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The human cell > Lecture 15 and 16 > Flashcards

Lecture 15 and 16 Flashcards

1
Q

What is the diameter of microtubules?

A

25nm outer

15nm inner

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2
Q

What are the monomers of microtubules?

A

alpha and beta tubulin

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3
Q

What is the diameter of microfilaments?

A

7nm

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4
Q

What are the monomers of microfilaments?

A

G actin

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5
Q

What is the diameter of intermediate filaments?

A

8-12nm

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6
Q

Name some intermediate filaments.

A

Keratins, vimentin, desmin, nuclear lamins

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7
Q

What are the two types of microtubules?

A

Cytoplasmic and axonemal

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8
Q

What do cytoplasmic microtubules do?

A

Regulation of cell shape
Formation of mitotic spindle
Vesicle transport

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9
Q

What do axonemal microtubules do?

A

Cell motility and signalling hub

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10
Q

Where are axonemal microtubules found?

A

Basal bodies, cillia, flagella

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11
Q

What are the three stages of microtubule polymerisation?

A

Nucleation, elongation, plateau (treadmilling)

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12
Q

Microtubule growth is _____ dependent.

A

Concentration

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13
Q

What is critical concentration?

A

The tubulin concentration at which MT assembly is balanced with dissaembly

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14
Q

What is the name given to the model in which one population of MT’s grow and others shrink by depolymerization?

A

Dynamic instability

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15
Q

What are the names given to the growth and shrinkage periods of MT’s?

A

Catastrophe and resuce

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16
Q

What causes dynamic instability?

A

GTP cap is hydrolysed, leading to catastrophe

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17
Q

What is the structure of a centriole?

A

Barrel shaped, 9 tubulin triplets, surrounded by pericentriole material

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18
Q

Name 3 microtubule stabilizing/bundling proteins.

A

tau
MAP2
+-TIP proteins

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19
Q

Name 3 microtubule detabilizing/severing proteins.

A

Stathmin/Op18
Catastophins
Katanins

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20
Q

Name two MT inhibiting drugs.

A

Colchicine (promotoes disassembly)

Nocodazole (inhibits MT assembly)

21
Q

What are 4 roles of microfilaments?

A

Muscle contraction
Intracellular tension/cell shape
Cell migration (lamellar and amoeboid movement)
Cytoplasmic transport

22
Q

What are the types of monomer that make up microfilamnets?

A 
Alpha actin (muscle specific)
Beta and gamma actin (all cells)
23
Q

What protein binds ATP actin and promotes polymerisation/

A

Profilin

24
Q

What protein binds ATP actin and blocks polymerisation?

A

Thymosin

25
Q

What protein promotes nucleation and branching in actin filaments?

A

Arp2/3

26
Q

What do formins do?

A

Bind actin filaments and promote elongation

27
Q

What do capping protiens do?

A

Binds the end of a filament and prevent further loss/addition of subunits (e.g. CapZ)

28
Q

What binds G-actin and F-actin and also severs filaments?

A

ADF/cofilin

29
Q

What receptors ljnk cells to the extracellular matrix?

A

Integrin

30
Q

What receptors link cells to other cells?

A

Cadherin

31
Q

What are two classes of cadherin?

A

Adherens junctions (link to microfilamnets) and desmosomes (link to intermediate filaments)

32
Q

What are the two major eukaryotic motility systems?

A

Interactions between motor proteins and microtubules

Interactions between actin and myosin motor proteins

33
Q

What proteins transport towards the minus end of MTs

A

Dynein

34
Q

What proteins transport towards the plus end of MTs?

A

Kinesins

35
Q

What three parts do kinesins consist of?

A

Globular head
Coiled helical region
Light chain region

36
Q

How do kinesins move?

A

Walk: ATP hydrolysis brings foot to bind new beta-tubulin subunit

37
Q

How long are cilia?

A

2-10 micrometers

38
Q

How long are flagella?

A

10-200 micrometers

39
Q

What name is given to the shared structure of cilia and flagella?

A

Axoneme

40
Q

What is the structure of the axoneme?

A

9+2 structure, separated by 9 dynein molecules

41
Q

How does dynein generate bending of cilia/flagella?

A

Sliding microtubule model: ATP hydrolysis of denein

42
Q

How many types of myosins are there?

A

24

43
Q

What myosin doesn’t move towards the plus end of f-actin?

A

myosin VI

44
Q

Which myosin walks along actin?

A

Myosin II

45
Q

What three proteins do thin filaments in muscles contain?

A

F-actin, tropomyosin and troponin

46
Q

Why is muscle contraction calcium dependent?

A

Calcium binds to a protein on tropomyosin, which changes conformation to reveal myosin binding site

47
Q

What is the prokaryotic homologue to tubulin?

A

FtsZ protein (involved in division regulation)

48
Q

What is the bacterial relative of the intermediate filament?

A

Crescentin (cell shape)

49
Q

What is similar to actin microfilaments in bacteria?

A

MreB protein (cell shape)

The human cell (10 decks)

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