Fermentation And Regulation Of Glycolysis

Question 1

What are the two types of fermentation

Answer 1

Alcoholic

Lactic acid

Question 2

What is fermentation

Answer 2

After pyruvate is formed from glycolysis, if the cell has no oxygen (anaerobic)

fermentation to form either ethanol or lactic acid occurs

Question 3

Why does fermentation happen

Answer 3

To provide redox balance in the cell

In glycolysis, NADH is formed, in fermentation NAD+ gets formed As a balance

It keeps glycolysis happening under anaerobic conditions

Question 4

What are the acceptors and donors of the electrons in fermentations

Answer 4

Organic compounds (not o2 because it’s not present)

Question 5

Describe the process of alcoholic fermentation

Answer 5

Pyruvate decarboxylase turns pyruvate to acetaldhyde (also realese co2)

Acetaldehyde accepts electrons (gets reduced) from Nadh through the use of the enzymes alchohol dehydrogenase

This forms ethanol and NAD+

Question 6

Doescribe the process of lactic acid fermentation

Answer 6

Pyruvate gets reduced by Nadh with the help of the enzyme lactate dehydrogenase

Lactate and NAD+ is formed

Question 7

What are obligate anaerobes

Facultative anaerobes

Answer 7

Bacteria that cannot tolerate oxygen (can’t have o2 around them, ex clostridium botulinum)

Can function with or without O2 (yeast)

Question 8

Slide 7

Answer 8

In I pad

Question 9

What are the three steps in glycolysis where regulation can occur

Answer 9

At the irreversible steps:

Hexokinase

Phsophopructokinase

Pyruvate kinase

Question 10

How does regulation happen in glycolysis

Answer 10

Allosteric effectors or covalent modification binds to one of the three enzymes to increase or decrease their activity

This regulation is tissue specific (it’s diff in muscle cells compare to liver cells)

Question 11

How is the regulation of phosphofruktokinase done

Answer 11

It’s the most important regulation

It’s caused by allosteric inhibition of the enzyme by ATP (atp binds, inhibited) because the energy charge is high (atp/amp)

If there is high atp, we don’t need glycolysis as much so the activity of the enzyme decrease, opposite for low atp (where amp binds and increases activity)

Question 12

How is the inhibition of phosphofructokinase reversed

Why not adp

Answer 12

AMP (mono phosphate) bind to the same site on the enzyme that atp does

Not adp because the. atp can be made from adp if it’s used up really quick

Amp acts as a counteracting molecule

Question 13

How is regulation of Hexokinase done

Answer 13

It gets inhibited by its product glucose 6 phosphate

If at rest, more atp inhibits pfk. This causes more fructose 6 phosphate to be made.

the equilibrium shifts to make more glucose 6 phosphate which then inhibits Hexokinase through negative feedback inhibition.

This is good because glucose 6 phosphate is use for things other than glycolysis.

Question 14

What is a commited step and what is the first one in glycolysis

Answer 14

Is the step that turns the substrate into something that has not choice but to proceeed into down a specific pathway

The conversion of fructose 6 phosphate and fructose 1,6 bi phosphate through the use of phosphofructokinase

Question 15

How does the regulation of pyruvate kinase occur

Answer 15

Depends on the energy charge of the cell (atp/amp)

It gets allosterically inhibited by atp

If low atp in the cell, pfk gets activated by amp and makes fructose 1,6 biphosphate. This then does feed forward stimulation to activate pyruvate kinase

Question 16

How does regulation in the muscle occur
When at rest

When activd

Answer 16

When at rest, inhibited glycolysis so Hexokinase is inhibits by negative feedback, atp inhibits pyruvate kinase and pfk

When active, more glycolysis so pyruvate kinase and pfk are stimulated by AMP binding to PFK

Question 17

In muscle regulation what can also inhibit pfk

Answer 17

Low ph
Due to lactose acid formation

Question 18

The liver has ______ than the muscle

Answer 18

More biochemical functions

Question 19

How does the liver store glucose

Answer 19

Stores it in the blood as glycogen

Releases it as needed

Question 20

How Is regulation in the liver done

Answer 20

Through biosynthesis where the power made from glucose is used to make building blocks for other macro molecules

Question 21

How is regulation of phosphofructokinase done in the liver

Answer 21

The ph is less important (compared to muscle) so most regulation is due to atp

A high concentration of citrate and atp inhibits PFK and makes less glycolysis

A high concentration of fructose TWO,6 bisphospohate and amp, activate PFK and does feedforward stimulation to make more glycolysis

Question 22

In the liver, when is fructose 2,6 bisphophate high

When does this mean

Answer 22

More of its is made in the liver when the glucose levels are high

F 26 p is concentration dependent

Question 23

If in the liver there is higher glucose supply, but there is also atp inhibiting what happens

Answer 23

If there’s higher glucose, there higher F 26 p

Higher F 26 p means more glycolysis

If there’s higher amount of glucose, the inhibitions by atp is lowered, and there’s more glycolysis

Question 24

How is Hexokinase regulated in the liver

Answer 24

Same a muscle cells, but the enzyme is now Hexokinase 4 (glucokinase)

Glucokianse is an isozyme of Hexokinase and can only get stimulated not inhibited (by g 6 p)

If glucose is high, glycolysis happens. If low, it leaves the glucose alone and lets of part of the body do glycolysis with it

Question 25

Km for glucose is ____ that of Hexokinase

Answer 25

50 times out of

Question 26

What are isozymes

Answer 26

They calatlyzs the same reaction

Have different kinetics/regulation, and primary structure

Question 27

How is regulation of pyruvate kinase done in the liver

Answer 27

The pyruvate kinase in the liver is in the L isozyme. (Muscle is m isozyme)

The L form is inhibited by atp, alanine, and reversible phosphorylation

When glucose is low, the kinase is phosphorylated and its activity is decreased. This causes less glycolysis

Question 28

How is glycolysis regulated by glucose transporters

Answer 28

These different transporters control the amount of available glucose in the cell for glycolysis

Glut 1 and 3 are always on

Glut 2 is only in when glucose is high

Glut 4 increases when more exercise