Mcat Biochemistry Chapter 3

Front 1

structural proteins compose what structures?

Back 1

cytoskeleton, anchoring proteins, much of extracellular matrix

Front 2

most common structural proteins (5)

Back 2

collagen, elastin, keratin, actin, tubulin

Front 3

common motor proteins

Back 3

myosin, kinesin, dynein

Front 4

binding protein purpose

Back 4

bind specific substrate, either to sequester it in the body or hold its concentration at steady state

Front 5

cell adhesion molecules (CAMs) purpose

Back 5

allow cells to bind to other cells or surfaces

Front 6

cadherins

Back 6

CAM, calcium-dependent glycoproteins that hold similar cells together

Front 7

integrins

Back 7

CAM, two membrane-spanning chains, permit cells to adhere to proteins in the extracellular matrix. some have signaling capabilities

Front 8

selectins

Back 8

CAM, allows cells to adhere to carbohydrates on the surfaces of other cells, most commonly used in the immune system

Front 9

antibodies/immunoglobulins/Ig

Back 9

used by immune system to target a specific antigen

Front 10

what region of an antibody is responsible for antigen binding, and what other regions are there?

Back 10

variable region (other region is constant)

Front 11

structure of an antibody

Back 11

two identical heavy chains and two identical light chains form a single antibody

held together by disulfide linkages and noncovalent interactions

Front 12

ion channels

Back 12

used for regulating ion flow into or out of a cell

Front 13

ungated ion channels

Back 13

always open

Front 14

voltage-gated ion channels

Back 14

open within a range of membrane potentials

Front 15

ligand-gated ion channels

Back 15

open in the presence of specific binding substance, usually hormone or neurotransmitter

Front 16

enzyme-linked receptors

Back 16

participate in cell signaling through extracellular ligand binding and initiation of second messenger cascades

Front 17

G protein-coupled receptors

Back 17

have membrane-bound protein associated with a trimeric G protein. initiate second messenger systems

Front 18

pathway of G protein-coupled receptor activation

Back 18

ligand binding engages G protein

GDP is replaced with GTP

alpha subunit dissociates from the beta and gamma subunits

activated alpha subunit alters activity of adenylate cyclase or phospholipase C

GTP is dephosphorylated by GDP

alpha subunit rebinds to beta and gamma

Front 19

electrophoresis

Back 19

uses gel matrix to observe migration of proteins in response to an electric field

Front 20

Native PAGE

Back 20

electrophoresis style, maintains protein's shape, but results are difficult to compare because the mass-to-charge ratio differs for each protein

Front 21

SDS-PAGE

Back 21

electrophoresis style, denatures the proteins and masks the native charge so that comparison of size is more accurate, but the functional protein cannot be recaptured from the gel

Front 22

isoelectric focusing

Back 22

electrophoresis style, separates proteins by their isoelectric point (pI). protein migrates toward an electrode until it reaches a region of the gel where pH=pI of protein

Front 23

chromatography

Back 23

separates protein mixtures on the basis of their affinity for a stationary phase or a mobile phase

Front 24

column chromatography

Back 24

uses beads of a polar compound, like silica or alumina (stationary phase), with a nonpolar solvent (mobile phase)

Front 25

ion-exchange chromatography

Back 25

uses a charged column and a variably saline eluent

Front 26

size-exclusiong chromatography

Back 26

relies on porous beads (larger molecules elute first because they are not trapped in the pores)

Front 27

affinity chromatography

Back 27

uses a bound receptor or ligand and an eluent with free ligand or a receptor for the protein of interest

Front 28

Edman degradation

Back 28

used for amino acid sequencing