Protein & DNA Flashcards
what provides most of the molecular functions of life?
proteins
what is a protein / another name for a protein?
a string (polymer) of amino acids / polypeptide
amino acid structure
central alpha carbon
amino group NH2
carboxyl group CO2H
hydrogen atom
side chain “R” group
how many “R” groups are there?
20 – different amino acids
what chemical differences can the “R” groups have?
polar/nonpolar
acid/base
others
what determines the proteins function?
structure of the protein
what is the key to life as we know it?
protein structure
define polypeptide
a string of amino acids linked together in a chain by peptide bonds
where do peptide bonds join the amino groups?
at the amino group of one end to the carboxyl group of another amino acid
what type of bond is a peptide bond?
covalent
dehydration rxn
molecule of H2O is lost to form a peptide bond
hydrolysis rxn
H2O is added to break a peptide bond
what direction do the O and H point in a peptide bond
opposite directions
can the peptide bond rotate?
no, it’s planar b/c part of O’s double bond is delocalized onto the N
sequence of polypeptide backbone
NCCNCCNCCN
In polypeptide sequence what # covalent bond is a peptide bond?
Every 3rd
When can a polypeptide be called a protein?
If it has a biological function and is long
Small vs. large proteins
Small can be less than 100 amino acids
Large can be more than 30,000