Mendel and Genetics Gregor Mendel Called the Father

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Mendel and Genetics

Mendel and Genetics

Gregor Mendel • Called the “Father of Genetics” because he was the first to

Gregor Mendel • Called the “Father of Genetics” because he was the first to study genetics • Researched how traits are inherited in pea plants

Mendel’s Experiments:

Mendel’s Experiments:

Mendel’s Experiments:

Mendel’s Experiments:

Mendel discovered that: 1. Parents transmit info about traits to offspring (he called them

Mendel discovered that: 1. Parents transmit info about traits to offspring (he called them “factors”, but we know that they are genes) 2. Each individual has 2 factors for each trait; 1 from each parent - this may result in homozygous (WW or ww) or heterozygous (Ww) combinations

3. The alternate forms of a factor are alleles 4. The presence of an

3. The alternate forms of a factor are alleles 4. The presence of an allele doesn’t mean that the trait is expressed (seen) - the dominant allele is seen the recessive allele is only seen if an individual has 2 recessive alleles

For example, in pea plants: • W = purple flower – purple is dominant,

For example, in pea plants: • W = purple flower – purple is dominant, therefore a capital letter • w = white flower – white is recessive, therefore a lower case letter WW = purple flower ww = white flower Ww = ?

Predicting offspring • Punnett squares help to predict what alleles offspring might inherit

Predicting offspring • Punnett squares help to predict what alleles offspring might inherit

Step 2 of Mendel’s Experiment:

Step 2 of Mendel’s Experiment:

Step 3 of Mendel’s Experiment:

Step 3 of Mendel’s Experiment:

Analyzing Results: • Probablility– the likelihood that something will happen – Example: the probability

Analyzing Results: • Probablility– the likelihood that something will happen – Example: the probability of a coin landing with heads or tails is 50% • Ratio – describes the probability of each phenotype or genotype – The ratio of heads: tails is 50: 50, or 1: 1

Ratio of tall to short (PHENOTYPE) ___: ___ Ratio of TT: Tt: tt (GENOTYPE)

Ratio of tall to short (PHENOTYPE) ___: ___ Ratio of TT: Tt: tt (GENOTYPE) ___: ___

% of brown rabbits ___ % of black rabbits ___ % of homozygous dominant

% of brown rabbits ___ % of black rabbits ___ % of homozygous dominant (BB)___ % of heterozygous (Bb)___ % of homozygous recessive (bb) ___ Ratios can also be fractions, like these What are the possible phenotypes of the rabbits? _____ What are the possible genotypes of the rabbits? ____

How to set up a Punnett Square • If you cross a heterozygous tall

How to set up a Punnett Square • If you cross a heterozygous tall pea plant with a homozygous short pea plant what will the genotypic and phenotypic ratio be? • Identify the letter to use to represent the trait. • List the possible combinations • Place the letter on the outside of the punnett square. • Solve.