cell division

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cell continuity means that all cells develop from pre-existing cells
what are chromosomes?
coiled threads of DNA and protein that become visible in the nucleus at cell division
how many chromosomes do humans have?
46
what is a gene?
short section of DNA that contains the instructions for the formation of protein
a haploid cell has 1 set of chromosomes
what is haploid is humans?
sperm and egg cells are haploid in humans.
diploid cells have 2 sets of chromosomes
chromosomes are in pairs in a diploid cell called homologous pairs
what is interphase?
The phase of the cell cycle where the cell is not dividing
90% of a cells life is in interphase
chromosomes duplicate in interphases to make identical copies of themselves
mitosis is a form of cell division in which 1 nucleus divides to form 2 nuclei, each containing the same number of chromosomes with identical genes
where does mitosis take place?
somatic cells
what happens in prophase?
chromosomes become visible as double stranded structures, spindle fibres form, nucleolus disappears and the nuclear membrane breaks down
what happens in metaphase?
The nuclear membrane completely breaks down, The chromosomes line up across the middle of the equator.
what happens during anaphase?
The spindle fibres contract at anaphase, chromosomes are pulled apart
what happens during telophase?
The spindle fibres break down, The nucleolus begins to reform. chromosomes elongate to form chromatin