lecture 21

Question 1

many intermediates formed during glycolysis and the CAC serve as

Answer 1

precursors to the production of important molecules like amino acids, nucleotides and fats

Question 2

what lies at the heart of the metabolic pathway?

Answer 2

glycolysis and CAC
but they only represent a fraction of all the rxns that occur in the cell

Question 3

the balance between glycolysis and gluconeogenesis is made by?

Answer 3

positive and negative feedback inhibition

Question 4

gluconeogenesis is energetically expensive! it requires…

Answer 4

4 ATP and 2 GTP for each molecule of glucose produced

Question 5

why is it important to carefully regulate glycolysis and gluconeogenesis?

Answer 5

so energy is not wasted

Question 6

glucose can be stored as

Answer 6

glycogen (in the cytoplasm of liver and muscle cells)

Question 7

how are fats stored?

Answer 7

as triacylglycerols in cells known as adipocytes

Question 8

plants store fats and starch in

Answer 8

chloroplasts

Question 9

starch=

Answer 9

a branched polymer of glucose that is similar to glycogen

Question 10

the controlled, stepwise oxidation of sugar allows the

Answer 10

capture of energy in small portions (captured by activated carriers ATP and NADH)

Question 11

3 stages of catabolism

Answer 11

1. Breakdown of food to subunits
2. Breakdown of subunits to acetyl coA
3. Oxidation of acetyl coA

Question 12

Glycolysis 2 phases

Answer 12

preparatory phase= an input of energy (2 ATP) is required to activate the glucose molecule

payoff phase= energy investment pays off in the form of 4 ATP and 2 NADH for each glucose

Question 13

what is the net result of glycolysis?

Answer 13

glucose –> 2 pyruvate + 2 ATP + 2 NADH

Question 14

does glycolysis involve any oxidation reactions?

Answer 14

yes!

Question 15

fermentation

Answer 15

= the breakdown of organic molecules in the absence of oxygen
- Ex. occurs in active muscle cells and in yeast
- Fermentation regenerated the NAD+ needed for glycolysis

Question 16

why is fermentation especially important in brewing and breadmaking?

Answer 16

The byproducts of fermentation include CO2 and ethanol. CO2 helps bread rise. Ethanol is the key component in most alcoholic beverages.

Question 17

Citric acid cycle (CAC)

Answer 17

Or the tricarboxylic acid cycle (TCA) or the Krebs cycle
- Takes place in the mitochondrial matrix (does not use O2 directly but depends on it! O2 is used in the ETC which regenerated NAD+)

Question 18

each turn of the CAC cycle produces

Answer 18

3 NADH, 1 GTP, 1 FADH2 and releases 2 molecules of CO2

and results in regeneration of oxaloacetate

Question 19

ETC drives the synthesis of

Answer 19

most of the ATP in most cells
(About 30 ATP from 1 molecule of glucose)

Question 20

ETC takes place using

Answer 20

using proteins embedded in the inner mitochondrial membrane

Question 21

gluconeogenesis

Answer 21

= the production of glucose from other small molecules (like pyruvate)

Question 22

glucose can be stored as

Answer 22

glycogen (in cytoplasm of muscle and liver cells)

Question 22

Why is it important to carefully regulate glycolysis and gluconeogenesis?

Answer 22

So energy is not wasted!

Question 23

fats can be stored as

Answer 23

triaglycerols in cells known as adipocytes

Question 24

plants store fats and starch in

Answer 24

chloroplasts