Kaplan Biochemistry: Chapter 9 Carbohydrate Metabolism I

Question 1

what type of cells would you find a GLUT 2 transporter

Answer 1

hepatocytes and pancreatic cells.

Question 2

Km for GLUT 2 is ___

Answer 2

high.
blood travelining through the hepatic portal vein from the intestine is rich in glucose after a meal. Glut 2 captures excess glucose primarily for STORAGE. with a high Km, GLUT 2 only captures EXCESS glucose.

Question 3

what type of glucose transporter is housed by adipose tissues and muscles

Answer 3

GLUT4.

Question 4

effects of insulin on GLUT4

Answer 4

when insulin binds upon a large meal, GLUT 4 transporters are brought to the surface and begin to pump glucose into the cell.

Question 5

where does glycolysis occur

Answer 5

in the cytoplasm of cells.

Question 6

yield of glycolysis of ONE glucose

Answer 6

2 pyruvates, 2 NADH, and net 2 ATP.

Question 7

name the intermediates of glycolysis

Answer 7

1. glucose + ATP
2. glucose 6 phosphate
3. fructose 6 phosphate + ATP
4. fructose 1,6 biphosphate
5. dihydroxyacetone phosphate, glyceraldehyde 3 phosphate
6. 1,3 diphosphoglycerate + NADH
7. 3 phosphoglycerate + ATP
8. 2 phosphoglycerate
9. phosphoenolpyruvate
10. pyruvate + ATP

Question 8

in fermentation, pyruvate is oxidized to ___, creating ___

Answer 8

oxidized to lactate, creating NAD+

Question 9

outline GALACTOSE metabolism.

Answer 9

mainsource of galactose is lactose, which is glucose-galactose.

1. galactose gets converted to galatose 1 Phosphate via galactokinase
2. gal-1-P gets converted to glucose-1-P via uridyltransferase.
3. glu-1-P can undergo glycolysis by getting converted to glucose - 6 PHOSPHATE (via phosphoglucomutase), or be converted to glucose and then glycogen for storage.

Question 10

sucrose is broken down into

Answer 10

glucose and fructose.
sucrose is hydrolyzed by disaccharidases at the brush boarder, and the resulting monosaccharides are absorbed into the hepatic portal vein.

Question 11

outline FRUCTOSE metabolism

Answer 11

liver phosphorylates fructose into fructose 1-P via fructokinase
fructose 1 P gets cleaved into dihydroxyacetone phosphate and glyceraldehyde via aldolase. these products can undergo glycolysis, glycogenolysis and gluconeogenesis.

Question 12

enzyme responsible for converting pyruvate to acetyl coA

Answer 12

pyruvate dehydrogenase. desults in acetyl coA and NADH.

Question 13

what type of anomer is found in glycogen

Answer 13

alpha glucoses with 1-4 linkages and 1-6 linkages.

Question 14

outline glycogenesis

Answer 14

1) glucose is converted to gluocse 6 p
2) glucose 6 P is converted to glucose 1 P
3) glucose 1 P is activate via UTP coupling, which forms UDP-glucose.
4) Glycogen synthase adds the UDP glucose to the anomeric carbon of a preexisting glycogen chain.

Question 15

____ ___ makes ____ glycosidic bonds between glucose 1 phosphate and the preexisting glycogen chain, and ____ enzymes makes the ____ linkages

Answer 15

GLYCOGEN SYNTHASE makes 1-4 ALPHA glycosidic bonds between glucose 1 phosphate and the preexisting glycogen chain, and BRANCHING enzymes makes the 1-6 ALPHA linkages

Question 16

ROLE OF phosphosphatase

Answer 16

removes a phosphate from a molecule

Question 17

___ __ BREAKS alpha 1-4- glycosidic bonds of glycgen during glycogenolysis

Answer 17

glycogen phosphorylase. it then releases a glucose-1-phosphate

Question 18

T/F: glycogen phosphorylase can break the 1-6 linkages of glycogen

Answer 18

false. you need a debranching enzyme. removes the branch and reattaches to the end of the 1-4-chain, where glycogen phosphorylase can break the branch.

Question 19

outline the parts of gluconeogenesis that occur in the mitochondria, and the parts that take place in the cytoplasm

Answer 19

mito: pyruvate is converted to oxaloacetate
cytoplasm: OAA SHUTTLES to the cytoplasm via MALATE ASPARATE SHUTTLE and gets converted to PEP via PEPcarboxykinase using GTP
- PEP turns into glyceraldehyde -3-P using the reverse steps of glycolyss

Question 20

PFK-1 catalyzes fructose 1 P into fructose 1-6biP. What catalyzes the reverse reaction

Answer 20

fructose-1-6 biphosphatase

Question 21

hexokinase catalyzes glucose into glucose-6-P. what catalyzes the reverse reaction

Answer 21

glucose-6-phosphatase.

Question 22

what does pyruvate carbolxylase do

Answer 22

creates oxaloacetate from pyruvate and CO2.

Question 23

2 main products of pentose phosphate pathway and its purpose

Answer 23

1) NADH
2) ribose 5 phosphate
for nucleotide synthesis.

Question 24

T/F the pentose phosphate pathway is reversible

Answer 24

false

Question 25

what induces the PP pathway? What inhibits it?

Answer 25

induces: insulin
inhibition: NADPH or ribose 5 phosphate.

Question 26

_____ is a biological reducing agent that can reverse radical formation before damage is done to the cell

Answer 26

Glutathione. its purpose is to nutralize H2O2 that is produced during aerobic metabolism.