Summary Cell Biology; cell cycle and division review

02/11/18

Dr Cleo Bishop

Cell Cycle and Division
Importance of Cell Division

• Life continues, replaces dead cells
• Passes on genetic information
• Universal (unicellular and multicellular)
• Long, complex series of cell divisions required



1 – G1

• Gap/growth phase 1
• Aim – to recover from mitosis and prepare for S
• DNA checking, and repair occurs
• Synthesis of RNA and proteins
• Generation of new organelles
• Increase in size to contain new components

2–S

• Synthesis phase
• Aim – to replicate genome
• Chromosome duplication
• Cohesins
o Hold sister chromatids together
o Large protein complex
o Deposited during DNA replication
• Karyotyping
o During metaphase = 4n
o Ordered by size
o Shape, size and position of chromosome’s centromere is important
• Nucleosome = DNA/histone complex

3 – G2

• Gap/growth phase 2
• Aim – to prepare for mitosis
• More DNA checking occurs
• RNA and protein synthesis resumes
• Cell confirms number of chromosomes and organelles present
• Microtubule synthesis begins for spindle

4 – Mitosis

• Aim – cell division
• Divides sister chromatids, nucleus and cytoplasm (cytokinesis)