Mitosis Noadswood Science, 2016

Mitosis Wednesday, July 04, 2018 To explain the process of mitosis

Precise Learning Cells divide in a series of stages called the cell cycle. Students should be able to describe the stages of the cell cycle, including mitosis. During the cell cycle the genetic material is doubled and then divided into two identical cells.   Before a cell can divide it needs to grow and increase the number of sub-cellular structures such as ribosomes and mitochondria. The DNA replicates to form two copies of each chromosome. In mitosis one set of chromosomes is pulled to each end of the cell and the nucleus divides. Finally the cytoplasm and cell membranes divide to form two identical cells. Students need to understand the three overall stages of the cell cycle but do not need to know the different phases of the mitosis stage. Cell division by mitosis is important in the growth and development of multicellular organisms. Students should be able to recognise and describe situations in given contexts where mitosis is occurring.

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Nucleus The genetic information passed from parent to offspring is contained in genes, carried by chromosomes in the nucleus All body cells have a nucleus which contains all genetic information nucleus

Chromosomes & Genes A gene is a section of DNA that carries the code for a particular protein (made from joined amino acids) Different genes control the development of different characteristics of an organism – many genes are needed to carry all the genetic information for a whole organism Chromosomes, found in the cell nucleus, contain many genes

Each chromosome is a very long molecule of tightly coiled DNA Chromosomes and their genes are made of a molecule called DNA DNA molecules carry the code that controls what your cells are made of and what they do Each chromosome is a very long molecule of tightly coiled DNA

Mitosis Mitosis is the type of cell division that leads to growth or repair When a cell divides by mitosis: - Two new cells form Each cell is identical to the other one, and the cell they were formed from

MITOSIS STAGES The pictures show cell division – can you work out the order? C D A E B

MITOSIS STAGES

Mitosis Stages Parent cell Chromosomes make identical copies of themselves They line up along the centre They split They move apart Two daughter cells form with identical chromosomes to the parent cell

Stages

Stages

Practice Questions – Application Different animals have different numbers of chromosomes in their body cells and in their gametes… Dog body cell – 78 chromosomes Cat egg cell – 19 chromosomes Horse sperm cell – 32 chromosomes How many chromosomes are there in a dog sperm cell? How many chromosomes are there in a body of a cat? How many chromosomes are there in a horse egg cell?

Answers Different animals have different numbers of chromosomes in their body cells and in their gametes… Dog body cell – 78 chromosomes Cat egg cell – 19 chromosomes Horse sperm cell – 32 chromosomes How many chromosomes are there in a dog sperm cell – 39 How many chromosomes are there in a body of a cat – 38 How many chromosomes are there in a horse egg cell – 32