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
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
