Foundations of Nutrition Exam 2: Chapter 7-13

dietary protein

macronutrient (carbohydrate, fat, protein)

made up of carbon, hydrogen, oxygen, and nitrogen

provides 4 kcals/gram

building block are amino acids

amino acids

central carbon, nitrogen (amino) group, carboxyl group, hydrogen, side chain (R)

20 amino acids in total; combined in a variety of ways

amino acids are described as

essential: must be consumed through food sources (9)

non-essential: can be synthesized in the body (11)

peptide bonds

link 2 amino acids together; formed between amino group of 1 amino acid and carboxyl group of another

protein organization

primary: sequential order of AAs

secondary: spiral or pleated sheet

tertiary: 3-dimensional folding

Quaternary: 2+ polypeptides linked

amino acids pool from

food sources and recycling of amino acids throughout the body

complete amino acids

contain adequate amount of all 9 essential amino acids

high PDCAAS score

“high quality”

mostly in animal based foods

incomplete

missing 1 or more essential AA

low PDCAAs score

“low quality”

mostly in plant based foods

key factors in protein quality

digestibility (amount of AA absorbed) and AA composition compared to reference protein

protein digestitbility

corrected amino acid score (PDCAAs): gives different food sources score of 0.0-1.0

complementary proteins

two or more plant proteins are combined to compensate for deficiencies in essential AA in protein

AA in one source makeup for limiting AA in other sources

yield a high quality/complete protein in the diet

generally achieved by mixed diet and balanced over the course of the day

nitrogen balance or protein balance

ability of the body to retain nitrogen, protein is 16% nitrogen

nitrogen (protein) intake matches nitrogen (protein) balance

negative nitrogen balance

nitrogen (protein) loss exceeds nitrogen (protein) intake

positive nitrogen balance

nitrogen (protein) intake exceeds nitrogen (protein) loss

protein and AA requirements

needs affected by, life stages, physical activity level, mix of food sources, illness

minimum protein requirement

lowest level of dietary protein that will maintain nitrogen balance

methods to assess protein needs

RDA: based on age, sex, life stages

AMDR: 10-33% total kcals

ratio” 0.8 grams/kg body weight

stomach

HCl dentures protein; enzyme pepsin begins to break polypeptide chains into shorter chains

small intestine

proteases, trypsin, chymotrypsin, and carboxypeptidase continue to break peptide bonds

absorbed as individual AA

portal vein takes AA to the liver, the home base for protein metabolism

liver

continually synthesizing a balanced amino acid mixture for the protein needs of the body (structure, function, etc)

protein metabolism

constant interchange of AA in the blood, liver, and body tissues (AA pool)

synthesize of nonesential AAs through transmination

removal of amino group through deamination

primary function of proteins

build and maintain body tissues

used for energy under 2 conditions: if we consume more than we need or if were in a state of starvation or semistarvation

amino acid pool

total number of amino acids found in the blood and the body fluids

nitrogen

componet of AA that cannot be storef; converted to urea for excretion

deamination

process by which amino (nitrogen-containing) group is removed

glucogenic

term for AAs that can be converted to glucose

ketogenic

term for AAs that can be converted into ketones and eventually into fat

excess protein intake

>35% total kcals

diets containing excessive or disproportionate amounts of protein do not provide additional health benefits

theoretical risks of high protein diet

taxing on kidneys’ capacity to excrete nitrogenous waste

may increase risk of dehydration as water is needed to dilute/excrete waste

diet quality overal when protein sources are animal-based or derived from AA supplements

essential amino acids must be supplied by the diet because the body cannot synthesize them in adequate amounts

true

which of the following is classified as a complete protein

milk

the sequential order of amino acids in a polypeptide chain is called

primary structure

alcohol

ethanol or ethyl alcohol

provides 7 kcals/gram

classified as wine, beer, or spirits

both adverse and beneficial implications to health, depending on how much is consumed on a regular basis

what constitutes as moderation

1 drink/day for women

up to 2 drinks/day for men

what constitutes as binge drinking

4 or more drinks per occasion for women

5 or more drinks per occasion for men

alcohol metabolism

no digestion required, rapidly absorbed by passive diffusion

20% absorbed in the stomach, remainder in the small intestine

primarily metabolized in the liver

liver can metabolize 0.3 oz of ethanol an hour

a standard drink is defined as the amount that provides approximately 14 g of alcohol. which of the following is considered a standard size drink

5 oz glass of wine

which of the following affects the metabolism of alcohol

all of the above

which of the following would be considered moderate drinking

1 day per day women, 2 drinks per day men

metabolism

the entire network of chemical processes involved in maintaining life

anabolic

metabolic pathways that use small, simpler compounds to build larger, more complex compounds, require energy

catabolic

metabolic pathways that break down compounds into smaller units, produce energy

ATP

the main form of energy used by the body; consists of adenosine bound to 3 phosphate groups

ATP production from carbohydrates

produced by cellular respiration (oxidation or electron removal of food molecules resulting in the eventual release of energy, CO2, and H2O)

four stages of ATP production from carbohydrates (aerobic)

glycolysis, transition reaction, citric acid cycle(kerbs cycle), electron transport chain

glycolysis

glucose oxidized and forms 2 molecules of pyruvate, produces NADH+H+ and generates 2ATP, occurs in cytosol

transition reaction

converts 2 molecules of pryuvate to 2 molecules of acetyl CoA, produces NADH+ and H+, occurs in cytosol

citric acid cycle (krebs cycle)

Acetyl- CoA enters citric acid cycle and produces NADH+H+, FADH2 and ATP, occurs in mitochondria and same for all macronutrients

electron transport chain

NADH+H+ and FADH2 enter electron transport chain, most ATP generated here, occurs in mitochondria, same for all macronutrients

metabolism of 1 glucose molecule

glycolysis: 2 ATP

transition reaction: 0 atp

citric acid cycle: 2 atp

electron transport chain: 28 atp

total: 32 atp

metabolism of 16-C fatty acid

beta oxidation: 0 atp

citric acid cycle: 8 atp

electron transport chain: 100 atp

total: 108 atp

Atp used for activation: -2 atp

net atp: 106 ATP

anaerobic metabolism

occurs in cells that lack mitochondria OR where O2 is absent

pyruvate (produced through glycolysis) converted to lactate

less efficient than aerobic respiration, only 5% of energy in glucose converted to ATP

cori cycle

lactate produced during high intensity activity is transported from muscle to liver, converted to glucose, then returns to muscle

ATP production from fats

lipolysis and beta oxidation

lipolysis

the breaking down of triglycerides into free fatty acids and glycerol

beta oxidation

the breaking down of fatty acids for energy production; takes place in the mitochondria; C-C (2 carbon) fragments from fatty acid chain converted to Acetyl-CoA which then enters the citric acid cycle

ketone bodies

incomplete breakdown products of fat; contain 3-4 carbons; produced during rapid lipolysis

ketosis

condition of having a high concentration of ketone bodies and related breakdown products in the blood or bloodstream

fed-fast cycle

4 stages, metabolic shifts following the last meal a person consumed, transition to next stage depends on nutrients stored, metabolic rate, energy demands, and composition of the last meal

fed state

3 hours after a meal

post absorption/early fasting state

3-18 hours after a meal

fasting state

18-48 hours after a meal

starvation/long term fasting

48+ hours after a meal

glycolysis is a biochemical pathway that

all of the above

when muscle tissue is exercising under anaerobic conditions, the production of _______ is important because it assures continuous supply of NAD

lactate

micronutrients

needed by the body in very small amounts

essential - cannot be synthesized by the body or are not synthesized in sufficient amounts

measured in IU, ug, mg

vitamin and mineral characteristics

essential for life and metabolic functions

most obtained through food

no one food contains all vitamins (balanced diet)

do not contain kcals

deficiency and toxicity are possible

4 stages of deficiency

1. preliminary

2. biochemical deficiency

3. physiologic

4. clinically manifested deficiency

fat soluble vitamins

vitamin A, vitamin D, vitamin E, vitamin K

water soluble vitamins

vitamin C, b-complex vitamins

water soluble

stored in the body in limited amounts

excess of water-soluble vitamins are excreted in the urine; lower risk of toxicity

fat soluble

found mostly in foods containing fat

absorption requires dietary fat and efficient use of bile and pancreatic lipase in the small intestine

transported as chylomicrons and other lipoproteins

stored in either the liver or adipose tissue until needed

food-first approach

striving to use foods and beverages to meet nutrient needs before considering a dietary supplement

vitamin and supplement facts

50% of americans taking vitamin supplements

typical american diet lacking in many vitamin/minerals especially calcium, vitamin d, iron, potassium

3 questions to ask

is it safe, is it legal, is it effective

are supplements safe

generally safe if taken in recommended dosage

supplements may be disabled

can have own side effects and may have significant interactions with other foods or drugs

are supplements legal

doping (use of drugs in sports, prohibited)

essential nutrients are not classified as drugs, and are therefore considered legal

are supplements effective

general rule of thumb for vitamins/minerals: food first, supplements second