L6- Carbohydrates 1

Question 1

catabolism

Answer 1

breakdown of larger molecules into smaller ones

- energy released

Question 2

catabolic reaction involve

Answer 2

oxidation-release of H atoms

Question 3

H atoms become

Answer 3

reducing powers

Question 4

anabolism

Answer 4

synthesises larger important cellular components from smaller molecules
- uses energy

Question 5

anabolic reactions are

Answer 5

reductive (uses H+ released In catabolism)

Question 6

sources of catabolism metabolism

Answer 6

amino acid (most excreted)
fatty acids
glucose
alchohol

Question 7

acetyl co A

Answer 7

is an intermediate for all source of catabolism

Question 8

Body composition predominately

Answer 8

lipids and proteins (even though we take in more CHO than lipids and proteins)

• we are only 1% CHO

Question 9

how many stages of catabolism

Answer 9

4

Question 10

stage 1

Answer 10

breakdown of molecules into molecules that can be absorbed

Question 11

stage 2

Answer 11

glycoluysis

Question 12

stage 3

Answer 12

Kreb/TCA cycle

Question 13

stage 4

Answer 13

electron transport chain

Question 14

formula of CHO

Answer 14

(CH2O)n

Question 15

CHO contain which groups

Answer 15

aldos enad ketose groups

Question 16

monosacchirdes

Answer 16

3-9 carbons

• glucose
• fructose
• galactose

Question 17

disaccharides

Answer 17

2 units

• sucrose
• maltose
• galactose

Question 18

oligosaccharides

Answer 18

(3-12 units)

- dextrin

Question 19

polysacchride

Answer 19

10-1000 units

• glycogen
• starch
• cellulose

Question 20

glucose is a

Answer 20

major source of sugar in the blood (5mM)

Question 21

all tissue can metabolise

Answer 21

glucose

Question 22

which cell have an absolute requirement for glucose

Answer 22

• RBC
• neutrophils
• innermost cells of kidney medulla
• lens of the eye

Question 23

uptake of glucose depends on

Answer 23

[glucose]

Question 24

the CNS uses … as fuel

Answer 24

glucose (approx 140g/24h) and no the rfules

Question 25

in starvation mode the brain can evolve energy from

Answer 25

ketone bodies- body needs time to adapt

Question 26

digestion of CHO starts in

Answer 26

mouth- amylase

Question 27

amylase in the mouth breaks down starch nd glycogen to

Answer 27

dextrins

Question 28

amylase does not work in

Answer 28

the pH of the stomach

Question 29

amylase is released by the

Answer 29

pancreas | amylase- converts dextrin to monosaccharides

Question 30

disaccharide attach to

Answer 30

the brush border fo the membrane of epithelial cells

Question 31

cellulose is

Answer 31

indigestible

Question 32

why is cellulose indigestible

Answer 32

no enzyme to breakdown the B1-4 linkage present in dietary fibre - alpha and beta bonds are different

Question 33

how are monosaccharides absorbed int he blood

Answer 33

Gut into epithelial cells - Active transport (low to high conc)- energy coming from a sodium dependent glucose transport (SGLT1) Passive transport from cells to capillaries Passive transport (high to low conc) - Using GLUT transporters

Question 34

GLUT transporters

Answer 34

Glucose uptake into cells from blood in via facilitated diffusion using transport proteins (GLUT1-5) - GLUTs can be hormonally regulated.

Question 35

GLUT 1

Answer 35

fetal tissue, adult erythrocytes, BBB

Question 36

GLUT 2

Answer 36

kidney, liver, pancreatic beta cells, small intestines

Question 37

GLUT 3

Answer 37

neurones and palcenta

Question 38

GLUT 4

Answer 38

adipose tissue, striated muscle

Question 39

GLUT 4 is regulated by

Answer 39

insulin

Question 40

GLUT 5

Answer 40

spermatozoa and intestine

Question 41

lactose intolerance causes

Answer 41

Causes… Bloating, flatulence, vomiting, diarrhea etc.

Question 42

types of lactose deficiency

Answer 42

- primary lactase deficiency - secondary lactase deficiency - congenital lactase deficiency

Question 43

primary lactase deficiency

Answer 43

• Primary lactase deficiency o Only occurs in adults o Absence of lactase persistence allele o High prevalence in Northwest Europe

Question 44

secondary lactase deificnecy

Answer 44

``` o Damage to small intestine  Gastroenteritis  Coeliac disease  Crohns disease  UC o Occurs in both infants and adults o Generally reversible ```

Question 45

• Congenital lactase deficiency

Answer 45

o Extremely rare o Autosomal recessive defect in lactase gene o Cannot digest breast milk

Question 46

stage 2 (glycolysis)- function

Answer 46

o Oxidation of glucose o Production of 2 NADH/ glucose molecule o Synthesis of 2 ATP molecules from ADP/ glucose molecule o Production of 2 pyruvate (C3) / 1 glucose molecule (C6)

Question 47

features of glycolysis

Answer 47

o Central pathway of carbohydrate catabolism o Occurs in all tissues o Cytosolic o Exergonic and oxidative- releases energy and hydrogen o No loss of CO2 o With one additional enzyme (LDH), the pathway can operate anaerobically o Irreversible pathway

Question 48

key enzymes of glycolysis

Answer 48

Key enzymes: Hexokinase (key glucose sensor), Phosphokinase-1 and pyruvate kinase

Question 49

why so many steps in glycolysis (10 enzymes, 5 coenzymes, 9 intermediates)

Answer 49

- Chemistry easier in small stages - Efficient energy conservation - Gives versatility o Interconnection with other pathways o Production of useful intermediates o Allows part to be used in reverse - Can be controlled

Question 50

glycolysis clinical application

Answer 50

- Can be used in the diagnosis of cancers o Rate of glycolysis up to 200 times greater in cancer o Can measure uptake of FDG (radioactive modified hexokinase substrate) o Imaging with positron emission tomography