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Flashcards in Central Carbon Metabolism Deck (26):
1

substrates of glycolysis

- 6 carbon sugars
- glucose
- investment of 2 ATP

2

substrates of pentose phosphate

- 5 carbon sugars

3

products of glycolysis

- 2 pyruvate (3 carbons)
- 2 NADH
- 2 ATP

4

Nonreversible steps of glycolysis

- Glucose to glucose-6-phosphate. 1 ATP used. Hexokinase
- Fructose-6-phosphate to Fructose-1,6-Bisphosphate. 1 ATP used. PFK 1
- Phosphoenol pyruvate to pyruvate. 2 ATP produced. pyruvate kinase

5

Substrates of gluconeogenesis

- 2 Pyruvate (3 carbons)

6

Products of gluconeogenesis

- Glucose

7

Nonreversible steps of gluconeogenesis

- Pyruvate to Oxaloacetate. 2 ATP used. pyruvate carboxylase
- Oxaloacetate to PEP. 2 GTP used. PEP carboxykinase
- Fructose-1,6-Bisphosphate to Fructose-6-phosphate. F-1,6-Bpase
- Glucose-6-phosphate to glucose. Glucose-6-phosphatase

8

If you try to synthesize carbs on amino acids or lipids

- start with GAP and avoid expense of investing 2 ATP

9

Substrates of TCA

- pyruvate (3 carbons) to acetyl-CoA (2 carbons)

10

Products of TCA

- 3 CO2
- 12 NADH
- 3 FADH2
- 3 GTP

11

Substrates of pentose-phosphate

- Glucose-6-phosphate
- 12 NADP

12

products of pentose-phosphate

- 6 CO2
- 12 NADPH
- 12 H+
- Pi
- Fructose-6-Phosphate
- Glyceraldehyde-3-Phosphate

13

Source of the amino group of amino acids

- glutamate
- done by glutamate dehydrogenase

14

Glutamate family

Precursor

- Glutamine
- Proline
- Arginine

- alpha-ketoglutarate (5 carbons) from TCA

(GPA)

15

Aspartate family

Precursor

- Asparagine
- Methionine
- Threonine
- Isoleucine (only made from pyruvate)
- Lysine

- Oxaloacetate (4 carbons) from TCA
(TAMIL)

16

Serine family

Precursor

- Cysteine
- Glycine

- 3-phosphoglycerate from glycolysis
(Super Cool Guy)

17

Pyruvate family

Precursor

- Valine
- Alanine
- Leucine

- from pyruvate in glycolysis
(VAL)

18

Aromatic family

Precursor

- Tryptophan
- Tyrosine
- Phenylalanine

- from phosphoenolpyruvate (from glycolysis) and Erythrose-4-phosphate (from pentose phosphate)
(ATTP)

19

Histidine family

Precursor

- Histidine

- from ribose-5-phosphate from pentose phosphate

20

Beta oxidation of fatty acids

Yields

- catabolizes 2 carbons at a time
- costs 1 ATP to prime fatty acid with CoA

- 1 FADH
- 1 NADH
- 1 Acetyl-CoA

21

Where glycerol from Beta oxidation enters

- enters glycolysis at glycerol phosphate

22

Where acetyl from Beta oxidation enters

- enters TCA condensing with oxaloacetate to form citrate

23

Glyoxylate cycle

- many of the same steps of TCA but the CO2 yielding steps are gone

- isocitrate cleaved to form succinate and glyoxylate instead of proceeding to alpha-ketoglutarate and succinyl-CoA
- glyoxylate combined with another acetyl-CoA to form malate
- two acetyl-CoA molecules have now entered the cycle, and no CO2 has been produced - oxaloacetate
- 1 oxaloacetate used in biosynthesis. the other can be used in TCA to accept acetyl-CoA

24

Glyoxylate cycle purpose

- allows cells to use simple carbon compounds (2C) when glucose isn't available to put into TCA

25

Nucleotides

- Carbon:
- Glycine
- Aspartate
Nitrogen:
- Glutamine

26

Why use pentose phosphate?

1. When the need for reducing power in the form of NADPH is greater than the need for NADH
2. When erythrose-4-phosphate or ribose-5-phosphate are needed as a precursor for amino acids.