Lecture 8

Question 1

microtubules

Answer 1

made of tubulin subunits
resists compression
radiate out from an organising centre centrosome
cell motility (whole cell and organelles)

Question 2

organelle motility

Answer 2

ATP powered motor protein walk
can transport vesicles to targets
can transport damaged organelles from distant sites

Question 3

microfilaments

Answer 3

actin subunits double chain linear strands 3D network
resist tension
cortical network under plasma membrane
gel-like consistency to outer cytoplasm

Question 4

intermediate filaments

Answer 4

various proteins keratin, vimentins, lamin
super-coiled into cables
less dynamic than MT MF
maintain cell shape, anchor organelles nuclear lamina

Question 5

tight junctions

Answer 5

neighbouring cells pressed tightly together
continuous seal
prevent movement of fluid across cell layers

Question 6

desmosomes

Answer 6

anchoring junction
attachment between sheets of cells muscle
act like rivers torn muscle/desmosome

Question 7

gap junctions

Answer 7

point of cytoplasmic contact between cells
ions and molecules may pass from cell to cell
allow rapid intercellular communication

Question 8

ECM composition

Answer 8

fibroblasts secrete glycoprotein (protein + carbohydrate) collagen most abundant- embedded in proteoglycan matrix (extensive sugar traps water in ECM-resist compression keep shape

Question 9

collagen fibres

Answer 9

great tensile strength
50% of total body protein
turned over replaced

Question 10

lack of vitamin C

Answer 10

failure collagen synthesis
hydroxyproline amino acids not formed
collagen fibres cannot cross link properly
scurvy