mitosis Flashcards
state the 3 importance factors of mitosis
- growth
- asexual reproduction
- tissue repair
summarise prophase
- chromatin coils and condenses into molecules which can wrap DNA around histones
- nuclear envelope breaks down
- centrioles move to opposite poles
summarise metaphase
- spindle fibres pull chromasomes to middle of cell equator (metaphase plate)
summarise anaphase
- centromeres divide
- chromatids separate to opposite poles
summarise telophase
- chromatids are now chromosomes
- nuclear membrane reforms
summarise cytokinesis
- the actual division of the 2 diploid daughter cells
describe mitosis in plants
- formation of cell plate
- wall material and new membrane deposit here
- no centrioles
- only meristems undergo mitosis
describe mitosis in animals
- cytoplasm constricts to create a cleavage furrow
- centrioles present
- most cells capable of mitosis
what does mitosis produce?
two genetically identical diploid daughter cells
why is mitosis important in repair?
- If cells are damaged through injury the healing process involves mitosis to produce cells which are genetically the same
- When cells need to be replaced constantly throughout life it is mitosis which produces the replacement cells e.g top layer of skin
why is mitosis important in growth?
-when sperm cell fertilises an ovum the nuclei fuse together to make a zygote. The zygote divided by mitosis so that all the cells in the new organism have exactly the same information- all the cells will contain exactly same alleles to give the same phenotype
why is mitosis important in asexual reproduction?
-asexual reproduction means that one parent plant produces genetically identical clones. This is helpful as one organism can produce many offspring very quickly if weather conditions aren’t changing
what is the purpose of chromosomes condensing in prophase?
by condensing the chromosomes become more compact so a large amount of DNA can be fitted into a small space and so that when the 2 daughter cells separate the DNA is organised and doesn’t get tangled up with other chromosomes
why is it important that the cell cycle is halted for tissues? (2)
- prevent excessive tissue production
- limits repair capacity of tissue