Topic 12 Cell division Flashcards
1
Q
What is a diploid cell?
A
- two copies of each chromosome in cell (human diploid number = 46)
2
Q
what is a haploid cell?
A
one copy of each chromosome (23) eg in gametes
3
Q
Why do cells divide by mitosis?
A
- more identical cells for tissue growth, repair and replacement
- for asexual reproduction
not cell repair! its tissue repair!
4
Q
what is asexual reproduction?
A
- involves only one parent
- no fertilisation
- no gametes
- cells in one part of body divide by mitosis
- new structure formed which breaks awy from parent cell and grows into new organism
- or single celled organism simply divides
eg runners like strawberries or tubers like potatoes
5
Q
describe mitosis
A
- cell begins to divide
- dna replicates to form two copies of each chromosome
- nuclear membrane breaks down, chromosomes line up across centre of cell
- one set of chromosomes is pulled to each end of cell and nucleus divides
- cytoplasm and cell membranes divide to form two identical cells
6
Q
what does meiosis result in?
A
4 geneticallt different haploid daughter cells used to create gametes, contain half number of chromosomes
7
Q
describe meiosis
A
mitosis, then 2nd division and chromosome separates into two parts, one part foes into each daughter cell
result is 4 cells, with half number of chromosomes of original cell
