02/11/18
Dr Cleo Bishop
Understanding the Cell Cycle
Microtubules
1. Astral – anchor spindle to plasma membrane
2. Polar – pull apart using motor proteins but don’t pull DNA directly
3. Kinetochore – pull DNA apart
Modelling the Cell Cycle
• Unicellular organisms reproducing asexually
• Binary fission
o Cell elongates, and DNA is replicated
o Cross wall forms via the septum
o Very error prone – drives adaptation
• Fission yeast – S.pombe
o Typical example of eukaryotic cell cycle
o Small G phase, long M phase
o End elongation occurs
o Not synchronised across organism – cells always at
different stages
• Budding yeast – S.cerevisiae
o No G2 phase
o S and M phase overlap
o Asynchronous culture also
• Yeast mutants are good for studying the cell cycle because:
o Divide rapidly
o Small genome
o Haploid organism – easy genetic manipulation
o Led to discovery of cell-division-cycle genes (CDC genes)
CDC Genes
• Search for cell cycle arrest
• Conditional temperature sensitive
mutation technique used
• Uniform cell cycle arrest at high
temperatures
Multicellular Modelling
• Early embryonic frog cells
o Large cells – 1mm diameter
o Easy to inject test samples
o Large cytosol volume that contains proteins for the cell cycle
▪ 100,000 x larger volume than human embryonic cells
Dr Cleo Bishop
Understanding the Cell Cycle
Microtubules
1. Astral – anchor spindle to plasma membrane
2. Polar – pull apart using motor proteins but don’t pull DNA directly
3. Kinetochore – pull DNA apart
Modelling the Cell Cycle
• Unicellular organisms reproducing asexually
• Binary fission
o Cell elongates, and DNA is replicated
o Cross wall forms via the septum
o Very error prone – drives adaptation
• Fission yeast – S.pombe
o Typical example of eukaryotic cell cycle
o Small G phase, long M phase
o End elongation occurs
o Not synchronised across organism – cells always at
different stages
• Budding yeast – S.cerevisiae
o No G2 phase
o S and M phase overlap
o Asynchronous culture also
• Yeast mutants are good for studying the cell cycle because:
o Divide rapidly
o Small genome
o Haploid organism – easy genetic manipulation
o Led to discovery of cell-division-cycle genes (CDC genes)
CDC Genes
• Search for cell cycle arrest
• Conditional temperature sensitive
mutation technique used
• Uniform cell cycle arrest at high
temperatures
Multicellular Modelling
• Early embryonic frog cells
o Large cells – 1mm diameter
o Easy to inject test samples
o Large cytosol volume that contains proteins for the cell cycle
▪ 100,000 x larger volume than human embryonic cells
