1. Mendel and Genetics

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

3. Mendel’s Experiments:

4. Mendel’s Experiments:

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

6. The alternate forms of a factor are alleles
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

7. 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 = ?

8. Predicting offspring
Punnett squares help to predict what alleles offspring might inherit

9. Step 2 of Mendel’s
Experiment:

10. Step 3 of Mendel’s
Experiment:

11. 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

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

13. % 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? ________

14. 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.