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Flashcards in Cellular Functions Deck (43)
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1

Structural proteins

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

2

most common structural proteins are

collagen, elastin, keratin, actin and tubline
- generally fibrous in nature

3

Collagen

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

4

Elastin

- 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

5

Keratins

- 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

6

Actin

- 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)

7

Tubulin

- 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

8

Motor Proteins

- 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

9

Most common applications of motor proteins

Muscle contraction, vesicle movement within cells, and cell motility

10

Myosin

- 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

11

Kinesins & Dyeins

- 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

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Kinesins main role

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

13

Dyeins main role

- involved in sliding movement of cilia and flagella
- bring vesicles toward the (-) end of the microtubule

14

Binding proteins

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

15

Cell adhesion molecules (CAMs)

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

16

3 major families of adhesion molecules

1. cadherins
2. integrins
3. selectins

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cadherins

group of glycoprotein that mediate calcium - dependent cell adhesion

18

integrins

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

19

Integrins major roles:

- 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

20

selectins

bind to carbohydrate molecules that project from other cell surfaces

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where are selectins expressed?

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

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selectins play an important role in...

host defense

including: inflammation and white blood cell migration

23

antibodies (aka Immunoglobins)

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

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antibodies are made up of

two identical light chains
two identical heavy chains

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constant region

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

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antibodies bind to

antigens

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antibodies binding to antigens can cause 3 outcomes:

1. Neutralization
2. Opsonization
3. Aggulinating

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Neutralization

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

29

Opsonization

making the pathogen for destruction by other white blood cells immediately

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Aggulinating

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