Transcript Inherited Features - Noadswood Science

Inherited Features
D. Crowley, 2007
Inherited Features
 To identify inherited features, and
understand how they came about
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
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
Fertilisation
Egg cell (female)
Sperm cell (male)
Head - contains
chemicals to help
the cell get inside
the egg
Cytoplasm contains a food
(energy) store
Nucleus
Tail for swimming (note there is little
cytoplasm, making the sperm cell
streamlined for swimming)
Nucleus
Jelly coat - helps
make sure only one
sperm can enter
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…
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
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?
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Gender
Eye colour
Hair colour
Skin colour
Lobed or lobeless ears
Lobed (left) & lobeless (right) ears
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
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?
Homework
 Research a famous family – real or otherwise
 Eg The Simpsons, or The Royal Family
 Draw a family tree (pictures are essential)
 Identify their characteristics
 Label which characteristics are inherited,
which are environmental, and ones that are
both (environment & inherited)
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 your 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
Homework
 For next lesson - find out from your biological parents the following
features: 
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Eye colour;
Hair colour;
Height;
If they are a tongue roller