Cell Division Flashcards
What word describes different cells being able to take on different jobs (being multicellular)
Cell differentiation
When an organism becomes multicellular, it needs to have systems that can:
- allow communication between all the cells in the body
- supply all the cells with enough nutrients
- control exchanges with the environment such as heat and gases
What is the name for the process that produces new cells for growth?
Mitosis
The cells that are made by mitosis are
Genetically identical
In mitosis, what must happen before cells divide?
DNA replication must take place
Why, in mitosis, must DNA replication take place?
So each cell produced still has two copies of each chromosome
Body cells in mammals have two copies of each chromosomes, what are these called?
Diploid cells
Before mitosis happens, DNA replicates, this involves:
- the two strands of the DNA molecule ‘unzipping’ to form single strands
- new double strands forming by DNA bases lining up in complementary pairings
When mitosis occurs after the DNA replication, what happens?
The chromosomes line up along the centre of the cell and divide. The copies then move to opposite poles(ends) of the cell
what is meiosis?
The type of cell division that produces gametes
What type of cells are gametes and why?
Gametes are haploid cells because they only contain one chromosome from each pair
What does meiosis mean for the zygote?
Get one copy of a gene from each parent - creates genetic variation
How is the structure of a sperm cell adapted to its function?
- many mitrochondria to provide the energy for swimming to the egg
- an acrosome that releases enzymes to digest th egg membrane
How many divisions are there in meiosis?
Two
What happens during meiosis?
The single strands are copied to made X-shaped chromosomes(same gene pair up) then:
•in the first division, one chromosome from each pair moves to opposite poles of the cell
•in the second division, the copies of each chromosome cope apart and move to opposite pole of the cell
