metabolism overview WF Flashcards
metabolism summary?
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.
how is acetyl CoA produced?
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
what is the Krebs / citric acid cycle?
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.
what is ATP and what is it used for
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.
standard/actual/effective free energy of hydrolysis?
standard = -31kJ/mol
actual = -60kJ/mol
effective = ~ -40kJ/mol
ATP reaction?
ATP + H2O <-> ADP +Pi +energy
metabolic role of ATP?
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
NADP forms?
NADP+ = oxidised form
NADPH = reduced form
what is the pentose phosphate pathway? what is it used for?
metabolic pathway parallel to glycolysis. generates NADPH and pentose as well as ribose-5-phosphate, a precursor for the synthesis of nucleotides.
pentose-phosphate pathway?
glucose ->pentose phosphate pathway -> CO2
NADP+ converted to NADPH
what is NADPH used for
cholesterol synthesis, fatty-acid synthesis, ribonucleotide reduction
what is NADP?
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.
what is NADPH used for?
essential electron donor and provides the reducing power for anabolic reactions and redox balance
sources of energy in typical western diet - carbohydrate?
energy yield = 16kJ/g
intake = 350g/day
contribution = 49%
sources of energy in typical western diet - fat?
energy yield = 38kJ/g
intake = 100g/day
contribution = 33%
sources of energy in typical western diet - protein?
energy yield = 16kJ/g
intake = 100g/day
contribution = 14%
sources of energy in typical western diet - alcohol?
energy yield = 29kJ/g
intake = [16]g/day
contribution = [4]%
enzymes in the parotid?
alpha-amylase
enzymes in the liver/gallbladder?
bile acids
bile salts
cholesterol
HCO3
enzymes in the small intestine?
peptidases
glucoamylase
sucrase/isomaltase
lactase
enzymes in the stomach?
pepsin
H+
enzymes in the pancreas?
alpha-amylase TAG
lipase trypsin
chymotrypsin
elastase
carboxypeptidase A & B
phospholipases
HCO3
carbohydrates in typical western diet?
starch (polysaccharide) sucrose = 160g/day
(disaccharide) lactose = 120g/day
(disaccharide) glucose = 30g/day
(monosaccharide) = 10g/day
important features of carbohydrates in the diet?
meet up to 50% of energy requirement
free glucose/glycogen usually unimportant
all major dietary carbohydrates convertible to glucose
no essential dietary sugars.
digestion of starch requires which enzyme
amylase
digestion of starch pathway?
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.
digestion of sucrose?
sucrose converted to fructose or glucose by sucrase in the small intestine. (fructose converted to glucose)
digestion of lactose?
lactose converted to galactose or glucose by lactase (aka galactosidase) in the small intestine. (galactose converted to glucose)
lactase distribution around the world?
more present in north west europe, middle east, western sahara. less present in east asia, south africa.
what can lactose intolerance cause? what is this caused by?
diarrhoea, bloating, abdominal pains
caused by lactase deficiency
glucose metabolism in the muscle?
glycolysis (2ATP per glucose, anaerobic, in cytoplasm)
TCA cycle + oxidative phosphorylation (~30ATP per glucose, aerobic, in mitochondria)
fatty acids main component?
palmitic acid
arachidonic acid
how are triacylglycerols formed? other important information?
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.
what happens to stored triacylglycerols when they are required for energy
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.
how are fatty acids transported
fatty acids are transported as chylomicrons in the blood, goes to liver, muscle and adipose tissue
chylomicrons structures
phospholipid and cholesterol on exterior
triacylglycerol and acyl cholesterol inside
why are fatty acids transported in chylomicrons
to prevent clotting - fat embolisms
what happens if you have a lot of circulating fatty acids
the body produces a lot of ketones
important waste end product of protein metabolism? why is this important
ammonia
important as enters urea cycle (in liver), detoxified into urea and excreted by kidneys
when does recommended daily protein intake increase
eg nursing, athletes
digestive enzymes that contribute to the breakdown of protein?
pepsin (stomach)
pancreas:
trypsin
chymotrypsin
elastase
carboxypeptidase A, B
why is elastase important
easiest pancreatic enzyme to detect in the stool
essential amino acids?
histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine
amino acids categories?
essential/non-essential
glucogenic/ketogenic
energy expenditure?
basal metabolism 60%
physical activity 30%
digestion 10%
thermogenesis ?%
insulin affect on liver?
promote glycogen synthesis
insulin affect on the muscle?
promote glucose uptake, glycose synthesis, protein synthesis
insulin affect on adipose
promote glucose uptake, TAG synthesis
lack of insulin - liver effects?
decreased glucose synthesis, increased glycogenolysis and gluconeogenesis
leads to hyperglycaemia
lack of insulin - muscle effects?
decreased glucose uptake/synthesis, decreased protein synthesis
increased glycogenolysis
leads to hyperglycaemia, weight loss
lack of insulin - adipose effects?
decreased glucose uptake and TAG synthesis
increased lipolysis
leads to ketoacidaemia, weight loss
metabolic syndrome features
affects 20-30% of population, males > females
increased girth/abdominal fat
dyslipidaemia
insulin resistance
impaired glucose tolerance
high blood-pressure
cardiovascular disease
how to differentiate type 1 and 2 diabetes
high levels of sugar but no ketones in type 2 diabetes
high ketones in type 1 diabetes
hormones that affect digestion?
ghrelin
cholecystokinin
