ch 6: proteins and amino acids

what is the basic structure of amino acids

• central carbon atom with hydrogen atom

• amino group (NH2)

• acid group (COOH)

• side group or side chain

how does the body interact with nonessential amino acids?

body can synthesize them for itself

how does the body interact with essential amino acids?

human body either cannot make it or not in sufficient amounts so it must be supplied by the diet

how does the body interact with conditionally essential amino acids?

used under certain conditions

which of the following is the simplest amino acid?

glycine, alanine, aspartic acid, phenylalanine

glycine

what is the primary structure of amino acids determined by?

sequence of amino acids that

what is the secondary structure of amino acids determined by?

weak electrical attractions within the polypeptide chain

how does the tertiary structure of amino acids occur

when polypeptide chains twist and fold into complex shapes

how is the quaternary structure of amino acids formed?

between interactions of two or more polypetides

define protein denaturation

when exposed to heat, acid, or other destabilizing conditions, proteins denature

describe protein digestion in each structure:

• stomach

• small intestine

• stomach: hydrochloric acid denatures protein strands and activates pepsin from pepsinogen which breaks proteins into smaller polypeptides and amino acids

• small intestine: proteases break polypeptides into shorter chains

what is the primary role of hydrochloric acid in protein digestion in the stomach?

it denatures proteins and activates pepsinogen from pepsin

define ribosome

protein making factory of the cell

define transcription

process of synthesizing mRNA from DNA

define translation

process of synthesizing proteins from mRNA

define gene expression

process of making a protein

what is the role of proteins as structural materials?

building blocks for most body structures

what is the role of proteins as enzymes?

catalysts, permitting reactions to occur much more quickly and efficiently

what is the role of proteins as hormones?

some hormones like insulin are proteins acting as chemical messengers

what is the role of proteins as regulators of fluid balance?

help maintain fluid balance

what is the role of proteins as acid base regulators?

by accepting/releasing hydrogen ions, proteins act as buffers to maintain the acid base balance of the blood and body fluids (7.35 to 7.45)

what is the role of proteins as transporters?

some transport proteins reside in cell membranes and act as pumps to pick up compounds from one side of membrane to release on other side

what is the role of proteins as antibodies?

defend the body against disease

what is the role of proteins as source of energy and glucose?

sacrificed to provide energy and glucose during times of starvation and insufficient carb intake

define nitrogen balance

comparison of nitrogen intake with nitrogen excretion (urine, feces, sweat)

how is the amino acid tyrosine used to make other compounds

tyrosine is used to make neurotransmitters norepinephrine and epinephrine

how much do amino acids contribute to energy needs?

10-15%

how are amino acids used to make glucose

when carb is low, amino acids from diet or lean tissue is used to make glucose

how are amino acids used to make glycogen and fat?

excess protein is converted to glucose/ketone bodies which are stored int the body as glycogen and fat

process of protein metabolism

1. deamination of amino acids: resulting in ammonia and a keto acid

2. conversion of ammonia to urea: concerted by the liver

3. excreting urea

why would a person on a high protein diet be at risk of dehydration? explain the role of urea in eliminating unused nitrogen from the body

• need plenty of water dilute and excrete urea from the body

• urea is primary vehicle for excreting unused nitrogen and inc protein incr urea

define reference protein

quality of protein determined by comparing amino acid composition with essential amino acid requirements

define high quality protein

contains all the essential amino acids in relatively the same amounts and proportions that human beings require

effects of protein deficiency

• many of body’s activities stop

• protein energy malnutrition

effect of protein on heart disease

high protein diets may contribute to the progression of heart disease as homocysteine is elevated in

how does protein effect cancer?

• processed meat and red meat as a probable carcinogen

• protein rich legumes, fish, and milk may lower risk

what is the recommended intake of protien?

• 0.8g/kg body weight/day for healthy adults

• 10% of total energy

define epigenetics

how environmental factors influence gene expression