1. Fundamentals of Genetics
CHAPTER 9

2. Patterns of Inheritance
The History of Genetics
Genetics – scientific study of heredity
Trait – characteristic that can be passed from parents to offspring

3. Father of Genetics Gregor Mendel (born 1822) Austrian Monk
Studied 7 different pea plant traits that are true-breeding
Produce offspring identical to themselves

5. Parental Cross
Cross-pollinated flowers with opposite traits (tall, short)
P generation
Plants from the first cross were all tall- hybrids.
F1 generation

6. F1 Cross Allowed f1 plants to self-fertilize
The recessive trait had reappeared!!
About 25% of the offspring (F2 generation) were short.

7. Mendel’s Conclusions https://www.youtube.com/watch?v=Mehz7tCxjSE
1. Biological inheritance is passed from one generation to the next- Genes
Alleles- different forms of a gene
2. Some alleles are dominant
Capital Letter -R,D
Some alleles are recessive
Lowercase letters – r, d
3. Principle of Segregation
Alleles separate from each other during formation of sex cells, or gametes.

8. Genes Represent Traits
Genotype – genes that make up an organism
Includes both genes in a homologous pair
Phenotype – outward expression of the trait
Homozygous – two alleles are identical (AA or aa)
Heterozygous – two alleles are different (Aa)
Also known as a hybrid organism
Purebred – organism receives the same genetic traits form both of its parents
Homozygous – AA or aa
Hybrid – organism receives different forms of a genetic trait
Heterozygous - Aa

9. Important Terms Genes – sections of a chromosome that code for a trait
Allele – distinct form of a gene
Dominant Allele – expressed when two different alleles are present; represented with capital letter
Recessive Allele – form of gene that is not expressed when paired with a dominant allele; represented with lower case letter

11. Genetics and Prediction

12. Predictions for One Trait
Probability – predict likelihood of an event or outcome
Punnett square – grid for organizing genetic information
Can be used to make predictions about a cross between two organsims
Monohybrid Cross – cross between two parents and one trait

13. Monohybrid Cross

14. Predictions for Two Traits
Dihybrid Cross – cross between
two parents and two traits
Use a 4 x 4
Punnett square
Sixteen possible outcomes

15. Incomplete Dominance
Heterozygous offspring show a phenotype that is in-between the phenotypes of the two homozygous parents
Blending of traits
Color in snapdragons;
instead of white or red,
color is pink

16. Codominance Both alleles are expressed Example: Blood type
IA, IB, i(O), or IAIB blood type
Both A and B are dominant so they are both expressed in the IAIB blood type

17. Polygenic Trait Trait controlled by more than one gene
Example: eye color