bio sci 93 - lecture 4: macromolecules ii: proteins & nucleic acids

describe structural characteristics and functions of proteins. Identify different types of amino acids (polar, nonpolar, charged)

discriminate and compare the different levels of protein organization. estimate the consequence of alterations in protein structure according to the organizational level involved

predict the functional consequences of “single base change in DNA → single base change in mRNA → single AA change in protein

justify the role of chaperone proteins in cells, their location and mechanism of action

justify the role of proteasomes in cells, their location and function

describe structural characteristics and functions of nucleic acids. identify different types of nucleotides, recognize nucleotide components. compare and contrast DNA and RNA structure and function. solve basic problems of DNA/RNA structure

compare the complexity of the genome vs proteome

protein function:

support, storage, transport, signaling, receptors, movement, catalysis, defense

protein structure:

amino acids - monomers, combine to form polymers

polypeptide - polymer of AAs in specific sequence

protein - one or more polypeptides w/ specific 3-d conformation

amino acids —> polypeptides —> proteins

proteins are all constructed from…

same set of 20 amino acids

structure of amino acid

1) amino group

2) hydrogen

3) carboxyl group

4) R group: variable side chain

nonpolar

hydrophobic

polar

hydrophilic

charged

hydrophilic

amino and carboxylic acid groups are in ionized form (as in a cell)

formation of polypeptide

amino end, carboxy end

three levels of structure in a single polypeptide that organize the folding:

primary, secondary, tertiary, quaternary

primary structure

determined by AA sequence

secondary structure

alpha helix (coils), beta pleated sheets (folds)

tertiary structure

R group interactions

weak: hydrogen bonds, ionic bonds, hydrophobic, van der Waals interactions

strong: covalent bond

quaternary structure

overall protein structure resulting from combined polypeptides: 2 or more

stabilized by R group interactions

the effect of a single change in primary structure can have pleiotropic consequences

carbohydrates, proteins, nucleic acids

polymer: long molecule built from similar subunits (monomers) linked by covalent bonds

lipids (not polymer)

diverse group of hydrophobic macromolecules

built from two or more different types of smaller subunits

nucleic acid function

store and transmit hereditary information

nucleic acid structure

polymers of nucleotide monomers

nucleotide monomers: pentose sugar, nitrogen base, phosphate group

two types of nucleic acids:

DNA & RNA

DNA

double stranded

C G A T

RNA

single stranded

C G A U

polynucleotides (nucleic acid polymer)

sugar connected to phosphate group of adjacent nucleotide

backbone: sugar-phosphate unit

side chains: nitrogen bases