PROTEINS PART 1 Flashcards
- chief nitrogenous macromolecules of cellular structure and orgnization
PROTEINS
([?] of cell’s dry weight)
50 to 70%
4 major elements found in proteins
Carbon, hydrogen, oxygen, nitrogen
Building blocks of proteins
Amino acids
- consists of a definite number of amino acids arranged in a specific sequence
PROTEINS
PROTEINS PH
amphoteric
- basic/alkaline; negative
amino group
- acidic; positive
carboxyl
- refers to the identity and specific order of amino acids in the polypeptide chain (amino acid sequence)
Primary structure
- determine the overall shape of the protein
Primary structure
Arrangement of amino acids in a polypeptide chain
Primary structure
Each circle represents
one amino acid
free amino acid group
(N-terminal)
free carboxyl group
(C-terminal)
Result in biuret test: copper sulfate attaches to the peptide linkage = violet color
peptide bond
Primary structure linkage
peptide bond
Secondary structure linkage
hydrogen bonds
Tertiary structure linkage
covalent disulfide bond
Quaternary structure linkage
none
strong bond
covalent disulfide bond
conformation of the segments of polypeptide chain
Secondary structure
intramolcular folding of the polypeptide chain into a compact 3-dimenional structure
Tertiary structure
association of several polypeptide chains into larger “oligomeric” aggregate unit
Quaternary structure
Secondary structure shapes
a. alpha-helix and
b. beta-pleated sheets
c. random coils
Each amino groups have R groups/side chains that interact to one another = 3D STRUCTURE
Bending and folding
Separate polypeptide units are bended and folded
oligomeric
Several polypeptide units
oligomeric
Hemoglobin has four polypeptide units
Quaternary structure
2 alpha and 2 beta and Conjugated protein
Quaternary structure
A nonprotein (heme) combined with a protein molecule
Hemoglobin
ultimate product of digestion are amino acids
Simple
the protein molecule is combined with a non-protein component
Conjugated
- a pigment is combined with a protein molecule
chromoprotein