Lecture 5 - Biomolecules II Flashcards
proteins account for what percent of the dry mass of cells
50%
name the monomers of proteins
amino acids
name the polymers of proteins
polypeptides
name the bonds of proteins
peptide bonds
what is the most diverse group of biomelecules
proteins
what is the difference between a polypeptide and a protein?
Polypeptide: string of animo acids
Protein: biologically functional molecule that consists of one or more polypeptides
describe the structure of an amino acid
amino group + alpha c + carboxyl group.
a side chain/ R group attached to the alpha carbon
how many amino acids are there? what differentiates them?
20 amino acids.
the R groups differentiate
how are amino acids attached?
opposite ends of a pair of amino acids can undergo a dehydration reaction to form a covalent bond.
the covalent bond between two amino acids is called a peptide bond
describe a functional protein
a functional protein consists of one or more polypeptides twisted. folded, and coiled into a unique shape (conformation)
what determines a proteins function?
its conformation
what determines a protein’s three dimensional conformation?
the sequence of amino acids
how many levels of protein structure are there?
4
describe primary protein structure
polypeptides unique sequence of amino aicds
describe the secondary structure of proteins
coils and folds within the polypeptide chain determined by interactions among various backbone components
describe tertiary structure of proteins
determined by interactions among various side chains (R groups)
describe quaternary structure of proteins
when protein consists of multiple polypeptide chains
primary prtoein structure is determined by what
the sequence of amino acids
determined by inherited genetic information
what does primary protein structure determine
ultimate structure (R group interaction) which determines function
describe structure of secondary protein structure
coils and folds of secondary structure results from hydrogen bonds between backbone constituents.
typically, secondary structures are a coil called alpha-helix and a folded structure called a pleated beta sheet
describe the structure of tertiary protein structure
overall shaoe of a polypeptide is determined by interactions between R groups, not by interactions between bacbone constituent
interactions between R groups include H bonds, hydrophobic interactions, and van der Waals interactions
describe the structure of quaternary protein structure
individual polypeptide chains = subunits
alpha chain subunits = alpha helices
beta chain subunits = beta sheets
when is tertiary structure final?
if protein is made from one polypeptide
when is quaternary structure final
if protein is made of multiple polypeptides
Proteorhodopsin, a light driven proton pump, consists of a single polypeptide chain. What is the highest level of structure found in this protein?
tertiary ***
double check notes
what is denaturation of proteins?
change in shape or even unfolding of protein because of change in environment (ex. pH, temp, ionic concentrations)
biologically inactive
most enzymes funtional in a narrow range
name functions of proteins
- catalyzing chemical reactions
- structural support
- storage
- transport
- cellular communications
- movement
- defense against foreign substances
name the polymers of lipids
lipids don’t form polymers
what is the unifying feature of lipids
little or no affinity for water
why are lipids hydrophobic?
consist mostly of hydrocarbons, which form non polar covalent bonds
name the most biologically important lipids
fats, phospholipids, steroids
describe fatty acids structure
long hydrocarbon chain (16-22 C long)
where are fatty acids found
fats, oils, phospholipids, and as free form fatty acids
describe fats functions
energy storage, insulation, protection
descirbe fats structure (names)
glycerol and fatty acids
describe glycerol
a 3 carbon alcohol with an OH group attached to each carbon
describe fatty acid
carboxyl group -COOH attached to a long carbon skeleton
