Glycolysis 1 and 2 Flashcards

1
Q

What does Metabolism describe ?

A

It describes the integrated set of chemical reactions occur in the body and compromises both anabolism and catabolism

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

What is Anabolism ?

A

This is the synthesis of complex molecules from simpler ones (e.g. glycogen from glucose) with the energy necessary for synthesis being usually derived from ATP

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

What is Catabolism ?

A

This is the breakdown of energy-rich molecules (carbohydrate/lipid/protein) to simpler ones (CO2, H20 and NH3) with the energy released being “conserved” as adenosine triphosphate (ATP), for use in anabolic reactions

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

Catabolic and anabolic pathways together constitute ?

A

The cell’s metabolism

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

Define Oxidoreductases and give an example ?

A

Transfer of electrons

- Dehydrogenases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Define Transferases and give an example ?

A

Transfer of functional groups (Pi)

- Kinases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Define Hydrolases and give an example ?

A

Hydrolysis reactions

- Trypsin / Lipase

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

Define Lyases and give an example ?

A

Cleavage of C-C, C-N and other bonds, often forming a double bond

  • Isocitrate lyase
  • Pyruvate decarboxylase
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Define Isomerases and give an example ?

A

Transfer of groups within a molecule

- Triose-phosphate isomerase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Define Ligases (synthetases) and give an example ?

A

Bond formation coupled to ATP hydrolysis

- Pyruvate carboxylase

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

What are the 3 main parts of Glycolysis ?

A
  1. Energy investment
  2. Cleavage
  3. Energy generation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are many metabolic reactions controlled by ?

A

The energy status of the cell

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

What is the Energy charge (EC) ?

A

It is an index used to measure the energy status of a cell and is related to the cellular concentrations of the adenylate nucleotides (AMP / ADP / ATP)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Explain the reaction ΔG<0 ?

A
  • The reaction is spontaneous
  • Products have less free energy than reactants and so are more stable than the reactants
    Their formation is considered to be “ downhill “ (spontaneous)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Explain the reaction ΔG>0 ?

A

Reaction is not spontaneous

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is Glycolysis ?

A

Metabolic pathway in which glucose is transformed to pyruvate with production of a small amount of energy in the form of ATP or NADH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What kind of process is Glycolysis ?

A

An anaerobic respiration (it does not require oxygen)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Glycolysis pathway is used by ?

A

Anaerobic as well as aerobic organisms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What happens in Glycolysis ?

A

One molecule of glucose is converted into two molecules of pyruvate

20
Q

In eukaryotic cells, glycolysis takes place in?

A

The cytosol

21
Q

What does it yield ?

A

2 ATP and 2 NADH per glucose

22
Q

Explain Location and Glucose Affinity for GLUT 1 ?

A
  • Erythrocytes, other tissues

- High glucose affinity

23
Q

Explain Location and Glucose Affinity for GLUT 2 ?

A
  • Liver, pancreatic B cells

- Low glucose affinity

24
Q

Explain Location and Glucose Affinity for GLUT 3 ?

A
  • Brain, other tissues

- High glucose affinity

25
Explain Location and Glucose Affinity for GLUT 4 ?
- Muscles, adipose | - Low glucose affinity
26
Briefly explain the uptake of glucose ?
1. The transport protein has a binding site for glucose that is open to the outside of the cell 2. Glucose binds to the binding site 3. This binding causes the protein to change shape, exposing glucose to the inside of the cell 4. Glucose passes into the cell and protein returns to its original shape
27
Give an overview of Glycolysis ? (Energy-Investment Stage)
1. Glucose is phosphorylated by ATP to form glucose 6-phosphate 2. The atoms of glucose 6-phosphate are rearranged to form fructose 6-phosphate. Fructose 6-phosphate is phosphorylated by ATP to form fructose 1,6-biphosphate 3. Fructose 1,6-biphosphate is divided to form glyceraldehyde 3-phosphate (G3P) and dihydroxyacetone phosphate (DHAP) 4. DHAP is rearranged to form another G3P
28
What is Hexokinase inhibited by ?
High levels of G6P inhibit (allosterically)
29
Why is this inhibition important ?
It's a control step; it prevents over consumption of cellular ATP to form G-6-P when glucose is not limiting
30
In liver and pancreatic β-cells, Hk is replaced by ?
Gk (glucokinase)
31
Gk has higher Km than Hk. How is it activated ?
By high blood glucose and insulin but NOT inhibited by G6P
32
So what does Glucokinase allow the liver to remove ?
Excess glucose for glycogen synthesis and minimise, after eating, hyperglycemia
33
What does Phosphoglucose Isomerase (PGI) convert ?
G6P into a fructose-based molecule through acid-base catalysis
34
What Phosphofructokinase transfer ?
A phosphate group from ATP to fructose-6-phosphate. This makes fructose-6-biphosphate
35
What can Phosphofructokinase-1 (PFK-1) be allosterically inhibited by and how can it be reversed ?
PFK-1 is allosterically inhibited by ATP (-) and this is reversed by AMP (+)
36
What effects does Citrate have on PFK-1 ?
Inhibits PFK-1 (high citrate signals sufficient TCA cycle intermediates so not necessary to metabolise any more glucose via PFK-1)
37
What effect does F2, 6-BP have on PFK-1 ?
It activates PFK-1
38
What effects does H+ have on PFK-1 ?
Inhibit PFK-1 when pH falls preventing excessive formation of lactic acid (prevents acidosis)
39
Explain the Energy-Conserving Stage ? (Continued cycle from Energy-Investing Stage)
5. Inorganic phosphates are added to the two G3P, and two NAD+ are reduced. 6. Two ADP are phosphorylated by substrate-level phosphorylation to form two ATP 7. The remaining phosphates are moved to the middle carbons. A water molecule is removed from each substrate 8. Two ADP are phosphorylated by substrate-level phosphorylation to form two ATP. Two pyruvic acid are formed
40
Pyruvate kinase is the last enzymatic reaction in glycolysis. What does it aid ?
It aids in the conversion of phosphoenolpyruvate (PEP) to pyruvate, thereby producing ATP
41
What happens when Pyruvate kinase is deficient ?
- Sufficient amounts of ATP are not available for red blood cell survival - Red cells are removed by the reticuloendothelial cells, particularly the spleen - Build up of 2,3-DPG occurs which aids in oxygen off loading into tissues
42
Explain Pyruvate Kinase Deficiency ?
- No ATP for Na/K pumps to maintain cell shape | - RBC's lack mitochondria; rely on glycolysis for ATP
43
Briefly explain Hemolytic anemia ?
Red blood cells swell and lyse
44
What process is involved in the Cori cycle ?
Gluconeogenesis - process of making glucose | Glycolysis - breakdown of glucose by enzymes
45
What catalyses the reaction of Pyruvate into Acetyl-CoA ?
Pyruvate Dehydrogenase Complex
46
What is Pyruvate inhibited by ?
Its products - Acetyl-CoA and NADH