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Cell Biology > Cytoskeleton > Flashcards

Cytoskeleton Flashcards

1
Q

What is the cytoskeleton?

A

Fibrous network- organelles are tethered

Provides structure & organisation

Cytosol- 55% total cell volume

20% of the cytosol is proteins

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2
Q

What 4 proteins does the cytoskeleton include?

A

1) microfilaments (actin)

2) myosin (type1&2)

3) microtubules (Tubulin)

4) intermediate filaments (cytokeratins)

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3
Q

What are 3 roles of the cytoskeleton?

A

(1) mechanical support to the cell

(2) highly dynamic

(3) cell motility relies on cytoskeleton structures

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4
Q

Describe the cell shaped of microfilaments;

A
  • muscle contraction
  • cytoplasmic streaming
  • cell motility
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5
Q

Describe G-actin;

A

5nm diameter globular protein that can polymerise to form F-actin which has a diameter of 7nm

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6
Q

Describe F-actin;

A

Has two intertwined polymer chains of G-actin that form a right handed double helix with 13 actin monomers per turn

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7
Q

Why do F-actin filaments have positive and negative ends?

A

Positive ends where polymerisation occurs

Negative ends where actin is lost

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8
Q

What does polymerisation require and control?

A

Requires hydrolysis of ATP

controlled by capping proteins

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9
Q

Describe mini-myosin type 1;

A

Globular head- with ATPase
Short tail- can bind to other proteins

Can attach to organelles

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10
Q

How does a cell move forward in ameoboid movement?

A

Due to G-actin flowing into pseudopodia

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11
Q

What does actin interact with and what happens?

A

Actin interacts with mini-myosin

Causing contraction of the cell which pulls the cells trailing end

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12
Q

What do nerve impulses cause?

A

Calcium release which promotes muscle contraction

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13
Q

Describe intermediate filaments;

A

10nm

Structural/mechanical strength of cells and tissues

Cable-like structure

Found only in vertebrates

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14
Q

Describe the intracellular organisation of IFs;

A

Complex network in the cytoplasm

Extends from plasma membrane to the nucleus

Keratin/vimentin anchor the nucleus within a cell

Integrates all aspects of the cytoskeleton (actin/myosin)

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15
Q

Describe the microtubule structure;

A

Alpha tubulin & beta tubulin

13 pro-filaments compromised of tubulin dimers, arrange to form cylinderical microtubule

Dynamic process of growth & shrinkage

Mediated by GTP hydrolysis

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16
Q

What are the 3 types of microtubule structure?

A

O singlets in cytoplasm & mitotic spindles

OO doublets in cilia & flagella

OOO triplets in centrioles & basal bodies

17
Q

What is the difference in the centromere and the centrosome?

A

Centromere - region of the chromosome

Centrosome - microtubule organising centre

18
Q

In many cells, what grows out from a centrosome near the nucleus?

A

Microtubules

19
Q

What’s in animals cells in their centrosome?

A

The centrosome has a pair of centrioles, each with nine triplets of microtubule arranged in a ring

20
Q

What is mitosis?

A

Partition of replicated chromosomes

21
Q

What do centroile pairs form?

A

Microtubule spindles during mitosis

22
Q

What is the mitotic spindle?

A

An apparatus of microtubules that controls chromosome movement during mitosis

23
Q

What is an aster?

A

A radical array of short microtubules

Extends from each centrosome

24
Q

What so the function of the centrosome?

A

Replicates, forming two centra zones that migrate to opposite ends of the cell, as spindle microtubule grow out of them

25
Q

What occurs during prometaphase?

A

Some spindle microtubules attach to the kinetochores of chromosomes and begin to move the chromosomes

26
Q

In metaphase where are the chromosomes at?

A

Lined up at the metaphase plate, the midway point between the spindle’s two poles

27
Q

What happens the mitotic spindle in anaphase?

A

In anaphase, sister chromatids separate and move along the kinetochore microtubules toward opposite ends of the cell

28
Q

How do microtubules shorten?

A

By depolymerising at their kinetochore ends

29
Q

How are microtubule dismantled?

A

By the kinetochore to release tubulin subunits

30
Q

What does kinesin mediate?

A

Anterograde movement of vesicles towards synapses along singlet microtubules

31
Q

Describe kinesin;

A

Anterograde (forwards)

Spindle length, movement during mitosis & depolymerisation

32
Q

Describe Dynein;

A

Retrograde (backwards)

Transport of cellular cargo

33
Q

What is cytoplasmic dynein and axonemal dynein?

A

cytoplasmic dynein: organelle function & integration

Axonemal dynein: cilia/ flagella movement

34
Q

What is cilia?

A

Move back and forth with a rapid power stroke and slower recover stroke eg- respiratory epithelium

35
Q

What is the flagellum?

A

Undulate in a snake-like motion drivinf the cell forwards eg-human sperm

36
Q

What is dynein?

A

A motor protein which drives the bending movements of a cilium or flagellum

Cell Biology (30 decks)

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