interaction between cells

Question 1

5 main tissues

Answer 1

epithelial
connective
muscle
nerve
blood

Question 2

why don’t we fall apart into single cell

Answer 2

cell adhesion molecules

Question 3

PLasma membrane

Answer 3

boundary of cell
divider living and non-living cell

Question 4

extracellular matrix

Answer 4

organized netork of secreted molecules providing scaffolding for the cell and surrounding tissue

Question 5

ECM function

Answer 5

1- determine cell shape
2- physical support for cell
3- regulatory role in cell signalling

Question 6

three types of ECM

Answer 6

1- bone
2- cartilage
3- connective tissue

Question 7

Bone

Answer 7

small number of interspered cellls

Question 8

cartilage

Answer 8

cells in flexible ECM

Question 9

connective tissue

Answer 9

gelatinous ECM surrounding blood vessel and glands

Question 10

collagen/elastin

Answer 10

provide strength and flexibility

Question 11

proteog;ycans

Answer 11

hydrated matrix

Question 12

fibronectin/laminis

Answer 12

adhesive/conncective glycoproteins

Question 13

collagen

Answer 13

most abundant protein
form fibers with high tensile strength

Question 14

collagen is secreted by

Answer 14

cells in connective tissue

Question 15

collagens are

Answer 15

trimer
triple helix of alpha chains

Question 16

collagens are very rich in

Answer 16

1- glycine: tightness of triple helix allow only small AA like glycine to fit in
2-proline and lysine: these are hydroxylated which increase the #HB

Question 17

collagen fibers

Answer 17

Fibril is made of many collagen molecules
fibersare very strong and composed of numerous fibrils

Question 18

in lumen of ER,three aplha chain form a triple helix

Answer 18

procollagen

Question 19

when procollagen secreted out of the cell,

Answer 19

its cleaved by procollagen peptidase to remove both ends of the molecule
resulting collagen will spontaneously associate into fibrils and then fibers

Question 20

HB between hydroxylated residues

Answer 20

within and between collagen molecules

Question 21

Elasticity

Answer 21

provided for ECM by stretchable elastic fibres composed of elastin

Question 22

elastins

Answer 22

rich in glycine and proline
cross-linked by covalent bonds between lysine

Question 23

tension cause

Answer 23

overall network to stretch

Question 24

relaxation cause

Answer 24

Individual molecules to relax to less-extended conformation

Question 25

with time elastins are lost examples?

Answer 25

wrinkling less flexible joints

Question 26

collagen and elastin are in a gel-like network of ----

Answer 26

proteoglycans

Question 27

proteoglycans

Answer 27

glycoproteins with lot of glycosaminoglycans

Question 28

GAGs

Answer 28

large carbohydrates with repeating disaccharide unit

Question 29

presence -- and --- attract cations wich bind water

Answer 29

charged sulphate carboxyl groups therefore, create hydrated matrix

Question 30

most gags in ECM are

Answer 30

covalently bind to protein

Question 31

fibronectin

Answer 31

5-6 functional unit Two very large polypeptide subunit linked by c-terminus by disulfide bond functional units bind numerous component of ECM, and also recptors on the cell surface (integrins)

Question 32

RGD

Answer 32

cell binding domain

Question 33

Laminins

Answer 33

family of proteins with three subunits linked by disulfide bonds -multiple domains binding sites for collagen, proteoglycans and other receptor --found mainly in basal lamina

Question 34

Basal lamina

Answer 34

part of ecm separating epithelial from connective tissues

Question 35

Integrins

Answer 35

integrate extra and intra cellular environments

Question 36

integrin component

Answer 36

two large transmembrane polypeptide alpha and betta which are non-covalently linked to each other

Question 37

integrin family is diverse consist of

Answer 37

18 alpha 8 betta

Question 38

integrin bent conformation

Answer 38

inactive state can't bind a ligand

Question 39

integrin upright conformation

Answer 39

active state ligand can bind

Question 40

intracellular domain bind proteins like Talin which

Answer 40

separates alpha and betta chain and activate integrin

Question 41

ligand binding happens in ---

Answer 41

cleft between alpha and betta chain

Question 42

integrin functions

Answer 42

1- adhesion 2- signal transduction

Question 43

inside-out signalling

Answer 43

induce integrin clustering which effect ECM binding

Question 44

outside-in signalling

Answer 44

act as receptors that activate intracellular signalling

Question 45

outside-in signalling example

Answer 45

anchorage-dependent growth

Question 46

anchorage-dependent growth

Answer 46

most cells to grow, must be attatched to substratum, if cannot, they will stop dividing

Question 47

attachment cell to substratum happen at sites called

Answer 47

focal adhesion

Question 48

connection to actin microfilaments in focal adhesion happens via

Answer 48

linker proteins talin, vinculin, alpha-actinin

Question 49

HEmidesmosomes

Answer 49

tighest attachments between a cell and its ECM

Question 50

hemidesmosomes found in

Answer 50

epithelial cells, contain integrin and attach cell to substrate like basal lamina

Question 51

in hemidesmosomes, integrins are

Answer 51

connected to intermediate filament called keratin

Question 52

integrin is connected to cytoskeleton via

Answer 52

hemidesmosomones forming a dense plaque with plectin