chap 5 - proteins Flashcards
whos most at risk for too little protein in their diet?
old people who typically cant cook for themselves
is it a waste to get protein enriched food?
yes
how many A.A are there?
20
9 essential and 11 non-essentail
how much Nitrogen in A.A?
average 16% of A.A by weight (amino group)
Essentail A.A
histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine
HIS
ISO
LUE
LYS
MET
PHE
THR
TRY
VAL
which A.A is an artifital sweetener?
phenyalanine
What is PKU and why do we get tested for it?
is an inherited disease in which the body cannot metabolize a protein called phenylalanine.
leads to build up of Phenylketones which is toxic to the brain*
babies are tested for this*
what determines a proteins final shape?
the amino acid sequece…
exmaple: insulin has disulfide bonds that make it curl
How can you denature a protein?
acid or heat
sickle cell anemia
reduced carrying capacity of oxygen in the blood
Amino acid change in H6
what is the structure of a bloodcell?
bloodcell —> millions of Hemoglobin —> 4 myoglobin —> A.A and Fe2+ & heme group
how many O2 can 1 hemoglobin carry?
4 because each hemoglobin is made of 4 myoglobin
what foods provide most of our protein?
Meat, dairy, grain
each about 21% of our protein intake
although meat is the most packed with protein
Reasons to need protein
- Regulate body processes Ex.
- hormones
- insulin
- enzymes
- neurotransmitters - Tissue growth and repair
- actin + myosin
- collagen - Immune Defense
- antibodies - Transport
- hemoglobin - Energy (last resort)
- 4kcal/g
transamination
process of which non-essentail amino acids are made
Protein digestion steps
- mechanical breakdown in the mouth
- digestion begins in the stomach HCL denatures proteins (pepsin is also activated which breaks proteins into polypeptides)
- they are broken further down into di- tri- peptides and amino acids by enzymes from the pacreas (trypsin and chymotripsin). this all happens in the small intestine
- they are then absorbved by the mucosal layer
what happens after digestion and absorbtion of protein? where does the A.A go?
goes to the liver.
-this is where non-essential A.A are made
-can convert A.A to glucose (if needed)
-liver can use these A.A for energy
-con convert to fat (if needed)
after the liver… goes into bloodstream (2 Priorities)
1. makes proteins (enzymes, antibodies, NT)
2. broken down into free Amonia (Deamination) and sent back to the liver to be excreted as Urea
what is endogenous protein? where does it come from?
within the body. the body takes A.A from the tissues
what is exogenous protein? where does it come from?
A.A that comes from the diet
Do we store excess A.A?
NO
what determines the QUALITY of a protein?
- digestability of the protein
- Types of A.A used
- proportion of A.A in that protein
what percentage of animal, plant, and Legume proteins are digested/absorbed?
animal: 90-99% digested
plant: 70-90% digested
Legumes: >90% digested and absorbed
Legumes are high in everything except ___ and ____
Methionine and Cystine
comaired to eggs and breast milk which are high in everything “GOLDEN STANDARD”
what are “complementary/supplementary proteins”?
combining two foods with limiting A.A
example:
Grains are high in Met+Cys but low in Lys
Legumes are high in Lys but low in Met+Cys
eat both, because they complement what eachother is missing (rice and beans)
