lecture 8:precursors of gluconeogenesis, cori cycle, hormonal regulation, beginingn of PPP

Question 1

is gluconeogenesis just the reverse of of glycolysis

Answer 1

no

Question 2

why is gluconeogenesis not the reverse of glycolysis

Answer 2

because there are 3 metabolic pathways that are unidirectional (not revresible)

ex: pyruvate cannot go back to phosphoenolpyruvate since it is unidirectional

Question 3

why are some reactions reversible in glycolysis

Answer 3

to allow the reaction to move in different directions depending on the amount of substrate present

Question 4

where does gluconeogenesis occur

Answer 4

in the liver

Question 5

what is the enzyme taht allows glucose to go back into the circulation from the liver and what is its function

Answer 5

glucose 6 phosphotase

glucose 6 phosphate to lose its phsopate (gives it to enzyme) and become glucose

Question 6

how many unique reactions are there in gluconeogenesis

Answer 6

4

Question 7

where do the unique reacitons happen

Answer 7

in the places of glycolysis that are non reversible

Question 8

what are the 4 unique reactions/enzymes in the liver for gluconeogenesis

Answer 8

glucose 6 phospate > glucose by GLUCOSE 6 PHOSPHOTASE
fructose 1-6 biphosphotate > frcutose 6 phosphate by FRUCTOSE 1-6 BIPHOPSOHOTASE
oxaloacetate > phosphoelolpyruvate by PEP CARBOXYKINASE
pyruvate > oxaloacetae by PYRUVATE CARBOXYLASE

Question 9

WHat is the first step pyruvate must to to because phosphoemolpyruvate

Answer 9

must turn into oxaloacetate by pyruvate carboxylase first

Question 10

what happens to oxaloacetate

Answer 10

goes to phosphoenolpyruvate by PEP carboxykinase

Question 11

true or false: all the precursors enter gluconeogenesis at the same time

Answer 11

false

Question 12

explain glycerol entering the gluconeogenesis pathway

Answer 12

glycerol (broken from fatty acid) enters liver and can be phosphorylated
> it can go to glycerol 3 phosphate (gets energy)
> it then has enough energy to enter and go through the glucogenogenitic pathweay and eventually become glucose

Question 13

explain alanine entering the gluconeogenic pathway

Answer 13

Alanine coming from a protein can easily be changed into pyruvate by losing a nitrogen group
ALANINE AMINO TRANSFERASE will change it to pyruvate and then continue the pathway as normal

Question 14

explain lactate (glycolitic end product) entering the gluconeogetic pathway

Answer 14

Lactate can easily go to pyruvate by the enzyme lactate dehydrogenase

Question 15

true or false: lactate and alanine enter the gluconegenesis process at the same place

Answer 15

true, both turn into tpyurvate by different enzymes

Question 16

when is the cori cycle used

Answer 16

during high intensity exercise (or recovered)
cellular hypoxia (altitude)

Question 17

why does cori cycle use gluconeogenesis

Answer 17

it uses it to bring the cells back down to homeogenesis

ex: eleminate high levels of lactic acid in the blood stream

Question 18

explain the cori cycle

Answer 18

When lactate exits the skeletal muscle and into the circulation, there will be an increase in lactic acid
To prevent lactic acidosis, the lactate will be taken up by the liver and be transfered into glucose so the cycle continues

Question 19

what is the energy cost for gluconeogenesis

Answer 19

6 atp

Question 20

what are the 3 main hormones that regulate gluconeogenesis

Answer 20

+ glucagon
+glucocorticords (cortisol)
- Insulin

Question 21

where is cortisol formed

Answer 21

adrenal medulla, in the cortex

Question 22

where are the two stimulators of gluconeogenesis

Answer 22

cortisol

glucagon

Question 23

what is the inhibiot of gluconeogeneis

Answer 23

insulin

Question 24

Does glucagon normally stimulate the break down or build up of things

Answer 24

breaking down/using things

Question 25

does insulin normally stimulate the breakdown or storate or tings

Answer 25

storage

Question 26

what two hormone regulators of glucogenogenenis are also seen in glycogenolysis and glycogeneis

Answer 26

glucagon and insulin

Question 27

insulin is an inhibiot or gluconeogensis AND…

Answer 27

glycogenolysis (promotes glycogenesis)

Question 28

glucagon is an actvivator of gluconeogenesis AND

Answer 28

glycogenolysis

Question 29

what is another pathway that branches off from glycolysis

Answer 29

pentose phosphate pathway

Question 30

what is the connecting compoiund of glycoglysis =, gluconeogenis and PPP

Answer 30

glucose 6 phospate

Question 31

what is the end porducts of the PPP

Answer 31

ribose

NADPH

Question 32

what type of raection is the PPP

Answer 32

oxidative.reduction

Question 33

what is one of the main functions of the PPP

Answer 33

elimination of free radicals

Question 34

what 3 componets does PPP generate

Answer 34

1) NADPH reducing agents
2) ribose 5P
3) glycolysis intermiediations through reversible reactions

Question 35

how does glucose end up as ribose

Answer 35

Donates its electrons and hydorgens to NADP+ which gets reduced to NADPH adn then changes to a form of ribose

Question 36

what type of reactions is NADPH important for

Answer 36

ANABOLIC REACTIONS

Question 37

what are 3 examples of the functions of NADPH

Answer 37

1) fatty acid synthesis
2) glutathione reduction (important for antioxidant)
3) detoxfications

Question 38

why is generating a ribose 5 phospahte important in PPP

Answer 38

because it is a precursor for synthesis of nucleotide biosynthesis

Question 39

do the intermediates of PPP get wasted

Answer 39

no , they are able to enter glycolysis to make atp by reversible reactions

Question 40

what is the main difference between NADH and NADPH

Answer 40

There is a negatively charged phoshpate group added on to the ribose sugar for NADP