What is a protein?
amino acids
What is the primary function of a protein?
structural or mechanical functions
enzymes
hormones
immune funciton
fluid balance
acid-base balance
transport function
source of energy and glucose
What is the chemical structure of an amino acid?
amino group, one of 20 unique side groups, carboxylic acid group (COOH-)
What are the elements in the chemical structure of the amino acids?
carbon hydrogen oxygen and nitrogen
Define indispensable amino acid (essential amino acids)
amino acids that the body cannot make at all or cannot make enough of to meet physiological needs. must be supplied in the diet
Define dispensable amino acid (nonessential amino acid)
amino acids that the body can make if supplied with adequate nitrogen, do not need to be supplied by diet
How many amino acids are there?
20
How many essential (indispensable) amino acids are there?
9
Define conditional indispensable (essential) amino acids
amino acids that are normally made in the body (dispensable) but become indispensable under certain circumstances, such as during critical illness
What is complete or high quality protein? Give some food examples
proteins that supply all the indispensable amino acids in the proportions the body needs
ex. red meats, poultry, fish, eggs, milk, milk products
What is an incomplete protein or low quality protein? Give some food examples
proteins that lack one or more amino acids
ex. grain products (pasta), legumes
What is a limiting amino acid? Give examples
the amino acid in shortest supply during protein synthesis. also the amino acid in the lowest quantity when evaluating protein quality
What does it mean to complement proteins? Give some food examples
the complementation of a protein is when one protein that is lacking sufficient amino acids is eaten with amino acids that are also insufficient. eating them together makes them complete
What plant source is a complete protein?
soybeans
What is a side group of an amino acid and its role in the type of amino acid?
side group is unique to each amino acid, mean that they differ in shape, size, composition, electrical charge, and pH
What is a peptide bond?
the bond between two amino acids formed when a carboxyl group of one amino acid joins an amino group of another amino acid, releasing water in the process
Define dipeptide, tripeptide, and oligopeptide
dipeptide-two amino acids joined by a peptide bond
tripeptide-3 amino acids joined by a peptide bond
oligopeptide-4-10 amino acids joined by peptide bonds
What is meant by the term "primary structure of an amino acid"?
sequence of amino acids forming one or more polypeptide chains
What is meant by the term "secondary structure of an amino acid?
the coiling or folding of its polypeptide chains due to hydrogen bonding within or between amino acid chains
What is meant by the term "tertiary structure of an amino acid"?
3-dimensional shape of the polypeptide caused by weak interactions among side groups, and between side groups and the fluid environment
What is meant by the term quaternary structure of an amino acid"?
final 3-dimensional structure of a protein formed by all the polypeptide chains
Define denature
an alteration in the three-dimensional structure of a protein resulting in an unfolded polypeptide chain that usually lacks biologoical activity
What happens to the protein when it is denatured?
loses its 3-dimensional shape
Give examples of substances/circumstances that will denature a protein
acidity, alkalinity, heat, alcohol, oxidation, and agitation
Define collagen and the role protein plays
the most abundant fibrous protein in the body, collagen is the major constituent of connective tissue, forms the foundation for bones and teeth, and helps maintain the structure of blood vessels and other tissues
Define antibodies and the role protein plays
large blood proteins produced by B lymphocytes in response to exposure to particular antigens, each antibody specifically binds to to and helps eliminate its matching antigen from the body, once formed, they circulate in the blood and help protect the bod
Define intravascular and the role protein plays
the fluid portion of the blood (plasma) contained in arteries, veins, and capillaries, counts for about 15% of the extracellular fluid
Define extra vascular and the role protein plays
...
Define acidosis and the role protein plays
an abnormally low blood pH due to increased acidity
Define alkalosis and the role protein plays
an abnormally high blood pH due to increased alkalinity
What is a buffer?
compounds or mixtures of compounds that can take up and release hydrogen ions to keep the pH of a solution constant - maintains blood pH
What is ammonia and what is its relationship to protein
...
What is Urea?
a compound made from nitrogenous waste produced in cells
Define nitrogen balance
nitrogen intake minus the sum of all sources of nitrogen excretion; nitrogen balance equals zero
What is positive nitrogen balance and give examples
nitrogen intake exceeds nitrogen excretion, means that the body is adding proteins- children, pregnant women, or people recovering
What is negative nitrogen balance and give examples
nitrogen excretion exceeds nitrogen intake, losing protein , people whoa re starving, in extreme weight loss or who suffer fever, illness, infection
What is the RDA for protein for adults?
.85 grams
What is the AMDR for protein?
10-35%
Where in the digestive tract does the chemical digestion of protein occur?
stomach, small intestine
What is HCL and how does it effect protein digestion?
hydrochloric acid-stimulates pepsinogen- changes into pepsin- denatures and digests proteins
What is pepsin?
Pepsin is an enzyme in the stomach that digests protein and makes amino acids.
Where is pepsin found?
stomach
What is the name of the inactive form of pepsin and how is it activated?
pepsinogen
What is trypsin and where is it manufactured, what is its inactive form and where does it digest protein?
a protease produced by the pancreas that is converted from the inactive proenzyme from (trypsinogen) to the active form (trypsin) in the small intestine
What is chymotrypsin and where is it manufactured, what is its inactive form and where does it digest protein?
a protease produced by the pancreas that is converted from the inactive proenzyme form (chymotrypsin) in the small intestine
What are peptidases and where are they manufactured and what are their roles in digestion?
enzymes that act on small peptide units by breaking peptide bonds
How are amino acids absorbed?
in duodenum and jejunum. transported via portal circulation to liver. then released into general circulation.
Where are amino acids absorbed?
..., lining of the Small intestine
Define transamination
...
Define deamination
The breakdown of excess amino acids in the liver"
Amino acid -> keto acid + ammonia
Describe the steps in protein synthesis
...
What is the relationship between DNA/RNA and protein synthesis
..., the structure of the protein is dictated by the DNA of the gene
Transcription: use of the genetic info in DNA to make mRNA
Translation: conversion of genetic inf mRNA to the amino acids sequence of a protein.
What happens if an amino acid is missing during protein synthesis?
..., ultimately it stops. but if dispensible (nonessential): cell will either make that AA or obtain it from liver. if indispensible (essential): body breaks down its own protein to supply missing AA
What is produced when Amino acids are broken down for energy?
lactic acid
What is the amino acid pool?
the amino acids in the body tissues and fluids that are avaliable for new protein synthesis
Define protein turnover
the constant syn and breakdown of proteins in the body
What are the different types of vegetarians and what do they or don't they eat?
lacto-ovo-vegetarians-milk, cheese, eggs
vegans- no animal based foods
fruitarians-eat only raw fruit, nuts, and green foliage
semi-vegetarian
mediterranean
What nutrients maybe deficient in a vegan diet?
zinc, calcium, vit. D, riboflavin, and vit B12
What are the risks associated with too much protein intake?
kidney function
mineral losses
obesity
heart disease
cancer
gout
What is Kwashiorkor
a type of malnutrition that occurs primarily in young children who have an infectious disease and whose diets supply marginal amounts of every and very little protein.
What is Marasmus
a type of malnutrition resulting from chronic inadequate consumption of protein and energy that is characterized by wasting of muscle, fat, and other body tissues