Heredity and Gene Expression Genetics the study of

Heredity and Gene Expression Genetics – the study of heredity

Lesson Objectives 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

Species A group of organisms capable of interbreeding and producing fertile offspring. Humans Cats Dogs Oak Trees Ash Trees

Tiger – a member of the cat family http: //commons. wikimedia. org/wiki/File%3 APanthera _tigris. jpg

Lion – a member of the cat family http: //commons. wikimedia. org/wiki/File%3 ALio n_in_masai_mara. jpg

Liger = Male Tiger + Female Lion http: //commons. wikimedia. org/wiki/File%3 ALiger _couple. jpg

Liger Family in Chinese Zoo http: //files. redux. com/images/f 2 f 1 c 0 d 86 ce 7601 a 4 ce 421 f 71 d 994 f 40/raw

Tigon = Male tiger + Female Lion http: //www. lifeinthefastlane. ca/wpcontent/uploads/2007/10/tigons_sfw. jpg Males are sterile but female are fertile – so not a new species

For a new species to be formed all the offspring must be fertile

Learning Check 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

Genes A gene is a length of DNA that codes for a specific protein It is the unit of inheritance It is found on a chromosome It contains instructions to make a particular protein It directly influences the characteristics of an organism

Genes 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.

Gene Expression 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

Learning Check 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

Chromosomes contain a number of genes

Chromosome Structure Chromosomes are made up of 60% protein 40% DNA Genes are arranged along the DNA of the chromosome

Non Coding DNA Large sections of the chromosome do not contain genes This DNA is called Non Coding DNA It’s function is not yet clear

Chromosome structure

Chromosomes Thread like structures Contain DNA Contain Protein Contain Genetic Information Occur in pairs Found in the nucleus of all cells

What have you learned? 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

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