Lecture 14 - interactions between cells

Question 1

which tissue type has the most extracellular matrix

Answer 1

connective tissue
this provides strenght

Question 2

what are tight junction function

Answer 2

seals neighbouring cells together
prevents leage between them

Question 3

what are adherens junctions

Answer 3

joins actin bundles between cells

Question 4

what is a desmosome

Answer 4

joins desmin intermediate filaments between cells

Question 5

what is a gap junction

Answer 5

channels allowing small water soluble molecules between cells

Question 6

what is a hemidesmosome

Answer 6

anchors intermediate filaments in a cell to basal lamina

Question 7

name the plant gap junction equivalent

Answer 7

plasmodesmata
doesnt have anything else

Question 8

what are tight junctions formed of

Answer 8

occludin and claudin proteins

Question 9

how are epithelia ‘functionally polarised’

Answer 9

secretions from apical surface e.g. in airways, stomach, mammary gland

but also transport of nutrients into the blood
e.g. in intestines

Question 10

what do adherin junctions and desmosomes use to link cells

Answer 10

cadherins

Question 11

what does hemidesmosom use to link cell to basal lamina

Answer 11

integrins

Question 12

what are cadherins

Answer 12

TM proteins that bind to each other between cells

Question 13

what does cadherin need to interact with other cadherin

Answer 13

Ca2+

Question 14

name of a contiuous band of adherin junctions

Answer 14

adhesion belt

Question 15

what do cadherins link to to form the coniuous belt between cells

Answer 15

actin filaments

Question 16

how could adherin junctions allow movement?

Answer 16

the actin filaments can be contractile
via myosin II
allowing the epithelial sheet to move

Question 17

an example of the movement of epithelial cell sheets

Answer 17

neurulation in neural tube development

Question 18

what type of wound closure associated with adhesion belt contractility

Answer 18

purse string wound closure

Question 19

how can intermediate filaments help strengthen cells

Answer 19

protect against stretching
keratin filaments also linked via desmosomes

Question 20

what can desmin mutations cause

Answer 20

muscular dystrophy
cardiac myopathy

Question 21

where are desmosomes more abundant

Answer 21

in tissues under high stress eg heart muscle
or exposed epithelia

Question 22

what do the integrins in the plasma memb bind to

Answer 22

between the laminin in basal lamina
and the IFs inside the cell

Question 23

how do cadherins determine which cells interact

Answer 23

diff cells have diff cadherin
can only bind to indentical cadherin
e.g. epithelial cells = E cadherin
muscle cells = N-cadherin

Question 24

how do cancer cells spread to other parts of the body (in terms of cadherin)

Answer 24

often no longer have cadherin that usually keep cell in right place
so it can just travel to diff parts of the body

Question 25

what are carcinomas

Answer 25

cancer that starts in epithelial tissue (85%)

Question 26

what forms the channel in gap junctions that allow movemnet between cells

Answer 26

connexons

Question 27

what molecules typicallly pass through plasmodesmata

Answer 27

proteins
regulatory mRNAs