Genetics:

1. Genetics: Inheriting Traits

2. Chromosomes • Chromosomes are columns of coiled DNA. • You have 2 sets from chromosome 1-23 (46 total)

3. Genes and Traits • Genes are rows on the column of chromosomes that code for a trait. (instruction manuals) • Traits are a notable feature or quality in a person. (physical, behavioral, medical conditions) Mr.. Emery?

4. Question • How many different chromosomes do you have? • How many sets of these chromosomes do you have? • What are chromosomes made of?

5. Answers • How many different chromosomes do you have? • 23 • How many sets of these chromosomes do you have? • 2 • What are chromosomes made of? • Tightly wound columns of DNA

6. Genotypes vs. Phenotypes • Genotype: The type of genes that make up a trait. They are expressed in letters and come in pairs (WW, Ww, ww) • Phenotype: An observable trait (widows peak) or the expression of the genotype. • [from Greek phaino- shining, from phainein to show] • The individual letters are called alleles. (W) or (w)

7. Dominant vs. Recessive Traits • Dominant traits: When two different traits are paired (widows peak vs.. straight hairline) the dominant trait shows. • Dominant traits are usually expressed genetically with an upper-case letter of the dominant trait (W)

8. Dominant vs.. Recessive Traits • Recessive traits: are ‘hidden’ when paired up with a dominant trait. • Recessive traits are most often expressed genetically with a lower-case letter of the dominant trait. • Straight hairline is expressed with (w), not an (s). The (w) matches the (W) for the dominant trait, a widows peak.

9. Question Widows peak is dominant trait over a straight hairline . • If the genotype is (Ww), what phenotype will be expressed? • If the genotype is (ww), what phenotype will be expressed? • Why is (ss) not a good set of letters for this trait?

10. Answers Widows peak is dominant trait over a straight hairline . • If the genotype is (Ww), what phenotype will be expressed? • Widows peak • If the genotype is (ww), what phenotype will be expressed? • Straight hairline • Why is (ss) not a good set of letters for this trait? • The letter representing the trait should be of the dominant trait.

11. Homozygous vs. Heterogygous • Homo: same • Hetero: different • Zygous: yoked, or joined

12. Homozygous vs. Heterozygous • Homozygous: same genes or trait • (WW) and (ww) are both homozygous. • (WW) is homozygous, and dominant • (ww) is homozygous, and recessive • Heterozygous: different genes or trait • Ww is heterozygous, that’s it.

13. Question Widows peak is dominant over a straight hairline. • What is the genotype of a homozygous dominant trait for widows peak? • If the genotype is heterozygous for widows peak, which phenotype will be ‘hidden?’ • What trait will be expressed if someone is homozygous, recessive?

14. Answers Widows peak is dominant over a straight hairline. • What is the genotype of a homozygous dominant trait for widows peak? • WW, not ww • If the genotype is heterozygous for widows peak, which phenotype will be ‘hidden?’ • Straight hairline • What trait will be expressed if the someone is homozygous, recessive? • Straight hairline

15. TwinsIdentical twins vs. Fraternal twins • Identical twins: share the same genetic code. • They come from the same egg and sperm.

16. Twins? • Fraternal twins: Not identical genetically. They are like brothers and/or sisters born at the same time. • By the way, these two are NOT twins, however they are brother and sister. These pictures were taken approximately the same time developmentally and in the same clothes.

17. Cougar fans:Same age vs.. present (A) #1 #2 Can you match the Cougar Fans same age vs.. present? (B)

18. Question • These two Cougar fans are not fraternal twins. • Could their DNA be even more closely related than a pair of fraternal twins?

19. Answer • Yes, it is possible. • And A=1, B=2