Introduction to Nutrition: Chapter 7

Protein synthesis

- DNA unwinds exposing a gene - gene undergoes transcription, forming messenger RNA - mRNA transfers info from the nucleus to ribosomes - ribosomes "read" the messenger RNA - RNA molecule conveys a particular amino acid to the ribosome - at the ribosome, the amino acid attaches to the peptide chain

Polypeptide

- Comprised of 50 or more amino acids - most naturally occurring proteins

Essential amino acid

Protein synthesis in cells cannot proceed when one or more ______________ is unavailable

Edema

accumulation of fluid in tissues

nonessential amino acids

amino acids that the body can synthesize

Symptoms of food allegries

- Swollen, itchy lips - difficulty swallowing - scaly rashly skin

Major functions of proteins in the body:

- build new cells and functional components of cells - component of structures such as hair and nails - enzymes to speed chemical reactions - lubricates to ease movement - clots compounds in blood - builds antibodies that fight disease - help maintain fluid and pH balance - transporter - makes certain hormones -energy source

Proteins

- chemically similar to lipids and carbohydrates because they contain carbon, hydrogen, and oxygen - also contain nitrogen • skin, blood, nerve, bone, and all cells contain this

high quality or complete protein

- contains all 9 essential amino acids - well digested and absorbed by the body • meat, fish, poultry, eggs, and milk

Treatment of children with PEM:

- hospitalization - frequent health assessments - carefully controlled refeedings

Vegetarian diet

- lower risk of diabetes, obesity, hypertension, and certain cancers - provide more fiber, photo chemicals, folic acid, vitamins E and C, potassium and magnesium - supplies less saturated fat

Personalized nutrition

- making dietary choices based on one's genetic makeup

acid-base balance

- proteins help maintain this - proper pH of body fluids

celiac disease

Autoimmune disorder that results in poor absorption of nutrients in the small intestine • cannot tolerate gluten

quarternary structure of protein

2 or more proteins joined to form a functional unit

0.8g/kg

A healthy adult's RDA for protein is __________ of body weight

Biological Value (BV)

A measure of protein quality based on how well and how quickly the body converts food into body tissue proteins

Gluten

A protein in wheat, barley, and other cereal grains

Urinary elimination of urea and creatinine

Accounts for most of nitrogen loss

protein-energy malnutrition (PEM)

Affects people whose diets lack sufficient protein and energy

Liver

After being absorbed, amino acids enter the hepatic portal vein and travel to the ________

essential amino acids

Amino acids that are needed, but cannot be made by the body; they must be supplied by food

Nitrogen

An element cells need to make a wide array of important biological compounds such as enzymes and hormones

conditionally essential amino acids

Become essential under certain conditions

Buffer

Can protect the pH of a solution

gluten sensitivity

Compared to celiac disease, people with gluten sensitivity do not have damage to the small intestine

peptide bond

Connection between amino acids

Peptides

Contain 2 or more amino acids

Protein Efficiency Ratio (PER)

Determined by measuring the weight gain of a growing lab animal that consumes a known amount of protein

Poor growth, slow recovery, and death

Diets that do not supply adequate amounts of essential amino acids can result in:

amino or nitrogen-containing group, R group, and carboxylic acid group

Each amino acid has a carbon atom that anchors a hydrogen atom and three different groups of atoms:

Amino acids

End product of protein digestion

Nitrogen, nitrogen, lost

Even though the body conserves ____________ by recycling amino acids, each day some protein and ___________ are lost

Proteins

Every organism synthesizes __________ that are unique to that specific organism

Small intestinal cells

Final digestion occurs within absorptive _____________

Amino acids

Following digestion, _______________ are transported by specific carrier systems into the absorptive cells

10-35%

For healthy adults, the level of consumption of protein is _________ of energy from protein

Trypsin and chymotrypsin

Further digestion occurs as the pancreas secretes protein-splitting enzymes including __________ and ____________

Eggs

Has a pattern of essential amino acids that closely resembles that used by humans

Food intolerance

Having a headache and intestinal discomfort from eating a food, without triggering the body's immune response

Genes

Hereditary material in a cell's nucleus

Pepsin

Initiates enzymatic digestion of proteins into smaller polypeptides

low quality or incomplete protein

Lacks adequate amounts of one or more of the essential acids

nutritional genomics

May explain why dietary interventions can have different effects on the health of different individuals

Protein digestibility corrected amino acid score (PDCAAS)

Most widely used measure of protein quality Derived by multiplying a foods chemical score by its digestibility.

Transamination

Occurs when the nitrogen-containing group is transferred to another substance to make a nonessential amino acid

Legumes

Plants with seed pods • peas, peanuts, lentils, soybeans

Fruit

________ is not a good source of protein

Stomach acid, pepsin

Proteins undergo denaturation by ______________ and partial digestion by __________

tertiary structure of protein

Refers to the proteins final three-dimensional form

Function

The shape of a protein influences the compounds ___________ in the body

Protein

___________ needs to increase during pregnancy, breastfeeding, periods of rapid growth, and recovery from illnesses, blood loss and burns

Multiply, 0.8g

To determine a person's RDA for protein, ______________ his or her weight by ________

20, DNA

To make proteins, cells assemble the _____ amino acids in specific sequences according to the information provided by ________

Dipeptide

Two amino acids bonded together and a molecule of water is released in the process

digestibility and amino acid composition

Two key factors in determining the quality of a protein:

Feces

Very little dietary protein is excreted in _________

Denaturation

When a protein is exposed to various conditions that alter its natural folded and coiled shape

negative nitrogen balance

When the body loses more nitrogen than it retains • occurs during starvation, serious illness, and severe injuries

Heat

________ causes proteins in food to undold

primary structure of protein

linear sequence of amino acids linked by peptide bonds

Casein

milk protein

Complimentary combinations

mixing certain plant foods to provide all essential amino acids without adding animal protein

secondary structure of protein

protein structure is formed by folding and twisting of amino acid chain

Amino acids

what proteins are made of