cell bio exam 1

carbon significance

can form up to four bonds with surrounding elements

ionic bonds

• strongest bond

  • + and - charge of molecules

hydrophilic

attracted to water

hydrophobic

not attracted to water, nonpolar

self assembly

once assembled macromolecules can assemble into structures themselves outside of the cell

molecular chaperones

assist in assembly/proper folding of proteins

monomers

building blocks of each macromolecule

macromolecule synthesis

• ATP activates monomer and adds carrier protein

  • activated monomers join together with forms water (condensation reaction)

polymerization

lengthening of activated monomers

carboxyl group, amino group, R group

components of a protein

amino acid

monomer of protein

N to C

amino acid directionality

primary structure

• order of amino acids in a polypeptide chain which directs formation for higher structures

  • covalent peptide bonds

secondary structure

• local structures as a result of hydrogen bonds on polypeptide backbone

alpha helix

• H bonds form between CO and NH groups about every four amino acids, usually repeated giving it a helix shape

• keratin

beta sheets

• forms peaks and troughs due to H bonding

• usually tightly packed

• silk

proline

cannot form H bonds due to its cyclic nature (no alpha helix or beta sheets)

motifs

secondary structures composed of a few secondary structure elements

tertiary structure

• most likely final folding of a protein

• determined by amino acid sequence and R group interactions

  • resulting from all total interactions (disulfide, H bonds, non/covalent bonds, etc)

fibrous proteins

have extensive regions of secondary structure giving it lots of order and rigidity

globular proteins

most proteins, folded into compact structure

most enzymes are this

quaternary structure

• can consist of identical or different polypeptides

• applies specifically to multimeric proteins

multimeric proteins

consist of more than one polypeptides

monomeric proteins

consist of one polypeptide

enzyme

special type of protein that lower activation energy of a reaction

-delta g

favorable + exergonic reaction (releases energy)

+delta g

unfavorable + endergonic reaction (absorbs energy)

activation energy

difference between reactants and transition state (max of graph)

catalysts

• provides a surface for reactions and temporarily bond with reactants to speed reaction

  • are not used in a reaction

oxidoreductase

enzyme involved in oxidation reduction reactions (electron transfer)

tranferases

enzyme that transfers a functional group from one molecule to another hy

hydrolase

enzyme that hydrolytically cleaves a molecule into two molecules

lyase

enzyme that removes or adds a group to another molecule

isomerase

enzyme that moves a functional group within a molecule li

ligase

enzyme that joins two molecules together to form a new one

why enzymes are pH dependent

a change in pH could protonate or deprotonate side chains in proteins, resulting in improper folding

active sites

• region of an enzyme where substrates bind to

• results from tertiary structure of a protein

cofactors

• nonprotein molecules sometimes needed for catalytic activity because they function as electron acceptors

induced fit

enzymes active sites change their shape slightly to form a tight grip on a molecule

denaturing

unfolding or improper folding of a protein resulting in a loss of function

bond distortion

substrate activation in which substrate the bonds within a substrate become more susceptible to catalytic attack

proton transfer

increased reactivity of a substrate

electron transfer

results in temporary covalent bonds between an enzyme and substrate

irreversible inhibition

• inhibitors bind to enzyme COVALENTLY and cause permanent loss of catalytic activity

reversible inhibition

enzyme binds NONCOVALENTLY

competitve inhibition

• type of reversible inhibition in which inhibitor binds to active sites of an enzyme

• dependent on concentration of substrates

noncompetitive inhibition

• reversible inhibition in which an inhibitor changes the shape of an enzyme so that a substrate will no longer fit into and bind with the active site

• not dependent on concentration of substrates

allosteric site

• place at which regulatory molecules can bind

  • located on the regulatory subunit, different from the catalytic subunit which contains the active site

allosteric activation

regulatory molecules bind to allosteric site which changes shape of the active site, allowing substrate molecules to bind to enzymea

allosteric inhibition

regulatory molecules bind to allosteric site which changes shape of the active site, preventing substrate molecules from binding to the enzyme