BIOCHEM Chp.3 Non Enzymatic protein Function & Analysis

Question 1

What is collagen?

Answer 1

a structural protein comprising more of the cellular matrix of connective tissue. provides strength and flexibility

Question 2

What is keratin?

Answer 2

an intermediate filament found in epithelial cells. contributes to the mechanical integrity of cells and functions as regulatory proteins

Question 3

What is actin?

Answer 3

a protein that makes up microfilaments and the thin filaments in myofibrils. it is the most abundant protein in animal cells

Question 3

What is elastin?

Answer 3

an important component of the extracellular matrix of connective tissue, the primary role is to stretch and recoil like a spring

Question 4

What is tubulin?

Answer 4

a protein that makes up microfilaments. important in providing structure, chromosome separation in mitosis and meiosis, and intracellular transport in kinesin and dynein

Question 5

What motor protein is in myofibrils?

Answer 5

myosin is the primary motor protein that interacts with actin

Question 6

What motor protein is associated with microtubules?

Answer 6

kinesin brings vesicles toward the positive end of the microtubules, and dyneins bring vesicles toward the negative end

Question 7

What are examples of binding proteins?

Answer 7

hemoglobin, calcium-binding proteins, DNA-binding protein (transcription factors)

Question 8

What are CAMs?

Answer 8

cell adhesion molecular proteins found on the surface of the cells that aid in binding the cell to the extracellular matrix or other cells

Question 9

What are cadherins?

Answer 9

a group of calcium-dependent glycoproteins that mediate calcium-dependent cell adhesion that hold similar cells together

Question 10

What are intergrins?

Answer 10

a group of proteins that all have 2-membrane-spanning chains called alpha and beta which are important in binding to and communicating with the extracellular matrix

Question 11

What is the role of integrins?

Answer 11

promoting cell divisions, apoptosis, white cell migration, stabilization of epithelium on its basement membrane, allowing platelets to stick to fibrinogen clotting factor to stabilize clotting

Question 12

What are selectins?

Answer 12

bind to carbohydrates that project from other cell surfaces, and are expressed on WBC and endothelial cells

Question 13

What are immunoglobins?

Answer 13

proteins produced by B-cells are made up of 2 heavy chains and 2 light chains held together by disulfide linkages and non-covalent interactions. contains a constant and variable region which is responsible for antigen binding

Question 14

What are the 3 outcomes of antibodies binding to their target antigen?

Answer 14

neutralize the antigen, targeting the pathogen for destruction by other WBS (opsonization), clumping together (agglutinating) and the antigen and antibody into large soluble protein complexes that can be phagocytosed and digested by macrophages

Question 15

What is facilitated diffusion?

Answer 15

a type of passive transport is the diffusion of impermeable (polar, large, or charged) molecules down a concentration gradient through a pore in the membrane created by their transmembrane protein. It also allows for integral membrane proteins to serve as channels for these substrates

Question 16

How are ungated channels open?

Answer 16

have no gates and are unregulated

Question 17

What are the primary structural proteins?

Answer 17

collagen, elastic, keratin, actin, and tubulin

Question 18

What are the major motor proteins?

Answer 18

myosiin, kinesin and dyneins

Question 19

What are the major adhesion proteins?

Answer 19

CAMS, cadherins, integrins, and selectins

Question 20

How are voltage-gated channels open?

Answer 20

regulated by the membrane potential near the channel. the channel is closed under resting conditions, but depolarization causes a protein conformation change that allows them to open and close as voltage increases quickly

Question 21

How are ligand-gated channels open?

Answer 21

the binding of a specific substance (usually hormone of neurotransmitter) or ligand to the channel causes it to open or close

Question 22

What are examples of enzyme-linked receptors?

Answer 22

receptor tyrosine kinases (RTK), serine/threonine-specific protein kinases and receptor tyrosine phosphatases

Question 23

What are the primary protein domains of enzyme-linked receptors?

Answer 23

participate in cell signaling through extracellular ligand binding proteins which often initiate a second-messenger cascade

Question 24

What are G-protein coupled receptors?

Answer 24

integral membrane proteins involved in signal transduction characterized by 7 membrane-spanning alpha helices. the receptors differ in the specificity of the ligand binding area found on the extracellular surface of the cell

Question 25

What are the 3 types of G-protein coupled receptors?

Answer 25

Gs, Gi, and Gq

Question 26

What does Gi stimulate?

Answer 26

adenylate cyclase, which increases levels of cAMP in the cell

Question 27

What does Gs inhibit?

Answer 27

adenylate cyclase, which decreases levels of cAMP in the cell

Question 28

What does Gq stimulate?

Answer 28

phospholipase C, which cleaves phospholipids from the membrane to form PIP2. PIP2 is then cleaved into DAG and IP3. IPS can open calcium channels in the ER increasing calcium levels in the cell

Question 29

What are the 3 subunits of G-protein coupled receptors?

Answer 29

alpha, beta, and gamma.

Question 30

What happens to G-protein coupled receptors when they become active?

Answer 30

ligand binding engages the G protein
GDP is phosphorylated to GTP; the alpha subunit dissociated from beta and gamma subunits
the activated alpha subunit alters the activity of adenylate cyclase of phospholipase C
GTP is dephosphorylated to GDP; the alpha subunit rebinds to the beta and gamma subunits

Question 31

How are proteins separated in electrophoresis?

Answer 31

used a gel matrix to observe the migration of a protein in response to an electrical field. Neg-charge compounds migrate towards the pos-charged anode, and vice versa

Question 32

What is the rate of migration in a Native PAGE?

Answer 32

polyacrylamide gel is the medium or protein electrophoresis. the gel is porous and allows small and highly charged molecules to pass through and be placed in a large electrical field

Question 33

What is the relationship b/w the migration velocity and the electrical field?

Answer 33

v = Ez/f
velocity (v) is proportional to the electrical field strength (E) and the net charge (z) of the molecule, and inversely proportional to the frictional coefficient (f) which is dependent on the mass and shape of the migrating molecule

Question 34

What is the disadvantage of PAGE over SDS-PAGE?

Answer 34

polyacrylamide gel electrophoresis analyses proteins in their native states, but it is not useful in comparing the molecular size or charge or proteins known to be similar in size

Question 35

What does SDS-PAGE separate proteins by?

Answer 35

sodium dodecyl sulfate-polyacrylamide gel electrophoresis denatures proteins and separates them based on their molecular size alone

Question 36

What happens when a protein stops moving in pI focusing?

Answer 36

in isoelectric point focusing, a protein is separated based on pI. the protein migrates toward an electrode and stops moving along the gel when the pH = pI of the protein. at that point, the protein takes on a neutral charge

Question 37

How are proteins separated in the Isoelectric point focus?

Answer 37

It sperates protiens base on pI. the mixture is placed in a gel with a pH gradient (acidic gel at the positive anode, basic gel at the negative cathode, and neutral in the middle). An electrical field is generated across the gel, and proteins that positively charge move toward the cathode and vice versa

Question 38

When would chromatography be used over electrophoresis?

Answer 38

when large amounts of proteins are being separated

Question 39

What is chromatography?

Answer 39

the separation of proteins based on their affinity for the mobile or stationary phase, except for seize-exclusion

Question 40

How are proteins separated in column chromatography?

Answer 40

a column is filled with beads of polar compounds such as silica or alumina beads (stationary phase) as an adsorbent, and gravity moves the nonpolar solvent (mobile phase) and compounds down the column. The less polar the compound and more similar it is to the solvent, the faster it can elute through the column (short retention time)

Question 41

How are proteins separated in ion exchange chromatography?

Answer 41

the beads in the column are coated with a charged substance, so they attract or bind compounds with an opposite charge and are retained. after all the compounds have moved through the column, a salt or saline gradient is used to elute the charge molecules

Question 42

How are proteins separated in size-exclusion chromatography?

Answer 42

the column is loaded with porous beads of varying sizes, allowing small compounds to enter the beads, thus slowing them down. large compounds can’t fit into the beads and are eluted faster through the column

Question 43

How are proteins separated in affinity chromatography?

Answer 43

beads are coated with receptors or ligands that bind the proteins or a specific antibody to the protein and eluent with free ligand or receptor for the protein of interest

Question 44

What is the purpose of X-ray crystallography?

Answer 44

to determine protein structure after the protein has been isolated

Question 45

What are the most prevalent extraocular proteins?

Answer 45

keratin, elastic, and collagen

Question 46

What are the primary cytoskeletal proteins?

Answer 46

tubulin and actin

Question 47

What is the use of calcium?

Answer 47

muscle concentration, exocytosis of nuetromamistters