# Reproduction by yurtgc548

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Heredity and Punnett Square
•   Recap WS 6
•   PowerPoint Slides – Mendel and Punnett
•   Activity 1 – Practice
•   Activity 2 – Consolidate
Recapitulation
• Why do we share common traits with our
parents?

• Why we share different traits from each
parent?
– BUT: Sometimes we don’t share some traits
Mendelian Genetics
Gregor Johann Mendel (1822 – 1884)
• Austrian monk

• Cultivated and studied pea plants in the garden of his
monastery

• Mendel’s Laws of Inheritance:
– We inherit one of two forms of a gene from each parent
– Inheritance of a gene is independent (50-50 chance)

• We inherit two forms of a gene – one from each parent
 Why do we express one form and not the other?
Dominant and Recessive genes
• Dominant gene: the gene that
expresses itself

• Recessive gene: can only express
itself when both genes are
recessive

“How do we find out the
combinations that are possible?”
The Punnett square
• Created by Reginald Crundall
Punnett (1875 – 1967)

• A British geneticist

• How to use a Punnett square?
– Refer to example
Activity 1 (5 minutes)
• Use the Punnett square to determine the
different combinations of traits inherited

• What is the probability for each trait?
– probability and percentage
Activity 2 - Consolidation
Farmer Bob grows two types of corn –
Purple (dominant) and Yellow
(recessive).

He would like to grow a new type of corn
that is 3:1 Purple to Yellow. Which
corn should he cross?

• Pair up to discuss
• Use the Punnett square to help
Farmer Bob solve his problem
Activity 2 – EXTENSION (optional)
• How can he know if the Purple or Yellow corn
he is using is a carrier and not dominant (both
genes)?

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