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