Proteins Flashcards
What are the many functions of proteins
Serve as catalysts (enzymes) in metabolic reactions Act in defense Aid in transport Contribute to structural support Cause movement Perform regulation Provide storage
what is the general structure of proteins
one or more strands of amino acid monomers
How many amino acids are there
20
Each protein has an
amine and a carboxyl functional group( both are covalently linked to same carbon atom)
The carbon is also covalently bonded to
a hydrogen and different side chain structures
Amino acids are covalently linked
by peptide bonds
strand of amino acid are
oligopeptide,polypeptide and protein
number of amino acids in a oligopeptide
3-20
number of amino acids in a polypeptide
21-199
number of amino acids in a protein
200+
Glycoproteins are
proteins with a carbohydrate attached
what are the categories of amino acids
nonpolar, polar, charged, special
Nonpolar amino acids
contain R groups with hydrogen or hydrocarbons
group with other nonpolar amino acids by hydrophobic interactions
Polar amino acids
Contain R groups with other elements besides hydrogen or hydrocarbons
Form interactions with other polar amino acids and with water
charged amino acids
Contain R groups with a negative or a positive charge
Form ionic bonds between negatively and positively charged amino acids
Hydrophilic
amino acids with special functions
Contain R groups with a negative or a positive charge
Form ionic bonds between negatively and positively charged amino acids
Hydrophilic
The structures of amino acids are
primary, secondary, tertiary, quaternary,
Primary structure
linear sequence of amino acids
Confromation is
three-dimensional shape of the protein
(Crucial for protein function
Levels of organization beyond primary structure
Arrangements dependent upon intramolecular attractions between amino acids
Obtained through folding with help of specialized proteins, chaperones)
Intramolecular interactions
Hydrophobic interactions with nonpolar amino acids farther from water
Hydrogen bonds between polar R groups, between amine and carboxylic acid groups
Ionic bonds between negative and positive R groups
Disulfide bonds between cysteine amino acids
secondary structures
Patterns that may repeat several times
Confer unique characteristics
Two types
two types of secondary structures
alpha helix(spiral coil) and beta sheet(planar pleat arrangement)
Tertiary structure is
Three-dimensional shape of poly-peptide chain
2 categoreis of tertiary structure is
Globular proteins fold into compact shape
Fibrous proteins are extended linear molecules
Quaternary structure is
Present in proteins with two or more polypeptide chains
E.g., hemoglobin with its four polypeptide chains
Prosthetic groups
Nonprotein structures covalently bonded to protein
Denaturation
Conformational change to a protein
Disturbs protein activity
Usually irreversible
May occur due to increased temperature or in response to changes in pH
