cytoskeleton

Question 1

what is a cytoskeleton and it’s function

Answer 1

• it is a network of protein polymers that:
• provide mechanical support for the cell to maintain shape
• involved in cell movement and cell division.
• the cytoskeleton protein are made up of thousands of subunits and are characterised as DYNAMIC (always assembling and disassembling)
• used as a transport network - moves organelles and vesicles around inside of the cell
• gives cells it’s structure: cells make tissues therefore also giving tissue structure

Question 2

what are the three types of cytoskeleton polymers

Answer 2

• actin filaments
• intermediate filaments
• microtubules

Question 3

where are actin filaments found and structure of actin filaments

Answer 3

• concentrated beneath the cell membrane and are everywhere in the eukaryotic cells
• narrow
• flexible
• highly organised and form cytoplasmic extensions eg. microvilli

Question 4

what processes is actin involved with

Answer 4

• phagocytosis
• cytokinesis (splitting of a cell into two during cell division)
• muscle contraction

Question 5

monomer and polymer of actin

Answer 5

• monomer: G (globular) actin

- polymer: F (filamentous) actin

Question 6

actin and myosin work together

what does myosin do

Answer 6

• myosin proteins are molecular motor proteins

- that use ATP to generate force along actin filaments, allowing muscle contraction

Question 7

examples of intermediate filaments

Answer 7

• keratin

keratin forms the top layer of skin along with hair

Question 8

function and structure of intermediate filaments

Answer 8

• made up of high tensile strength ‘rope like’ filaments
• widely distributed
• mechanical strength
• helps with tissue structure

Question 9

what is a heteroploymer and type 1 and type 11 keratin protein

Answer 9

• heteropolymer - made up of two or more proteins that come together to form the polymer

type 1 and type 11 - particular type that tell you where you are in the body and what’s cells are doing eg. differentiation status

Question 10

three step process of immunohistochemistry

Answer 10

• incubate section of tissue with an antibody to a particular protein

1. primary antibody binds to antigen
2. secondary antibody binds to primary antibody
3. enzyme linked to secondary antibody converts substrate to a coloured product

• tells u where the protein is in the tissue

Question 11

keratin mutation

Answer 11

• mutation in keratin 14 or keratin 5
• keratin is involved in structure of cells and tissue therefore a mutation can lead to cell tissue fragility
• leads to blistering

Question 12

function and structure to microtubules

Answer 12

• hollow, rigid polymers of tubule and provide cell with the strongest resistance to compression
• built of two different types of protein
• long and straight - one end attached to centromere
• each cell organisation fo microtubules differ and have a huge role in mitosis and and reorganise to form the mitotic spindle along with the microtubule - dependent motor proteins (dynein)

Question 13

what are cilia and flagella made from and function

Answer 13

• long bundles of microtubules and molecular motors

- cilia moves mucus and debris out of the airway - the motor and tubules generate that force

Question 14

what are molecular motors

Answer 14

• proteins - enzymes that generate force and ‘walk’ along microtubules
• kinesins and dyneins are examples of molecular motors that use microtubules
• requires atp

Question 15

how do actin and microtubules work together

Answer 15

• they work together in cell migration and cell division
• microtubules have an influence on assembly of actin and can be bound together by linker protein
• indirect signalling between each other
• microtubules pulls chromosomes apart and actin contracts to separate the two cells

Question 16

microtubule interacting drugs

Answer 16

• anti cancer drug called Taxol
• bind and prevents microtubules from depolymerising therefore preventing mitosis
• stops tumour from growing
• coichicine - microtubule disruption
• treats four - blocks white cell migration decreasing inflammation

Question 17

actin polymerisation

Answer 17

1. G actin binds to nucleus (nucleation)
2. forming F actin leading to cell elongation
3. multi step process and tightly regulated
4. proteins bind the actin to control this process

• filaments are polarised allowing the cell to recognise which end is which