12/20 & 12/21 - 7 th Grade Agenda 

Learning Objective: Learn about Punnett Squares

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Collect HW: Reading & Note Taking p. 89 – 92

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BrainPop Genetics, Heredity & Genetic Mutations

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Video: Test your Brain

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HW: Science Fair Background due 1/17 & 1/18 (10 Points)

Reflection

• Prompt: Complete the following Punnette Square

Tt T t Tt T t

Reflection

• Prompt: Complete the following Punnette Square

Tt T t Tt T TT Tt t Tt tt

Mendel’s Experiment

• • What would happen if you cross pollinate a tall plant with short plant?

Why?

What is a allele?

• One part of a gene pair. Alleles represent different varieties of one trait such as height of pea plant.

• Two alleles form a gene pair

What is a Dominant Allele?

• • One whose trait always shows up in the organism when the allele is present Dominant allele is represented by a

CAPITAL

letter

What is a Recessive Allele?

• • A recessive allele is always covered up or masked whenever the dominant allele is present Recessive allele is represented by a

lowercase

letter

Phenotype Genotype TT X tt Tt X Tt TT Tt Tt tt

What are Genotype & Phenotype?

• Phenotype: Physical appearance • Genotype: Genetic makeup

Punnette Squares

Practice Creating Punnett Squares BB B B Bb bb b Bb b Bb Bb

Practice Creating Punnett Squares Bb B b Bb Bb B BB b Bb bb

Practice Creating Punnett Squares Bb B b bb bb b Bb b Bb bb

Practice Creating Punnett Squares GG G G Gg gg g Gg Gg Gg g

What is Codominance?

• The alleles are neither dominant nor recessive

What is incomplete dominance?

• Both alleles are blended in the offspring

Human chromosomes

• Each human body cell contain 23 chromosomes • • chromosomes.

There are 35,000 genes in the chromosomes in the same order on both chromosomes

Meiosis

• Meiosis is the process by which the number of chromosomes is reduced by

alf rm

eggs.

Meiosis Meiosis I Meiosis II