1. Genetics

2. Heredity and Genetics
Heredity is the passing of traits from parents to offspring
Traits are controlled by genes, so GENETICS is the study of how traits are inherited through the action of alleles

3. Gregor Mendel – “Father of Genetics”
Austrian monk born in
1822 who is responsible for the laws governing the inheritance of traits
Between 1856 and 1863, Mendel cultivated and tested over 28,000 pea plants
Mendel performed cross-pollination by transferring pollen from one plant to selected ova of other plants, thereby controlling which plants mixed

4. Mendel’s Experiments
Mendel produced pure strains by allowing plants to self-pollinate, meaning the pollen (male gamete) from one plant fertilizes ova (female gamete) of same plant

5. Mendel’s Peas…. s S y Y I i G g

6. Mendel’s Peas…. P p a A T t

7. Mendel’s Results…. (F2 from crossing to heterozygous F1s)

8. Genetics Terminology
Traits – any characteristic that can be passed from parents to offspring
Heredity – the passing of traits from parents to offspring
Alleles – one form (dominant or recessive) of a gene
Body cells have TWO forms or alleles for a single gene (you get one from mom and the other from dad)
Dominant – is always expressed; masks a recessive trait
Recessive – can only be expressed if there are no dominant alleles present

9. Genetics Terminology
Dominant alleles are represented by a capital letter
Recessive alleles are represented by a lower case letter
Example: B = Brown eye color (dominant)
b = Blue eye color (recessive)
“Purebred” species have two of the same alleles; this is also called HOMOZYGOUS, e.g., BB (homozygous dominant) or bb (homozygous recessive)
Species with two different alleles are called HETEROZYGOUS, e.g., Bb
Genotype: the alleles present in the organism, i.e., BB, Bb, or bb
Phenotype: the expression of the genes; what is observed

10. Genotype and Phenotype in Flower
All genes occur in pairs, so TWO alleles affect a trait.
Possible combinations if:
R = Red flower
r = Yellow flower
Genotypes RR Rr rr
Phenotypes Red Red Yellow

11. Genetic Crosses
BrainPop - Heredity
Offspring’s genotype and phenotype is determined using a Punnett square B b B BB Bb b Bb bb

12. Punnett Square, cont.

13. Punnett Square Practice
Trait: Seed Color
Alleles: Y – Yellow y – Green
Cross: Yellow seeds X Green seeds
YY X yy
Crossing two true-breeding (pure) plants Y Y Yy
Genotype: Yy
Phenotype: Yellow
Genotypic Ratio: 100% Yy
Phenotypic Ratio: 100% Yellow y y

14. copyright cmassengale
Mendelian Genetics
11/13/2018
Female Carriers
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