cell division topic summary

CELL CYCLE

INTERPHASE

G1:

- protein synthesis for replication of organelles

- Cell grows in size

S: DNA (semi-conservative) replication

G2:

- cell grows in size + mass

- Increased energy stores

- Duplicated DNA is checked for errors

G0: cell leaves cell cycle b/C :

- Differentiation: carry out function indefinitely

- DNA damage: enter permanent cell arrest (but try to repair damage first)

- Lymphocytes in immune response triggered to re-enter cell cycle

CHECKPOINTS

Control mechanisms so that daughter cells have :

- Enough organelles

- Energy stores

- Correct number of chromosomes

G1: check for




1

, ● cell size

● concentration of nutrients

● DNA damage

G2: check for

● Cell size

● DNA replication ? correct

● DNA damage

METAPHASE : check for

● Chromosome attachment to spindle fibres


MITOSIS

PROPHASE

➔ Chromatin condenses to form chromosomes

➔ Nucleolus disappears

➔ Nuclear envelope breaks down

➔ Centrioles migrate to opposite ends of cell to form spindle fibres

METAPHASE

➔ Spindle fibres attach to centromere & move chromosomes to equator

ANAPHASE

➔ Centromeres divide

➔ Separating chromatids and pulling them to opposite poles by shortening spindle

fibres

TELOPHASE

➔ 2 new sets of chromosomes assemble at each pole


2