Proteins - Exam 2

Protein has what elements

carbon, hydrogen, oxygen, nitrogen, and a side group

There are … nonessential amino acids

11; the body can synthesize

There are … essential amino acids

9; human body can’t make so we must eat it

Transamination

the transfer of amine group from one molecule to another to create an amino acid

Conditionally essential amino acids

nonessential amino acid becomes essential under certain conditions such as infancy, disease, inborn error of metabolism

Amino acids are linked by

peptide bonds

Dipeptide

2 amino acids

Tripeptide

3 amino acids

Polypeptide

4+ amino acids

Primary structure of a protein is determined by

the sequence of amino acids

Secondary structure of a protein is determined by

polypeptide shapes weak electrical attractions within the polypeptide chain

Tertiary structure of a protein is determined by

polypeptide tangles; occurs when polypeptide chains twist and fold into complex shapes

Quaternary structure

multiple polypeptide interactions; interactions between 2 or more polypeptides

Protein denaturation

Loss of protein structure and function because of heat, acid, or basically anything that isn’t the optimal conditions > at a certain point it becomes irreversible

Delivering instruction steps

DNA>mRNA>protein

A change in amino acid sequence can cause a protein to change

shape

Sickle cell anemia

Change in a single amino acid that makes the protein bad

Functions of protein in the body (8)

structural materials, hormones, body structure and blood, fluid balance, transport, acid base balance, immune function, enzymes

Protein in structural material examples

collagen (hair, skin, nails, tissue) , replacement of dead/damaged cells; most of muscle cells is structural proteins not contractile

Enzymes

Catalysts for chemical reactions

Deficiencies in enzymes

inborn errors of metabolism

Hemophilia

excessive bleeding from minor injuries

Nongenetic causes of enzyme deficiency

illness, inadequate nutrition, and medications

Hormones

messengers that help regulate the various systems and functions of the body; made of lipids or proteins

BLANK is the least efficient function of proteins

energy production

The body uses protein for … as a …

energy source; final resort

Proteins maintain balance between

fluid inside and outside of the cells

Albumin

most abundant protein in the blood

Edema

swelling due to an excess of fluid in tissues

Ferroprotein

transporter of iron into intestinal wall

Ferritin

iron storage in blood

Transferrin

iron transport in blood

Proteins have … and …

water repelling; water attracting ends which allows for the interaction of fats and water

Proteins act as … (think pH)

buffers

Protein role in immune response

Foreign substances that enter the body and trigger an immune response; Antigens

Proteins form body’s … against …

first barriers; immune invaders

Protein Turnover

The balance of protein synthesis and breakdown

Protein synthesis

requires the presence of essential amino acids in adequate amounts

Limiting Amino acid

missing/present in the lowest amount to supply; relative to the bodies needs and may result in no function; synthesis may be limited

Protein breakdown

free amino acids become part of the amino acid pool; Stripped of nitrogen and used for energy

Transamination

required to make nonessential amino acids; occurs mainly in the liver; amino group is moved from one keto acid to another

Deamination

required for elimination of excess amino acids; mainly occurs in the liver; amino group converted to urea

What 4 things does protein turnover require?

protein synthesis, protein breakdown, transamination, deamination

Nitrogen balance

nitrogen intake vs nitrogen excretion; where the amount of nitrogen is equal to the amount that is excreted

What is the basis of many nutrition recommendations in the RDA?

Nitrogen balance

Nitrogen excretion

amino group converted to urea; kidneys filter out urea from blood for excretion

Positive nitrogen balance

nitrogen intake is greater than the output; where the body requires more nitrogen to build new tissues; occurs during growth, recovery, and during pregnancy

Negative nitrogen balance

nitrogen excretion from protein exceeds intake or when intake is inadequate to meet body’s needs; occurs during illness and malnutrition

RDA for protein

0.8g per kg of body weight

AMDR for protein

10-35%

Protein needs are higher for …

growing children, pregnant women, injury/sickness, athletes

Complete/ high quality proteins

provide all essential amino acids in amounts that are needed for the body; easily absorbed and digested

Protein digestibility corrected amino acid score (PDCAAS) 3 factors

amount of each essential amino acid compared to the reference foods, amount digested, amount of lowest essential amino acid in a serving of the food

The Protein digestibility corrected amino acid score (PDCAAS) has a value from

0-1

Digestibility indispensable amino acid score value is based on 4 factors

amount of each essential amino acid compared to reference food; amount of the amino acid digested based on ileal sample; amount of lowest essential amino acid in a food.

The Digestibility indispensable amino acid score(PDCAAS) has a value from

0-1 but can be above

Incomplete Proteins

don't have all essential amino acids at appropriate levels required by the body

Incomplete proteins examples

legumes, grains, vegetables

Complementary Proteins

amino acids content combined provide all essential amino acids

Supplemental Proteins

additional source of protein for specific populations; vegetarians, active people, underweight people.

Vegetarianism reasons

hormones, religion, health, treatment of animals, environmental impact

Vegetarian benefits

decrease risk of heart disease, decrease rates of obesity

Vegans

omit all animal products from their diet

Lacto

Includes dairy products but limits all other animal foods

Lacto-Ovo

includes dairy and egg products but limits all other animal products

Pesco

Includes fish but limits all other animal products

Flexo/Semi

Occasionally eat meat and seafood

Nutrients to consider for a vegetarian lifestyle

protein, iron, zinc, calcium/Vitamin D, vitamin B12, Iodine

Health Benefits associated with Soy consumption

protection against certain cancers and CVD disease, prevention of bone loss

Nutritional composition of soy

complete, high protein source, low in saturated fat and cholesterol, B-vitamins, calcium, potassium, vitamin A, iron, isoflavones (phytoestrogens)

Protein energy malnutrition (PEM)

disorder that occurs with inadequate protein and/or energy consumption, common nutrient deficiency in hospital and nursing home populations in US

Protein underconsumption is more common

in third world countries/ countries at war type shi

Marasmus

condition of starvation characterized by emancipation or skeletal appearance

Marasmus causes

inadequate protein and calorie intake

Kwashiorkor

characterized by a swollen appearance especially the belly, frequent in children being weaned from breastmilk to cereal

Proposed causes of kwashiorkor

low protein intake; altered gut bacterial populations

Health benefits of protein

weight loss, increased satiety, better lean mass preservation

Health risk of proteins

certain cancers, chronic kidney disease, adult bone loss

High intake of animal protein is associated with which types of cancer

colon prostate, breast, and pancreatic

Protein intake and muscle growth

does not ALONE stimulate increased muscle growth

Increase in muscle mass/hypertrophy

resistance training, adequate protein intake

Protein intake most bang for buck

1.6g/kg