvate catalyzed to pyruvate by phosphoglycerate kinase

D. phosphoenolpyruvate catalyzed to pyruvate by pyruvate kinase

A

A. 1,3 Biphosphoglycerate catalyzed to 3 phosphoglycerate by phosphoglycerate kinase

62
Q

What are the three irreversible reactions in glycolysis?

A. Glucokinase, phosphofructokinase, pyruvate kinase

B. Hexokinase, phosphofructokinase, pyruvate kinase

C. Hexokinase, phosphofructokinase, phosphoglycerate kinase

D. Glucokinase, pyruvate kinase, phosphofructokinase

A

B. Hexokinase, phosphofructokinase, pyruvate kinase

63
Q

All of these inhibit PFK EXCEPT:

High ATP levels

High lactate levels

High citrate levels

High fructose 2,6-bisphosphate levels

A

High fructose 2,6-bisphosphate levels

64
Q

Under anaerobic conditions, _______ is regenerated by conversion of pyruvate to lactate.

NADH2

NAD+

ADP

ATP

A

NAD+

65
Q

Glucose uptake by beta cells is catalyzed by a transporter called ________.

GLUT2

GLUT5

UCP2

VDCC

A

GLUT2

66
Q

What enzyme catalyzes the rate-controlling step in glucose-stimulated insulin secretion of pancreatic beta cells?

Hexokinase

PFK

Glucokinase

Pyruvate kinase

A

Glucokinase

67
Q

A rise in [ATP/ADP] ratio in the cell serves to inhibit/close the _________ causing the membrane to ___________.

ATP-sensitive K+ channels; depolarize

ATP-sensitive K+ channels; polarize

Voltage dependent Ca2+ channels; depolarize

Voltage dependent Ca2+ channels; polarize

A

ATP-sensitive K+ channels; depolarize

68
Q

Mechanisms by __________ stimulates insulin secretion in the preabsorptive and absorptive phase in food intake.

Choline

Acetylalcohol

Acetylcholine

N-acetyl glucosamine

A

Acetylcholine

69
Q

Lactate is recycled from erythrocytes (or muscles cells) to the liver in the Cori Cycle.

True

False

A

True

Biochemistry - Block 2 (4 decks)

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