Lecture 2: Cells and Stem Cells Flashcards
1
Q
which part of the phospholipid bilayer is hydrophobic and which part is hydrophilic
A
- hydrophilic phosphate head
- hydrophobic lipid tails
2
Q
what is special about the tails of phospholipids
A
they have a cis double bond which kinks it, making it more fluid
3
Q
what are the proteins in the membrane
A
- transporters
- anchors
- receptors
- enzymes
4
Q
how permeable are the membranes of mitochondria
A
- permeable outer membrane
- less permeable inner membrane folded into cristae
5
Q
what are peroxisomes
A
- small cytoplasmic vesicles requireed for hydrogen peroxide generation
- this reaction breaks down fatty acids, detoxifying toxic substances like ethanol
6
Q
functions of the cytoskeleton
A
- pulls chromosomes apart during mitosis
- drives and guides intracellular traffic of RNA and proteins
- supports plasma membrane
- enables some cells to move, eg neutrophils
- controls cell shape
7
Q
what are the major components of the cytoskeleton
A
- intermediate filaments
- microtubules
- actin filaments
8
Q
what are actin filaments
A
- polymers of actin
- necessary for movement
- can form contractile bundles and microvilli
- carry cargo-bearing motor proteins, eg myosin
9
Q
what are intermediate filaments
A
- 10nm diameter filaments
- twisted into ropes to provide tensile strength
- needed to maintain cell shape
- made up of a family of fibrous proteins
10
Q
what are microtubules
A
- 20nm diameter polymers of tubulin dimers
- form the spindle in mitosis
- carry cargo-bearing motor proteins from one end of the cell to another. If dysfunctional, causes motor neuron disease
11
Q
how does apoptosis work
A
1) degrade intracellular structures and organelles
2) collapse the cytoskeleton
3) fragment the cell into mini-cells, which are engulfed by phagocytes
12
Q
how does necrosis work
A
- cells simply lyse and burst
- cell membrane’s integrity is destroyed
- soluble contents released into tissue fluids, so inflammation occurs
- cell components degraded by extracellular enzymes and phagocytic cells engulf the remains
