Carb Metabolism

Question 1

Glycolysis

Answer 1

breakdown of glucose (6 carbon) into pyruvate; “fed” state means glucose levels are high

Question 2

Gluconeogenesis

Answer 2

the synthesis of glucose from two 3-carbon pyruvates; “fasting” state mean glucose levels are low

Question 3

Redox reactions

Answer 3

NADH is oxidized (loses hydrogens) while pyruvate gains hydrogens and is reduced

Pyruvate + NADH+ H+ lactate + NAD+

Question 4

Pentose Phosphate Pathway

Answer 4

• occurs after glycolysis
• starts with glucose-6-phosphate (which came from glu)
• two phases: 1. oxidative phase (produces NADPH), 2. non-oxidative phase
• produces pentose sugars (ribose-5-phosphate) that make up DNA and RNA
• no energy in the form of ATP is produced or used up
• NADPH is product
• there are 10 times more NADPH than NADP+, meaning it is the reducing agent

Question 5

4 steps of CR (memorize!)

Answer 5

1. glycolysis (in cytosol) produces two pyruvates
2. pyruvate transformed into acetyl CoA in mitochondria
3. CAC (NADH and FADH2 are produced)
4. ETC

Question 6

glycolysis (step 1)

Answer 6

the investment phase:

step 1: produces two 3-carbon phosphoglyceraldehydes (see picture)
- uses 2 ATP

Question 7

glycolysis (step 2)

Answer 7

the reward phase:

the 3-carbon-1-phosphate becomes a pyruvate

+ gain 1 NADH
+ gain 2 ATP

Question 8

gluconeogenesis* (steps)

Answer 8

produces a 6-carbon molecule from two pyruvates

1. pyruvate converted to oxaloacetate
2. phosphate group is moved to another carbon
3. a second phosphate group is added to each 3-carbon molecule
4. NADH -> NAD+ (NADH provides electrons for removal of a phosphate)
5. two 3-carbon molecules are combined to form a 6-carbon molecule
6. rearrangement
7. phosphate group is removed, forming glucose

Question 9

CR equation

Answer 9

C6H12O6 + 6O2 -> 6CO2 + 6H2O + heat + 38 ATP

see picture

Question 10

Krebs cycle

Answer 10

• after glycolysis
• requires oxygen
• produces two 2 ATPs
• leads to ETC

Question 11

gluconeogenesis

Answer 11

takes a precursor from a non-carbohydrate source (amino acid, lactate) and rearranges into glucose

Question 12

AMP*

Answer 12

a sign the cell is running low on ATP

Question 13

three ways glycolysis and gluconeogenesis regulated*?

Answer 13

1. le Chatelier (fast)* - high ATP dampen glycolysis; see video again
2. Hormonal
3. transcriptional

Question 14

NAD+/NADP+ ratios

Answer 14

NAD+/NADH = 1000

NADP+/NADPH = 0.1