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Biochemistry + Cell Bio > Week 8 - Cytoskeleton > Flashcards

Week 8 - Cytoskeleton Flashcards

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Biology 101 flashcards
1
Q

What are the three roles of a cytoskeleton

A

Cell shape
Cell strength
Movement

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2
Q

What are the three types of cytoskeleton filament

A

Actin filaments
Microtubules
Intermediate filaments

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3
Q

What is the role of actin

A

Cell surface shape, whole cell locomotion and pinching one cell into two

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4
Q

What is the role of microtubules

A

Position of organelles, intracellular transport and motitic spindle

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5
Q

What is the role of intermediate filaments

A

Mechanical strength

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6
Q

How does each filament get utilised in the small intestine

A

Actin - enables microvilli formation and connects to cell junctions
Intermediate - anchors across cell to provide structure and strength via desmosomes
Microtubules - run from basal to apical surfaces providing transport network

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7
Q

What are filaments held together by and why are they strong

A

Non covalent interactions which when multiple filaments join together are very strong collectively

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8
Q

Describe how actin forms

A

G actin monomers polymerise to form 2 protofilaments which twist to form F actin which is in a helix shape

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9
Q

Describe F actin structure

A

Large clefts which bind to ATP and all G actin faces same way to make it polar

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10
Q

Describe nucleation

A

The first step in formation of a new structure via self assembly

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11
Q

What is the critical condition of actin determined by

A

Rate of addition of G actin (K on) and rate of dissociation of G actin (K off)

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12
Q

Describe how G actin associates and dissociates

A

If [G actin]> critical condition then G actin added
If [G actin]< critical condition then G actin dissociated

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13
Q

Define treadmilling

A

Where subunits are added at + end and removed from - end yet the length remains constant

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14
Q

Explain how Microtubules are formed

A

Polymerisation of tubulin heterodimers to form subunits which form protofilaments. 13 protofilaments form a hollow cylinder with a central lumen

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15
Q

Explain how Microtubules are polar

A

Alpha tubulin at the - end and beta tubulin at the + end creates polarity

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16
Q

Why are Microtubules unstable

A

Dissociation of tubulin GDP is favourable at the plus end, so it tends to grow a cap and shrink.
Minus end is stable at the MTOC

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17
Q

What is the MTOC

A

The centrosome

18
Q

What are two distinct features of centrosomes

A

A pair of centrioles and pericentriolar material (protein matrix)

19
Q

What is the site of nucleation for Microtubules

A

Gamma tubulin ring complex found on the pericentriolar material

20
Q

What are the two associated motor proteins for microtubules

A

Kinesin and dynein

21
Q

What does kinesin do

A

Moves towards the + end of the Microtubules (anterograde = away from centre)

22
Q

What does dynein do

A

Move towards the - end of the Microtubule (retrograde = towards centre)

23
Q

Describe intermediate filaments

A

Great tensile strength, non polar and no associated motors

24
Q

Give an example of intermediate filaments in a cell

A

Nuclear laminar

25
Q

Name the 4 types of tissue

A

Epithelial
Muscle
Nervous
Connective

26
Q

What are the three types of cell junction

A

Anchoring junction
Occluding junction
Communicating junction

27
Q

Describe anchoring junctions

A

Anchor cytoskeleton between cells or between cells and Extracellular matrix

28
Q

Describe occluding junctions

A

Prevents passage of ions and small molecules between cells

29
Q

Describe communicating junctions

A

Direct connections between cytoplasm of two cells

30
Q

Anchoring junctions: what do adherens junctions do

A

Connects actin filament of one cell with actin filament of another cell

31
Q

Anchoring junctions: What do desmosomes do

A

Connects intermediate filaments from one cell to intermediate filaments of another cell

32
Q

Anchoring junctions: What do Actin linked cell matrix (FA) junctions do

A

Anchors actin filaments in cell to extracellular matrix

33
Q

Anchoring junctions: what do hemidesmosome do

A

Anchors intermediate filaments in a cell to the extracellular matrix

34
Q

What do gap junctions do

A

Allow passage of small water soluble molecules between cells

35
Q

What is the name for the transmembrane protein responsible for cell cell attachment in anchoring junctions

A

Cadherins

36
Q

What is the name for the transmembrane protein responsible for cell matrix attachment

A

Integrins

37
Q

What is the term for when Cadherins bind to the same type of cadherin

A

Homophilic adhesion (different type is heterophilic adhesion)

38
Q

What is cadherin binding dependant on

A

Extracellular Ca2+

39
Q

What is the extracellular matrix

A

Network of proteins carbohydrates and water which provide support for cells and tissues and secreted by fibroblasts

40
Q

Hat are the three types of macromolecule in the ECM

A

Glycosaminoglycans
Fibrous proteins
Glycoproteins

Biochemistry + Cell Bio (10 decks)

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