Cell divison Flashcards
why is cell division important
- for an organism to grow
- for repair of damaged or dead tissue
- for the replacement of dead or damaged cells
what are diploid cells
cells with two matching sets of chromosomes in the nucleus
what are haploid cells
cells with only one set of chromosomes
example of a haploid cell
sperm and egg cells
example of diploid cells
all other cells apart from sperm and egg cells
what happens to the chromosomes during mitosis
the cells replicate prior to mitosis
why do the cells replicate before mitosis
so the daughter cells produced have exactly the same number of chromosomes as the parent cell
this is important so there is no loss of genetic info in the daughter cell
what are chromosomes made of
each chromosomes are made up from two identical chromatids joined at the centromere
what happens in stage one of mitosis
dna in the nucleus coils into single stranded chromosomes (visible in the nucleus )
what happens in stage two of mitosis
the single stranded chromosomes replicate in preparation for cell division
what happens in stage three of mitosis
chromosomes ( pairs of chromotids ) line up along the equator of the cell
what happens in stage four of mitosis
spindle fibre form, attaching to the centromere. As these contract they pull the chromotids apart towards opposite ends of the cell
what happens in stage five of mitosis
nuclear membrane reforms around both sets of chromosomes
what happens in stage six of mitosis
cytoplasm splits producing two identical daughter cells
what does the specialisation of cells lead to
the formation of a variety of cells, tissues and organs
