1. Predicting Inheritance
Mendelian genetics

2. Genetics Vocabulary Gregor Mendel
First person to successfully predict how traits are transferred from one generation to the next.
Used pea plants to show how genes were passed down
The “father of genetics.”

3. Genetics Vocabulary
Homozygous/Purebred: Two alleles for a trait are the same Examples: RR, rr, FF, qq, mm
Heterozygous/Hybrid: Two alleles for a trait are different Examples: Rr, Ff, Qq, Mm

4. Heterozygous or Homozygous?TT Pp dd Ff Tt FF

5. Heterozygous or Homozygous?
TT- homozygous
Pp- heterozygous
Dd- homozygous
Ff- heterozygous
Tt- heterozygous
FF- homozygous

6. Rule of Unit Factors
Alleles: expressions of a gene; carried in gametes
Each organism has two alleles that control each of its traits, one from father and one from mother.
Example: PP, Pp, pp
Never: P, p, Ppp, PPp

7. Genotype versus Phenotype
Genotype: Individual’s genes
Gen-
Produce
Birth
Origin
Phenotype: Individual’s physical appearance
Pheno-
Appear

8. Rule of Dominance
Only one trait is observed. The observed trait is called dominant and the trait that disappeared is called recessive.
Example: →

9. Rule of Dominance
In Squidward’s family, a blue body color (B) is dominant to green (b). Determine the phenotype for each genotype below based on this information. BB Bb bb

10. Rule of Dominance
In Squidward’s family, a blue body color (B) is dominant to green (b). Determine the phenotype for each genotype below based on this information.
BB- blue
Bb-blue
bb- green

11. Law of Segregation
Every individual has two alleles for each gene. Each gamete receives one of these alleles.
During fertilization, these gametes randomly pair to produce four combinations of alleles.
Example: →

12. Law of Independent Assortment
Genes for different traits are inherited independently of each other.
Example: seed shape (round or wrinkled) and seed color (green or yellow)

13. Review
What is the name for an individual with two of the same alleles?
What is the name for an individual with two different alleles?
What is the name of the trait that disappears?
The name of the trait that is observed?
How many alleles for each trait does an organism have?

14. Answers to the Review
What is the name for an individual with two of the same alleles? Homozygous
What is the name for an individual with two different alleles? Heterozygous
What is the name of the trait that disappears? Recessive
The name of the trait that is observed? Dominant
How many alleles for each trait does an organism have? Two

15. Let’s put this into action!
SpongeBob is known for his big round eyes (R), which are dominant over an oval eye shape (r). If he is heterozygous for his round eye shape and marries a woman with oval eye shape, what type of eyes might his kids have?
Step 1: List the genotypes of the parents:
Heterozygous round eyes: ____
Oval eyes: ____

16. Step 2: Punnett Square
Heterozygous round eyes: Rr
Oval eyes: rr

17. R r r r Step 3: Punnett Square Heterozygous round eyes: Rr
Oval eyes: rr R r r r

18. Rr rr rr Rr R r r r Step 4: Punnett Square Heterozygous round eyes: Rr
Oval eyes: rr R r Rr rr r rr Rr r

19. Predictions & Ratios
Based on the results of the Punnett Square, identify the possible offspring combinations.
% Homozygous round eyes (RR) ___________
% Heterozygous round eyes (Rr) ___________
% Homozygous oval eyes (rr)___________

20. Predictions & Ratios
Based on the results of the Punnett Square, identify the possible offspring combinations.
Homozygous round eyes (RR) _0%_________
Heterozygous round eyes (Rr) ___50%______
Homozygous oval eyes (rr)__50%_________

21. Now you try one on your own.
If two heterozygous round seed pea plants (Rr) are crossed, what percentage of offspring will be homozygous recessive? Use a Punnett square to find the answer.