Metabolism 2.

Question 1

___________________ combines with coenzyme A (CoA) to form acetyl CoA and CO2.

Answer 1

pyruvic acid

Question 2

Anaerobic respiration includes two metabolic processes : __________________ and _______________________.

Answer 2

glycolysis and lactic acid formation

Question 3

In the absence of oxygen, the electron transport chain stops supplying ________________ to the glycolysis pathway; however, it can be obtained from ____________________.

Answer 3

a) NAD+

b) actic acid formation

Question 4

Oxidative phosphorylation

a. occurs in the cytoplasm
b. occurs in the absence of oxygen
c. produces more ATP per molecule of glucose than does glycolysis
d. produces more NADH per molecule of glucose than glycolysis
e. only uses molecules generated by catabolism of glucose

Answer 4

c. produces more ATP per molecule of glucose than does glycolysis

Question 5

What is the function of uncoupling proteins? Mention when and where they are produced (3 marks).

Answer 5

• uncoupling proteins channel energy away from ATP synthesis to heat
• uncoupling proteins are in the inner mitochondria of membranes
• they are produced in brown fat of infants in response to cooling

Question 6

Carbohydrates make up about _______ of the weight of the average person.

a. 0.1
b. 3%
c. 15
d. 30
e. 50

Answer 6

b. 3%

Question 7

_____________ is a substance that stimulates uptake of glucose by cells and increased glycolysis.

Answer 7

insulin

Question 8

Describe what gluconeogenesis is. Mention three different types and where it occurs.

Answer 8

• gluconeogenesis is the formation of glucose from lactic acid, amino acids or fatty acids
• it occurs in the liver when there is insufficient dietary carbohydrates and the glycogen supplies have been used

Question 9

_______________ is a substance that stimulates gluconeogenesis.

Answer 9

glucagon (or catecholamines)

Question 10

Extremely low blood glucose levels would result in impairment of the function
of _________________________.

Answer 10

nervous tissue, especially higher brain functions

Question 11

Glycogen is most prevalent in two tissues: _______________ and
_________________.

Answer 11

skeletal muscle and the liver

Question 12

Describe when glycogenesis is most likely to occur and name the hormone
that stimulates it.

Answer 12

• occurs when concentration of glucose in the blood is higher than that required to power cells (after eating)
• stimulated by insulin

Question 13

Describe when glycogenolysis is most likely to occur and name the hormone
that stimulates it.

Answer 13

• occurs when dietary intake of glucose is insufficient to supply the body’s need for energy (fasting)
• stimulated by glucagon

Question 14

List the names of the four most prevalent lipids in the body (2 marks).

Answer 14

• triglycerides
• fatty acids
• phospholipids
• cholesterol

Question 15

Lipids make up about _______ of the weight of the average person.
a. 0.1 b. 3% c. 15 d. 30 e. 50

Answer 15

c) 15%

Question 16

Briefly describe the two main steps in lipogenesis

Answer 16

• fatty acids are synthesized by the stepwise addition of 2 carbon units from malonyl CoA
• three fatty acids are joined with a glycerol molecule

Question 17

List three tissues in which lipogenesis is most common.

Answer 17

• adipose tissue
• liver
• mammary gland

Question 18

Briefly describe the role of malonyl CoA in lipid metabolism.

Answer 18

-malonyl CoA is a 3 C molecule that releases 2 C units that combine to form fatty acids

Question 19

List three kinds of lipids that incorporate fatty acids in their synthesis.

Answer 19

• triglycerides
• phopholipids
• cholesterol
• prostaglandins

Question 20

Describe the composition and location of adiposomes.

Answer 20

droplets of triglycerides surrounded by a layer of phospholipids in the cytoplasm of adipocytes