Mitosis Flashcards
Where does mitosis occur?
In the body cells, flowering plants and bacteria - yeast
Are the chromosomes genetically identical or genetically different to the parent cell?
Daughter cells are genetically identical to parent cell
Same number of chromosomes as parent cell
What is the role of mitosis?
Used for growth, repairing tissues and replacing dead cells
Is the reproduction asexual or sexual?
Asexual reproduction bc offspring are genetically identical to parent cell Same number
What happens if uncontrolled mitosis occurs?
Cells fail to divide or divide to frequently so tumours may form
Prophase
First stage of mitosis
DNA condenses Forming chromosomes
Chromatids are visible
Centrioles move to opposite ends of the cell
Microtubules form from centrioles and spindle forms
Nuclear membrane disintegrates
Metaphase
Chromosomes arrange themselves at the centre of equator of spindle
Chromosomes attach to spindle at centromere
Chromosome separate to form chromatids
Anaphase
Centromere splits
Spindle fibres contract
Chromatids separate and pulled to opposite ends of the cell
Telophase
Chromosomes uncoil and lengthen
Spindle breaks down
Nucleolus reappears and nuclear membrane reforms
Advantage of asexual reproduction
Ability to increase in numbers quickly to take advantage of an environment
Disadvantage of asexual reproduction
Inability to adapt to environmental changes due to lack of variation
Mitotic index
N. Of cells in prophase, metaphase, anaphase and telophase
Divided by n of cells
X 100
Where does meiosis take place?
Takes place in reproductive organs in plants and animals
What does meiosis form?
Gametes with half the number of chromosomes (haploid)
Do cells have genetic variation?
Yes cells are genetically different to parent cells to produce different offspring
Interphase
DNA replication
Making and replication of organelles
ATP synthesis
Protein synthesis
Prophase I
DNA condenses forming chromosomes
Chromatids become visible
Centrioles move to opposite pole of the cell
Microtubules forms from each centriole and spindle forms
Nuclear membrane disintegrates
Metaphase 1
Homologous chromosomes arrange themselves on the equator randomly
Produces new genetic combinations
Anaphase I
Spindle fibres contract
Chromosomes separate and pulled to opposite ends of the cell
Telophase I
Nuclear envelope reforms
Chromosomes stay in condensed form
Prophase II
New spindle developes at right angles to old spindle in animal cells
Metaphase II
Chromosomes line up on spindle fibres at equator
Anaphase II
Spindle fibres contract
Centromere splits
Chromatids are pulled to opposite ends
Telophase II
Spindle disappears
Nuclear membrane reforms
Product of meiosis
4 genetically different daughter cells
