2.1.6 Cell division, cell diversity and cellular organisation Flashcards
What happens during stage G1 of interphase?
(Growth stage 1)
- Cellular contents (mitochondria, chloroplasts) are duplicated
- Cell increases in size
What happens during stage S of interphase?
(Synthesis stage)
Chromosomes are duplicated in nucleus
What happens during stage G2 of interphase?
(Growth stage 2)
- Cell continues to increase in size
- Energy stores increased
- Chromosomes checked for repairs
What happens during stage G0 of interphase?
(Resting state)
Cell leaves cycle temporarily or permanently
Why does cell enter stage G0 of interphase?
- Differentitation
- Damage to DNA
What are checkpoints in interphase?
Requirements that have to be fulfilled before the next stage can begin
What is checked for in the checkpoints of interphase?
- Cell size
- DNA damage
- DNA replication without error
- Nutrient availablity
- Chromosome attachment to spindle
What are the three checkpoints of interphase?
- G1 checkpoint
- G2 checkpoint
- Spindle assembly checkpoint
How many daughter cells are produced from mitosis?
Two genetically identical diploid cells
How many daughter cells are produced from meiosis?
Four genetically different haploid cells
What is mitosis important for?
- Growth and repair
- Asexual reproduction
In terms of n what are the changes in chromosome number before, during and after for mitosis?
2n -> 4n -> 2n
What type of division is meiosis known as?
Reduction division
What are homologous chromosomes?
Matching sets of chromosomes where each one has the same genes at the same position (loci)
What are alleles?
Different versions of the same gene (located in the same positions)