1 - Overview - Egbert

Question 1

Why is cell biology more eukaryotic cell based? broad terms

Answer 1

• eukaryotic cells are much larger than bacterial cells and even with the development of cryo EM to for eg image a B. subtilis then we still cannot identify any main features

Question 2

what are the 5 main attributes of eukaryotic cells and give examples/expand on each

Answer 2

1) highly complex
2) compartmentalised eg EM showing an E. coli and a kidney cell. 328 - 1 word
3) use a cytoskeleton to generate spatial patterning eg fibroblast
4) showing polarity eg zygote cells, human intestinal mucosa
5) highly dynamic and motile

Question 3

what contributed to the emergence of prokaryotic cell biology?

Answer 3

• refocus of attention onto organisms other than E. coli and B. subtilis revealed a no. complex structures, shapes, sizes indicative of a complex cell biology
• development of fluorescent reporters eg GFP therefore in vivo monitoring of spatial and temporal expression of proteins @ high res
• super res light microscopy (eg STORM, PALM) with a res below 0.2um therefore allowing us to track labelled proteins
• X-ray structure and electron microscopy identified proteins homologous/analogous to eukaroytic proteins

Question 4

describe what happens to a cell in order for it to be visualised by a microscope

Answer 4

• cells need to undergo dehydration (with ethanol - can cause DNA to precipitate outside the cell), cell also needs to be cut. this can alter the overall structure

Question 5

describe the features of this E. coli cell - ie what are the dark and light parts. what actually happens in vivo? (328- 1 word)

Answer 5

• light parts show space for nucleoid. with no proteins. dark structures show ribosomes which are v e- dense
• actual structure is more homogenous with DNA interlinked with the rest of the cytoplasm

Question 6

what are the components of the cytoskeleton. name some of their functions

Answer 6

Components; 
- tubulin
- actin 
- intermediate filaments 
Functions; 
- cell shape 
- motility 
- endocytosis 
- cell division 
- intracelllular transport 
- signalling

Question 7

draw a diagram showing a migrating eukaryotic cell

Answer 7

328 - 1 word

Question 8

Answer the following questions with examples;
Do prokaryotes have to…
a) have simple morphologies
b) be small
c) have simple intracellular architectures
d) are they compartmentalised?
e) do they have a cytoskeleton
f) show spatial patterning?
e) show intracellular dynamics or motility?

Answer 8

NO
a) no. varying morphologies, sizes and shapes indicative eg Bascillus species has varying diameters
b) eg Thiomagarita has diameter ranging from 300-750um
eg epulopiscium reside on fish paramecium cell 200-700um
c) cyanobacteria have complex internal sructures
d) yes;
large scale compartments; periplasm, thylakoid lumen
organelle - like; carboxysome, gas vesicle, magnetosome
inclusion like; starch granules, protein inclusion bodies
e) Actin homologues; FtsA, MreB
Tubulin homologues; FtsZ, TubZ
IM filament homologues; Crescentin, FliP
bactofilin
f) show polarity eg Streptomyces FliP @ the poles allows polar growth. eg Caulobacter crescentus, stalk, holdfast, swarmer, flagella
e) bacterial motility includes both swimming and gliding. motile proteins also exist eg ParA/B in C. crescentus

328 - 1 word

Question 9

name some microscopic set ups that can be used to study prokaryotic sub-strucutres

Answer 9

• light; STORM
• electron; cryo EM

both allow v good resolutions

Question 10

what are the 2 main differences between prokaryotes and eukaryotes?

Answer 10

• degree of complexity is much higher in eukaryotes - stemming from their complex evolution and endosymbiosis invovling prokaryotes
• most attributes discussed eg polarity, moltility, cytoskeleton in prokaryotes is achieved on the molecular level not the cellular level