1. Glycolysis Flashcards

1
Q

what is glycolysis

A

oxidation of 1 glucose to 2 pyruvate - catabolic/exergonic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what 4 components does glycolysis require

A

1) 1 glucose
2) 2 ATP
3) 2 NAD+
4) 4 ADP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what are the main products of glycolysis

A

1) 2 pyruvate
2) 4 ATP - net gain = 2 ATP
3) 2 NADH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what are the 3 main regulatory steps in glycolysis

A

1 - glucose to glucose-6-P by HEXOKINASE (or glucokinase)

2 - fructose-6-P to fructose-1,6-bisP by PHOSPHOFRUCTOKINASE (main regulatory step)

3 - phosphoenolpyruvate to pyruvate by PYRUVATE KINASE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what is the difference between hexokinase and glucokinase

A

hexokinase

  • all tissues
  • higher affinity to glucose: lower Km, always active
  • regulated by product: inhibited by high [glucose-6-P]

glucokinase

  • liver
  • lower affinity to glucose: higher Km, only active after meal
  • regulated by substrate availability: stimulated by high [glucose]
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

how is phosphofructokinase regulated

A

allosterically in muscle:

  • inhibited by high ATP
  • stimulated by high AMP

hormonal regulation in liver:

  • inhibited by glucagon
  • stimulated by insulin
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

how is pyruvate kinase regulated

A
  • inhibited by glucagon

- stimulated by insulin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

name 2 important intermediates of glycolysis

A
  1. DHAP

2. 2,3-BPG

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

in which cells is DHAP produced and why

A
  • adipose and liver
  • DHAP is converted to glycerol phosphate via GLYCEROL 3-PHOSPHATE DEHYDROGENASE, which is used for:
    • phospholipid synthesis (polar head)
    • triacylglycerol synthesis (= glycerol phosphate + fatty acids)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

in which cells is 2,3-BPG produced and why

A
  • RBCs

- regulation of haemoglobin O2 affinity (decreases affinity)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

how is NAD+ required for glycolysis regenerated in different tissues

A
  • most tissues with O2 supply: via oxidative phosphorylation (NADH to NAD+ at ETC)
  • but in RBCs (lack MT) and in reduced O2 conditions (eg muscle and gut): via lactate dehydrogenase
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

which reaction does lactate dehydrogenase catalyse

A

pyruvate + NADH + H+ to lactate + NAD+

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what are the 2 fates of lactate

A

travels via blood to:

1- heart… converted back to pyruvate via lactate dehydrogenase… oxidised for energy production

2- liver/kidney… converted back to pyruvate via lactate dehydrogenase… converted to glucose via gluconeogenesis… returns to tissues

How well did you know this?
1
Not at all
2
3
4
5
Perfectly