Nutrition Ch. 7: Proteins

denaturation

altering a protein's natural shape and function by exposing it to conditions such as heat, acids, and physical agitation. - can be reversible or irreversible (straightening hair, cooking an egg).

conditionally essential

amino acids that are normally nonessential but become essential under certain conditions.

celiac disease

an autoimmune disorder in which a person's immune system reacts to gluten. - not an allergic reaction, but an autoimmune response. - inflames or destroys villi.

Nitrogen balance or equilibrium

balancing nitrogen intake with nitrogen protein turnover losses.

blood urea nitrogen (BUN)

blood test often used to asses kidney function. - normal levels are between 6-20 mg/dL

diagnosing celiac disease

blood tests and intestinal biopsies

amino acids

building blocks of proteins; contain nitrogen. - 20 different amino acids in the human body.

amino acid structure

carbon atom that anchors a hydrogen atom and: - the amino/nitrogen-containing group. - R group. - carboxylic acid group.

peptide bond

chemical attraction that connects two amino acids together.

structural proteins

collagen and keratin, for example

inborn errors of metabolism

conditions that occur when genes undergo mutations that disrupt metabolism of specific nutrients. - PKU is an example

vegan diets

consist solely of plant foods and completely eliminate all animal foods, including any food produced by an animal, such as honey.

complete protein

contains all essential amino acids in the proper proportion that promote the deposition of protein in muscle and other tissues

incomplete protein

contains inadequate amounts of one or more of the essential amino acids.

high protein diet

eating pattern that provides dietary protein levels higher than the RDA; usually 20-35% of calories

the amino acid pool is a/an _____ source of nitrogen

endogenous or internal

limiting amino acids

essential amino acid found in the lowest concentration in an incomplete protein

kwashiorkor

form of undernutrition that results form consuming adequate energy and insufficient high quality complete protein. - usually when an infant loses their mom as nourishments (typically to a younger sibling) and their new diet lacks enough high quality protein.

marasmus

form of undernutrition that results from starvation; diet lacks energy and nutrients. - signs: weakness and loss of body tissue mass

marasmic kwashiorkor

form of undernutrition that results in a child with kwashiorkor who then starts to not consume enough energy; characterized by edema and muscle waisting.

positives of a plant based diet

high... - vitamin C, E, and folate - phytonutrients - fiber - magnesium and potassium low... - saturated fatty acids

signs and symptoms of food allergy

hives, swollen/itchy lips, eczema, difficulty swallowing, wheezing, abdominal pain, vomiting, and diarrhea

undernutrition

inadequate consumption of nutritious food

food allergy

inflammatory response when body's immune system reacts inappropriately to a normally harmless substance (protein in food). - genetic predisposition.

non celiac gluten sensitivity (NCGS)

intolerance to gluten containing foods in the absence of celiac disease or wheat allergy. - symptoms: IBS, headache, joint and muscle pain, fatigue, anemia

protein complementation

involves eating combinations of certain plant food protein sources that together contain a proportion of amino acids similar to complete proteins from animals sources.

possible disadvantages of high protein diets

kidney stress - increased nitrogen burden on kidneys CVD risk - high saturated fat intake Cancer risk Osteoporosis Risk - increased urinary excretion of calcium - increased risk of bone fragility.

to ensure an adequate mix of incomplete proteins, combine....

legumes with grains, seeds, and/or tree nuts

negatives of a plant based diet

low.... - vitamin B-12, D, and riboflavin - zinc, iron, and calcium - omega-3 fatty acids - certain essential amino acids - energy

protein-energy malnutrition (PEM)

malnutrition that occurs when the diet lacks sufficient protein and energy. - children are more likely to develop it. - uncommon in the U.S - 3 kinds: marasmus, kwashiorkor, and marasmic kwashiorkor

urine urea nitrogen (UUN)

measure of the concentration of urea in urine. - normal values form a 24 hour urine are between 12-20g.

antibodies

molecules that tag invading organisms for destruction by the immune system

transamination

occurs when the nitrogen-containing group is transferred to another substance to make a nonessential amino acid. - reactions are reversible.

2020-25 dietary guidelines for americans recommends...

people consume a greater variety of protein foods in their diet, especially seafood consumption

vegetarian diets

plant based eating patterns that may or may not include some animal foods

legume

plants that produce pods with single row of sees; peas, lentils, and peanuts

what happens when diets don't supply adequate amount of essential amino acids and theres not enough nonessential acids?

protein synthesis cannot proceed because the "pool" of AA's is lacking; when an amino acid is not available, production of a protein stops

polypeptides

proteins comprised of 50 or more amino acids

anaphylaxis

serious, life-threatening allergic reaction to food, an insect bite, a drug, or another substance such as latex. - anaphylactic shock: an extreme drop in blood pressure that affects the whole body

diagnosing food allergies

skin testing by an immunologist

treating food allergies

strict avoidance of the offending foods.

Why is the shape of a protein important?

structure determines function

nutritional genomics

study of nutrigenomics and nutrigenetics

secondary structure

the coiling of the polypeptide chain due to chemical attractions between certain components of the amino acids

tertiary structure

the final 3D form of the protein

primary structure

the linear chain of amino acids linked by peptide bonds

protein turnover

the process of breaking down old or unneeded proteins into their component amino acids and recycling them to make new proteins.

nutrigenetics

the study of how inherited genetic variations influence the body's responses to specific nutrients and nutrient combinations. - ex. how genes influence diabetes and obesity development

nutrigenomics

the study of how nutrients affect the expression of a person's genome - ex. how nutrients influence food allergies and intolerances in vulnerable people

nonessential amino acids

- 11/20 amino acids. - group of amino acids that the body can make. - often produced from essential amino acids in the liver. - "dispensable"

essential amino acids

- 9/20 amino acids. - amino acids the body cannot make or cannot make enough of to meet its needs. - must be supplied by foods. - "indispensable"

protein absorption and transport: liver

- AA's enter the hepatic portal vein and travel to the liver. - keeps some AA's for its needs and releases the rest to general circulation.

derivatives of amino acids

- amino acids are used to form nitrogen-containing compounds that are not proteins but have important physiological roles. - ex. melanin, regulatory amines like serotonin and epinephrine.

complementary protein dishes

- beans and rice - peanut butter sandwich - hummus on whole-grain pita bread - split pea soup with toasted whole wheat bread

Major functions of proteins in the body

- build new cells and many functional components of cells. - component of hardened structures (hair, nails). - enzymes that speed up chemical reactions. - lubricants to ease movement. - clotting components in blood. - antibodies that fight disease-causing organisms. - fluid and pH balance. - transporters. - hormones. - energy source (last resort).

high-quality proteins

- complete proteins that are well-digested, absorbed, and used by the body. - animal products. - contain all essential amino acids.

what does a high BUN level (>20 mg/dL) indicate?

- congestive heart failure - high protein intake - GI bleeding - heart attack - kidney disease, kidney failure, urinary tract obstruction - shock

protein digestion: small-intestinal cells

- final digestion occurs within absorptive cells. - di/tripeptides contact the microvilli and are either absorbed directly or further broken down

low-quality proteins

- incomplete and are generally less digestible and bioavailable. - beans, nuts, seeds, grains. - most plant sources, EXCEPT soy and quinoa

Proteins

- large, complex organic molecules made up of amino acids. - contains C, H, and O (like lipids and carbs) but also contains nitrogen.

what does a low BUN (<6 mg/dL) indicate?

- liver failure - inadequate protein intake - malnutrition - overhydration

sources of protein

- meat - eggs - nuts - quinoa - whole grains - legumes

signs and symptoms of celiac disease

- mild to severe abdominal pain, gas and bloating, chronic diarrhea, and weight loss. - children experience poor growth. - anemia, osteoporosis, liver disease, intestinal cancer, and dementia

treating celiac disease

- no cure, but people can follow a gluten-free diet to help

diagnosing and treating non-celiac gluten sensitivity

- often self diagnosed and self treated. - generally rule out celiac disease and wheat allergy using antibody testing and intestinal biopsy. - all gluten containing foods are strictly avoided.

protein digestion: small intestine

- pancreas secretes trypsin and chymotrypsin to break down polypeptides. - enzymes released by the absorptive cells of the sm. int. break down shortened peptides into di/tripeptides, and amino acids.

phenylketonuria (PKU)

- rare genetic metabolic disorder characterized by the inability to convert the amino acid phenylalanine into tyrosine, resulting in accumulation of phenylalanine. - phenylalanine or its toxic by products build up in tissues and damage cells, including nerve cells in the brain. - important to test in infants.

excess protein intake

- saturated fat and CVD, some cancers - process meat and some cancers - red meat and breast cancer - dehydration - caution for people with liver/kidney disease

protein absorption and transport: absorptive cells

- short peptides and AA's are transported into the enterocyte and broken down into AA's. - AA's move into the capillary of the villus. - AA's travel to the liver via the hepatic portal vein

protein digestion: stomach

- starts in the stomach. - HCl denatures proteins and converts inactive pepsinogen to active pepsin-> digests proteins into smaller peptides. -

positive nitrogen balance

- state in which the body retains more nitrogen than it loses. - occurs during periods of rapid growth, pregnancy, recovery from illness/injury, increased levels of hormones, and resistance exercise

edema

- swelling. - during starvation, the level of protein in blood decreases and water leaks out of the blood stream causing an accumulation of fluid in tissues.

If a person consumes more protein than they need, what happens to the extra amino acids?

- the body doesn't store excess amino acids. - the unnecessary amino acids undergo deamination. - some of the excess NH2 is transported to the liver-> liver removes NH2 from glutamine, forming ammonia-> liver converts ammonia to urea

negative nitrogen balance

- the body loses more nitrogen than it retains. - occurs during starvation, serious illness, and serious injury.

deamination

- the process of removing the nitrogen-containing group from an unneeded amino acid. - the amino acid gives up its amino group and becomes a carbon skeleton.

RDA for protein

0.8 g/kg of body weight

AMDR for proteins

10-35%

What information does the human body use to make proteins?

DNA; the hereditary material in a cell's nucleus that are in genes.

what does the R group do?

Determines the type of amino acid

gluten free labeling

FDA says a product can be labeled 'gluten free' if it contains less than 20 parts per million (ppm) of gluten.

Advantages of high protein diets

Weight loss - increased satiety, reduced hunger. Blood sugar regulation - improved blood glucose control. - increased insulin sensitivity. Cardiovascular effects - reduced LDL cholesterol, blood triglycerides, and blood pressure. Bone health - increased intestinal Ca absorption. - Increased bone growth promoting hormones.

sickle cell anemia

a genetic disorder that causes abnormal hemoglobin, resulting in some red blood cells assuming an abnormal sickle shape

urea

a metabolic waste product that is released into the bloodstream; kidneys filter urea and eliminate it through urine.

personalized nutrition

the use of information on individual responses to food and nutrients based on nutritional genomics and other clinical markers, which allows dietary recommendations to be tailors to a person's physiology and medical history.

what happens when the wrong AA is inserted into the chain consistently?

this can cause genetic defects

quaternary structure

two or more polypeptide chains associate with each other to form large complexes

food intolerances

unpleasant physical reactions, including headaches and intestinal discomfort, after they consume nonprotein substances in foods such as lactose, monosodium glutamate (MSG), or sulfites. A food intolerance is not the same as a food allergy because the offending substance in the food does not trigger the body's immune response. the reaction does not normally involve a protein

what happens when you remove the amino group from an amino acid?

you are left with the carbon skeleton; the R group, carboxylic acid group, and anchoring carbon atom