lecture #4 proteins Flashcards
what are the different types of proteins
enzymatic, defensive, storage, transport, hormonal, receptor, motor, structural (p. 81)
what do enzymatic proteins do
regulate metabolism by acting as catalysts, chemical agents that selectively speed up chemical reactions without being consumed by the reaction. Because an enzyme can perform its function over and over again, these molecules can be thought of as workhorses that keep cells running by carrying out the processes of life.
what are proteins made of
Proteins are all constructed from the same set of 20 amino acids, linked in unbranched (not just straight) polymers.
what is the bond between amino acids called
peptide bond
what is a polymer of amino acids called
polypeptide
by definition, what is a protein
a biologically functional molecule made up of one or more polypeptides, each folded and coiled into a specific three-dimensional structure.
what is amino acid made of
alpha carbon in the center, amino group to the left, a carboxyl group to the right, H on the bottom and a variable group on top (p.81)
what determines the unique characteristics of a particular amino acid
the side chain (R group)
what are the 3 different types of amino acids
non-polar side chains : hydrophobic , polar side chains: hydrophilic, electrically charged side chains: hydrophylic
how are polypeptides formed
When two amino acids are positioned so that the carboxyl group of one is adjacent to the amino group of the other, they can become joined by a dehydration reaction, with the removal of a water molecule. The resulting covalent bond is called a peptide bond. Repeated over and over, this process yields a polypeptide, a polymer of many amino acids linked by peptide bonds (p.83)
what determines the nature of a protein
determined by the kind and sequence of the side chains.
what do all amino acids have
N terminus (free amino acid, nitrogen side) C terminus (free carboxyl end). this confers polarity in the polypeptide
what is the primary structure
number and sequence of amino acids making up the polypeptide chain
what is the secondary structure
turns and folds (due to H bonding)
alpha helix (coiled, “bouclette”, bonds occur every 4 amino acids
beta pleated sheet , folded
what is the tertiary structure
iregular loops and folds which give the proteins its overall shape. Results from the interaction between the R groups. (H bonds, ionic bonds, Disulfide bonds, hydrophobic interactions)
what is the quanternary structure
the fusion of 2 or more polypeptides
what is a monomeric protein
proteins made of a single polypeptide chain
what is a oligomeric protein
consists of 2 or more polypeptide chains
what is denatuation, what does it do
proteins can loose their shapes, influenced by their environments, can be temporary or permanent
disrupts normal alpha helix or beta plated sheet
in what structure does the denaturation occur
secondary and tertiary structure
what does alcohol do to protein
disrupts H bonds that occur in the secondary and tertiary levels
what is an important protein found in our cells
ribosomes:
- displays quaternary structures
- uses rna to make other proteins
- made in the nucleolus
what causes sickle cell disease
modification of 1 amino acid in the primary structure
(can cause blood clothing)
what can cause denaturation
If the pH, salt concentration, temperature, or other aspects of its environment are altered, the weak chemical bonds and interactions within a protein may be destroyed, causing the protein to unravel and lose its native shape, a change called denaturation
(protein becomes inactive)
