Eukaryote Cytoskeleton

Question 1

F Actin

Answer 1

• microfilament
• cell periphery
• Size: 7-9nm
• Functions:
  1. SHORT RANGE transport
  2. CELL MIGRATION
  3. CELLULAR PROTRUSIONS
  4. INTRACELLULAR MOTILITY: myosin
• Monomers:
  1. G ACTIN
  2. forms a PROTOFILAMENT (2 coiled strings)
• Action:
  1. TREADMILLING
  2. ATP polymerisation
• Forms:
  BUNDLING:
  - Ordered
  - Cross Linking
  - Dynamic Cross Linking

Question 2

Microtubules

Answer 2

• concentrated around nucleus
• Size: 25nm
• Functions: - LONG RANGE TRANSPORT
  - CELL DIVISION
  - INTRACELLULAR MOTILTY: dynein, kinesin
• Monomers: - ALPHA + BETA TUBULIN
  - forms a PROTOFILAMENT
  - 13 protofilaments form a MICROTUBULE
• Action: - CATASTROPHE AND RESCUE
  - GTP polymerisation
  - DYNAMIC INSTABILITY
  Forms: - Microtubule organising centre at nucleus
  - PLUS END: cell periphery, kinesin
  - MINUS END: nucleus, dynein

Question 3

Intermediate Filaments

Answer 3

• loose meshwork
• animal cells only
• Size: 10nm
• Functions: - MECHANICAL STRENGTH
  - SIGNALLING
  - REGULATION OF TRANSCRIPTION
  - CYTOPLASMIC ARCHITECTURE
• Monomers: - VARIETY of proteins
  - ALPHA HELIX
• Action: - SELF ASSEMBLY
• Forms: - Nuclear Lamina
  - Lens of the eye
  - Resistance to force