1. INTRO TO GENETICS Gregor Mendel -FATHER OF GENETICS
CHAPTER 8
INTRO TO GENETICS
Gregor Mendel -FATHER OF GENETICS

2. GENETICS-STUDY OF HEREDITY
HEREDITY-PASSING OF CHARACTERISTICS FROM PARENT TO OFFSPRING
TRAIT-INHERITED CHARACTERISTIC
TRUE-BREEDING-PURE FOR A TRAIT

3. Monohybrid Cross
Crossed tall and short pea plants that were true-breeding for those traits
Monohybrid cross -produced offspring whose parents differed by one trait (height)
Offspring were called hybrids

4. P1 Tall plants X short plants
F1 Tall Pea Plants

5. Monohybrid Cross P1 Tall plants X short plants F1 Tall Pea Plants
F2 F1 x F1
3 Tall; 1 short

7. EACH PERSON RECIEVES TWO COPIES OF A GENE -ONE FROM EACH PARENT -WHEN REPRODUCTION TAKES PLACE.

8. ALLELES THERE ARE ALTERNATE FORMS OF A GENE CALLED ALLELES
YOUR TRAITS ARE DETERMINED BY THE ALLELES YOU RECEIVE FROM YOUR PARENTS.

9. WHEN TWO ALLELES OCCUR TOGETHER, ONE OF THEM MAY BE EXPRESSED (PHYSICALLY SEEN) WHILE THE OTHER MAY NOT BE OBSERVED IN THE ORGANISM’S APPEARANCE (HIDDEN)
The expressed gene is called the dominant gene. (represent by capital letters)
The hidden gene is called the recessive gene. (represented by lower case letters)

10. Law of segregation
When gametes are formed during meiosis, the alleles separate so that each gamete recieves only one allele for each trait.

11. If the two alleles of a gene are the same the individual is said to be homozygous.
TT -homozygous dominant
tt -homozygous receive
If the two alleles of a gene are different the individual is said to be heterozygous Tt

12. The set of alleles an organism recieves from their parents is calle the.
genotype genotype =type of gene
The physical appearance of an organism (which is determined by the genotype) is called the phenotype.
phenotype=physical

13. Example
Let's say that for the red-throated booby bird, red throat is the dominant trait and white throat is recessive. Since the "red-throat code" and the" white-throat code" are alleles (two forms of the same gene), we abbreviate them with two forms of the same letter.  So we use "R" for the dominant allele/trait (red throat) and "r" for the recessive allele/trait (white throat).
Our possible genotypes & phenotypes would be like so:
Symbol
Genotype name
Phenotype RR
Homozygous pure dominant
Red throat Rr
Heterozygous rr
Homozygous pure recessive
White throat

14. Punnet square
Diagram that predicts the possible genotypes and phenotypes of offspring

15. Use these parental genotypes: Tt x tt.

16. Dihybrid crosses (DI=2)
Cross that involves parents who differ by two traits
Law of independent assortment-the inheritance of one trait had no effect on the inheritance of another trait.
Seed color has no effect on seed shape.

17. Dihybrid cross Cross involving parents that differ by two traits
Law of independent assortment-genes for different traits are inherited independently of each other
RRYY x rryy = RrYy
RrYy x RrYy
R and r will separate; Y and y will separate
Recombine to produce 4 different gametes

18. Example of a Dihybrid Cross

19. Diagram of a Dihybrid Cross

20. Images and examples are taken from various websites.