Do Now:• If the world were hit with a massive outbreak of a

disease like Bubonic Plague. What would the impact be on human?

Homework – Thursday’s class• Review your tests, make corrections and

be ready to re-take the test tonight at 7:45.in the Biology room. Read pages 338 – 343

• Define these terms:• Transformation• Bacteriophage

Review • Write these questions and be prepared to

answer them:• Why did Gregor Mendel choose the Pea

to study genetics and what did he find? – The pea has a simple design.– Fertilization -– Hybrids – Pollination– Gametes

Review• What is heredity:• The sum of the characteristics and potentialities genetically

derived from one's ancestors• What are traits? The specific characteristic of an organism such as

height, or color• What is the Law of Segregation?• Each parent passes along one trait (allele) to the off-spring• What is the difference between Genotype & Phenotype?• Genotype = the genetic make up. For example blonde hair

would be bb, meaning two recessive genes.• Phenotype = actual physical characteristics. In this case

blonde hair.

Review• Genotype – the genetic makeup of a

gene (TT, Tt, tt) Homozygous –Same type of

alleles (Tall – Tall= TT) or (short- short=tt)

Heterozygous – both different (Tall-short = Tt).

Review• What is the difference between Homozygous &

Heterozygous?• Homozygous are genotypes that are the same and either

dominant or recessive, not one of each. For Example – blonde hair (bb) or Brown hair (BB).

• Heterozygous are genotypes that are both different, meaning one dominant and one recessive.

• Mendel’s law of Dominance would simply be that although two different genotypes are present, the dominant gene would expressive itself. The recessive would just be passed along without being expressed.

Review• This is an example of what? (Two

possible answers)• Inbreeding and / or Genetic Drift

Small gene pool / inbreeding• Inbreeding and / or Genetic Drift aka the

Founder’s Effect.• A small isolated community will

naturally have less genetic diversity. Some random and / or rare conditions tend to appear more often. For example the British Royal Family and hemophilia.

DihybridDi-hybrid – deals with two traits. (p. 316) – each box will have 4

alleles = BbTt X BbTt. B- Brown Hair, b – Red Hair, T – Tall, t – Short

DihybridDo the following - BbTt X BbTt. B- Brown Hair, b – Red Hair, T –

Tall, t – Short• BT bT Bt bt

• BT

• bT

• Bt

• bt

Ratios• How many Brown Hair and Tall will you

have?• 9• How many Brown Hair & short• 3• How many Red Hair & Tall• 3• How many Red Hair & short• 1

Review stuff• What is Co-Dominance? • Both are expressed equally.• Incomplete Dominance? • Neither one is fully expressed, they are blended (meaning neither

red nor white is expressed, but the blending in this case pink.

Dominant vs Recessive• Hitler’s hope was to have his “super race” by

creating genes that were recessive, which he considered to be “pure”.

• Explain why he felt that the use of recessive genes was “pure?”

• Because on the rarity of the traits. Also, once doing the Di-Hybrid (16 box Punnett Square) there is only one totally recessive box. That recessive cannot be altered or in his mind corrupted.

• There is no way to tell if someone with brown hair is homozygous (BB) or heterozygous (Bb). Very easy to see Blonde hair - bb

Principle of Dominance• Principle of Dominance. • Create a scenario that illustrates the Principle of

Dominance.• Blue eyed mom (bb) homozygous and brown eyed

dad (you pick either heterozygous (Bb) or homozygous (BB). Use the punnet square below.

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Before leavingBefore you leave, clean up the area around your table. Make sure you have the homework(s) for tonight.