Cellular Functions

Question 1

Structural proteins

Answer 1

compose the cytoskeleton, aching proteins, and much of the extracellular matrix

Question 2

most common structural proteins are

Answer 2

collagen, elastin, keratin, actin and tubline

- generally fibrous in nature

Question 3

Collagen

Answer 3

• makes up most of the extracellular matrix of connective tissue
• important in providing strength and flexibility

Question 4

Elastin

Answer 4

• important component of the extracellular matrix of connective tissue
• primary role: to stretch and then recoil like a spring, which restores the original shape of the tissue

Question 5

Keratins

Answer 5

• intermediiate filament proteins found in epithelial cells
• contribute to the mechanical integrity of the cell
• functions as regulartory proteins
• primary protein that makes up hair and nails

Question 6

Actin

Answer 6

• protein that makes up microfilaments & thin filaments in the myofibrils
• most abundant protein in eukaryotic cells
• have a (+) and a (-) side; this polarity allows motor proteins to travel unidirectional along an actin filament (like a 1 way street)

Question 7

Tubulin

Answer 7

• protein that makes up microtubules
• microtubules are important in providing structures, chromosome separation in mitosis, and intracellular transport with kinesin and dyneid
• like actin, tubular has polarity; the (-) end of a microtubule is usually located adjacent to the nucleus, whereas the (+) end is usually periphery of a cell

Question 8

Motor Proteins

Answer 8

• have one or more heads capable of force generation through a conformational change
• have catalytic activity, acting as ATPases to power movement
• responsible for muscle contraction and cellular movement
• Common examples include : myosin, kinesin and dynein

Question 9

Most common applications of motor proteins

Answer 9

Muscle contraction, vesicle movement within cells, and cell motility

Question 10

Myosin

Answer 10

• primary motor protein that interacts with actin
• thick filament in a myofibril
• can be involved in cellular transport
• movement at the enact is responsible for the power stroke of sarcomere contraction

Question 11

Kinesins & Dyeins

Answer 11

• motor proteins associated with microtubules
• have 2 heads, at least one of which remains attached to tubular at all times
• important for vesicle transport in the cell but have opposite polarities

Question 12

Kinesins main role

Answer 12

• align chromosomes during metaphase and depolarizing microtubules during anaphase of mitosis
• bring vesicles toward the (+) end of the microtubule

Question 13

Dyeins main role

Answer 13

• involved in sliding movement of cilia and flagella

- bring vesicles toward the (-) end of the microtubule

Question 14

Binding proteins

Answer 14

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

Question 15

Cell adhesion molecules (CAMs)

Answer 15

proteins found on the surface of most cells that aid in the bidding of the cell to the extracellular matrix or other cells

Question 16

3 major families of adhesion molecules

Answer 16

1. cadherins
2. integrins
3. selectins

Question 17

cadherins

Answer 17

group of glycoprotein that mediate calcium - dependent cell adhesion

Question 18

integrins

Answer 18

group of proteins that all have 2 membrane - spanning chains called alpha and beta

Question 19

Integrins major roles:

Answer 19

• in cellular signaling and can greatly impact cellular function by promoting cell division, apoptosis or other processes
• used for white blood cell migration, stabilization of epithelium on its basement membrane and other processes

Question 20

selectins

Answer 20

bind to carbohydrate molecules that project from other cell surfaces

Question 21

where are selectins expressed?

Answer 21

on white blood cells and the endothelial cells that line blood vessels

Question 22

selectins play an important role in…

Answer 22

host defense

including: inflammation and white blood cell migration

Question 23

antibodies (aka Immunoglobins)

Answer 23

proteins produced by B cells that function to neutralize targets in the body such as toxins and bacteria, and then recruit other cells to help eliminate the threat

Question 24

antibodies are made up of

Answer 24

two identical light chains

two identical heavy chains

Question 25

constant region

Answer 25

involved in the recruitment and binding of other cells of the immune system - such as macrophages

Question 26

antibodies bind to

Answer 26

antigens

Question 27

antibodies binding to antigens can cause 3 outcomes:

Answer 27

1. Neutralization
2. Opsonization
3. Aggulinating

Question 28

Neutralization

Answer 28

Neutralizing the antigen, making the pathogen or toxin is unable to exert its effect on the body

Question 29

Opsonization

Answer 29

making the pathogen for destruction by other white blood cells immediately

Question 30

Aggulinating

Answer 30

Clumping together the antigen and the antibody into large insoluable protein complexes that can be phagocytized and digested by macrophages

Question 31

ion channels

Answer 31

can be used for regulating ion flow into or out of the cell

Question 32

motor enzymes are not enzymes (TRUE/FALSE)

Answer 32

False.

Motor function is generally considered nonenzymatic, but the ATPase functionality of motor proteins indicates that these molecules do have catalytic activity

Question 33

3 main types of ion channels

Answer 33

ungated channels
voltage gated channels
ligan gated channels

Question 34

Antibodies are held together by

Answer 34

disulfide linkages and noncovalent interactions

Question 35

enzyme linked receptors

Answer 35

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

Question 36

G protein - coupled receptors

Answer 36

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

Question 37

Ligand binding engages the _____

Answer 37

G protein

Question 38

GDP is replaced with

Answer 38

GTP

the alpha subunit dissociates from the beta and gamma subunits

Question 39

The activated alpha subunit alters the activity of

Answer 39

adenylate cyclase or phosopholipase C

Question 40

GTP is dephosphorylated to

Answer 40

GDP

the alpha subunit rebind to the beta and gamma subunit

Question 41

Function of the Gs protein:

Answer 41

stimulates adenylate cyclase, which increases levels of cAMP in the cell

Question 42

Function of the Gi protein:

Answer 42

inhibits adenylate cycles, which decreases levels of cAMP in the cell

Question 43

Function of the Gq protein:

Answer 43

activates phospholipase C, which cleaves a phospholipid from a membrane