Cell division Flashcards
what are chromosomes when the cell isn’t dividing
chromatin
Genes
A section of DNA with the instructions to make a protein such as enzymes which controls the cell. Collections of genes = genome
Haploid cells
Has 1 set of chromosomes, eg. Egg/sperm. Symbolised by “n” and the no. of chromosomes. Eg. Sperm = n=23
Diploid cells
Has 2 sets of chromosomes. Symbolised by 2n = no of chromosomes. Human diploid no. = 2n = 46 meaning 23 from mam + 23 from dad
Pairs of chromomes from each parent are called
homologous pairs
Mitosis acronym
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Interphase
90% of cell cycle, chromosomes are chromatin, cell isn’t dividing, At end chromosomes double creating 2 strand chromomes
Prophase
Chromatin starts to contract + chromones are visible 2 strands structure. Strands are held together by centromere, nucleolus disappears + spindle fibres form in the cytoplasm
Metaphase
Nuclear membrane completes breakdown. Spindle fibres from each end connect to centromere + chromosomes line up across cell equator
Anaphase
Spindle fibres contract + centromeres split. ½ of each double is pulled to opposite poles of the cell. Cell has 8 1-stranded chromosomes. Shortest phase
Telophase
The 4 chromosomes at each pole lengthen, spindle fibres break down 1/more nucleoli reform, nuclear membranes form around chromatin -> 2 identical cells
Mitosis results
Daughter cells have same no. of chromosomes as parents
Identical genes
2 cells
Functions of mitosis
Allows single celled organisms to reproduce
Allows for growth + repair in multicellular organisms
Cancer
A group of disorders where certain cells lose their ability to control the rate of mitosis and how much it takes place
Benign tumours
Stops dividing after some time, non life threatening, doesn’t invade other tissues
