Cell division Flashcards
Mitosis
When cells divide to create 2 genetically identical cells. Used for growth and repair of tissue.
Name the stages of mitosis
1) DNA replicates and creates 2 copies of each chromosome
2) Nuclear membrane breaks down. All chromosomes line up in the centre of the cell.
3) Both sets of chromosomes pulled to one side
4) Cytoplasm + cell membrane break down to form 2 IDENTICAL cells
Meiosis
Cell division that produces gametes only. 4 genetically different cells.
Name the stages of meiosis
1) Chromosomes make identical copies
2) Sections of DNA swapped
3) Pairs of chromosomes divide, so does the cell
4) Chromosomes divide again, so does the cell
5) 4 gametes are created with 23 chromosomes each
Haploid
Gamete that has 23 chromosomes (only one set)
Diploid
Cell that has 46 chromosomes (2 sets). Any other cell that isn’t a gamete.
Mitosis vs Meiosis
Mitosis divides once, meiosis twice
Mitosis in every cell, meiosis only gametes
Mitosis makes identical diploids, meiosis different haploids
Mitosis makes 2 cells, meiosis makes 4
Mitosis for cell growth and repair
Meiosis for gamete production
The cell cycle
Replication of cell DNA
Mitosis (nucleus divides)
2 identical cells
Can take many years or less than a day depending on the age of organism
Binary fission
How prokaryotic cells such as bacteria divide and reproduce
Why doesn’t bacteria undergo mitosis?
Because it doesn’t have a nucleus to split
How to calculate number of bacteria created after a period of time.
Number of bacteria = 2ⁿ
n = number of rounds of division
Stages of binary fission
Bacteria contains a circular loop of DNA and additional plasmids with genetic information
The bacteria would make a copy of all of these organelles
The cell would begin to grow
Each main loop of DNA is taken to opposite sides of the cell but plasmids are distributed randomly
Cytoplasm splits and new bacteria has formed
What conditions do bacteria need to reproduce.
Warm temperature
Lots of nutrients
