OB P2-Epithelial Cell Biology and the Cell Cycle. Flashcards

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1
Q

What is the defintion of epithelium?

A

Tissue of closely packed cells that forms a surface or lines a cavity or tube

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2
Q

what does epithelium line?

A

the inside surfaces of fluid or air filled tubes and spaces inside the body

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3
Q

when is epithelium protective?

A

In skin

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4
Q

When is epithelium secretory?

A

In the lining of gut

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5
Q

When is epithelium joined together?

A

desmosomes

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6
Q

What drives proliferation of epithelial cells?

A

basal lamina

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7
Q

How are epithelial cells classified?

A
  • depends on the number of layers

- depends on shape of cells

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8
Q

what are the 2 types of one layer epithelial cells?

A
  • simple

- multi layered nuclei

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9
Q

what is the name for two or more layers of epithelium?

A

stratified

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10
Q

Name the type of multi layered nuclei.

A

pseudostratified

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11
Q

What are the 3 shapes of cells?

A
  • Flattened scale like - squamous
  • Cells are cubes - cuboidal
  • cells are columns - columnar
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12
Q

Name the 3 types of oral mucosa.

A
  • Masticatory
  • lining
  • specialised
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13
Q

Where is masticatory oral mucosa found?

A

gingival and hard palate- keratinising

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14
Q

Where is lining oral mucosa found?

A

floor of mouth, buccal regions and oesophagus- non keratinising

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15
Q

Where is specialised oral mucosa found?

A

the dorsum of the tongue- both.

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16
Q

what are the functions of oral mucosa epithelium?

A
  • Protection of underlying tissue
  • The different epithelium form lipid based permeability barriers.
  • Protect from fluid loss
  • Protect from ingress of potentially harmful environmental agents
17
Q

What is the definition of cell proliferation?

A

An increase in the number of cells; as a result of cell growth and cell division

18
Q

What is the cell cycle?

A

A cell reproduces by performing an orderly sequence of events in which it duplicates its contents and then divides in two

19
Q

What are the phases of the cell cycle?

A

M (mitosis + cytokinesis)
G1
S (DNA replication)
G2

20
Q

What controls the cell cycle?

A
  • Timer
  • Events in correct order
  • Event takes place only once per cycle
  • On/Off switch trigger events in a complete and irreversible fashion
  • Robustness
  • Adaptability
21
Q

Name cell cycle controllers.

A

Family of protein kinases:

Cyclin dependent kinases (Cdks)

22
Q

How do cyclin dependent kinsases control the cell cycle?

A
  • Activity rises and falls.
  • Cyclical changes in phosphorylation- intracellular proteins
  • Initiate and control major events of cell cycle- DNA replication, mitosis and cytokinesis
23
Q

What are Cdk’s controlled by?

A

cyclins

24
Q

what do Cdk need cyclins for?

A

protein kinase activity

25
Q

What do cyclins undergo during the cell cycle?

A

cycle of synthesis

26
Q

What are the 4 classes of cyclins?

A

G1/S-cyclins bind at end G1- commit cell to DNA replication
S-cyclins bind Cdks during S phase initiate DNA replication
M-cyclins promote events of mitosis
G1- cyclins promote passage through restriction point

27
Q

What are keys point to remember about cyclins?

A
  • Points to remember:
  • Cyclin does not simply activate the Cdk but directs it.
  • Different proteins phosphorylated.
  • Accessibility
28
Q

What is involved in proliferation control?

A
  • Receptors
  • Signalling
  • Extracellular matrix
  • Phosphorylation
29
Q

What is the definition of growth factor?

A

Polypeptides that control animal cell growth and differentiation. Usually produced near where they act. Can be stored and released by ECM

30
Q

What is the definition of transcription factor?

A

a protein that regulates the activity of RNA polymerase

31
Q

What cells make up the cell proliferation unit?

A

progenitor cells in the basal cell layer

32
Q

how do dividing cells appear ?

A

in clusters

33
Q

what are the two populations (in proliferations)?

A
  • Two populations one slow dividing but always retain proliferative potential.
  • Faster dividing but limited number of divisions
34
Q

What are problems with proliferation (Stem cells)?

A
  • Cyclin D1- no stopping G1/S
  • P53 in leukoplakia
  • VEGF and Akt