Proteins Flashcards
Built from
amino acids
Contain
carbon, hydrogen, oxygen, and nitrogen (amino: contains nitrogen)
Amino Acids
n = 20
- essential, non-essential (your body can make them) , conditionally essential (usually your body can make it but if your food doesn’t supply the other things necessary to create them then your body will need them in your diet)
protein structure
Amino acids bind together to create chains
Dipeptide
2 amino acids bound together
Tripeptide
3 amino acids bound together
Structure =
Function (ex. hemoglobin
Protein Functions (8)
- Structure
- Enzymes
- Transporters
- Fluid and Electrolyte
- Antibodies
- Acid-Base Balance
- Hormones
- Energy and Glucose
Protein needs increase significantly with…
acute illness
Fluid and Electrolyte Balance
Proteins cannot move freely across membranes
Cells cannot make water but they can make water water attracting proteins (oncotic pressure)
When protein leaks out fluid follows leading to excess fluid in interstitial spaces = edema
Acid-Base Balance
Changes in pH levels affect proteins negatively
Albumin gathers up extra hydrogen ions (acid) if excess OR provides hydrogen ions if there are too few = buffer
Energy and Glucose (remember: without energy, cells die)
- During inadequate carbohydrate intake, amino acids are used for energy
- Nitrogen-containing amine groups are stripped of and used elsewhere or are incorporated by the liver into urea and sent to the kidneys
Protein Function: Turnover
The continuous breakdown and synthesis of body proteins involving the recycling of amino acids
- the balance between protein synthesis and protein degradation
Protein Function: Nitrogen Balance
- Scientific method of measuring net protein loss/gain
- Signifies if catabolism or anabolism is leading to changes in protein stores
- Certain conditions can lead to constant net nitrogen losses
Protein Digestion & Absorption: Mouth and Salivary Glands
Chewing and crushing moisten protein-rich foods and mix them with saliva to be swallowed
Protein Digestion & Absorption: Stomach
Hydrochloric acid (HCl) uncoils protein strands and activates stomach enzymes:
Protein —> Pepsin, HCl —> smaller polypeptides
Protein Digestion & Absorption: Small Intestine and Pancreas
Pancreatic and small intestinal enzymes split polypeptides further:
Poly-peptides –> pancreatic and intestinal proteases –> tripeptides, dipeptides, amino acids
Then enzymes on the surface of the small intestinal cells hydrolyze these peptides and the cells absorb them
Peptides –> intestinal tripeptidases and dipeptidases –> Amino acids (absorbed)
How much is enough?
- Acute and chronic illness affects protein needs
- a large portion of acutely and chronically ill patients are not getting enough protein
Can you have too much?
- Shifting trend in the public to increase protein intakes
Risks of excessive protein intakes
- Nutrient displacement
- Increased fat intakes
- Increased stress on kidneys
- Increased calcium excretion
Vegetarianism
- includes many dietary patterns
- Bioavailability matters: some plant based nutrients are less available for our body (ex. iron, calcium)
- a balanced vegetarian diet requires intentional planning
Various Vegetarian dietary plans
- Lacto-Ovo
- Pescatarian
- Vegetarian
- Lacto
Vegan
Complementary Proteins
two or more protein foods whose amino acids from one provide the missing amino acids from the other
Protein Digestibility
measure of the amount of amino acids absorbed from a given protein intake
Examples of incomplete proteins
Grains
Beans
Examples of complete proteins
- Dairy
- Seafood
- Tofu
- Meat/Seafood
Digestibility
proteins must be digested before they can provide amino acids; what is the amount of amino acids absorbed from a given protein intake
Amino acid composition
to prevent protein breakdown, dietary protein must supply at least the nine essential amino acids plus enough nitrogen - containing amino groups, as well as energy for the synthesis of others; the body can only make whole proteins
Amino acid composition
to prevent protein breakdown, dietary protein must supply at least the nine essential amino acids plus enough nitrogen - containing amino groups, as well as energy for the synthesis of others; the body can only make whole proteins
Amino acid composition
to prevent protein breakdown, dietary protein must supply at least the nine essential amino acids plus enough nitrogen - containing amino groups, as well as energy for the synthesis of others; the body can only make whole proteins
Amino acid composition
to prevent protein breakdown, dietary protein must supply at least the nine essential amino acids plus enough nitrogen - containing amino groups, as well as energy for the synthesis of others; the body can only make whole proteins
High-quality proteins
these are dietary proteins containing all the essential amino acids in relatively the same amounts that human beings require; they may also contain nonessential amino acids
Complementary proteins
two or more proteins whose amino acid assortments complement each other in such a way that the essential amino acids missing from one are supplied by the other
