Animal Cells (Part Four) Flashcards
How many types of integral proteins in a transport vesicle?
50
How many phospholipids in a transport vesicle?
7,000
How many cholesterol molecules in a transport vesicle?
5,700
Name the most abundant transport vesicle.
v-SNARE
What is the diameter of a transport vesicle.
30nm
Name the three kinds of potential coating for a vesicle.
- Clathrin
- COPI
- COPII
Where are clathrin-coated vesicles found in the pathway?
- trans Golgi network (of the Golgi)
- early endosome
- plasma membrane
Where are COPI-coated vesicles found in the pathway?
The Golgi apparatus
Where are COPII-coated vesicles found in the pathway?
The ER
Name the 3 filamentous biopolymers that make up the cytoskeleton.
- F-actin
- Microtubules
- Intermediate filaments
State the diameter of
a) F-actin
b) Microtubules
c) Intermediate filaments
a) F-actin = 7-9nm
b) Microtubules = 25nm
c) Intermediate filaments = 10nm
What is the role of
a) F-actin?
b) Microtubules?
c) Intermediate filaments?
a) F-actin = short-range transport, cell migration
b) Microtubules = Long-range transport, chromosome inheritance
c) Intermediate filaments = Mechanical strength
Describe the structure and composition of F-actin.
- Monomers of G-actin form an F-actin polymer
- F-actin polymers join to form 2 protofilaments which together form a helix
How many different actin-binding proteins are known?
Over 160
Name the proteins that organise F-actin.
Actin-binding proteins
Where can ordered bundling of F-actin be found in the body?
- Microvilli
- Stereocilia
Where can cross-linking of F-actin be found in the body?
- Stress-fibres
- Muscle
Where can dynamic cross-linking of F-actin be found in the body?
Network formation
What proteins hold together the structure of F-actin in
a) Ordered bundling?
b) Cross-linking?
c) Dynamic cross-linking?
a) Ordered bundling = Fibrin, alpha-actinin
b) Cross-linking = Filamin, spectrin
c) Dynamic cross-linking = myosin
Describe the structure and composition of microtubules.
- 13 protofilaments forming a ‘tube-like’ structure
- Protofilaments composed of Tubulin dimers, with a Beta-tubulin and Alpha-tubulin component
Explain polymerisation of the microtubules.
- GTP-bound tubulin dimers are added to the ‘plus’ end of the microtubules
- A cap of GTP-tubulin stabilises the growing microtubule
Explain ‘pausing’ in the microtubules.
- Tubulin hydrolyses the bound GTP to GDP whilst the microtubule polymerises
- Polymerisation slows down, and the GTP cap disappears
What is the moment of transition into depolymerisation in a microtubule called?
Catastrophe
What is the moment of transition back into polymerisation from depolymerisation in a microtubule called?
A rescue event
