Cell Division Flashcards
(22 cards)
What is the purpose of cell division?
Growth
Repair
What are the three phases in interphase?
1) G1
2) S
3) G2
What happens in the G1 phase of interphase?
Cell grows bigger and organelles start to replicate
What happens in the S phase of interphase?
The cell replicates it’s DNA
What happens in the G2 phase of interphase?
The cell keeps growing until all organelles have duplicated
When are the G checkpoints in mitosis?
Before and after the S phase
What is the G0 phase?
The phase that cells that don’t undergo cell division are in
What do chromosomes consist of?
- Two sister chromatids
- centromere
What happens in prophase in mitosis?
1) Chromatin condenses into chromosomes
2) Nuclear envelope breaks down
3) Centrioles move towards opposite poles
What happens in metaphase in mitosis?
Spindle fibres attach to each side of the centromere of each chromosome and lines them up at the centre of the cell
What happens in anaphase in mitosis?
Spindle fibres shorten to pull chromatids apart
-> observed under a microscope by V shaped chromatids
What happens in telophase in mitosis?
1) Chromatids decondense
2) Nuclear envelope reforms
3) Spindle fibres breakdown
In Meiosis, what happens in Prophase 1?
- Homologous chromosomes pair up and the nuclear envelope breaks down
In Meiosis, what happens in Metaphase 1?
Homologous pairs line up at the cell equator
In Meiosis, what happens in Anaphase 1?
Homologous chromosomes are pulled to opposite poles
In Meiosis, what happens in Telophase 1?
Homologous pairs decondense and nuclear envelope forms around the two grpups
In Meiosis, what happens in Prophase 2?
Chromatin recondense into 23 chromosomes
In Meiosis, what happens in Metaphase 2?
Spindle fibres attach to either side of each chromosome, and line them up at the cell equator
In Meiosis, what happens in Anaphase 2?
The sister chromatids are pulled towards opposite poles
In Meiosis, what happens in Telophase 2?
The nuclear envelope reforms around each group of 23 chromosomes, which decondense back into chromatin
When does independent assortment occur?
When homologous pairs of chromosomes line up randomly
When does crossing over occur?
When chromatids from homologous chromosomes twist around each other
