Biochem Quiz 4 (Bioenergetics, Glycolysis, Gluconeogenesis, Glycogen)

Oxidized

- More bonds to oxygen

- Fewer electrons

- Fewer hydrogens

Reduced

- Fewer bonds to oxygen

- More electrons

- More hydrogens

Regulatory enzymes

Control rate of metabolic reactions based on what the cell needs

Glycolysis Step 1

- ATP hydrolyzed

- Glucose to G6P

- Enzyme = Hexokinase

- Unidirectional (FAR FROM EQUILIBRIUM)

Glycolysis Step 3

- *ATP hydrolyzed*

- Fructose-6-phosphate into fructose-1,6-bisphosphate

- Enzyme = Phosphofructokinase

- Unidirectional (FAR FROM EQUILIBRIUM)

Glycolysis Step 10

- ATP made

- Phosphoenolpyruvate to pyruvate

- Enzyme = Pyruvate kinase

- Unidirectional (FAR FROM EQUILIBRIUM)

Phosphofructokinase Reaction (REGULATORY ENZYME)

Regulatory step in which:

- A lot of phosphoenolpyruvate inhibits the phosphofructokinase enzyme from converting Fructose-6-phosphate to fructose-1,6-bisphosphate (Step 3)

- A lot of ADP signals phosphofructokinase to continue glycolysis

Gluconeogenesis Bypass Enzymes

Steps 1 and 2 = pyruvate carboxylase and phosphoenol pyruvate carboxykinase

Step 9 = fructose 1,6-bisphosphatase

Step 11 = glucose 6 phosphatase

Regulatory enzyme of gluconeogenesis

Fructose 1,6-bisphosphatase

If there is a lot of ATP in the cell what happens?

The cell does gluconeogenesis to use a net of 2 ATP

What is the purpose of fermentation?

It occurs when there is no oxygen present and a buildup of pyruvate and NADH to convert them to lactate and NAD+

What is the enzyme used in fermentation?

Lactate dehydrogenase (LDH)

What happens to the lactate produced in fermentation?

In the liver, LDH converts the lactate back into pyruvate. The pyruvate then goes through gluconeogenesis to generate the glucose needed for glycolysis (CORI CYCLE)

Pyruvate Structure

Lactate Structure

Where is glycogen stored?

In the cytosol of liver and muscle cells

Glycogenogenesis Enzymes

1. Phosphoglucomutase

2. Glycogen synthase

3. Branching enzyme

What does phosphoglucomutase do?

- Glucose 6 phosphate to Glucose 1 phosphate

- Reversible

- COMMITMENT STEP

Where does the energy for glycogen synthesis come from?

UTP

What does glycogen synthase do?

UDP-Glucose + Glycogen ----> Glycogen (linear) + UDP

What does branching enzyme do?

- Cleaves off a 7 residue segment

- Attaches it to C6 OH group via alpha (1,6) bond

Glycogenolysis

- Glycogen to Glucose 1 phosphate

- Enzyme = glycogen phosphorylase