Carbohydrates 4

Question 1

What are some tissues that completely rely on glycolysis for their energy?

Answer 1

Brain

Nervous system

RBCs

Testes

Embryonic tissue

Question 2

What happens if we have no more carboyhydrates but need more glucose?

Answer 2

It can be generated from non-carbohydrate molecules in the liver

Question 3

Why is gluconeogensis not the direct reverse of glycolysis?

Answer 3

Due to the 3 irreversible steps (steps 1, 3 and 10)

Question 4

What is gluconeogensis?

Answer 4

The generation of glucose from non-carbohydrate substances

Question 5

How many reactions are used to bypass the irreversible steps of glycolysis?

Answer 5

4

Question 6

What does the bypassing of the irreversible steps of glycolysis allow?

Answer 6

Gluconeogenesis and glycolysis to be regulated seperately

Question 7

What irreversible reaction does A and B of gluconeogenesis deal with?

Answer 7

PEP to glycolysis

Question 8

What is step A?

Answer 8

The conversion of pyruvate to oxaloacetate

Question 9

What is step B?

Answer 9

The conversion of oxaloacetate to PEP

Question 10

What do reactions A and B look like?

Question 11

What step of glycolysis does reaction C bypass?

Answer 11

F-6-P to F-1,6-bisP

Question 12

What does reaction C look like?

Question 13

Why is reaction C not the direct reverse of F-6-P to F-1,6-bisP?

Answer 13

It would require the transfer of a phosphyl group which is energetically unfavourable

Question 14

What step of glycolysis does reaction D bypass?

Answer 14

Glucose to G-6-P

Question 15

What does reaction D look like?

Question 16

Where is G-6-P converted to glucose?

Answer 16

In the lumen of the endoplasmic reticulum

Question 17

What does the conversion of G-6-P to glucose in the ER require?

Answer 17

G-6-P to be shuttled into the ER and glucose to be shuttled out, an inorganic phosphate is also shuttled out

Question 18

What does this pump controlling the conversion of G-6-P to glucose look like?

Question 19

How many points can galactose and fructose enter glycolysis?

Answer 19

Several

Question 20

What is fructose converted into to enter glycolysis?

Answer 20

Glucose-6-phosphate

Question 21

What is fructose converted into in adipose tissue to enter glycolysis?

Answer 21

Fructose-6-phosphate

Question 22

What is fructose in the liver converted into to enter glycolysis?

Answer 22

Glyceraldehyde-3-P (GAP) or dihudroxyacetone-P (DHAP)

Question 23

Where is most fructose metabolised?

Answer 23

Liver

Question 24

What pathway does fuctose use to become DHAP or GAP in the liver?

Answer 24

Fructose-1-phosphate

Question 25

How much ATP does the conversion of fructose to DHAP or GAP use?

Answer 25

1 or 2

Question 26

What does the conversion of fructose to DHAP or GAP look like?

Question 27

What is galactose converted to G-1-P through?

Answer 27

UDP-galactose

Question 28

What are the steps of galactose becoming glucose-6-phosphate to enter glycolysis?

Answer 28

1. Galactose comes in and is phosphorylated 2. UDP glucose transfers UDP molecule to galactose 3. Captures electrons by producing NADH

Question 29

What does the pentose phosphate pathway produce?

Answer 29

NADPH and pentoses (5C) sugars

Question 30

Where and what is NADPH used for?

Answer 30

Liver (fatty acid synthesis) Mammary gland (fatty acid synthesis) Adrenal cortex (steroid synthesis) RBC (antioxidant)

Question 31

What are pentoses precursers for?

Answer 31

ATP RNA DNA

Question 32

What are the two stages of the pentose phosphate pathway?

Answer 32

Oxidation (irreversible) Non oxidation (reversible)

Question 33

Is the oxidation stage of the pentose phosphate pathway reversible?

Answer 33

No

Question 34

Is the non oxidation stage of the pentose phospate pathway reversible?

Answer 34

Yes

Question 35

What happens during the oxidative stage of the pentose phosphate pathway?

Answer 35

Generates NADPH Converts G-6-P to a pentose phosphate

Question 36

What happens during the non oxidative stage of the pentose phosphate pathway?

Answer 36

Forms lots of different 3, 4, 5, 6 and 7 carbon sugars

Question 37

What does the pentose phosphate pathway look like?

Question 38

What does NADPH link?

Answer 38

Anabolic and catabolic pathways

Question 39

Are NAD⁺ and NADP⁺ the same?

Answer 39

They are both electron carriers but they are not the same

Question 40

What are NAD⁺ and NADP⁺?

Answer 40

Electron carriers

Question 41

What is NAD⁺ used for?

Answer 41

Metabolism of sugars in glycolysis and the citric acid cycle

Question 42

What is NADP⁺ used for?

Answer 42

Anabolism to make things like fatty acid

Question 43

What does breaking down ethanol require?

Answer 43

NAD⁺

Question 44

What does the breakdown of ethanol look like?

Question 45

Why does breaking down lots of ethanol inhibit gluconeogenesis?

Answer 45

Low NAD⁺ to facilitate the reaction as most has bean used to breakdown ethanol

Question 47

What does a low level of NAD⁺ lead to?

Answer 47

Lacticacidaemia (increase[blood lactate]) Hypoglycaemia (decreased [blood glucose])

Question 48

What is black water fever?

Answer 48

A difficiency of G-6-P dehydrogenase

Question 49

What does black water fever cause?

Answer 49

Low RBC NADPH levels Build up of free radicals and H₂O₂ which damages cells