Exam 3 Content Flashcards by Emily Vianney

What is the first step of glycolysis?

glucose –> glucose-6-phosphate (hexokinase)

How well did you know this?

Not at all

Perfectly

What is the second step of glycolysis?

Glucose-6-phosphate —> Fructose-6-phosphate (phosphoglucose isomerase)

How well did you know this?

Not at all

Perfectly

What is the third step of glycolysis?

Fructose-6-Phosphate –> fructose- 1,6- biphosphate (phosphfructokinase)

How well did you know this?

Not at all

Perfectly

What is the fourth step of glycolysis?

Fructose-1,6- biphosphate—> DHAP and GAP (aldolase)

How well did you know this?

Not at all

Perfectly

What is the fifth step of glycolysis?

DHAP—> GAP (triose phosphate isomerase)

How well did you know this?

Not at all

Perfectly

What is the sixth step of glycolysis?

GAP—> 1,3-biphosphoglycerate (glyceraldehyde 3- phosphate dehydrogenase

How well did you know this?

Not at all

Perfectly

What is the seventh step of glycolysis?

1,3-biphosphoglycerate—> ATP and 3-phosphoglycerate (phosphoglycertae kinase)

How well did you know this?

Not at all

Perfectly

What is the 8th step of glycolysis?

3-phosphoglycerate –> 2-phosphoglycerate (phosphoglycerate mutase)

How well did you know this?

Not at all

Perfectly

What is the 9th step of glycolysis?

2-phophoglycerate—> PEP (enolase)

How well did you know this?

Not at all

Perfectly

What is the tenth step of glycolysis?

Phosphoenolpyruvate —> ATP and Pyruvate (pyruvate kinase)

How well did you know this?

Not at all

Perfectly

What step is the rate limiting step for glycolysis?

step 3

How well did you know this?

Not at all

Perfectly

what steps are irreversible in glycolysis?

steps 1,3, and 10

How well did you know this?

Not at all

Perfectly

What happens without the synthesis of NAD+

glycolysis cannot continue

How well did you know this?

Not at all

Perfectly

How is NAD+ regenerated?

oxidation of pyruvate to CO2 or by the formation of ethanol or lactate from pyruvate

How well did you know this?

Not at all

Perfectly

What is NAD+ derived from

Vitamin b3 (niacin)

How well did you know this?

Not at all

Perfectly

What are fermentations?

ATP generating pathways in which electrons are removed from one organic compound and passed to another organic compound

How well did you know this?

Not at all

Perfectly

What are the steps of alcoholic or ethanol fermentation?

(a molecule from glucose forms 2 molecules of ethanol)
alcohol dehydrogenase regenerates NAD+ in a 2 step process

How well did you know this?

Not at all

Perfectly

What is lactic acid fermentation

NADH is oxidized by converting pyruvate to lactate in a reaction catalyzed by lactate dehydrogenase

conversion of glucose molecule into 2 lactic acid molecules

How well did you know this?

Not at all

Perfectly

What is the ultimate electron donor in lactic acid fermentation and alcoholic fermentation?

GAP

How well did you know this?

Not at all

Perfectly

What is the ultimate electron acceptor in lactic acid fermentation?

Pyruvate

How well did you know this?

Not at all

Perfectly

What is the ultimate electron acceptor in alcoholic fermentation?

acetal aldehyde

How well did you know this?

Not at all

Perfectly

how does galactose enter the tissue?

As glucose-6-phosphate

How well did you know this?

Not at all

Perfectly

How does fructose enter the tissue and the liver?

in most tissue fructose is phosphorylated by ketohexokinase but in the liver fructose is metabolized by fructose-1-phosphate pathway

How well did you know this?

Not at all

Perfectly

Why is excess fructose linked to obesity,fatty liver, and type 2 diabetes ?

because the key regulator enzyme of glycolysis phosphofructokinase is bypassed and excess acetyl CoA is synthesized and converted to fats

How well did you know this?

Not at all

Perfectly

What are the enzymes that regulate glycolysis ?

hexokinase, PFK, pyruvate kinase

How is hexokinase inhibited? in muscle

by its own product glucose-6-phosphate

How is PFK inhibited? in muscle

- low pH - ATP

What prevents ATP from inhibiting PFK? in muscle

- AMP blocking allosteric site, which prevent inhibition by ATP

How is pyruvate kinase inhibited? in muscle

allosterically inhibited by ATP

What stimulate pyruvate kinase

fructose-1,6- biphosphate

When does hexokinase glucose-6-phosphate build up?

only builds up if the other two latter enzymes are inhibited

what is a isozyme?

proteins with different amino acid sequence but the same function

What happens when glucose levels are low?

GKRP sequesters glucokinase in the nucleus

When is glucokinase active?

only after a meal

What are the regulators of PFK in the liver?

Citrate (inhibits) and fructose 2,6-biphosphate (activator)

What are the two steps in alcohol fermentation?

1. pyruvate --> acetaldehyde (Pyruvate decarboxylase) 2. acetaldehyde--> Ethanol (alcohol dehydrogenase

Is more energy released when a carbon is more reduced or more oxidized

The more reduced a molecule is the more energy that is released upon oxidation (so the more hydrogens the more energy that is released during oxidation)

When a carbon molecule is oxidized what can it form

Oxidation of a carbon molecule may form something with high phosphoryl transfer potential which can then be used to make ATP

What does ATP carry

phosphoryl groups

What does NAD+ and FAD carry

electrons

What does acetal CoA carry

acyl groups

What does NADP+ carry

electrons in anabolism reactions

Where is FAD derived from

Riboflavin B2

Where is NAD+ derived from

Nicotinic acid (niacin,B3)

Where is coenzyme A derived from

pantothenic acid (B5)

How are metabolism processes regulated

1. Amount of enzymes present 2. Catalytic efficiency of enzymes 3. Accessibility of substrates

Why does ATP have a high phosphoryl-transfer potential

1. Charge repulsion 2. Resonance stability 3. Increase in entropy 4. Stabalization of ADP and pi by hydration

what is glucogenesis?

The synthesis of glucose from pyruvate

What is the major site of glucogenesis

The liver

How is pyruvate formed

by lactate in the liver by lactate dehydorgenase

What steps must be bypassed in glucogenesis

steps 1,3, and 10 the irversible steps of glycolysis

to form PEP from pyruvate what enzymes are required?

1. pyruvate carboxylase 2. phosphoenolpyruvate

what is step one of glucogenesis

the conversion of pyruvate into oxaloacetate this takes place in the mitochondria it is then reduced to malate where it is transported to the cytoplasm and oxidized back to oxaloacetate

What is step 2 of glucogenesis

PEP is synthesized from ocaloacetate by PEPCK

How does glucogenesis occur

in the reverse order of glucogenesis besides the fact that the irreversible steps need to be bypassed

what is step 9 of glucogenesis?

Fructose 1,6-biphosphate ---> fructose-6-phosphate (fructose 1,6-biphosphotase

what is step 10 of glucogenesis?

another glycolytic enzyme is reused

What is step 11 of glucogenesis?

glucose-6-phosphate is transported into the lumen of the endoplasmic reticulum integral membrane catalyzes glucose-6-phosphate---> glucose

What are the energy molecules used to form one molecule of glucose?

4 ATP 2 GTP 2 NADH

What is the type of regulation used by glycolysis and glucogenesis?

reciprocal regulation --> one pathway is active while the other pathway is inactive

when is glucogeneis and glycolysis favored?

When ATP is need glycolysis is favored when glucose is needed glucogenesis is favored

What are the main regulatory sites

1. Fructose 1,6-biphosphate and glucose 6 phosphate 2. PEP and pyruvate

What is the key regulator of glucose in the liver

Fructose 2,6-biphosphate

What is Fructose-2,6-biphosphate made and broken down by?

PFK-2

When is Fructose-2,6-biphosphate made and when is it broken down

made when glucose is abundant and broken down when glucose levels are low

What is the Cori cycle?

lactate produced by muscle contraction is released into the blood the liver removes the lactate and converts it into glucose which is then released into the blood

Exam 3 Content Flashcards

(66 cards)