Carbohydrates

Question 1

what is the function of carbohydrates?

Answer 1

to store potential energy and yield it from them

cell-cell communication

Question 2

what is a carbohydrate

Answer 2

organic molecule occurring in food and living tissues etc
sugars
soluble in water

Question 3

what is a monosaccharide

Answer 3

simplest form of sugar
1 sugar monomer
examples are
glucose, fructose and galactose

Question 4

disaccharide

Answer 4

2 sugar monomers joined by a glycosidic bond
OH and anomeric carbon usually join

maltose, lactose and sucrose

Question 5

polysaccharide

Answer 5

a few monomers stitched together (large or small)

glycogen and starch

Question 6

define anomeric

Answer 6

mirror images of each other

usually carbon number 1

Question 7

why do we store glucose in polymers

Answer 7

compactness- highly ordered, neatly folded structure takes up less space
polymers aren’t really in solution which is good as free glucose would take in water surrounding it and cause the cell to burst
osmotic lysis

Question 8

what is a glycoprotein

Answer 8

more protein than carbohydrate (sugar)

increases solubility
influences protein folding/confirmation
protect the protein from degradation

Question 9

which amino acid contains sulfur atoms?

Answer 9

cysteine, methionine

Question 10

what geometrical structure does the peptide bond show?

Answer 10

planar

Question 11

what is not found in the glycogen molecule out of glycogenin and glycogen phosphorylase?

Answer 11

glycogen phosphorylase

Question 12

what is glycogenin

Answer 12

enzyme involved in converting glucose to glycogen

Question 13

what is glucose readily converted into once it enters any cell in the body

Answer 13

G-6-P so that it is trapped and can’t leave

don’t want free glucose leaving cells

Question 14

where is free glucose generated at the end of gluconeogenesis

Answer 14

in the endoplasmic reticulum

Question 15

why are fatty acid chains said to be energy rich molecules

Answer 15

they have lots of covalent bonds

Question 16

how many moles of CO2 are produced on each turn of the C.A.C

Answer 16

2

Question 17

what is amylose

Answer 17

a polymer of glucose- makes up part of starch

Question 18

what can only liver glycogen do

Answer 18

provide glucose for other tissues

Question 19

in high levels of ATP what happens to pyruvate dehydrogenase?

Answer 19

it is inactivated

Question 20

oligomycin blocks proton transport through ATP synthase. What effect does this have on a) ATP synthesis and b) electron transport?

Answer 20

both a and b reduce

Question 21

hexokinase

Answer 21

enzyme that phosphorylates glucose to make G-6-P
low km due to high affinity for glucose
low Vmax
high prevelance in tissues

Question 22

glucokinase

Answer 22

high km
high Vmax
high prevelence in liver

Question 23

which 2 enzymes are important in first rate determining step of glycolysis

Answer 23

hexokinase

glukokinase

Question 24

when is hexokinase most prevalent?

Answer 24

in state of hypoglycemia (low blood glucose)
because of low km it requires less time to fill active sites- high affinity for substrate
low Vmax means if there is a high amount of glucose then there is a higher chance of saturation and becomes ineffective quickly
so works more effectively in lower concentrations of glucose

Question 25

when is glucokinase most prevalent?

Answer 25

has high km and high Vmax this means it has a low affinity for glucose- more time taken for active sites to fill up but a high Vmax means the capacity is v high- more active sites available for longer works well in state of hyperglycaemia- more efficient than hexokinase in this state

Question 26

In vigorously working muscles glucose is converted to lactate. Why?

Answer 26

NAD+ levels in the cell are limited When O2 is limited the oxidation of NADH to NAD+ (complex 1) by the electron transport chain is insufficient to maintain glycolysis so pyruvate cannot be made diverted to make lactate

Question 27

insulin function and structure

Answer 27

a hormone that regulates glucose levels in the body lack of insulin causes type 1 diabetes structure stabilised by two disulfide bonds between peptide chains

Question 28

what is and alpha keto acid

Answer 28

it is simply the carbon skeleton of an α-amino-acid

Question 29

Structure and characteristics of glycogen

Answer 29

has alpha 1-4 linked subunits alpha 1-6 branches HIGHLY BRANCHED high amounts found in liver and skeletal muscle many non-reducing ends

Question 30

what do non-reducing ends mean for a polymer

Answer 30

it can be readily synthesised and degraded to and from monomers

Question 31

which two carbohydrates have a lot of non-reducing ends

Answer 31

glycogen | amylopectin (makes up starch with amylose)

Question 32

why are polymers not 'in solution'

Answer 32

they are osmotically inactive as if it was just free glucose, the glucose would move out the cell down its concentration gradient so being in a polymer prevents the movement

Question 33

GAGs

Answer 33

mucus and synovial fluid unbranched polymers genetic disorder involving GAGs= mucopolysaccharidoses

Question 34

Hurler syndrome

Answer 34

clouding and degradation of cornea | dementia