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Phenotype. Genotype. physical appearance of an organism. the set of genes (alleles) that an organism possesses. Homozygous. Heterozygous. when two alleles (gene types) are identical. when the two alleles are different. Genetics Buzzwords. Allele. different forms of the same gene.
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Phenotype Genotype physical appearance of an organism. the set of genes (alleles) that an organism possesses Homozygous Heterozygous when two alleles (gene types) are identical when the two alleles are different Genetics Buzzwords Allele different forms of the same gene
Dominant allele which controls the characteristic whenever it is present. BB or Bb recessive allele whose characteristics only show up when it is present on both chromosomes bb
Determining characteristics In pea plants, tallness (T) is dominant to dwarfness (t) A tall pea plant could have a genotype of: TT Tt Both combinations have the same phenotype- tall. homozygous dominant heterozygous A dwarf pea plant could only have the genotypett Phenotype- dwarf. homozygous recessive
Gene combinations The simplest genetic cross involves one characteristic and is called a monohybrid cross. In this the parents (P) are crossed (bred) with each other, and the offspring (F1 generation) observed and counted. Follow the procedure on the board!!
Mother XX Father XY X X X Y XX XY XX XY gametes 1:1 ratio male to female offspring Offspring: Male or female? F M F M This explains how the sex of a child is determined by X and Y chromosomes. This can also be shown and combinations worked out using a Punnett square:
Task 1. Complete the problems in the Monohybrid Crosses booklet • DO NOT SKIP STEPS!! • Always define the alleles • Always draw the Punnet square 2. Let´s play Traits Bingo! (15 min)
Keywords review • Can you match up the key words to the definitions? • You only have 4 min before the bomb goes off!
STARTER: Get your brains in gear!NO NOTES!!! A – normal skin pigmentation a – albino What percentage chance is there of producing a child with albinism?
Tasks this lesson 1: Finish the Monohybrid Crosses revision booklet (15 min) 2: Try the problems in the More Monohybrid crosses booklet! (20 min) 3: Let’s play Traits bingo! (15 min)
STARTER Who is known as “the man of 1000 peas?” How long has he been running his experiments for? How many plants did he grow? What did he notice when he first grew pea plants? What field of biology has come about because of his experimenting on peas?
Tasks this lesson • Finish the More Monohybrid Crosses booklet • Attempt the past paper questions (put the theory into practice!) • Finish the lyrics!
Tasks this lesson • Have a go at the past paper question booklet • Read the Mendel´s Laws booklet and answer the questions • The genetics of skin colour TED talk