1. Introduction to Mendelian Genetics

2. Objectives
Define key terms used in Mendelian Genetics

3. Key Terms
Heredity: The passing of characters from parents to offspring.
Genetics: The branch of biology that focuses on heredity.
Traits: Specific characteristics that vary from one individual to another. Ex. Hair color, skin color
Gene- a specific nucleotide sequence of DNA that codes for a protein

4. Key Terms
Allele –alternative forms of a gene. Ex. flower color –purple (P) or white (p)

5. Key Terms Phenotype- organism’s expressed traits; Ex. Brown coat
Genotype – An organism’s genetic makeup; the combination of alleles in the homologous chromosomes. Ex. - BB, Bb, bb
Homozygous – having identical alleles for the trait – Ex. WW, ww
Heterozygous – having two different alleles for the trait- Ex.Ww.

6. Definitions
Dominant- an allele that determines the phenotype of heterozygote. (Ex. YY-yellow plant or Yy).
Recessive – the allele that is masked by the dominant allele in heterozygotes;
not observed in the phenotype unless homozygous recessive (yy-green plant).

7. Purpose of Punnet Square
Examines the probability of getting a particular phenotype based on combination of gametes
Trait resides on the homologous chromosomes
Each square in a monohybrid cross (i.e. one trait) represents 25% chance
Summarize result with genotypic ratio and phenotypic ratio

8. Practice Problem Draw a Punnett square for the following cross:
Tt X Tt
Give the genotypic and phenotypic ratio.

9. Practice Punnett Square Problem
A plant that is heterozygous for green (G) pods is crossed with a plant that has yellow (g) pods. Green pod is dominant and yellow pod is recessive. What are the probable genotypic and phenotypic ratios in the offspring from this cross? What is the probability that plant will produce yellow pods?

10. PROPERTY OF PIMA COUNTY JTED, 2010
Paraphrase
Write down two genetic terms you learned today
Write the definitions of those terms in your own words
6. Paraphrase
student writes down one or two main ideas directly from the text or notes
student now paraphrases these ideas in their own words
teacher provides feedback
PROPERTY OF PIMA COUNTY JTED, 2010 6
PROPERTY OF PIMA COUNTY JTED, 2010 10

11. Human Traits

12. Detached Earlobes

13. Hitchhiker’s Thumb

14. Tongue Rolling

15. Dimples

16. Cleft Chin

17. Widow’s Peak