metabolism overview WF

Question 1

metabolism summary?

Answer 1

protein/fat/carbohydrate from diet broken down by catabolic pathways, produces CO2, intermediates, energy (ATP), reducing power (NADPH).
energy contributes to work and heat
energy, reducing power and intermediates contribute to biosynthesis (anabolic pathways). this leads to production of macromolecules -> growth -> cell structures.

Question 2

how is acetyl CoA produced?

Answer 2

acetyl is produced from breakdown of pyruvate (derivative of carbohydrate)
when pyruvate breaks down it produces small bonded carbon molecules (C 2). when they react with CoA the combined molecule becomes acetyl CoA. vitamin B5 helps make coenzyme A

Question 3

what is the Krebs / citric acid cycle?

Answer 3

series of chemical reactions in the mitochondria use to release stored energy derived from carbohydrates fats and proteins in the body. it is used by organisms to generate energy for various metabolic processes.

Question 4

what is ATP and what is it used for

Answer 4

adenosine triphosphate is a nucleotide that provides energy to drive and support many processes in living cells such as muscle contraction, nerve impulse propagation, chemical synthesis etc.

Question 5

standard/actual/effective free energy of hydrolysis?

Answer 5

standard = -31kJ/mol
actual = -60kJ/mol
effective = ~ -40kJ/mol

Question 6

ATP reaction?

Answer 6

ATP + H2O <-> ADP +Pi +energy

Question 7

metabolic role of ATP?

Answer 7

glucose/fatty acids/amino acids go through various processes, produce CO2, ADP + Pi converted to ATP.

ATP used for muscle contraction, biosynthetic reactions, ion-pumping

Question 8

NADP forms?

Answer 8

NADP+ = oxidised form
NADPH = reduced form

Question 9

what is the pentose phosphate pathway? what is it used for?

Answer 9

metabolic pathway parallel to glycolysis. generates NADPH and pentose as well as ribose-5-phosphate, a precursor for the synthesis of nucleotides.

Question 10

pentose-phosphate pathway?

Answer 10

glucose ->pentose phosphate pathway -> CO2
NADP+ converted to NADPH

Question 11

what is NADPH used for

Answer 11

cholesterol synthesis, fatty-acid synthesis, ribonucleotide reduction

Question 12

what is NADP?

Answer 12

NADP is a coenzyme that functions as a universal electron carrier. its involved in anabolic or biosynthetic reactions, or reactions that build large molecules from small molecules. NADP can accept electrons and hydrogen atoms to form NADPH.

Question 13

what is NADPH used for?

Answer 13

essential electron donor and provides the reducing power for anabolic reactions and redox balance

Question 14

sources of energy in typical western diet - carbohydrate?

Answer 14

energy yield = 16kJ/g
intake = 350g/day
contribution = 49%

Question 15

sources of energy in typical western diet - fat?

Answer 15

energy yield = 38kJ/g
intake = 100g/day
contribution = 33%

Question 16

sources of energy in typical western diet - protein?

Answer 16

energy yield = 16kJ/g
intake = 100g/day
contribution = 14%

Question 17

sources of energy in typical western diet - alcohol?

Answer 17

energy yield = 29kJ/g
intake = [16]g/day
contribution = [4]%

Question 18

enzymes in the parotid?

Answer 18

alpha-amylase

Question 19

enzymes in the liver/gallbladder?

Answer 19

bile acids
bile salts
cholesterol
HCO3

Question 20

enzymes in the small intestine?

Answer 20

peptidases
glucoamylase
sucrase/isomaltase
lactase

Question 21

enzymes in the stomach?

Answer 21

pepsin
H+

Question 22

enzymes in the pancreas?

Answer 22

alpha-amylase TAG
lipase trypsin
chymotrypsin
elastase
carboxypeptidase A & B
phospholipases
HCO3

Question 23

carbohydrates in typical western diet?

Answer 23

starch (polysaccharide) sucrose = 160g/day
(disaccharide) lactose = 120g/day
(disaccharide) glucose = 30g/day
(monosaccharide) = 10g/day

Question 24

important features of carbohydrates in the diet?

Answer 24

meet up to 50% of energy requirement
free glucose/glycogen usually unimportant
all major dietary carbohydrates convertible to glucose
no essential dietary sugars.

Question 25

digestion of starch requires which enzyme

Answer 25

amylase

Question 26

digestion of starch pathway?

Answer 26

amylose/amylopectin converted to maltose/isomaltose by amylase in saliva and pancreas. isomaltose converted to glucose by isomaltase in small intestine maltose converted to glucose by glucoamylase in the small intestine.

Question 27

digestion of sucrose?

Answer 27

sucrose converted to fructose or glucose by sucrase in the small intestine. (fructose converted to glucose)

Question 28

digestion of lactose?

Answer 28

lactose converted to galactose or glucose by lactase (aka galactosidase) in the small intestine. (galactose converted to glucose)

Question 29

lactase distribution around the world?

Answer 29

more present in north west europe, middle east, western sahara. less present in east asia, south africa.

Question 30

what can lactose intolerance cause? what is this caused by?

Answer 30

diarrhoea, bloating, abdominal pains caused by lactase deficiency

Question 31

glucose metabolism in the muscle?

Answer 31

glycolysis (2ATP per glucose, anaerobic, in cytoplasm) TCA cycle + oxidative phosphorylation (~30ATP per glucose, aerobic, in mitochondria)

Question 32

fatty acids main component?

Answer 32

palmitic acid arachidonic acid

Question 33

how are triacylglycerols formed? other important information?

Answer 33

ester linkage of fatty acids to three alcohol groups in glycerol. stored in large quantities in adipose tissue to be used later as fuel. TAG also main constituent of vegetable oils.

Question 34

what happens to stored triacylglycerols when they are required for energy

Answer 34

lipases in adipose tissue are activated to hydrolyse stored triacylglycerols into fatty acids and glycerol and release them into the bloodstream. at destination, used to generate acetyl-CoA and eventually ATP.

Question 35

how are fatty acids transported

Answer 35

fatty acids are transported as chylomicrons in the blood, goes to liver, muscle and adipose tissue

Question 36

chylomicrons structures

Answer 36

phospholipid and cholesterol on exterior triacylglycerol and acyl cholesterol inside

Question 37

why are fatty acids transported in chylomicrons

Answer 37

to prevent clotting - fat embolisms

Question 38

what happens if you have a lot of circulating fatty acids

Answer 38

the body produces a lot of ketones

Question 39

important waste end product of protein metabolism? why is this important

Answer 39

ammonia important as enters urea cycle (in liver), detoxified into urea and excreted by kidneys

Question 40

when does recommended daily protein intake increase

Answer 40

eg nursing, athletes

Question 41

digestive enzymes that contribute to the breakdown of protein?

Answer 41

pepsin (stomach) pancreas: trypsin chymotrypsin elastase carboxypeptidase A, B

Question 42

why is elastase important

Answer 42

easiest pancreatic enzyme to detect in the stool

Question 43

essential amino acids?

Answer 43

histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine

Question 44

amino acids categories?

Answer 44

essential/non-essential glucogenic/ketogenic

Question 45

energy expenditure?

Answer 45

basal metabolism 60% physical activity 30% digestion 10% thermogenesis ?%

Question 46

insulin affect on liver?

Answer 46

promote glycogen synthesis

Question 47

insulin affect on the muscle?

Answer 47

promote glucose uptake, glycose synthesis, protein synthesis

Question 48

insulin affect on adipose

Answer 48

promote glucose uptake, TAG synthesis

Question 49

lack of insulin - liver effects?

Answer 49

decreased glucose synthesis, increased glycogenolysis and gluconeogenesis leads to hyperglycaemia

Question 50

lack of insulin - muscle effects?

Answer 50

decreased glucose uptake/synthesis, decreased protein synthesis increased glycogenolysis leads to hyperglycaemia, weight loss

Question 51

lack of insulin - adipose effects?

Answer 51

decreased glucose uptake and TAG synthesis increased lipolysis leads to ketoacidaemia, weight loss

Question 52

metabolic syndrome features

Answer 52

affects 20-30% of population, males > females increased girth/abdominal fat dyslipidaemia insulin resistance impaired glucose tolerance high blood-pressure cardiovascular disease

Question 53

how to differentiate type 1 and 2 diabetes

Answer 53

high levels of sugar but no ketones in type 2 diabetes high ketones in type 1 diabetes

Question 54

hormones that affect digestion?

Answer 54

ghrelin cholecystokinin