1. 2. early interphase late interphase + prophase, metaphase and anaphase telophase Units of DNA To show the relative amounts of DNA at different points in the cell cycle – can you explain what is happening?

G1 S G2 mitosis Cytokinesis: new protein and organelles made DNA replicates Proteins needed for cell division made Nucleus divides cytoplasm divides The cell cycle growth

Mitosis and meiosis Why do living organisms need two types of cell division? Key words:- diploid fertilization haploidgametes 2Nzygote Nchromosome numberconstant doublehalf

The importance of mitosis and meiosis Can you fill in the missing words? Mitosis produces two ………………. identical daughter cells Because DNA makes exact copies by …………………….. ……………………………… during………………………. Mitosis produces new cells for ……………., for replacing cells and for repairing ……………… Mitosis produces the cells which form new organisms in …………………. reproduction Meiosis halves the number of …………………. A …………. cell with 2N or 2 sets of chromosomes becomes a ……………… cell with N or 1 set of chromosomes. This means the number of chromosomes will not double after ……………………………….. in sexual reproduction.

The importance of mitosis and meiosis Mitosis produces two genetically identical daughter cells Because DNA makes exact copies by semi- conservative replication during interphase Mitosis produces new cells for growth, for replacing cells and for repairing tissues Mitosis produces the cells which form new organisms in asexual reproduction Meiosis halves the number of chromosomes. A diploid cell with 2N or 2 sets of chromosomes becomes a haploid cell with N or 1 set of chromosomes. This means the number of chromosomes will not double after fertilization / fusing of gametes in sexual reproduction.

Brain warm-up List 5 key facts about mitosis List 5 key facts about cancer Share your facts with the rest of your bench and decide on the most important key facts – one for mitosis and one for cancer

Cancer Explain the link between mitosis and cancer. How may the chance of developing cancer in the human body be increased? And how can it be decreased? 10 marks Include examples of cancer in humans and their relative frequency e.g. breast, lung, skin, testes And include these words:- uncontrolled cell division, tumour, benign, malignant, oncogene / mutated gene/damaged DNA, carcinogen (with examples)

1. 2. early interphase late interphase + prophase, metaphase and anaphase telophase Units of DNA To show the relative amounts of DNA at different points in the cell cycle – can you explain what is happening?

Cancer and mitosis Key words:- uncontrolled cell division / mitosis examples + frequency in the human population worldwide tumour - benign or malignant oncogene / mutated gene / damaged DNA carcinogen

homologous chromosomes – a pair of chromosomes of same size; one inherited from mother and one from father karyotype –chromosomes from photo arranged in homologous pairs sex chromosomes – they determine sex of organism; in humans XX female, XY male autosome - chromosome which is not a sex chromosome diploid – cell with pairs of homologous chromosomes – 2 sets; called 2N haploid – cell with one set of chromosomes, one of each homologous pair; called N

Brain warm-up on chromosomes With a partner make a pair of homologous chromosomes. Can you name the parts and explain why they are called homologous? What will happen to them during mitosis?