3: How cells become different? Flashcards
1
Q
Why do cells in the body share common genome?
A
- cells are able to retain the entire genome
- descendant of single fertilised egg cell and retains same DNA ish
2
Q
How do cell-specific characteristics arise (intrinsic/extrinsic)?
A
- environmental cues (temperature, oxygen levels)
- proteins (growth factors etc.)
- hormones
- small molecules
= activates signalling pathways results in cell fate decisions and behavioural changes
3
Q
totipotent?
A
- immature/stem cell
- fertile adult individual
4
Q
pluripotent?
A
- give rise to all cell types
5
Q
multipotent?
A
- develop into more than one type of cell
- more limited than pluripotent
6
Q
nullipotent?
A
- terminally differentiated cells
7
Q
How does the cytoskeleton play a major role on cellular shape and movement?
A
- organisation of organelles
- consists of filaments
- dynamic
- movement of cells/organelles
- maintenance of cell shape
- cell contraction
- movement of cilia and microvilli
- endocytosis
8
Q
What are the three main components of the cytoskeleton?
A
- microtubules
- microfilaments
- intermediate filaments
9
Q
Microtubules?
A
- stiff
- resist compression
- composed of alpha and beta-tubulin => hollow cylinder
- assemble and disassemble dependant of temperature and surrounding tubulin concentration
10
Q
What are the functions of microtubules?
A
- make up centrioles -> form spindle in mitosis and meiosis
- form flagella and cilia
- pathway for intracellular movement of organelles, vesicles and proteins
- axonal migration - determine axonal length
11
Q
Microfilaments?
A
- semi-flexible
- helical filamentous polymers => two intertwined chains of globular actin monomers -> G-actin
- reversible assembly => grows in direction of cell movement by pushing plasma membrane forward
12
Q
What are the functions of microfilaments?
A
- relax/contract muscles
- front of moving cells
- stress fibres
- actin cortex - framework to resist tension -> determines cell shape
13
Q
Intermediate filaments?
A
- flexible
- no unique structural basis
- epithelial cells
- keratin filaments: hair, nails, hooves
- desmin filaments: muscles
- lamin in nucleus: nucleus
- neurofilaments: support axons and regulate axon diameter
14
Q
What are the functions of intermediate filaments?
A
- mechanical stability
- part of assembly of nuclear envelope
- support plasma membrane
15
Q
How are elements of the cytoskeleton being constantly assembled and disassembled?
A
microtubules and microfilaments
