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 He was monk living in a monastery in Czechoslovakia in mid-1800’s.  He was in charge of the monastic vege garden.  He did breeding expt on peas.  He cultivated ~29,000 peas plants!! …..his data was meticulously recorded.  The amount of data is what makes his findings so reliable.

We know about words like….  Homozygous dominant and recessive  Heterozygous  Genes  Alleles  Genotype  Phenotype  Mendel’s laws…. YOU WOULD HAVE LEARNT THESE TERMS LAST YEAR To see what you can remember.... Match and paste...

 Chromosome structure ◦ Gene – unit of inheritance – segment of DNA  Alleles ◦ 2 versions of a gene (alleles) ◦ Dominant, recessive ◦ Alleles separated in the formation of gametes ◦ Each gamete carries one allele for each pair ◦ At fertilisation there is random uniting of gametes

 You learnt about these in Y11 science….  They are genetic crosses of just one trait.  Punnet squares have 4 squares.

 An individual that displays a dominant trait can either be homozygous dominant or heterozygous ◦ Eg. Straight thumb (H) is dominant to hitchhikers thumb (h) How do we tell if a straight thumbed individual is homozygous dominant or heterozygous?

 Tongue rolling (T) is dominant to non-tongue rolling (t). A tongue roller and non-tongue roller had children and produced tongue rollers and non-tongue rollers as children.  What were the genotypes of the parents?  Draw a punnet square to show possible off spring combinations.

 Sometimes alleles are not completely dominant over another allele. red whitepink  Example: A red snapdragon flower crossed with a white flower could create a pink offspring.  F1 are all heterozygous.  Self-crossed F2 yields a ratio of: 1 : 2 : 1 Red: Pink: White

 The heterozygous genotype shows both traits.  Example: BB = Black spotted cat bb = orange spotted cat Bb = Black and orange spotted cat Ratio 1 : 2 : 1 Black : Black+Orange : Orange  BLOOD GROUPS ALSO SHOW CODOMINANCE

 Alleles which cause death when occurring as one of the homozygous genotypes  These cause death at embryo stage and so the ratio is 1:2  Example: Achondroplastic dwarfism… 1 : 2 : 1 AA : Aa : aa Died:Dwarf:Normal

 Dwarfism is a result of autosomal dominant mutation in the fibroblast growth factor receptor gene 3 (FGFR3), which causes an abnormality of cartilage formation. In normal circumstances, FGFR3 has a negative regulatory effect on bone growth. In achondroplasia, the mutated form of the receptor is constitutively active and this leads to severely shortened bones.autosomal dominant mutationfibroblastgrowth factor receptorFGFR3cartilageFGFR3

 More than one allele can be positioned at a gene loci (address)  Example: Blood groups in people….. The protein's structure is controlled by three alleles; i, IA and IB. The first allele is, i, the recessive of the three, and IA and IB are both co-dominant when paired together

 A and B are co-dominant and both are dominant to O….so O is recessive.  I is the allele that makes the antigen.  The antibody causes foreign antigens to clump together.

 Wool Fibre Diameter – B2A gene ◦ A finest wool ◦ B ◦ C thickest wool  Another wool fibre gene KRT 1.2 ◦ Wool protein ◦ Many alleles

 A cross between two organisms where the inheritance patterns of TWO GENES are studied  There are a greater number of gamete types produced when two genes are considered  The genes are carried by separate chromosomes and are sorted independently of each other (WE WILL COVER THIS POINT SOON!)

 Answer questions ◦ Dihybrid Easy ◦ More difficult dihybrid ◦ Problems in

 Definitions

 Genes located on one sex chromosome but not on the other are called sex-linked genes.  The traits that show this kind of inheritance are almost always carried on the X chromosome  Examples: red-green colour blindness, haemophilia,

 For males, any sex linked gene on the X chromosome will show up because the Y has no matching gene to mask the effect  In females (having two X’s) the effect usually is masked – however they are ‘carriers’ (we will make sense of this statement!!)

 A woman with normal vision whose father was colour- blind marries a man who is colour blind. Give the possible phenotype and genotype of such a cross. C = normal c = colour blind

 Research the genetics of tortoisehell cats and hand to me tomorrow on a separate piece of paper

1. Mendel’s law of segregation 1. Mendel’s law of segregation – ‘of the two genes controlling each characteristic, only one is present in each gamete’. 2. Mendel’s law of Independent Assortment 2. Mendel’s law of Independent Assortment – ‘the segregation of one pair of alleles does not affect the segregation of another pair’

 The Law of Segregation states that the members of each pair of alleles separate when gametes are formed. A gamete will receive one allele or the other. 

 the pair of alleles of each parent separate and only one allele passes from each parent on to an offspring  which allele in a parent's pair of alleles is inherited is a matter of chance  segregation of alleles occurs during the process of gamete formation (meiosis)  randomly unite at fertilization

 The Law of Independent Assortment: As chromosome pairs line up, each chromosome pair is sorted independently. Which chromosome of each pairs ends up in which cell is random = produces different combinations of parents chromosomes in gametes.  The Law of Segregation states that the members of each pair of alleles separate when gametes are formed. A gamete will receive one allele or the other.

 During meiosis the homologous chromosomes line up at the equator of the spindle in pairs during Metaphase 1.  How they line up provides the basis for Independent Assortment.

 mations/content/independentassortment.htm l

 During the process of meiosis, independent assortment and crossing over (recombination) can occur. This results in genetic variation in the offspring of sexually reproducing individuals ◦ Describe what happens during independent assortment ◦ Explain how crossing over (recombination) can contribute to the genetic variation that results from sexual reproduction. You may wish to draw a diagram. ◦ Genetic variation can be a results from mutation. Explain the results of mutation sin somatic and gametic cells