Heredity

1. Heredity • Genetics is the study of heredity • Inherited characteristics are called traits.

2. Why do I have brown eyes?Traits, and Genes. • Phenotype :What you look like • Genotype:What genes you have • combination of genes in an organism • genotype usually determines the phenotype • Genotype does not always 100% determine phenotype We can see this clearly in Identical twins who although they share ALL of their genes they do not always appear the same.

3. What is a Gene? • A gene is a segment of DNA that is the code to make a protein • Is starts at a start codon (code says start here!) and goes to a stop ( the same section that enzyme translated) • Why did we spend so much work making that protein? • Depending on what kind of protein that you make will change the trait that you have. • *Trait • Blue or brown eyes • Tall or short • How does this affect me? • Your body is run, maintained, and defined by the proteins working in our cells

4. How are phenotype, and genotype connected? • Dominant • Represented by a capital letter and indicates that if this gene is present this trait will be exhibited • Free hanging earlobes= F • Recessive • Represented by a lowercase letter and indicates that if both genes passed on this trait will be exhibited, but if a dominant gene is present then the recessive gene will not be exhibited. • Attached earlobes are = f

5. Gene pairs • You have two genes for the same trait. • One was given to you by your mother, and one was given to you by your father. • The law of segregation states that gene pairs separate during gamete formation. So you only pass on either the gene from your mother, or father.

6. Allele • Genes can exist in alternative forms • These are called alleles. • Tall or short alleles • You can carry dominant, or recessive alleles, or one of each ( one from each parent) Or two of the same

7. Dominant Recessive For Peas Seed shape Flower color Pod color Seed color Flower position Pod shape Plant height Dominant trait axial (side) purple yellow round green tall inflated Recessive trait (tips)terminal green short white yellow wrinkled constricted

8. Mendel • Worked at a tutor, but really wanted to work do experiments. • He joined a monastery, and was placed in charge of gardening where he spent the rest of his life raising food for the monks, but more important to Mendel was working with and studying pea plants, and their offspring.

9. More terms • Homozygous • Pure • Heterozygous • Hybrid

10. Why Peas? • 1.Peas are easy to raise • 2.He noticed that there were a lot of pairs of contrasting traits. Tall short yellow green • Pea plants reproduce sexually • He could contol • Self pollination • Inbreeding to produce pure lines of traits • Can prevent self pollination • He could choose which plants bred Flower position Pod shape Seed shape Flower color Pod color Seed color Plant height Dominant trait Recessive trait

11. How did he do it? • One trait at a time. • Mendel used Punnett squares to show possibilities and predict ratios of offspring. • Dominant traits are written with Capital letters, and recessive traits are with lowercase letters

12. The six steps • Write down the problem. • List the Genotype of the parents. • Form the gametes. ( law of separation) • Make a Punnett square • List the genotype of the offspring • List the phenotype of the offspring.

13. The six steps Punnett squares • 1 read / or write down the problem • Cross a herterozygous brown eyed dog with a with a hybrid brown eyed dog • 2. This means Bb x Bb • 3. B, b x B, b • 4.  • 5. 25% BB or ¼ 50% Bb or ½ 25% bb ¼ • 6. 75% or ¾ Brown 25% or ¼ yellow

14. So lets do a problem together • Y= yellow seed color and y= green seed color • Note that yellow seed color is dominant. • Cross a pea plant that is Homozygous for yellow seed with a plant that is pure for green seeds. • Cross a hybrid yellow see with a green seed

15. Generation after generation • P1 generation (P stands for “parent”) • This would be your parents • F1 generation (F stands for “filial”-son or daughter) • This would be you • F2 generation • Your children

16. Dihybrid • Next we will work with two traits at once , and do a Punnett square. • Do this problem (back of your last page.) The Six steps!!!. • 1 read / or write down the problem • B=Brown eyed b= blue eyedT= Tall t= short • Cross a homozygous Tall, homozygous brown eyed man with a Homozygous short homozygous blue eyed woman

17. Cross a homozygous Tall, homozygous brown eyed man with a Homozygous short homozygous blue eyed woman • 2. This means BBTT xbbtt • 3. B,B,T,t x B, b, T,t • 4.  • 5. • BbTt= 100% • 6. • Brown eyes Tall =100%

18. Cross a Homozygous tall pure brown eyes with Heterozygous Brown Heteroxytous short . . • 2. BB,TT x BbTt • 3. BT, BT, BT, BT x BT, Bt, bT, bt

19. . . . • Step 5 • BBTT=4 =1/4 • BBTt=4=1/4 • BbTT=4=1/4 • BbTt=4= 1/4 • Step 6 • Brown eyed tall =16 or 100%

20. Dihybrid Cross 9:3:3:1 ratio 9 Brown Tall3 Brown short3 blue tall 1 blue short

21. What if a trait isn’t dominant or recessive? • Incomplete dominance • The two genes that a person can carry can create three different phenotypic results • For instance on page 316 ( chapter 12.20 in your book there is an example of the snapdragon

22. Snapdragons • When a snapdragon has • RR the flower color is red • WW the flower is white • RW, the flower is the third color Pink.

23. What are R and R’? When neither allele is completely dominant the letters R and R’ are used R’ is pronounced “R prime” R would be like R for red, and R’ would be for white. Remember in reality the letter just represents the gene we are talking about, and any letter can be used. R’ is how scientists identify that the gene is another Dominant gene for a trait.

24. Codominance • Co-dominance • The two genes can carry can create three different phenotypic results • For instance on page 317 ( chapter 12.20 in your book there is an example of the chickens….

25. We will use BB=BlackWW=White, and BW = Checkered(For quizzes and homework)Note both are “dominant genes so they must be capitalized

26. Sex linked • Sex linked inheritance when a gene is found on the x chromosome • Color Blindness • Xr Y – Color blind man. • Xr Xr – Color blind woman • XRXr – Carrier • XRXR – cannot have color blind children

27. Multiple alleles • Some traits have multiple alleles possible for them • Blood type is one such instance • There are three different alleles for blood type • A, B, and o • A, and B are co-dominant • o however is recessive to both • So what combinations of genes can you have for blood type? • What blood type do you have?

28. Eye color is Polygenic • Brown Blue grey green, and hazel all result from different combinations of genes. • Brown typically is dominant to all of these, but as seen with hazel eyes brown can be present along with other colors. • Polygenic trait

29. Polygenic • Polygenic inheritance: means that more than one gene determines the trait expressed • These genes can be on multiple chromosomes • A good example of this is skin colors • Additive

30. Donating blood

31. Who can give blood to who? • So what combinations of genes can you have for blood type? • What blood type do you have? • Who can you give blood to? • Who can give you blood?