Chapter 7

used for energy converted to other compounds, such as glucose

After deamination, the remaining carbon skeleton can be:

trypsin and chymotrypsin

After polypeptides enter the small intestine, the pancreas secretes protein-splitting enzymes:

peptide bond

Amino acids are chemically linked together via the acid group of one amino acid and the amino group of the next one, forming a:

amino acid pool to use for future protein synthesis

Amino acids not incorporated into proteins become part of an:

Seeds, tree nuts, legumes supply more Fruits or edible leaves, roots, flowers, and stems of vegetables provide less

Certain parts of plants provide more protein than other parts:

dipeptides, tripeptides, and individual amino acids

Enzymes released by absorptive cells break down shortened peptides into:

15%

Protein comprises about what percentage of the typical adult American's total energy intake?

Pregnancy, Breastfeeding, Periods of rapid growth, Recovery from serious illness, blood losses, burns

Protein needs increase during:

Can be used as a marker of protein intake Normal values are 12 to 20 g in a 24-hour urine sample

UUN:

deamination

Unnecessary amino acids undergo:

denaturation

When exposed to certain conditions, a protein undergoes unfolding in a process called:

tripe-tides

molecules that consist of three amino acids

amino acids

nitrogen-containing chemical units that constitute proteins

tyrosine

precursor for epinephrine

tryptophan

precursor for serotonin

carbon skeleton

remains of an amino acid following deamination

secondary structure

the coiling of a polypeptide chain

tertiary structure

the three dimensional, twisted structure of a polypeptide chain that includes interactions between various amino acid groups on the chain

endogenous

within the body

0.8 g/kg of healthy body weight

A healthy adult's RDA for protein is:

Travel to the liver via hepatic portal vein Liver keeps some amino acids and releases the rest into circulation

After absorption, the peptides are broken down into amino acids, and the amino acids enter the capillary of villus:

capillary of villus

After absorption, the peptides are broken down into amino acids, and the amino acids enter the:

denaturation

Altering a protein's natural shape and function by exposing it to conditions such as heat, acids, and physical agitation

Used to assess kidney function Normal values are 6 to 20 mg/dL

BUN:

nitrogen balance (equilibrium)

Balancing nitrogen intake with nitrogen losses

trypsin and chymotrypsin

Break down polypeptides into shorter peptides and amino acids

Hydrogen atom Amino or nitrogen-containing group R group (side chain) carboxylic acid group

Each amino acid has a carbon atom that anchors:

nitrogen balance (equilibrium)

In a healthy adult, the body maintains its protein content by maintaining:

ammonia

NH3, a potentially toxic waste product

amino acid derivatives

Nitrogen-containing compounds that are not proteins but have important physiological roles

R group (side chain)

Part of an amino acid that determines its physical and chemical properties

specific carrier systems

Short peptides and amino acids move into absorptive cells via:

nitrogen, providing about two-thirds of the amino acid supply The remaining one-third is from exogenous sources

The amino acid pool is an endogenous source of:

amino acid derivatives

The body uses amino acids as precursors to form:

peptide bond

The chemical attraction that connects two amino acids together

Absorbed directly by microvilli Further broken down into amino acids by enzymes within the microvilli

The dipeptides and tripeptides can be:

function

The shape of a protein is important because it determines its:

reversible

Transamination reactions are:

NH2 is transported to liver (as glutamate) where cells remove the NH2, forming ammonia Liver converts NH3 to urea Kidneys filter urea, ammonia, and creatinine

Unnecessary amino acids undergo deamination:

dietary protein intake and chronic disease

Urea levels in both blood and urine are used as markers of:

vitamin B-12 supplement

Vegan pregnant women should consult healthcare provider about the need of a:

creatinine

a nitrogen- containing waste produced by muscles

urea

a waste product of amino acid metabolism

conditionally essential amino acid

amino acids that are normally nonessential but became essential under a certain condition

essential amino acids

amino acids the body cannot make or cannot make enough of to meet its needs

protein turnover

cellular process of breaking down proteins and recycling their amino acids

mutation

change in the normal DNA sequence of a gene

complementary combinations

combining certain plant foods to provide all essential amino acids

high quality proteins

complete proteins that are well-digested, absorbed, and used by the body

nutrigenomics and nutrigenetics

components of nutritional genomics:

amines

compounds that include amino groups in their chemical structure

inborn errors of metabolism

conditions that occur when genes undergo mutations that disrupt metabolism of specific nutrients

peptides

contain two or more amino acids

vegan diet

diet based solely on plant foods, with complete elimination of animal foods and products

personalized nutrition

dietary recommendations based on individual response to food and nutrients

Creatine Melanin Regulatory amines such as serotonin, epinephrine, histamine

examples of amines:

complete protein

food source of protein that contains an adequate proportion of each of the nine essential amino acids

incomplete protein

food source of protein that contains inadequate amounts of one or more of the essential amino acids

marasmus

form of undernutrition that results from starvation; diet lacks energy and nutrients

Kwashiorkor

form of undernutrition that results from consuming adequate energy and insufficient high-quality protein

marasmic kwashiorkor

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

dipeptide

forms when two amino acids bond, and a water molecule is released

20

how many different amino acids are found in the proteins of the human body?

undernutrition

inadequate consumption of nutritious food

low quality proteins

incomplete and generally less digestible, making their amino acids less bioavailable than high-quality proteins

proteins

large, complex organic molecules made up of amino acids

protein-energy malnutrition (PEM)

malnutrition that occurs when the diet lacks sufficient protein and energy

blood urea nitrogen (BUN)

measure of the concentration of urea in blood

urine urea nitrogen (UUN)

measure of the concentration of urea in urine

dipeptides

molecules that consist of two amino acids

complete proteins exceptions are quinoa and soy protein

most plant foods are not sources of:

During starvation, serious illness, and as a result of severe injury Recovery from the illness or injury involves replacing the protein that was lost (refeeding), resulting in positive nitrogen balance until nitrogen equilibrium is restored

negative nitrogen balance:

Exogenous

outside the body (dietary or other external source)

vegetarian diet

plant-based eating pattern that may or may not include some animal foods

legumes

plants that produce pods with a single row of seeds

gene

portion of DNA that codes for a protein

During periods of rapid growth, such as pregnancy, infancy, and puberty When people are recovering from illness or injury When performing weight (resistance) training

positive nitrogen balance:

High: Vitamins C , vitamin E, and folate Phytonutrients Fiber Magnesium and potassium Low: Saturated fatty acids

possible advantages for plant based diets:

Low: Vitamin B-12, vitamin D, and riboflavin Zinc, iron, and calcium Omega-3 fatty acids Certain essential amino acids Energy

possible disadvantages for plant based diets:

stomach

protein digestion begins in the:

polypeptides

proteins comprised of 50 or more amino acids

carbon, hydrogen, oxygen, and nitrogen

proteins contain:

high protein diet

provides an amount of protein greater than the RDA, usually 20 to 35% of calories

deamination

removal of the nitrogen-containing group from an amino acid

negative nitrogen balance

state in which the body loses more nitrogen than it retains

positive nitrogen balance

state in which the body retains more nitrogen than it loses

hydrochloric acid (Hal)

denatures food proteins and converts inactive pepsinogen to active pepsin

To build new cells and many functional components of cells As a component of hardened structures, such as hair and nails As enzymes to speed chemical reactions As lubricants to ease movement In clotting compounds in blood To build antibodies that fight disease organisms As compounds that help maintain fluid and pH balance As transporters To make certain hormones As an energy source (as a last resort, only under certain conditions)

functions of proteins:

nonessential amino acids

group of amino acids that the body can make

nutrigenetics

study of how inherited genetic variations influence the body's responses to specific nutrients and nutrient combinations

nutrigenomics

study of how nutrients affect the expression of a person's genome

nutritional genomics

study of nutrigenomics and nutrigenetics

primary structure

the basic structure of protein; a linear chain of amino acids linked by peptide bonds

limiting amino acid

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

wasting

the loss of organ and muscle proteins as the body breaks down these tissues to obtain amino acids for energy metabolism

amino or nitrogen-containing group

the portion of an amino acid that contains nitrogen

carbon skeleton

the remains of an amino acid following removal of the nitrogen-containing component (amino group) of the amino acid

quaternary structure

the structure of protein that is comprised of two or more polypeptide chains arranged together in a complex matter

transamination

transfer of the nitrogen-containing group from an unneeded amino acid to a carbon skeleton to form an amino acid

Walnuts Cashews Almonds

tree nuts include:

urinary elimination of urea and creatinine

what accounts for most the lost nitrogen:

10-35%

what is the AMDR percentage of energy from protein?