Slide 1

Heredity and Gene ExpressionGenetics the study of heredityLesson ObjectivesAt the end of this topic you should be able to Discuss the variation and diversity of organismsDefine the term speciesDefine the term heredityGive an example of heredityDefine the term gene expressionExample of a gene expressionDefinition of a geneOutline the role of a geneKnow the structure of a chromosome refer to DNA and protein structure

VariationVariation 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 humanSpeciesA group of organisms capable of interbreeding and producing fertile offspring.

HumansCatsDogsOak TreesAsh Trees

Tiger a member of the cat family

http://commons.wikimedia.org/wiki/File%3APanthera_tigris_tigris.jpgLion a member of the cat family

http://commons.wikimedia.org/wiki/File%3ALion_in_masai_mara.jpgLiger = Male Tiger + Female Lion

http://commons.wikimedia.org/wiki/File%3ALiger_couple.jpgLiger Family in Chinese Zoo

http://files.redux.com/images/f2f1c0d86ce7601a4ce421f71d994f40/rawTigon = Male tiger + Female Lion

Males are sterile but female are fertile so not a new specieshttp://www.lifeinthefastlane.ca/wp-content/uploads/2007/10/tigons_sfw.jpgFor a new species to be formed all the offspring must be fertileLearning CheckWhat is meant by variation?

Give the definition for species

Why is a liger not a new species?HeredityHeredity is the passing on of features from parents to offspring by means of genes

Also calledGenetic InheritanceGenesA gene is a length of DNA that codes for a specific proteinIt is the unit of inheritanceIt is found on a chromosomeIt contains instructions to make a particular proteinIt directly influences the characteristics of an organismCharacteristics 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.GenesGene ExpressionNot all genes are expressed

Genes produce characteristics or traits that are inherited

Eg: Gene for TallnessOrganism is small Why?Maybe due to poor nutrition

CharacteristicsCharacteristics = 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.

Learning CheckChromosomes

Chromosomes contain a number of genesChromosome StructureChromosomes are made up of

60% protein40% DNA

Genes are arranged along the DNA of the chromosomeNon Coding DNALarge sections of the chromosome do not contain genes

This DNA is called Non Coding DNA

Its function is not yet clear

Chromosome structure

ChromosomesThread like structuresContain DNAContain ProteinContain Genetic Information Occur in pairs Found in the nucleus of all cells

What have you learned?Can you .Define the term heredityDefine the term gene Outline the role of a geneDefine the term gene expressionKnow the structure of a chromosome

End