Summary OCR A-Level Biology - Cell Division and Organisation

well division




Contents:
• Cell Cycle
• Mitosis
• Meiosis
• Cell Specialisation
• Organisational Levels
• Stem Cells

, cell cycle

we cycle
cell
cycle is a
precisely
series of timed and carefully regulated stages of growth/DNAreplication/
division thatcells progress through


interphase involves cell growth and replication
DNA



interphase is sub-divided into 3 growth stages:61/S/62
61involves cell growth
S involves DNA
synthesis
62 involves further cell
growth before mitotic phase


mitotic phase involves separation of replicated and
DNA cytoplasmic contents as the cell divides



enkaryotic cells divide produce
to 2 daughter cells with identical copies of DNA produced by
the parent cell during DNA
replication
multicellular organisms go through mitosis to grow and repair damaged tissues




we
cycle regulation
internal checkpoints regulate the cell cycle
61Checkpoint

checks DNA
to ensure no
damage
cell size checked

cell checked for enough energy reserves

62 checkpoint

chromosomes checked to ensure all replicated
duplicated checked
DNA to ensure none is
faulty
M checkpoint

check sister chromatics attachmentto spindle is suitable