UF BRUNNIG Nutrition Exam 3

proteins contain?

carbon, hydrogen, oxygen, nitrogen

amino acids are made of?

carbon, hydrogen, amino group, acid group, side group or side chain

all amino acids have a common

chemical structure

but each amino acid has a different

side group

amino acids can be categorized by

essential, nonessential, and conditionally essential

essential amino acids

9

histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, valine

our body must ingest these because we cannot make enough in quanity

non-essential amino acids

11

alanine, arginine, asparagine, aspartic acid, cysteine, glutamic acid, glutamine, glycine, proline, serine, tyrosine

our body can make these

conditionally essential amino acids

arginine, cysteine, glutamine, glycine, proline, tyrosine

sometimes a nonessential amino acid can become essential

what links amino acids?

covalent peptide bonds created through condensation reactions

Dipeptide

Two amino acids bonded together

tripeptide

three amino acids bonded together

polypeptide

ten or more amino acids bonded together

protein structure

primary, secondary, tertiary, quaternary

primary protein structure

sequence of a chain of amino acids

secondary protein structure

local folding of the polypeptide chain into helices or sheets

weak electrical attractions between H+ and O-

tertiary protein structure

3D folding or coiling pattern of a protein due to side chain interactions

quaternary protein structure

protein consisting of more than one amino acid chain

few proteins that reach quaternary structure

hemoglobin, DNA polymerase, ribosomes, antibodies, and ion channels

secondary protein structure can result in

alpha-helixes or beta-pleated sheets

Most proteins stop at the tertiary structure and are functional, but some work in groups of polypeptides called

subunits

hemoglobin always has

two alpha subunits and two beta subunits

amino acid sequence of human insulin

include 51 amino acids in short polypeptide chain

two di-sulfide bridges link the two chains

a third bridge spaces a section in the chain

a protein can only do its job when its working in its

shape

proteins are often very

complex structures that include folds, loops, and curves

protein denaturation

when proteins are subject to heat, acid or other conditions that disturb their stability; protein uncoils, loses its shape, and loses its function

protein digestion occurs in

mouth, stomach, and small intestine

protein digestion in mouth

mechanical processing of protein due to chewing

protein digestion in stomach

hydrochloric acid denatures proteins

pepsinogen to pepsin

pepsin

Enzyme that breaks down proteins into smaller polypeptide fragments

protein digestion in small intestine

fate of pepsin

pancreas and intestinal wall enzymes

amino acids absorbed

What does hydrochloric acid do?

denatures proteins so digestive enzymes can attack the peptide bonds

converts the inactive form of the enzyme pepsinogen to its active form, pepsin

protein absorption is

straightforward

protein absorption transporters

there are about 7 transporters and 20 amino acids so they share transporters

once protein is absorbed

energy in small intestine cells

manufacture proteins in small intestine cells and mucus

rest go to liver

the liver turns amino acids into

glucose

pre-digested proteins are not

useful

we do not store

amino acids (constant flux of pool)

once in the pool amino acids can be used to make more

proteins, ATP, glucose, fatty acids (for storage)

protein synthesis

the formation of proteins by using information contained in DNA and carried by mRNA

protein synthesis cont.

the process of synthesizing mRNA

transcription

protein-making factory of the cell

ribosome

Another type of RNA carries amino acids to the mRNA

tRNA

the overall process of making a protein

gene expression

Process by which mRNA is decoded and a protein is produced at the ribosome

translation

an error in translation, therefore amino acid sequence, alters the final protein

true

the amino acid sequence determines the shape or structure, and this shape determines the

function

sequencing error: sickle cell vs red blood cell

hemoglobin has four polypeptide chains - in sickle-cell two of these chains have a variation

sickle cell anemia

Normally, red blood cells are disc-shaped, but in the genetic disorder sickle-cell anemia, red blood cells are sickle- or crescent-shaped. This difference in shape occurs because valine replaces glutamic acid in the amino acid sequences of two of hemoglobin's polypeptide chains. As a result of this difference in hemoglobin's shape, the capacity to carry oxygen is diminished.

gene expression and protein sysnthesis

capability of body cells

cell only makes proteins it needs

dietary influence on gene expression

nutrients affects your genes

genes affect your nutrients

role of protein

building blocks for most body structures

replacement or dead or damaged cells

enzymes

hormones

regulators of fluid balance

acid-base regulator

transporter

storage

antibodies

source of glucose and energy

collagen matrix

Filled with mineral crystals for bones or teeth

enzyme

a catalyst that speeds up chemical reactions in living cells

protein hormones

messenger molecules

transported in blood to target tissues

oxytocin and prolactin

support lactation

insulin and glucagon

hormones secreted by the pancreas to control levels of blood glucose

thyroxine

regulates metabolism

calcitonin and parathyroid hormone

regulate blood calcium

angiotension, renin, and antidiuretic

regulate fluid and electrolyte balance

protein as a regulator of fluid balance

fluid belongs in cell, between cells and in blood vessels

protein attracts water

edema

puffy swelling of tissue from the accumulation of fluid

protein as an acid-base regulator

body fluid needs right pH

protein acts as a buffer - both attracts hydrogen ions and releases hydrogen ions

blood stays at a pH of

7.35-7.45

protein as an antibody

defend against disease

immunity-memory

protein as a source of glucose and energy

gluconeogenesis

ATP 10%

in times of starvation and insufficient carb intake you use a lot of protein for energy

excess protein creates

fat

protein metabolism

nitrogen balance

the amount of nitrogen consumed compared with the amount excreted in a given time period

nitrogen balance in most healthy adults

0

disease/issues/condition could be indicated by

positive or negative nitrogen balance

when nitrogen intake and output are equal, a person is in nitrogen

equilibrium

infants, children, and pregnant women are in state of

positive nitrogen balance

if protein is being lost and nitrogen excretion is greater than intake, a person is in a state of

negative nitrogen balance

True or false?

Similar to fat and carbohydrates, protein is also easily stored in the body.

False

Proteins are not stored in the body. Recall from the amino acid pool that amino acids and proteins are in a constant state of flux or turnover.

using amino acids to make proteins

if an essential amino acid is missing?

break down lean tissue

skip making protein

using amino acids to make proteins

if a non-essential amino acid is missing?

make it

transanimate

deaminating amino acids produces

urea

deaminating amino acids

to use for energy must remove N

urea is the principle vehicle for excreting

unused nitrogen

urea

A chemical that comes from the breakdown of proteins

urea increases with

protein intake

urea requires water to

dilute and excrete urea

in order to use amino acids for energy

nitrogen must be removed

Without extra water, a person on a high-protein diet risks

dehydration (because the body uses its water to rid itself of urea. This explains some of the water loss that accompanies high-protein diets.)

protein quality determined by

digestibility and amino acid composition

digestibility of protein

▪Animal proteins high (90 - 99%)

▪Legumes close (~90%)

▪Other plants lower (70 - 90%)

amino acid composition of protein

have all essential amino acids?

protein synthesis stops if an essential amino acid is missing

complementary protiens

proteins which can be paired in order to form a complete protein; categories

include grains, legumes, nuts and seeds

high quality (complete) complementary proteins

animal foods, soy (all contain essential amino acids)

The egg is "nature's most nearly perfect food"

gold standard

low quality (incomplete) complementary proteins

other plant foods (low or lacking some amino acids)

complementary proteins

two or more dietary 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

egg protein

Egg protein has a 'chemical score' (essential amino acid level in a protein food divided by the level found in an 'ideal' protein food) of 100, a 'biological value' (a measure of how efficiently dietary protein is turned into body tissue) of 94, and the highest 'protein efficiency ratio' (PER: ratio of grams of weight gain to grams of protein ingested in young rats) of any dietary protein

we do not store

amino acids

we have an amino acid

pool in constant flux

health effects of protein deficiency

consequences, protein-energy malnutrition, marasmus and kwashiorkor

Marasmic and Kwashiorkor

combination of chronic energy deficit and chronic or acute protein deficiency

high animal-protein intake can cause

cancer

cancer

protein not the contributing factor

some protein foods are carcinogens