Biochem class 1

Question 1

Competitive Inhibitor exception

Answer 1

Competitive inhibitors cannot be overcome if they are convalently bonded to the active site

Question 2

How do catalyst and inhibitors affect reaction rates? How is ∆G affected by enzymes?

Answer 2

Catalyst increase reaction rate

inhibitors decrease reaction rates

∆G is not affected by enzymes.

Question 3

Name cellular location and end products per glucose for the following: glycolysis, pyruvate dehydrogenase complex, Krebs cycle, electron transport, fermentation.

Answer 3

**Glycolysis: **Cytoplasm, 2 ATP, 2 pyruvate, 2 NADH

**PDC: **Mitochondrial matrix, 2 NADH, 2 acetyl-CoA, and 2 CO2

Krebs Cycle: Mitochondrial matrix, 6 NADH, 2 GTP, 2FADH, 4 CO2

**ETC: **inner mitochondrial membrane, end product is a proton gradient 30 ATP generated

**Fermentation: **cytoplasm, 2 ATP, 2 lactic acid (muscle) or 2 ethanol (yeast)

Question 4

Name the cellular location in main products for the following biochemical pathways:

1. gluconeogenesis,
2. glycogenesis,
3. glycogenolysis,
4. fatty acid oxidation,
5. fatty acid synthesis,
6. pentose phosphate pathway.

Answer 4

All reactions occur in the cytosol except fatty acid oxidation, which occurs in the mitochondrial matrix.

The main products in gluconeogenesis is **glucose-6-phosphate. **

Glycogenolysis: glucose-1-phosphate

Glycogenesis: Glycogen

**Fatty acid oxidation: **acetyl CoA units

**Fatty acid syn: **16-C fatty acid (palmitate)

PPP: NADPH (oxidative), ribulose-5-phosphate(non oxidative)

Question 5

Name the four important macromolecules their monomers and their functions.

Answer 5

1. Proteins: AA, channels, pores, hormones, enzymes
**2. Lipids: **hydrocarbons, stored energy, cell membranes, cholesterol/steriods
3. Carbohydrates: Monosaccharides; energy
**4. Nucleic Acids: ** nucleotide, DNA, RNA protein syn

Question 6

Glucose exists predominantly as a:

Answer 6

hexose, aldose and pyranose

Question 7

Transketolase links the pentose phosphate pathway to:

Answer 7

glycolysis

transketolase functions in the production of fructose-6-P and glyceraldehyde-3-P. Both of these substances are intermediates in the glycolytic pathway

Question 8

When is glucose-6-phosphatase activity expected to be highest?

Answer 8

After fasting for 12 hours

glucose-6-phosphatase is used to convert glucose-6-phosphate to glucose, which is then released into the blood stream under low blood glucose conditions.

Question 9

Which best describes the role of inorganic phosphate in the reaction catalyzed by glycogen phosphorylase?

Answer 9

inorganic phosphate is used to assist in the hydrolysis of the α1 → 4 linkage and results in the release of glucose-1-phosphate. This means that the phosphate attacked the glucose residue on the glycogen chain and is now linked to the freed glucose molecule at the 1 position. Nucleophiles are the species that use their electrons to attack other atoms and attach themselves to the atoms.