Epithelial cells

Question 1

What happens in the nucleolus?

Answer 1

Ribosomal subunits are synthesised

Question 2

What three types of filament constitute the cytoskeleton?

Answer 2

Microtubules
Intermediate Filaments
Microfilaments

Question 3

What are microtubules made of and what is the diameter of a microtubule?

Answer 3

Alpha and beta tubulin

20nm

Question 4

What are microtubules used for?

Answer 4

• Movement of organelles through the cell – involves motor proteins
• Involved in spindle fibre formation

Question 5

Describe the organisation of microtubules in cells.

Answer 5

They originate from a point within the cell called the microtubule organising centre (MTOC)

Question 6

Microtubules are an important structural component for which cellular features?

Answer 6

Cilia and flagellae

9 + 2 arrangement

Question 7

Which component of the cytoskeleton distinguished different cell types?

Answer 7

Intermediate Filaments – different for different cell types

Question 8

function of intermediate filaments?

Answer 8

Desmosome cell cell adhesions

- mechanical strength

Question 9

Where else are intermediate filaments found than in the cytoplasm?

Answer 9

Nuclear lamin – on the internal surface of the nuclear envelope – provides support

Question 10

What are microfilaments made of?

Answer 10

globular actin 5- 9 nm long

Question 11

What do microfilaments associate with?

Answer 11

Adhesion belt

Question 12

What is the monomer of microfilaments?

what is the polymer of microfilaments?

Answer 12

G-actin (globular actin)

filamentous actin F actin

Question 13

Define ‘Extracellular Matrix’.

Answer 13

The insoluble material found extracellularly.

composed of fibrillar proteins in hydrated gel

Question 14

What are the four main types of cell-cell junctions (in order of apical to basal)?

Answer 14

• Tight (zonula occludens)
• Adhesion junction (zonula adherens)
• Desmosome junction (macula adherens)
• Gap Junctions ( macula communicans)
• hemidesmosomes

that arsehole dont get hate

Question 15

What is the role of tight junctions?

Answer 15

Seals off the paracellular pathways.
Allows polarity.
Stops proteins that diffuse through membranes.
- strands of occludin

Question 16

Describe the structure of the adhesion belt.

Answer 16

It consists of a cadherins, which interact with similar molecules on the adjacent cell and clusters to form these junctions.
- Actin filaments are bound to the adhesion belt.

Question 17

Describe the structure of desmosomes.

Answer 17

Also involves cadherins interacting to maintain adhesion. Intermediate filaments are associated with desmosomes.

Question 18

What is the role of Gap junctions?

Answer 18

Allows transport of small molecules between cells

Question 19

what is the cytoskeleton ?

Answer 19

filaments formed by polymerisation

Question 20

structure of the intermediate filaments?

Answer 20

• filamentous proteins forming rope like filaments
• ## 10- 15 nm diameter

Question 21

what are intermediate filaments found on the
 - epithelia
- mesenchymal cells 
- neurones 
- muscles 
called?

Answer 21

• epithelia = cytokeratins
• mesenchymal cells = vimentin
• neurones = neurofilament protein
• muscles = desmin

Question 22

what are the four main cell group types?

Answer 22

• connective tissue - fibroblasts
• contractile tissue - muscle
• hematopoietic cells - blood cells
• neural cells - cells of the nervous system
• epithelial cells - cells forming continuous layers

Question 23

what are tumours of

• mesenchymal
• hematopoietic cells
• neural cells
• epithelial cells

Answer 23

• sarcomas
• leukemia
• neuroblastoma
• carcinoma

Question 24

function of adhesion belt?

Answer 24

• control assembly of other junctions

Question 25

``` what do the following words mean? zonulae maculae apex basal ```

Answer 25

``` zonulae = belt maculae = point apex = top of cell basal = bottom of cell ```