Protein Flashcards
What are proteins made up of?
made from strands of amino acids
composed of carbon, hydrogen, oxygen, and nitrogen atoms; some
amino acids also contain sulphur atoms
What makes proteins different than carb and lipid-carbon, hydrogen, and O2?
Protein contains nitrogen atoms
What is each amino acid made up of?
amine (-NH2, containing nitrogen) and carboxylic
acid (-COOH) functional groups, a hydrogen atom and a distinctive side group,
all linked to the same central carbon atom
How many amino acids are there?
20
How many essential amino acids are there?
9
1. Histidine
2. Isoleucine
3.Leucine
4. Lysine
5. Methionine
6. Phenylalanine
7. Threonine
8. Tryptophan
9. Valine
How many non-essential amino acids are there?
11
1. Alanine
2. Arginine
3. Asparaginee
4. Aspartic acid
5. Cysteine
6. Glutamic acid
7. Glutamine
8. Glycine
9. Proline
10. Serine
11. Tyrosine
What is transamination
– transfer the amine (NH2) group from one amino acid to another molecule (keto acid, amino acid without an amine group) to make a
new amino acid and a new keto acid
- Occurs in the liver
-Converts essential to non-essential
What is conditionally essential?
an amino acid that is normally nonessential
but must be supplied by the diet in special circumstances when the need for it becomes greater than the body’s ability to produce it
How are proteins made?
link amino acids to form peptides
- condensation reaction to form a peptide bond (release of water)
What is a dipeptide?
two amino acids bonded together
What is a tripeptide?
three amino acids bonded together
Polypeptide
10 or more amino acids bonded together
How many amino acids long are proteins?
30-300
Protein synthesis
- makes messenger RNA or mRNA
- mRNA moves out of nucleus to cytosol
- Ribosomes attach to mRNA strand
- Ribosomes decipher code and line up transfer
RNA (tRNA) accordingly - tRNA helps decode a messenger RNA (mRNA)
sequence into a protein
What does transcription mean?
is the process by which the
information in a strand of DNA is copied into
a new molecule of messenger RNA (mRNA)
What is translation during protein synthesis?
which is a process that
synthesizes a protein from an mRNA molecule
How many sequencing errors are there?
- Genetic error
- copying error
- reading error
What is synthesis limiting?
improper combination and quantity of essential (limiting) amino acids – incomplete or low quality protein source
What is limiting amino acids?
is an essential amino acid that is present in
dietary protein in the shortest supply relative to the amount needed for protein synthesis in the body
How many different kinds of protein are there?
10,000 - 50,000
What is denaturation?
-Loss function
-Destroy all structure except primary
Digestion of protein in the mouth
-chewing protein foods and mix them
with saliva to be shallowed
what is HCI?
Hydrochloric acid : denatures proteins
What is pepsin?
activated by HCL and cleaves proteins into smaller polypeptides
What breaks down polypeptides?
Pancreatic protease and intestinal protease that break it down into dipeptides and amino acids
What is the primary site of amino acid absorption into the blood
Small intestine
How are amino acids transported directly to the liver?
portal vein: used to makes proteins or broken down to produce glucose
What is competitive inhibition?
consumption of too much of one amino acid (supplementation) may inhibit absorption of another
What is incomplete protein?
– does not contain all nine
essential amino acids
– considered “low quality”
– plant sources (e.g. legumes)
What is complete protein?
– contains all nine essential
amino acids
– considered “high quality”
– animal sources (e.g. egg) and
soy (e.g. tofu, soy milk)
What are the two factors that determine protein quality or completeness?
- Amount of essential amino acids
- Protein digestibility
What percentage of animal foods are digestible?
90-99% highly digestible
What percentage of soy food are digestible?
> 90% highly digestible
What percentage or other plant foods are digestible?
70-90% less digestible
What are PDCAAS?
Protein digestibility-corrected amino acid score
-amino acid score (based on amount of essential amino acids) X protein digestibility
What is PDCAAS used for?
The method is based on comparison of the concentration of the first limiting essential amino acid in the test protein with the concentration of that amino acid in a reference (scoring) pattern
What is DIAAS?
Digestible indispensable amino acid score
Protein quality method
DIAAS determines amino acid digestibility, at the end of the small intestine (ileum, ileal digestibility), while PDCAAS determines amino acid digestibility based on total tract digestibility
provides a more accurate measure of the amounts of amino acids absorbed by the body and the protein’s contribution to human amino acid and nitrogen requirements
What has greater DIAAS values than plant proteins?
meat and milk
What is mutual supplementation?
– obtain complete amino acid requirements from two or more incomplete protein sources
What are complementary proteins?
- two or more proteins whose amino acids complement each other
- essential amino acids missing from one are supplied by another
What provides plenty of isoleucine and lysine but is short in methionine and tryptophan?
legumes
grains have the opposite strengths and weaknesses making them a perfect match for legumes
Acid-base balance for proteins
help maintain the acid-base balance of body fluids by acting as buffers
Protein turnover
Within each cell of the body, proteins are continually being made and broken down
What percentage of available amino acids are stripped of their nitrogen and used for energy?
25%
What is nitrogen balance?
Nitrogen intake from protein in food balances with nitrogen excretion via urine
What is positive nitrogen status?
- Body synthesizes more than it degrades
- Growing children, pregnant women, and other life stages
What is negative nitrogen status?
- Occurs in the starving, and people who have severe burns, injuries,
infections, or fever
How much protein should we eat?
AMDR for adults = 10-35% /day
(0.8 g/kg body weight)
People who require more protein include:
– infants and children – 0.95-1.5 g/kg/day
– adolescents – 0.85-0.95 g/kg/day
– pregnant or lactating women – 1.1 g/kg/day
– vegetarians – 0.9-1 g/kg/day
– athletes – 1.2-1.7 g/kg/day
Too much protein can cause what?
-high cholesterol and heart disease
- Bone loss
-Kidney disease
what is semivegitarian?
Vegetables, nuts, grains, legumes, sometimes seafood, poultry, eggs
and dairy
What is pescovegetarian?
veg, nuts, grain, legumes, , eggs, dairy, seafood
excludes poultry
What is laco-ovo
veg, nuts, grain, legumes, poultry, eggs, dairy
no seafood
What is lactovegetarian
veg, nuts, grains, legumes, poultry, dairy, seafood
excludes eggs
What is Ovovegetarian
veg, nuts, grains, legues, poultry, seafood, eggs
excludes dairy
What is the only complete plant source of protein?
Tofu
What is an example of complementary protein sources?
beans or lentils with rice
