Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Kaplan Biochem > Chapter 9 - Carbohydrate Metabolism 1 > Flashcards

Chapter 9 - Carbohydrate Metabolism 1 Flashcards

1
Q

What is normal blood glucose concentration?

A

around 100 mg/dL (5.6 mM), and the normal range is 4-6 mM

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

GLUT 2

A

low-affinity transporter in hepatocytes and pancreatic cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

GLUT 4

A

in adipose tissue and muscle, responds to the glucose concentration in peripheral blood; rate of glucose transport in these two tissues is increased by insulin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What happens to GLUT 4 transporters when insulin levels are decreased?

A

the number of GLUT 4 transporters on the plasma membranes decreases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the rate-limiting enzyme of glycolysis?

A

phosphofructokinase-1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the rate-limiting enzyme of fermentation?

A

lactate dehydrogenase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the rate-limiting enzyme of glycogenesis?

A

glycogen synthase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the rate-limiting enzyme of glycogenolysis?

A

glycogen phosphorylase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the rate-limiting enzyme of gluconeogenesis?

A

fructose-1,6-bisphosphatase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the rate-limiting enzyme of pentose phosphate pathway?

A

glucose-6-phosphate dehydrogenase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the importance of hexokinase?

A

in most tissues, inhibited by its product glucose-6-phosphate, low Km (reaches max velocity at low [glc]

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the importance of glucokinase?

A

in hepatocytes and pancreatic beta-islet cells (along with GLUT 2), high Km, induced by insulin in hepatocytes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Phosphofructokinase-1 (PFK-1)

A

PFK-1 is rate-limiting enzyme and main control point in glycolysis, it’s inhibited by ATP and citrate, activated by AMP; insulin stimulates and glucagon inhibits PFK-1 in hepatocytes by an indirect mechanism involving PFK-2 and fructose 2,6-bisphosphate,

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Phosphofructokinase-2 (PFK-2)

A

glucagon inhibits PFK-2, which lowers F2,6-BP and inhibits PFK-1, PFK-2 is mostly in the liver

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Glyceraldehyde-3-Phosphate Dehydrogenase

A

catalyzes an oxidation and addition of inorganic phosphate (Pi) to its substrate; creates a high-energy intermediate 1,3-bisphosphoglycerate + reduction of NAD+ to NADH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

3-PG Kinase

A

transfers high-energy phosphate from 1,3-BPG to ADP to form ATP and 3-PG

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Substrate-Level Phosphorylation

A

ADP is directly phosphorylated to ATP using a high-energy intermediate

18
Q

Pyruvate Kinase

A

catalyzes a substrate-level phosphorylation of ADP using the high-energy substrate PEP

19
Q

Fermentation

A

key enzyme is lactate dehydrogenase which oxidizes NADH to NAD+, replenishes oxidized coenzyme for G3P; main objective is to replenish NAD+

20
Q

Dihydroxyacetone phosphate (DHAP)

A

used in hepatic and adipose tissue for triacylglycerol synthesis; DHAP is formed from F1,6-BP, can be isomerized to G3P which can convert to glycerol

21
Q

How is ATP gained during anaerobic respiration?

A

1,3-BPG and PEP are high-energy intermediates used to generate ATP by substrate-level phosphorylation

22
Q

How Glycolysis Pushes Forward the Process: Kinases

A

Hexokinase, Glucokinase, PFK-1, Pyruvate Kinase

23
Q

How does adaptation to high altitudes (low pO2) work?

A

Increased respiration, increased O2 affinity for Hb (initial), increased rate of glycolysis, increased [2,3-BPG] in RBCs (12-24 hr period), normalized O2 affinity for Hb restored by the increased level of 2,3-BPG, increased Hb (over days to weeks)

24
Q

Glycolysis in Erythrocytes

A

anaerobic glycolysis represents the only pathway for ATP production, yielding a net 2 ATP per glucose

25
Q

Why do red blood cells have bisphophoglycerate mutase?

A

to produce 2,3-BPG from 1,3-BPG in glycolysis

26
Q

2,3-BPG

A

binds allosterically to the beta-chains of hemoglobin A (HbA), decreases affinity for O2, goal is to unload O2 in tissues

27
Q

What physiological changes promote a rightward shift of the oxygen dissociation curve (the Bohr effect)?

A

High 2,3-BPG, low pH, high [H+], high pCO2

28
Q

The Bohr Effect

A

increases in CO2 partial pressure of blood or decreases in blood pH result in a lower affinity of Hb for O2

29
Q

Galactose Metabolism

A

lactose is a disaccharide that is hydrolyzed to galactose and glucose by lactase

30
Q

Pyruvate Dehydrogenase Complex (PDH)

A

irreversible, cannot be used to convert acetyl-CoA to pyruvate or glucose, activated by insulin in the liver, in the nervous system it is not responsive to hormones

31
Q

Glycogenesis

A

synthesis of glycogen granules, begins with a core protein called glycogenin

32
Q

Glycogen Synthase

A

rate-limiting enzyme of glycogen synthesis, and forms the alpha-1,4 glycosidic bond found in the linear glucose chains of the granule, stimulated by G6P and insulin, it is inhibited by epinephrine and glucagon through a protein kinase cascade that phosphorylates and inactivates the enzyme

33
Q

Branching Enzyme (Glycosyl alpha-1,4:alpha-1,6 Transferase)

A

introduces alpha-1,6-linked branches into the granule; hydrolyze one of the alpha-1,4 bonds to release a block of oligoglucose, which is moved and added to a slightly different spot via an alpha-1,6 bond to make a branch

34
Q

Glycogen Phosphorylase

A

breaks alpha-1,4 glycosidic bonds, releasing G1P from periphery of granule

35
Q

Debranching Enzyme (Glucosyl alpha-1,4:alpha-1,4 Transferase and alpha-1,6 Glucosidase)

A

two-enzyme complex: one moves the terminal end of a glycogen chain to the branch point (alpha-1,4:alpha-1,4 transferase), and one removes glucose monomer at branch point (alpha-1,6)

36
Q

What are important substrates of gluconeogenesis?

A

Glycerol-3-phosphate
Lactate (from anaerobic glycolysis)
Glucogenic amino acids (from muscle proteins)

37
Q

What are glucogenic amino acids?

A

All AAs except leucine and lysine, can be converted to intermediates that feed into gluconeogenesis

38
Q

What are ketogenic amino acids?

A

can be converted into ketone bodies, can be used as an alternative fuel mainly during prolonged starvation

39
Q

Pentose Phosphate Pathway (PPP) or Hexose Monophosphate (HMP) Shunt

A

two major functions: production of NADPH and serve as a source of ribose 5-phosphate for nucleotide synthesis

40
Q

Glucose-6-phosphate Dehydrogenase

A

rate-limiting enzyme of the PPP which is activated by NADP+ and insulin; inhibited by NADPH

Kaplan Biochem (6 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions