1. Noadswood Science, 2011

2. Inheritance & Genes  To understand how we inherit characteristics from our parents and how genes accomplish this Saturday, August 29, 2015

3. Inherited  Children usually look a little like their father, and a little like their mother, but they will not be identical to either of their parents  Why is this?  Offspring get half of their inherited features from each parent  During fertilisation, the nucleus from the sperm cell joins with the nucleus in the egg cell, and a new nucleus is formed with all the genetic information needed  Label a sperm and egg in as much detail as you can…

4. Fertilisation Sperm cell (male) Egg cell (female) Nucleus Cytoplasm - contains a food (energy) store Jelly coat - helps make sure only one sperm can enter NucleusHead - contains chemicals to help the cell get inside the egg Tail for swimming (note there is little cytoplasm, making the sperm cell streamlined for swimming) The sperm cell is extremely streamlined, with a powerful tail for swimming. It also has special chemicals in its head to help it penetrate the egg cell. The egg cell is full of cytoplasm, used as an energy store for when fertilisation occurs. It also has a special barrier, which only allows one sperm to penetrate and fertilise it. Both contain a nucleus, containing genes…

5. Fertilisation

6. Genetic Information  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

7. Genetic Information  In a fertilised egg there are 23 pairs of chromosomes (23 unpaired chromosomes from your mother and 23 unpaired chromosomes from your father)

8. Chromosomes & Genes  A gene is a section of DNA that carries the code for a particular protein  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

9. Species  The number of chromosomes and genes varies from species to species  For example, cells in human beings have 46 chromosomes (23 pairs) that carry about 30,000 genes in each cell; and cells in fruit flies have eight chromosomes that carry about 13,600 genes

10. DNA  Genes are made up of short lengths of DNA (deoxyribose nucleic acid)  In the 1950’s Watson and Crick were the first to come up with the structure of DNA

11. Alleles  Some characteristics are controlled by only one gene  Some genes have different forms, known as alleles  On each chromosome of the pair there can be different version of the same gene, i.e. blue or brown eyes – the variations are known as alleles  The allele expressed is the dominant gene  The allele not expressed is the recessive gene

12. DNA

13.  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

14. DNA Investigation Complete the DNA extraction experiment: - 1. Dissolve 3g of salt into 100cm 3 of water in a 250cm 3 beaker. Add 10cm 3 of washing up liquid, and stir gently until it dissolves 2. Mash your fruit pieces using the pestle and mortar – when it is as mashed as possible put it into another 250cm 3 beaker and add an equal volume of the solution made in the previous step to it – stir the mixture 3. Place the beaker inside a larger beaker of hot water, and leave for 15 minutes 4. Pour the mixture through a filter funnel with filter paper inside – collect the juice in a small beaker. Tilting the beaker slightly pour ice-cold ethanol down the side very slowly – stop when you have added as much ethanol as you have juice

15. DNA Structure

16. Inherited  Some variations are inherited, whilst other variations are due to environmental factors  Inherited variation is a characteristic you have got from your parents - what can you inherit?  Gender  Eye colour  Hair colour  Skin colour  Lobed or lobeless ears Lobed (left) & lobeless (right) ears

17. Summary