1 Genetics At the cellular level Delving into Cells, Chromosomes, DNA and Genes

Cells What is a cell? What is a cell? 2

Cells What is the difference between animal and plant cells? What is the difference between animal and plant cells? 3

4 You have trillions of cells in your body! Source: Blood cells: Nerve cell: Fat cells: Muscle cells: Bone cell: Red blood cells to carry oxygen around the body And White blood cells to fight infections Fat Cells to store excess energy Nerve cells send electrical signals so your brain can communicate with the rest of the cells in your body Muscle cells for movement Here are some examples of cells in your body. Can you guess what they are and what they do? Click on them to check your answer. Bone cells produce calcium carbonate to support the body

5 You find DNA inside nearly every cell in your body. Each cell contains the same DNA. The DNA is found inside the nucleus of the cell.

6 DNA is in the cell nucleus All mature cells contain DNA except your red blood cells. DNA is found in the nucleus. This is a large structure found in the cell. Can you locate it in the cell below? Nucleus Source:

7 DNA is packed into chromosomes You have 46 chromosomes in each of your body cells. You inherited these from your parents: 23 from mum and 23 from dad Click on the button to see what your chromosomes look like. The chromosomes you inherit determine what you look like. Source: Chromosome: blog.com/lib/0/4/3540/pics/Articles/chromo some.jpg

8 Fertilisation Event An egg has 23 chromosomes and a sperm has 23 chromosomes. The cell that results from fertilisation contains 46 chromosomes or 23 pairs.

9 Embryo Development Pictures from Nova Online Embryo Development All of your body cells come from this one fertilised cell. Every time cells divide they copy their DNA and pass it on to their daughter cells. This means that all of your body cells have the same copy of DNA or the same chromosomes as the original cell. Cells end up doing different jobs because of the genes that are turned on or off.

10 Genes Sections of the chromosome shown here have been coloured in. Each section is a piece of DNA called a gene. Source: Chromosome: Look at some genes on your chromosomes. Click on Tour and then “Genome spots”

11 Chromosome Number One is the largest chromosome. It has 2,968 genes.

Re-call the cells in the human body each contain 46 chromosomes. The Chromosomes are arranged in 23 matching pairs in females and 22 matching pairs and a single unmatched pair in males. Gametes contain only 23 single chromosomes, 1 from each pair.

MUTATIONS Mutations are changes in genes or chromosomes (this lesson we will focus on chromosome mutations) Mutations are changes in genes or chromosomes (this lesson we will focus on chromosome mutations) Mutations may be: Mutations may be:  Spontaneous - arise naturally as random errors in DNA, or  Induced - deliberately or accidentally produced by chemicals or radiation. Mutagens are chemicals or forms of radiation that cause mutations. Mutagens are chemicals or forms of radiation that cause mutations.

TYPES OF CHROMOSOME MUTATIONS Chromosomal mutation are caused by changes to the chromosome number. Chromosomal mutation are caused by changes to the chromosome number. In humans most chromosomal mutations are lethal and foetuses are usually miscarried. In humans most chromosomal mutations are lethal and foetuses are usually miscarried. However, 3 varieties can survive: Downs’ Syndrome Downs’ Syndrome Klinefelter Syndrome and Klinefelter Syndrome and Turner Syndrome Turner Syndrome Do activity Do activity

DOWN SYNDROME Trisomy 21

KLINEFELTERS SYNDROME

TURNER SYNDROME (MONOSOMY)

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