Inheritance and evolution

Pre Assessment Label the parts of the below given image.

Cell The structural, functional and biological unit of all organisms.

Nucleus The nucleus is a membrane bound structure Contains the cell's hereditary information Controls the cell's growth and reproduction.

DNA-Deoxyribonucleic Acid

Location of DNA

DNA It is a nucleic acid containing the genetic instructions It is used in the development and functioning of all known living organisms

There are 46 chromosomes in every cell-23 from female parent and 23 from male parent.

Chromosomes A chromosome is an organized structure of DNA and protein found in cells.

Genes The DNA segments carrying this genetic information are called genes. A unit of heredity of all living organisms. It codes for a specific protein

Video on Genes http://www.youtube.com/watch?v=5MQdXjRPHmQ

Why are you unique?

Inheritance What we are like depends on the genes we inherit from our parents The study of inheriting characteristics is called genetics

The same but different ! Variation

Student activity Write down similarities and differences between you and your pet. Now get into pairs and write down the similarities and differences between you and your partner.

What is Variation? Individuals within a species have different characteristics Variation ensures survival

Types of variations Continuous vs. Discontinuous Continuous Variation - Small differences between individuals that varies over a range. - Mostly caused by environment. - e.g. height, shoe size, length of hair - Bell shaped graph Discontinuous Variation - Differences that are classed or categorised - Always caused by genes. - e.g. blood group, sex, hair colour, eye colour - Bar graph

Types of variation Intra specific variations Inter specific variations Differences between organisms belonging to different species/ group . Eg: Differences between a water lily and a cat. Differences between organisms belonging to the same group/ species Eg: differences between a boy and a girl

Discontinuous and Continuous Variation Number of people Hair colour only a few options Height varies over a continuous range

What causes Variation? Variation can come about for two reasons: Some features can be inherited. That means that you get them from your parents Other features are affected by the environment ( acquired). Lots of features are a combination of both Examples?

Environmental Variation Causes: climate, diet, lifestyle, culture, accidents Environment affects how our inherited characteristics develop Twins who grow up separately might become very different: e.g. fashion, taste, hair colour, build, personality, aptitudes

Genetic Variation Causes: - Mixing of parent information during meiosis - Gamete forms from a unique combination of genetic information Siblings can have both similar and very different traits They are mixtures of their parents, each sibling can receive different characteristics of their parents e.g. natural hair colour, eye colour, blood type

Get into groups and discuss whether these features are Inherited, environmental or both? Example Cause Sex Weight Height Dyed blonde hair Strength Beard Cut on face Intelligence Got a bad cold Blood group Eye colour

TASK:- Read Pg. No 143-144 from your text book and ans ques no 1-4 on pg no 143.

Identify the similarities and differences among the members of this family ! Look at the picture and identify 5 similarities between the parents and the children.

Video on Variation http://www.youtube.com/watch?v=B_PQ8qYtUL0 http://www.britannica.com/EBchecked/topic/623389/variation - info on variation

Gregor Mendel

Identified “genes” and called it as Inherited traits. Father of Genetics

Homozygous and heterozygous Types of Gene Today’s Objective Homozygous and heterozygous Types of Gene Dominant Gene Recessive Gene Genotype and Phenotype

Human Chromosomes

Homozygous - two alleles the same Heterozygous - two different alleles

Types Of Genes

Genes Dominant gene Recessive Gene They are ‘stronger’ and expressed They are ‘weaker’ and not expressed They are written as capital letters -‘B’ They are written as small letters -‘b’

Brown eyes are dominant than blue eyes bb BB Rabbits black fur is dominant than white fur bb BB

Genotype and Phenotype

So what is Phenotype and Genotype??

Phenotype The physical appearance of individuals within a species is termed as the Phenotype.

Genotype The different genes that each individual has is their genotype

B + b = Bb b + b = bb B + B =BB Genotype BB Genotype - Bb Phenotype - Black fur B + b = Bb b + b = bb Genotype - Bb Phenotype - Black fur Phenotype - White fur Genotype - bb

MONOHYBRID CROSSES Things to know before attempting to solve a monohybrid cross:- http://www.s-cool.co.uk/gcse/biology/genetic-crosses/revise-it/monohybrid-crosses

Monohybrid worksheet posted on the Bio website.

Mutations: a source of variation

Mutations are the source of variation A mutation is a heritable change in genetic material. Addition or deletion of the certain codes in the genes can lead to mutations. Major Causes Diet Lifestyle Radiation Chemicals Stress

DISCLAIMER – The following Picture might be disturbing for some.

THE TREE MAN

How can Mutation be a source of evolution??

Natural Selection The competition between the individuals for food, space, resources, environment led to the struggle for survival The individuals that can compete successfully for the resources are most likely to survive This is known as survival of the fittest and also known as natural selection.

Mutation:- http://www. bbc. co Mutation:- http://www.bbc.co.uk/schools/gcsebitesize/science/add_ocr_gateway/living_growing/proteinsrev4.shtml Natural selection http://www.bbc.co.uk/schools/gcsebitesize/science/ocr_gateway/understanding_environment/natural_selectionrev1.shtml

Read the articles in the given sites and answer the questions below, in your C.W. Name a disease that is an example of an inherited disorder. Explain how it came into being. ‘Individuals that are poorly adated to their environment are less likely to survive and reproduce’ –Explain this statement.