Glycolysis

Question 1

What are the 3 stages of obtaining energy from food?

Answer 1

1. large food molecules are broken down through digestion
2. small molecules made into key molecules of metabolism ie. acetyl CoA
3. ATP is produced from the complete oxidation of acetyl CoA

Question 2

Starch, glycogen are broken down by ___, ____ and oligosaccharides by ___ and ____ amylase.

Answer 2

glucose, maltose

saliva, pancreatic

Question 3

cellulose is coveted to ____ by cellulase in cows

Answer 3

glucose

Question 4

Explain how lactose, sucrose and maltose are broken down in the small intestine.

Answer 4

Lactose>glucose + fructose (by fructose/ B-galactosidase)

sucrose>glucose + fructose (by sucrase)

maltose> glucose (by maltase)

Question 5

Monosaccharides are transported into the ___ and ___

Answer 5

cells, bloodstream

Question 6

What does GLU2T do and where?

Answer 6

Pancreas= regulates of insulin

Liver= removes excess glucose from blood

Question 7

what does GLUT4 do and where?

Answer 7

Muscle and fat cells= amount in muscle plasma membrane increases w/endurance training

Question 8

First 5 reactions (2 parts) of glucose to pyruvate conversion:

Answer 8

1. Glucose is converted into 2 glyceraldehyde-3-phosphate molecules (2 molecules of ATP are used)
2. Energy consuming pathway

Question 9

Last 5 reactions of glucose to pyruvate (3 parts) reaction:

Answer 9

1. G3P is converted into pyruvate and energy is produced
2. energy producing pathway
3. glucose is converted into 2 pyruvate molecules

Question 10

What are the 2 stages of glycolysis?

Answer 10

1. traps glucose in the cell and modifies it so that it can be cleaved into pairs of phosphorylates 3-carbom compounds
2. oxidizs 3-carbon compounds to pyruvate while generating two molecules of ATP

Question 11

Hexokinase reaction in muscle. Enzyme and inhibition by G6P or not

Answer 11

Hexokinase 1, inhibited by G6P

non-specific

Question 12

Hexokinase reaction in liver. Enzyme and inhibiton by G6P or not.

Answer 12

glucokinase, not inhibited by G6P

specific

Question 13

turning glucose into G6P is an ____ reaction, however, coupled with the hydrolysis of ____ to make it thermodynamically favorable

Answer 13

unfavorable, ATP

Question 14

T/F High amounts of ATP slows down reaction velocity of G6P.

Answer 14

true

Question 15

What are the products of glycolysis?

Answer 15

2 pyruvate, 2 ATP (4 produced and 2 used), 2 NADH (2.5 ATP per NADH molecule= 5 ATP)

Total energy= 7 ATP

Question 16

6 types of reactions

Answer 16

1. Phosphoryl transfer- kinases
   (phosphoryl > ATP > glycolytic intermediate and vice-versa)
2. phosphoryl shift- mutase
   (shift w/in a molecule from 1 oxygen to another)
3. isomerization- isomerases
   (interconversion between ketone and an aldose)
4. dehydration - enolase
   (removal of water molecule)
5. aldol cleavage - aldolase
   (Split of C-C bond)
6. dehydrogenation- dehydrogenase
   (oxidation-reduction reaction)

Question 17

3 functions of Phosphate group

Answer 17

1. gives phosphorylated intermediated a negative charge. glucose can get in and out while lactate and pyruvate only can get out)
2. essential for formation of ATP from ADP
3. serve as recognition for the proper fit of the intermediates to the active sites of their corresponding enzymes

Question 18

What is Fermentation

Answer 18

ATP-generating pathways where electrons are removed from one organic compound and passed to another

Question 19

2 reactions involved in Metabolism of Pyruvate to Ethanol

Answer 19

1. decarboxylation reaction that is catalyzed by the enzyme pyruvate decarboxylase.
   - pyruvate > acetaldehyde
   - carboxyl group comes off pyruvate molecule as CO2
   - enzyme required vitamin thiamine (B1)
   - pyruvate decarboxylase has TPP as a prosthetic group
   - irreversible
2. Oxidation reduction reaction is catalyzed by the enzyme alcohol dehydrogenase.
   - acetaldehyde > ethanol
   - acetaldehyde = reduced while NADH = oxidized > NAD+

Net energy= 2 ATP since hycolysis is oxidized in second step-

Question 20

3 reactions for the metabolism of fructose

Answer 20

• can be directly converted to F6P in adipose tissue>catylized by hexokinase> glycolytic pathway
• In the liver undergoes 2 reactions before entering the pathway
  1. Fructose= phosphorylated by fructokinase

2. F1P split into 2 three-carbon molecules (glyceraldehyde and DHAP)
   - catalyzed by F1P aldose
   - reversible
3. Glyceraldhydd is then phosphorylated into GAP
   - catylized by triose kinase

Question 21

4 steps of the metabolism of Galactose.

Answer 21

• in liver tissues
  1. Galactose> G1P by galactokinase
  2. G1P> UPD-galactose by G1P-uridyl transferase
  3. UDP-galactose> G6P by phosphoglucomutase

Question 22

What results from excess consumption of fructose? (3)

Answer 22

1. obesity
2. fatty liver
3. type 2 diabetes

Question 23

What does galactosemia cause (3) and who does it affect most?

Answer 23

1. vision impairment
2. tissue enlargement (liver)
3. mental deficiencies

occurs mainly in babies

Question 24

In Glycolytic pathways when the energy is ____ the pathways is inhibited. When it is ____ it is activated.

Answer 24

high, low

Question 25

What are the 3 pathway inhibitors?

Answer 25

1. hexokinase w/G6P
2. Phosphofructosekinase 1
3. Pyruvate Kinase

Question 26

What are the 3 pathway activators?

Answer 26

1. Phosphofructokinase 1
2. Pyruvate Kinase
3. sometimes ADP