2.6 Proteins

primary structure

linear sequence of amino acids

denaturation

loss of normal shape and function of a protein due to a change in heat or pH

hormones

regulatory proteins that serve as intercellular messengers that influence the metabolism of cells.

support

some proteins are structural proteins. Keratin makes up skin and nails. Collagen lends support to ligaments, tendons, and skin.

quaternary structure

The shape resulting from the association of two or more polypeptide subunits. Most enzymes have this structure, as does hemoglobin.

polypeptide

3 or more amino acids linked by peptide bonds

tertiary structure

3D shape where many proteins establish their function

alpha helix

A coiled region constituting one form of the secondary structure of proteins, arising from a specific pattern of hydrogen bonding between atoms of the polypeptide backbone (not the side chains).

amino group + carboxyl group + R group

amino acid structure

beta helix

an accordion shape, hydrogen bonds hold the shape

defense

antibodies are proteins. they combine w/ foreign substances, called antigens. in this way, they prevent antigens from destroying cells and upsetting homeostasis

Alzheimer's and human mad cow disease (C-J)

both diseases are due to changes in protein shape

enzymes

bring reactants together thus speeding along chemical reactions in the cell. Specific to the type of reaction. function at a specific pH and body temp.

COOH

carboxyl/acid group

transport

channel and carrier proteins in the plasma membrane allow substances to enter and exit cells, some other protein move molecules in the blood of animals; hemoglobin in red blood cells is a complex protein that moves oxygen.

secondary structure

comes about when a polypeptide takes on a certain orientation in space. Hydrogen bonding is possible between the C=O of one amino acid chain and the N-H of another amino acid chain.

motion

contractile proteins actin and myosin allow parts of cells to move and cause muscles to contract.

peptide bond

covalent bond formed between amino acids

covalent, ionic, hydrogen

different types of R-group bonding

NH2

Amino group

nonpolar

R groups can be polar and

R group

a functional group that defines a particular amino acid and gives it special properties. R= rest of the molecule.

DNA

amino acid sequence is determined by

unevenly (-O, +N)

peptide bond atoms share electrons

support, enzymes, transport, defense, hormones, motion

protein main functions

amino acids

protein monomers

3 levels

the structure of a protein has at least

structures and functions of cells

type of protein controls the