protein metabolism

Question 1

protein metab

Answer 1

proteins are consumed- digested to break down into amino acids
some amino acids dont make it through digestion
amino acids enter free amino acid pool
continual building of protein in body (tissue protein) - always a bidirectional flow (protein turnover)
oxidation of amino acids to form co2

Question 2

amino acids

Answer 2

proteins are polymers + monomers are amino acids
20 different amino acids found in food and body protein
central carbon atom, amino (nh3) and carboxylic acid (coo) group
r group is side chain which makes amino acid unique

polar= hydrophillic
non polar= hydrophobic

Question 3

aa classification

Answer 3

essential- amino acids which cannot be made by body cells, must be provided in the diet
non essential- amino acids which are made by body cells in amounts that meet requirements
conditionally essential- made by body cells but only under certain conditions- cannot be made in adequate amounts to meet requirements - extra requirements met by diet

Question 4

aa to proteins

Answer 4

proteins are linear polymers of amino acids
a carboxylic acid condenses with an amino group with the release of water
amino acid sequence called primary structure

Question 5

ingesting protein

Answer 5

dietary protein is digested by protease enzymes in gut
products= amino acids + dipeptides
absorbed through small intestine into bloodstream
travel to all parts of the bodt- important for muscle protein uptake
transported into body cells
used to make new body protein

Question 6

sources of protein

Answer 6

animal- meat, fish, cheese, eggs
vegetable- cereals, nuts
mycoprotein- fungal

Question 7

factors determining protein quality

Answer 7

essential amino acid content- increased essential amino acid= increased quality
excess used for energy prodyctuon - not protein synthesis
limiting amino acid - lowets amount relative to body requirement

bioavailability of protein- amount lost in digestion, absorption, metabolism. Digestability changes in animal, plant and legumes

presence of anti-nutritive factors- protease inhibitors inhibit protein digestion in gut,

Question 8

mutual supplementation

Answer 8

eating a variety of proteins to provide complete amino acid intake

Question 9

transamination

Answer 9

dispensible amino acids synthesisis
can only do this with non essential amino acids
transfer of amine group from amino acid to keto acid
catalysed by transaminases, all need pyridoxal phosphate (PLP) - coenzyme derived from B6
specific transaminases for each amino keto pair

Question 10

amino acid catabolism

Answer 10

oxidation- where we gain energy from AA
urine- nitrogen removed from the body
hydrolyse protein to amino acid, remove n2 by transamination, oxidise remainder for energy
catabolism- creating atp
anabolism- using atp

muscles obtain energy from all amino acids except alanine which takes n2 to liver

Question 11

protein in liver

Answer 11

liver removes n2
urea formation
prevents ammonia (NH3) toxicity
passed into blood and filtered by kidneys
glucogenesis follows- increases blood glucose to go back to muscle

Question 12

protein metab (turnover)

Answer 12

sedentary individuals skeletal mass is essentially stable
different proteins are synthesised and degreaded at different rates
proteins with regulatory or signalling function turnover rapidly
structural or contractile proteins turnover slowly

Question 13

mus

muscle mass gain

Answer 13

an increase in muscle mass is only achieved through positive protein balance
+ protein balance is when synthesis exceeds breakdown
must have increased protein synthesis or decreased protein breakdwon

Question 14

muscle protein synthesis measurement

Answer 14

resistance exercise- often unilateral and lower body
manipulation of post exercise protein nutrition
infusion of labelled amino acids in combination with blood and muscle sampling to determine protein synthesis

Question 15

endurance exercise and protein balance

Answer 15

BCAAs oxidised during exercise- oxidation rate is dependent on CHO availability
genereally contribute <5% so not a major contributor
required for mitochondrial biogenesis - allowing for increased protein synthesis
increased requirements for endurance atheltes

endurance exercise increases protein breakdown
protein intake increased protein synthesis and bigger effects were seen when carbs and protein were consumed together

after endurance exercise- CHO
C+P- muscle protein synthesis is higher when indivduals are fed this comapred to CHO

Question 16

resistance vs endurance training

Answer 16

how muscles respond to different types of training
measured muscle protein synthesis responses before and after study (10 weeks of either exercise)
stable isotope methods used before and after training
with training, protein synthesis responses become exercise specific
myofibrillar PS- bigger increase in resistance group
mitochondrial PS- bigger increase in endurance

Question 17

protein balance

Answer 17

eating a higher amount of protein will increase the rate of muscle breakdown
exercise will make muscle more responsive to those at rest

Question 18

chronic effects of protein

Answer 18

effect of protein supplementation on resistance training induced gains in muscle mass and strength training in healthy adults
protein supplementation produced small but sig increases in 1RM, fat free mass and muscle size
no efefcts on fat free gain mass when protein intake >1.62kg/ dat

Question 19

athletic protein requirements

Answer 19

when and how protein is consumed is important for athletes
endurance/strength- 1.6kg
sedentary- 0.8kg/day
if based on 3000kcal a day- should be 12-15% protein