Glycolysis Flashcards

1
Q

What are the two stages of Glycolysis?

A

Energy-investing reactions (consume ATP)

Energy-harvesting reactions (produce ATP)

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2
Q

Which stage of Glycolysis produces ATP?

A

stage 2- energy-harvesting raactions

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3
Q

what is the purpose of Glycolysis?

A

Convert 6-C Glucose –> two 3-C Pyruvate

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4
Q

What are the two steps in Parts 1 (reactions 1-5)

A

Glucose phosphorylated (add P) at C1 and C6

Glucose 6C ring is cleaved into 2 3C glyceraldheyde-3-phosphate

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5
Q

What are the four steps in Parts 1 (reactions 6-10)

A

Convert metabolic energy of GP3 –> ATP

4 new ATPS produced

2 ATPSs used in part 1

Net yeild = 2 ATPS

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6
Q

What is the first step of glycolysis? (enzyme and reaction)

A

Hexokianse

D-Glucose + ATP –> Glucose 6-phosphate + ADP

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7
Q

What is the second step of glycolysis? (enzyme and reaction)

A

Hexose Isomerease/ Phosphohexose Isomerase

Glucose-6-P <–> Fructose-6-P

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8
Q

What occurs in the 2nd step of glycolysis? (words)

A

Ring rearranges into 5-mememebred fructose ring 9moves carboynal group)

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9
Q

What is the third step of glycolysis? (enzyme and reaction)

A

Phosphofructokinase

F-6-P –> F1.6-bisphosphate + ADP

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10
Q

What occurs in the 3rd step of glycolysis? (words)

A

Adds second phosphate to ring

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11
Q

What steps of glycolysis are irreversible and why?

A

Steps 1-3, 5-6 and 10, due to negative Gibbs free energy (non-spontaneous).

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12
Q

What is the fourth step of glycolysis? (enzyme and reaction)

A

Aldolase A

F1,6-bisphosphate <–> dihydrochalcone phosphate + glyceraldehyde-3-p

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13
Q

What occurs in the 4th stage (words)?

A

Ring is opened and cleaved into two 3 carbon sugar phosphates

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14
Q

What are the two rings called that Aldolase A produces?

A

1 = dihydroxy-acetone phosphate

2= glyceraldehyde 3-phosopahte

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15
Q

What is the fifth step of glycolysis? (enzyme and reaction)

A

isomerase

DHAP –> G3P

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16
Q

What is the sixth step of of glycolysis? (enzyme and reaction)

(first energy harvesting)

A

Glyceraldehyde 3-phosphate dehydrogenase

G3P + Pi + NAD+ <–> 1,3 Bisphosphoglyceate + NADH2

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17
Q

What occurs in the 6th stage (words)?

A

Converts G3P into 1,3-PGA as well as NAD –> NADH2

Transfers free P to C1

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18
Q

What is the seventh step of of glycolysis? (enzyme and reaction)

A

3-Phosphoglycerate Kinase (subsrate level of phosphorylation)

1,3BPG + ADP <–> 3PG + ATP

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19
Q

What occurs in the 7th stage (words)?

A

Forms high energy P bonds where not previols

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20
Q

What is the eighth step of of glycolysis? (enzyme and reaction)

A

Phosphogoglycerate Mutase

3PG <–> 2PG

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21
Q

What occurs in the 8th stage (words)?

A

P moves from C2 to C3

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22
Q

What is the ninth step of of glycolysis? (enzyme and reaction)

A

Enolase

2PG <–> Phosphoenolyruvate (PEP) + H2O

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23
Q

What occurs in the 9th stage (words)?

A

Removes water from 3PG to make PEP

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24
Q

What is the tenth step of of glycolysis? (enzyme and reaction)

A

Pyruvate kinase

PEP + ADP <–> Pyruvate + ATP

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25
Q

What occurs in the 10th stage (words)?

A

Transfers phosphate from PEP to ADP

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26
Q

What is Substrate-level phosphorylation?

A

enzyme catalysed transfer of phosphate from donor molecules to ADP

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27
Q

for every mole of glucose that enters glycolosys, how many moles of pyruvate are produced?

A

2 Moles

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28
Q

in Energy-Investing steps, how much ATP tp glucose is hyrolysed?

A

hydrolysis of 2 ATP molecules per one glucose molecule

29
Q

What do enegry releasing steps produce and how many?

A

two molecules of NADH

30
Q

What occurs if O2 is present in glycolysis?

A

three stages of cell respiration = Pyruvate oxidation, citric acid cycle and respiratory chain/ATP synthesis

31
Q

What is the overall reaction for glycolysis?

A

Glucose + 2NAD+ + 2P + 2ADP –> 2 Pyruvate + NADH + 4H + 2ATP + 2H2OWhich

32
Q

What is the rhyme to remember glycolysis Steps?

A

Goodness Gracious, father Franklin, Did Go By Picking Pumpkins (to) Prepare Pies

33
Q

What is the Rhyme for remembering Glycolysis Enzymes?

A

High Profile People Act Too Glamorous, picture Posing Every Place

34
Q

What is allosteric regulation?

A

mechanism of control: effector binds to regulator site and induces conformational change to influence activity.

35
Q

What are isozymes?

A

2 genes that encode proteins with similar functions

36
Q

What are the two isozymes of phosphofructokinase? What do they do?

A

Phosphofructokianse-1 (PFK-1) = catalyses reaction 3

Phosphofructokianse-2 (PFK-2) synthesises F-2,6BP (allosteric regulator of PFK-1)

Both control rate of glycolysis via allosteric regulation

37
Q

What are allosteric inhibitor examles?

A

ATP and Citrate

38
Q

What are allosteric activator examples?

A

F2,6BP, ADP and AMP =

39
Q

What activates PFK1?

A

F2,6BP

40
Q

What is the nature of the two binding sites on PFK1?

A

1- high affinity for F6P
2- low affinity for F6P

41
Q

What are the three modes of regulation of glycolysis?

A
  1. Difference between hexokinase and glucokinase Km vales
  2. phosphofructokinase controls rate of glycolysis
  3. Pyruvate kinase: allosteric regulation
42
Q

What happens to glyclosys at a HIGH ATP?

A

Glycolysis slows down. ATP binds to PFK1 and decreases it’s affinity for F6P.

43
Q

What can AMP do to regulate glyclyosis?

A

Is an Allosteric activator:

can displace ATP and increase affinity (lower Km)

44
Q

What is F2,6BP regulated by?

A

Insulin and glucagon

45
Q

What is the effect of Insulin on PFK2, F2,6BP and glycolysis?

A

promotes PFK2 activity, increases F2,6BP and glycolysis levels

46
Q

What is the effect of glucagon on PFK1, F2,6BP, glycolysis and F2,6Bpase?

A

increases F2,6Bpase activity, decreases F2,6BP, PFK1 and glycolysis levels.

47
Q

How does Pyruvate Kinase provide allosteric regulation?

A

via allosteric effector and phosphorylation

Insulin = dephosphorylation = active

Glucagon = phosphorylation = inactive

48
Q

What is one major structural difference between fructose and glucose?

A

Glucose = aldehyde group

Fructose= ketone group

49
Q

Where is the major site of metabolism for Fructose?

A

The Kidneys

50
Q

Where is lactase located?

A

in the brush border/microvilli of cells in the small intestine

51
Q

what is lactase essential for?

A

complete digestion of milk

52
Q

what are the three enzymes used in galactose breakdown?

A

Galactokinase (GALK)

Galactose-1-phosphate uridyltransferase

UDP-galactose-4’-epimerase

53
Q

is NAD+ in an oxidised or reduced state?

A

oxidised

54
Q

what happens to NAD+ in the 6th step?

A

it is reduced: adds a H ion and becomes NADH2

55
Q

What type of reaction is step 6 (G3P Dehydrogenase)?

A

redox reaction

56
Q

Which steps are regulated?

A

the irreversible ones

57
Q

where do ADP and AMP come from?

A

ATP

58
Q

What occurs if there is too much ADP and AMP?

A

As they are products of ATP, it indicates that there is not enough ATP in the body. Sends a message to the enzyme via a negative feedback loop to increase ATP synthesis.

Km decreases so moves in the forward direction (less substrate needed).

59
Q

What is the role of insulin in hormonal control of phosphofructokinase-2?

A

increases the transcription of genes that make glucose. UP REGULATION

60
Q

What is the role of glucagon in hormonal control of phosphofructokinase-2?

A

DOWN REGULATION

increases production of gene that makes glycogen in the liver.

61
Q

How (generally) is glucose transported to tissues?

A

monosaccharides absorbed from the intestine after being digested in diet, enter the blood and then travel to tissue where can be metabolized.

62
Q

what organs are involved in the metabolism of glucose?

A

kidney and liver

63
Q

what occurs after glucose is transported to cells?

A

hexokianse phosphorylates glucose into glucose-6-phosphate. This can then enter three common processes:
a- glycolysis
b-pentose phosphate pathway
-glycogen synthesis

64
Q

what is the major fate of glucose-6-phosphate in the body?

A

oxidation via glycolysis

65
Q

what are the hormones of metabolic homeostasis?

A

insulin and glucagon

66
Q

What is different from fructose metabolism versus glucose metabolism

A

Regulated reaction of Phosphofructokinase is avoided.

Excess fructose can exhaust Aldolase B and use ATP up.

same ATP and pyruvate yield.

67
Q

what is dominanat in a fasted state?

A

g) Glycogen = gluconeogenesis, glycogenolysis and ketogenesis increased

68
Q

How is galactose transported into a cell

A

facilitated by Na transporter

Glut1, glut2 and Glut12

69
Q

What is the difference between glycogen and glucagon?

A

Glycogen is how glucose is stored in the body.

Glucagon is the hormone that triggers liver glycogen to convert back into glucose