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Flashcards in Test 4 Deck (21):
1

Where do Gluceogenesis occur in humans?

Liver
Kidneys
Small Intestines

2

Purpose of Glucose

-used for energy storage
-serves as a precursor for 5 carbons sugars (ribose and deoxyribose) used in nucleic acids

3

Describe the transport mechanism to bring lactate from the muscle to the liver

since the muscle does not carry out gluceoneogenesis
-lactate is transported out of the muscle, through the blood, and transported into the liver where it can be used in gluceoneogenesis
-process called the cori cycle

4

Cori Cycle

-synthesis of glucose in the liver
-transfer of glucose to muscle where it is used for ATP
-Transport of lactate back to liver where it is used for gluceoneogenesis

5

Where doe the regulatory enzyme ATP work?

inhibits glycolysis at the enzyme PFK-1 and Pyruvate Kinsae

6

Where doe the regulatory enzyme Citrate work?

inhibits glycolysis at the enzyme PFK-1

7

Where does the regulatory enzyme AMP work?

activates glycolysis at the enzyme PFK-1
inhibits gluceoneogenesis at the enzyme Fructose 1,6-phosphatase

8

Where does the regulatory enzyme Fructose 1,6-bisphosphate work?

activates glycolysis at the enzyme Pyruvate Kinase
-feed forward activation

9

Where does the regulatory enzyme Acetyl-CoA work?

activates gluceoneogenesis at the enzyme pyruvate carboxylase

10

What is a very important allosteric regulatory in Glycolysis and gluceogenesis?

Fructose 2,6-bisphosphate
-induces the glycolysis pathway by activating PFK-1
-at the same time it suppresses the gluceogenesis pathway by inhibiting the enzyme fructose 1,6-bisphosphatase

11

PKA involvement in gluceogenesis and glycolysis

-the enzyme pyruvate kinase is inhibited by phosphorylation carried out by the kinase PKA

12

Glycogen synthesis

-occurs in the liver, kidney, and small intestine

Steps:
Glucose
Glucose 6-phosphate
Glucose 1-phosphate
UDP glucose

The UDP glucose is then synthesized by the glycogen synthase to make glycogen

13

Glycogen degradation

glycogen is reacted with Pi by the enzyme polysaccharide phosphorylase to produce glucose 1-phosphate

14

Glucagon

secreted by the pancreas in response to low blood glucose levels
-role is to induce gluconeogenesis

15

How does Glucagon induce gluceogenesis?

binds to receptors in the liver that activate cAMP synthase
-cAMP synthase activates PKA

16

PKA

-phosphorylates pyruvate kinase and inhibits it, inhibiting the last step of glycolysis
-results in phosphorylation of glycogen phosphorylase-activating it- which results in synthesis of Glucose 1-phosphate from glycogen
-phosphorylates glycogen synthase which it inhibits it and no more glycogen is made

17

Insulin

-activates phosphoprotein phosphatase-1

18

Liver cells and glucagon

glucagon raises glucose concentration by producing glucose from glycogen and blocking glycogen resynthesis

19

Liver cells and insulin

insulin lowers glucose concentration by activating glycogen synthesis and blocking glycogen phosphorolysis

20

Why do other cells not have an effect on glucagon

these cells do not have glucagon receptors.
Instead muscle, adipocytes, and the heart respond to epinephrine to raise glucose concentration

21

What does the Pentose phosphate pathway result in?

-results in the biosynthesis of ribose 5-phosphate for nucleic acids and other 5-carbon sugars from glucose
-also results in two reduced coenzymes (NADPH)