Genetics – the study of heredity
At the end of this topic you should be able to
Discuss the variation and diversity of organisms
2. Define the term species
3. Define the term heredity
4. Give an example of heredity
5. Define the term gene expression
6. Example of a gene expression
7. Definition of a gene
8. Outline the role of a gene
9. Know the structure of a chromosome – refer to
DNA and protein structure
1.
 Variation
means that there are differences
between members of the same species i.e.
a population
 Think
of all the variations within your class
even though you are all human
A group of organisms capable of
interbreeding and producing fertile
offspring.
Humans
Cats
Dogs
Oak Trees
Ash Trees
http://commons.wikimedia.org/wiki/File%3APanthera
_tigris_tigris.jpg
http://commons.wikimedia.org/wiki/File%3ALio
n_in_masai_mara.jpg
http://commons.wikimedia.org/wiki/File%3ALiger
_couple.jpg
http://files.redux.com/images/f2f1c0d86ce7601a4ce421f71d994f40/raw
http://www.lifeinthefastlane.ca/wp-content/uploads/2007/10/tigons_sfw.jpg
Males are sterile but female are fertile –
so not a new species
 What
is meant by variation?
 Give
the definition for species
 Why
is a liger not a new species?
Heredity is the passing on of features from
parents to offspring by means of genes
Also called
Genetic Inheritance
A
gene is a length of DNA that codes
for a specific protein
It
It
is the unit of inheritance
is found on a chromosome
It contains instructions to make a
particular protein
It directly influences the characteristics
of an organism
 Characteristics
are controlled by genes.
 For
example everyone has genes which
determine hair colour.
 But
not everyone has the same version of
those genes.
 So
there is more than one type of gene
for hair colour that you could have.
Not all genes are expressed
Genes produce characteristics or traits that
are inherited
Eg: Gene for Tallness
Organism is small – Why?
Maybe due to poor nutrition
Characteristics =
heredity + environment
Heredity is the passing on of _________ from
parents to ______________ by means of ______.
A gene is the unit __________________. They
are found on a _________________. They
contain ________________ to make a particular
_______________. Gene expression is the way
in which _____ ________ in a gene is decoded.
Chromosomes contain a number of genes
Chromosomes are made up of
60% protein
40% DNA
Genes are arranged along the DNA of the
chromosome
Large sections of the chromosome do not
contain genes
This DNA is called Non Coding DNA
It’s function is not yet clear






Thread like structures
Contain DNA
Contain Protein
Contain Genetic Information
Occur in pairs
Found in the nucleus of all cells
Can you …………….
1.
2.
3.
4.
5.
Define the term heredity
Define the term gene
Outline the role of a gene
Define the term gene expression
Know the structure of a chromosome