Proteins Flashcards
(48 cards)
Protein turnover
Proteins are continually being made and broken down = degradation & synthesis of protein
Unlike glucose and fatty acids, amino acids are __ for later use
not stored
Out of the protein from the diet, how much is absorbed?
95 % absorbed into free amino acid pool (is then broken down or recycled back)
95% goes to urine
How much proteins is being synthesised each day?
What does this mean?
300 g
It means amino acids are being recycled
Output of free amino acid pool
aa are broken down (into nitrogen and carbon skeleton)
or recycled into aa pool
Zero nitrogen balance
intake = output
in healthy individuals (+body builder)
Positive balance
intake > output
body synthesises more than it degrades
ex: growing children pregnancy, recovery
Negative balance
intake < output
body degrades more that it synthesises
loss of protein (nitrogen)
ex: starvation, severe stress : burn, infection, injury
Nitrogen balance =
N intake - Fecal N - Urinary N
Protein is __% nitrogen
16
__ g proteins = 1g nitrogen
6.25g
Does eating more protein, above the RDA drive protein synthesis?
No
Exercise drives protein synthesis
AA can’t be fattening, T/F
FALSE
depending on the R group, it goes to glucose or fat
First step of breaking down protein
- deamination (removal of the amino group)
produces : ammonia + keto acid
Keto acids
= carbon structure without its amino group
What can keto acids do?
Enter metabolic pathways
are used for energy or production of glucose, cholesterol fat, ketones
If the amino acid is glycogenic what does the carbon fragment produce
glucose
If the amino acid is ketogenic what does the carbon fragment produce
ketone bodies, fat, sterols
ex: leucine is ketogenic
if a particle nonessential amino acid is not available, cells can make it from __
keto acids
The deamination of aa produces __ + __
ammonia + keto acids
Given a source of __, the body can make nonessential aa from __
ammonia
keto acids
What are 2 ways the body can make nonessential aa
- from keto acids, if given ammonia
- by transferring an amino group from 1 amino acid to its corresponding keto acid (=transamination)
Ammonia is converted to __ by the liver
urea
Which organ filters urea out of the blood for excretion in urine
kidney
