1. Inherited Features
D. Crowley, 2007

2. Tuesday, November 13, 2018
Inherited Features
To identify inherited features, and understand how they came about

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

4. Fertilisation
Look at the above sex cells - can you name them, and describe how each one is functioned for its job?
Copy them out, name them, and label their adaptations

5. Fertilisation Egg cell (female) Sperm cell (male)
Cytoplasm - contains a food (energy) store
Head - contains chemicals to help the cell get inside the egg
Nucleus
Jelly coat - helps make sure only one sperm can enter
Tail for swimming (note there is little cytoplasm, making the sperm cell streamlined for swimming)
Nucleus
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…

6. Worksheet Complete the fertilisation worksheet
The male sex cell is called the sperm cell
The female sex cell is called the egg cell
The nucleus contains half the genetic information of a normal body cell
Fertilisation
The fertilised egg cell contains the same amount of genetic information as a normal body cell
Fertilised egg cell
Sperm: head containing chemicals to get into egg cell; tail for swimming
Egg: large cytoplasm for energy store; special barrier, letting just one sperm cell in

7. Lobed (left) & lobeless (right) ears
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

8. Parents & Offspring
Look at the pictures below - can you see any similarities or differences?
Gwyneth Paltrow & Blythe Danner; Kirk & Michael Douglas; Elizabeth & Jerry Jagger; Martin & Charlie Sheen; Sharon & Kelly Osbourne

9. Key Points Offspring are similar, but not identical to their parents
Some characteristics are inherited - and this occurs in both animals and plants
Why though do we not look 100% like our parents?

10. Genetics
During fertilisation half the genes are transferred from the male (sperm), and half from the female (egg)
This is why you inherit characteristics from both your mum and your dad (half from each)
Likewise, your siblings (brothers and sisters) also have half the genes of your mum, and half of your dad (but you are not identical to them because the genes can mix slightly)
Thousands of genes make up a living organism, and these can sometimes come in different forms - e.g. a gene for blue eyes, and a gene for brown eyes
This is why your parents may both have one eye colour, but you might have another
*identical twins share 100% genes, as after fertilisation the embryo split into two

11. Homework
For next lesson - find out from your biological parents the following features: -
Eye colour;
Hair colour;
Height;
If they are a tongue roller