PROTEINS
Different types of proteins function in
different ways:
Functions of proteins:
-->speed up metabolic rxns
-->make up many animal/plant structures ex:bone, feathers, webs
-->move other molecules
-->energy source
-->affect function of other molecules
-->recognize & destroy invaders
All types of proteins come from
Amino acid =
Primary structure = sequence of amino acids
Amino acids are linked by
= covalent bond between amino group of one amino acid with the acid
group
(carboxyl) of another amino acid
3 or more amino groups joined with peptide bonds = -->incorporates N into "backbone"
-N-C-C-N-C-C-N-C-C-N-C-C-N-
backbone of polypetide chain
Each protein is coded for by specific combinations of the 20 available amino acids
Primary structure of proteins= =unique to each protein-->determined by DNA
3-D Structure of Proteins
1. Fibrous proteins=
ex: cilia (movement of cells)
2. Globular proteins=
ex: enzymes
3. Combination of fibrous & globular
3-D shape determined by the primary structure-->way
atoms are arranged & amino acid seq.
-->depending on arrangement-->may cause
polypeptide to
-->Affects interaction rate
;
Especially important for
Primary structure affects shape in the following
ways:
1. patterns of
between the O- (of the carboxyl group) & other atoms of the amino
acid causes coiling or extension =
2. secondary structure puts
in positions that allow them to interact-->causes it to bend & twist=
3. bending, twisting, & extension
caused by secondary and tertiary structure may cause it the protein to
=
ex: hemoglobin=
(with secondary, tertiary, and quartenary structure)
keratin (hair)=
(with secondary, tertiary, and quartenary structure)
collagen(skin, bone, tendons)=
(with secondary, tertiary, and quartenary structure)
Denaturation
Protein loses
due to
(both hydrogen bonds & R group bonds)
Unwind, change shape-->
as enzymes
Does NOT cause protein to lose
Ex: egg white (=
); add heat-->causes protein
(3-D shape) but does not change
-->still albumin, however can no longer function
Enzymes=
ex: lactase
the breakdown (breaking bonds) of
=sugar in cowís milk
5 categories of rxns controlled by enzymes:
1.
=move function group from one molecule to another
2.
=1 or more e- stripped from one molecule & passed to another
3.
=Change of internal bonds on molecule-->converts to new, more reactive,
molecule
4.
=2 molecules combine to form a larger molecule
5.
=1 larger molecule splits into 2 smaller
Ex: condensation rxn
production of a polysaccharide from monosaccharides
enzyme removes
from one molecule &
from another (type of reaction?)
-->
This is how starch forms=
=large molecule formed from the bonding of many smaller subunits
Another ex: Hydrolysis
special type of
Enzyme causes breaks at functional
groups-->splits large molecule into
-->involves
and an enzyme