Bio

Genetics & Mendel Study Guide

Who was Gregor Mendel, and why is he important?

Gregor Mendel was an Austrian monk and scientist known as the “Father of Genetics.” He discovered the basic principles of heredity by studying how traits are passed from parents to offspring.

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What organism did Mendel use, and why?

Mendel used Pea Plant plants because they:

• Grow quickly

• Produce many offspring

• Have easily observable traits

• Can self-pollinate or be cross-pollinated

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How did Mendel conduct his experiments?

He cross-pollinated pea plants with different traits and carefully recorded the offspring over many generations. He used:

• Controlled pollination

• Large sample sizes

• Repeated experiments

• Careful observation and counting

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Traits Mendel Studied

Mendel studied 7 pea plant traits:

• Plant height (tall/short)

• Flower color

• Seed color

• Seed shape

• Pod shape

• Pod color

• Flower position

Patterns Observed

• Some traits appeared more often (dominant)

• Others disappeared and reappeared (recessive)

• Traits are inherited in predictable ratios

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How Mendel’s Work Influenced Modern Genetics

Mendel’s discoveries led to:

• Modern genetics

• Understanding inherited diseases

• Genetic engineering

• DNA research

• Selective breeding

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Punnett Squares

What is a Punnett Square?

A Punnett square is a chart used to predict the probability of offspring inheriting certain traits.

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What do the letters represent?

• Outside letters = parent alleles

• Inside letters = possible offspring genotypes

Example:

• T = dominant tall trait

• t = recessive short trait

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How is a Punnett Square used?

It predicts:

• Possible genotypes

• Possible phenotypes

• Probability of traits appearing

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Genotype vs Phenotype

• Genotype = genetic makeup (TT, Tt, tt)

• Phenotype = physical appearance (tall or short)

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Dominant vs Recessive Alleles