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molecules to cells - biochemistry > Lecture 11. Glycolysis > Flashcards

Lecture 11. Glycolysis Flashcards

1
Q

Where would you find the glucose transporter GLUT3 and what is an important feature ?

A
  1. Brain
  2. Low Km allows relatively constant rate of glucose uptake independent of extracellular concentration over the normal range
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2
Q

What are 8 factors that effect the control of the glycolytic flux ?

A
  1. Enzyme abundance
  2. Enzyme kinetics
  3. Thermodynamic favorability
  4. Covalent modification eg. phosphorylation of pyruvate kinase
  5. Compartmentalisation eg. cytosol verses mitochondria
  6. Redox state eg. NAD+ /NADH2
  7. Physiological situation eg. starvation or adrenalin
  8. Isoenzyme eg. glucokinase
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3
Q

What happens when there is hypoxia ?

A
  1. HIF -1 activated
  2. Metabolic adaptation (increase in glycolytic enzymes)
  3. Blood vessel growth
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4
Q

Where is the hypoxia inducible factor highly expressed ?

A

Tumours

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5
Q

What is hypoxia inducible factor ?

A

A transcription factor that is turned on when there is no oxygen

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6
Q

What effect does alanine have on enzymes ?

A

Makes them less active

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7
Q

What are the energy requirements in the glycolytic pathway ?

A
  1. ATP production
  2. ATP consumption
  3. NADH2 prouction
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8
Q

What is NADPH2 associated with ?

A

Anabolism

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9
Q

What does the enzyme pyruvate kinase do ?

A
  1. Covalent modification
  2. Product inhibition
  3. Allosteric modulation
  4. Abundance sensitive to insulin/glucagon ratio and hypoxia inducible factor
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10
Q

What is phosphofructokinase sensitive to ?

A
  1. ATP
  2. Fructose-2,6-biphosphate
  3. Citrate

Abundance sensitive to insulin/glucagon ratio and hypoxia inducible factor

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11
Q

What is an allosteric enzyme ?

A

Has sites on enzymes other than active site which allow enzyme to modulate function

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12
Q

What type of enzyme is phosphofructokinase ?

A

An allosteric enzyme

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13
Q

Why is phosphofructokinase a controlling step in flux down pathway ?

A

Its sensitive to environment and the metabolites its in. Its irreversible

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14
Q

Why is hexokinase a controlling step in the flux down pathway ?

A

Has a low Vmax

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15
Q

What type of ring does Fructose 6-phosphate have ?

A

Furano ring of fructose

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16
Q

What type of ring does Glucose 6-phosphate have ?

A

Pyran ring of glucose

17
Q

What does glucokinase respond to ?

A

The ratio of insulin/glucagon and the hypoxia inducible factor

18
Q

Where is glucokinase found ?

A

Liver

19
Q

What enzyme is insensitive to Glucose-6-phosphate ?

A

Glucokinase

20
Q

What are the three key enzymes involved in the glycolytic pathway ?

A
  1. Hexokinase
  2. Phosphofructokinase
  3. Pyruvate kinase
21
Q

What does glycolysis convert pryuvate to under anaerobic conditions ?

A

lactate

22
Q

What do red blood cells convert pyruvate to ?

A

Lactate

23
Q

Why can red blood cells only perform glycolysis ?

A

They have no mitochondria

24
Q

What is the end products of glycolysis ?

A

Two pyruvate molecules

25
Q

Where does glycolysis occur ?

A

Cytoplasm

26
Q

How does Glut 4 transporter work ?

A

Insulin recruits vesicles containing Glut 4 and causes them to be translocated to the cell surface where Glut 4 functions as a pore for glucose entry

27
Q

What type of transport moves glucose to the blood by Glut 2

A

Passive transport

28
Q

What drives glucose uptake ?

A

Sodium gradient

29
Q

Where would you find the glucose transporter SGLT1 and what is an important feature ?

A
  1. Duodenum, jejunum, renal tubules

2. The sodium glucose co-transporter of the small intestine

30
Q

Where would you find the glucose transporter GLUT5 and what is an important feature ?

A
  1. Jejunum

2. Probably responsible for fructose uptake from the intestine

31
Q

Where would you find the glucose transporter GLUT4 and what is an important feature ?

A
  1. Muscle, adipose tissue

2. The insulin sensitive glucose transporter

32
Q

Where would you find the glucose transporter GLUT2 and what is an important feature ?

A
  1. Liver, kidney, intestine, pancreatic B-cell

2. High Km allows glucose to equilibrate across

33
Q

Where would you find the glucose transporter GLUT1 ?

A

Erythrocytes, fetal tissue, placenta, brain

34
Q

Why cant cellulose be broken down easily ?

A

The angle of the bonds makes it difficult

35
Q

How does glucose form rings ?

A

Reacts with itself

molecules to cells - biochemistry (17 decks)

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