carbohydrate and lipid metabolism

Question 1

formation of enolate anions

Answer 1

formed from alpha beta systems, alpha carbon is slightly acidic so a strong base reacts with it to form enolates

Question 2

formation of acetals and ketals

Answer 2

alcohol attacks ethers twice to form carbons with ether linkages under acidic conditions (AASPEN + extra activation)

Question 3

what is an acetal

Answer 3

carbon with 2 ethers and one hydrogen

Question 4

what is a ketal

Answer 4

carbon with 2 ethers and 2 hydrogens

Question 5

formation of imines

Answer 5

addition of primary amines to carbonyl group of aldehyde/ketone followed by acid catalysed elimination of water

Question 6

what is an aldol reaction

Answer 6

produces an enolate from an aldehyde or ketone which then attacks another carbonyl compound to form a beta-hydroxyl carbonyl compound

Question 7

what is an elimination reaction

Answer 7

nucleophile attacks the hydrogen instead of the carbon to form an alkene

Question 8

what are the two types of monosaccharides

Answer 8

aldoses and ketoses

Question 9

what are the three common sugars

Answer 9

d-glucopyranose (all OH equatorial) , d-galactose (OH-4 axial, all others equatorial) , d-mannopyranose (OH-2 is axial, others equatorial)

Question 10

define axial

Answer 10

above/below

Question 11

define equatorial

Answer 11

away from the ring

Question 12

what is a lipid

Answer 12

defined by a physical property rather than a common structural feature, natural and not very water soluble

Question 13

hydrolysable lipid characteristics

Answer 13

tri-acyl glycerides
used for energy storage
contain alcohols and fatty acids

Question 14

non-hydrolysable lipid characteristics

Answer 14

steroid hormones - bile acids etc

Question 15

define metabolism

Answer 15

sum of all biochemical reactions

Question 16

define catabolism

Answer 16

large biochemical molecules being broken into smaller ones

Question 17

define anabolism

Answer 17

small biochemical molecules joined to larger ones

Question 18

what is ATP used for

Answer 18

energy carrier within the cell, froduced by food catabolism

Question 19

what is NAD (nicotinamide adenosine dinucleotides) used for

Answer 19

redox factor - enzyme catalysed reduction mechanism, H added across carbonyl to form alcohol

Question 20

NAD structure

Answer 20

nicotinamide, ribose, adenine and ADP

Question 21

FAD (flavin adenosine dinucleotide) structure

Answer 21

riboflavin, adenosine diphosphate

Question 22

what is FAD used for

Answer 22

redox factor - reduction is enzyme catalysed, H added across carbonyl to form alcohol

Question 23

AcetylCoA structure

Answer 23

2-aminoethanethiol, pantothenic acid and phosphorylated ADP

Question 24

role of AcetylCoA

Answer 24

acyl carrier, HS group can form thioesters

Question 25

steps in glucose metabolism

Answer 25

1. digestion 2. glycolysis - 2 pyruvate and 4 ATP 3. pyruvate - acetylcoa 4. citric acid cycle 5. electron transport chain

Question 26

products of the citric acid cycle

Answer 26

- 1 FADH - 3 NADH - 1 GTP - 2 CO 2

Question 27

what is the electron transport chain

Answer 27

a series of biochemical reactions that use electrons and hydrogen from NADH/FADH2 (from citric acid cycle) which are passed through carriers to pump H+ into the intermembrane space and then back into the matrix through ATP synthase

Question 28

products of the electron transport chain

Answer 28

for each AcetylCoA: 10 ATP are formed

Question 29

glycerol head of lipids metabolism

Answer 29

oxidised - catalysed by ATP and converted to pyruvate for citric acid cycle

Question 30

fatty acid chains metabolism

Answer 30

- combined with CoA and dehydrogenated to FADH2 - hydrated to form 2nd alcohol, - dehydrogenated to ketone to form NADH - release of another CoA - loop continues until all C2 groups broken down to produce acetylcoa which goes through citric acid cycle

Question 31

anabolic reactions of acetylcoa

Answer 31

- lipogenesis - cholesterol biosynthesis - ketogenesis

Question 32

lipogenesis

Answer 32

- fatty acid synthesis from acetylcoa - acetyl acp + malonyl acp condensated - Acetoacetyl ACP is hydrogenated using NADPH - beta hydroxybutyryl ACP dehydrated - crotonyl acp hydrogenated with nadph - forms butyryl acp

Question 33

ketogenesis

Answer 33

- 2 acetylcoa join - acetylacetylcoa - forms 3-hydroxy-emethylglutayl (also used for cholesterol) - this forms ketone bodies

Question 34

metabolism of carbon portion of amino acids

Answer 34

- triaglycerols via fatty acid synth - glucose via gluconeogenesis - ATP via citric acid - ketogenesis

Question 35

metabolism of nitrogen portion of amino acids

Answer 35

- elimination - biosynth of non-essential amino acids or other nitrogen compounds

Question 36

deamination (Schiff base)

Answer 36

oxidation and hydrogenation of an amine to form imine

Question 37

trans-amination

Answer 37

interchanging of amino group of an alpha amino acid with a keto group from an alpha-keto acid

Question 38

excess amino acids

Answer 38

transferred to glutamate and converted to urea by glutamate dehydrogenase and the urea cycle

Question 39

what is oxidative stress

Answer 39

generation of high levels of toxic oxidising molecules which cause tissue damage

Question 40

how are reactive oxygen species usually neutralised

Answer 40

glutathione (GSH)

Question 41

hyperglycaemia induced superoxide production

Answer 41

increased glucose through citric acid cycle, increasing NADH, increasing ETC.

Question 42

problems with superoxide overproduction

Answer 42

increasing superoxide inhibits GADPH which diverts glycolysis metabolites to the 4 pathways of hyperglycaemic damage (polyol, hexosamine, PKA, AGE)

Question 43

polyol hyperglycaemic damage pathway

Answer 43

increased glucose = increased aldose reductase = increased sorbitol = increased NADPH = reduced GSH = reduced protection

Question 44

PKC hyperglycaemic damage pathway

Answer 44

excess DHAP converted to DAG that activates PKC which activates other proteins that use NADPH to produce superoxides

Question 45

AGE (advanced glycation end-products) hyperglycaemic damage pathway

Answer 45

DHAP and GAP levels increase and degrade to methylglyoxal which reacts with lysine to form imines - can inactivate proteins

Question 46

what is methylglyoxal

Answer 46

reactive electrophile which can alkylate amino groups on proteins and nucleic acids to disrupt their function

Question 47

w is methylglyoxal detoxified

Answer 47

glyoxalase pathway - it is reduced to lactic acid by glutathione