1. Foundations of Genetics

2. Genetics Alleles- different forms of a gene –Ex: Genes for eye color can be brown or blue. –You can have alleles that are homozygous for a trait or heterozygous for a trait

3. Homozygous- the organism has the same alleles for the trait. –EX: BB or bb Heterozygous/Hybrid- the organism has different alleles for a trait. –EX: Bb or Yy

4. Genotype vs. Phenotype Genotype- is the actual genetic make up of an organism. What is not seen. Phenotype- is the actual PHYSICAL appearance of the organism. What is seen.

5. Dominant vs. Recessive Dominant Traits- are the traits that are expressed Recessive Traits- are only expressed when no dominant allele is present.

7. Genetics Genetics- is the branch of biology that studies how hereditary material is passed from parent to offspring –Gregor Mendel- Austrian monk who began to genetically investigate pea plants.

8. Mendel’s Law of Dominance Mendel’s first law It states that when an organism is homozygous dominant and another is homozygous recessive then the dominant trait is always seen. T T tttt Tt

9. Law of Segregation and Recombination 2 nd Law  Alleles separate during gametogenesis and recombine during fertilization. **He used offspring from law of dominance**

10. Types of Dominance There are four types of dominance: –Incomplete dominance –Co dominance –Multiple Alleles –Polygenic traits

11. Incomplete Dominance When one allele is not completely dominant over the other. –Ex. Japanese Snapdragon flowers RR WWWW RW KE Y RR  Red WW  White RW  Pink

12. Co-dominance When both alleles contribute to the phenotype. –Ex. Seen in cattle C R C R CWCWCWCW CRCWCRCW CRCWCRCW CRCWCRCW CRCWCRCW C R C R  RED C W C W  WHITE C R C W  ROAN KE Y

13. Multiple Alleles When genes have more than two alleles for a trait Blood Types are an example A– I A I A (Homozygous) or I A i (Heterozygous) B– I B I B or I B i AB– I A I B O– i i (recessive) I A i i I A i

14. Sex Determination & Chromosomes Sex Chromosomes Diploid cells have one pair of chromosomes that are not alike Human Sex Chromosome- –Human cells contain 22 pairs of autosomal (body cells) chromosomes and 1 pair of sex chromosomes Males are XY Female XX Egg Cells always carry an X Sperm Cells can carry a X or Y

15. Karyotype

16. Sex Linkage The “X” chromosome carries many alleles that the Y does not. The expression of the gene is affected by the sex of the individual. Ex: Lorenzo’s Oil (ALD) Females are “XX”. In order for the trait to be expressed it must be on both X’s. Males only have one X so if it lands on the X it will be expressed.

17. For Example: Colorblindness and hemophilia are sex linked traits. Carrier Female Affected boy

18. X- X X- Y X-X- X-X X-Y XY 25% Affected Female 25% Carrier Female 25% Affected Male 25 % Normal Male

19. Genetic Disorders Phenylketonuria- inability of the body to make an enzyme needed to break down a certain amino acid. –Diet products like: Diet Coke, Equal, Splenda Have this amino acid in it and people with this disease can’t consume these products Tay Sachs- Deterioration of nerve tissue due to the accumulation of fatty material Down’s Syndrome- Chromosomal disorder resulting in an extra number 21 chromosome. (Caused by non- disjunction during meiosis)