heredity

1. heredity

2. Genetics • Inheriting Trait • Heredity is the passing of traits from parent to offspring • Genetics is the study of how traits are inherited through the interactions of alleles • Alleles are the different forms of a trait that make up a gene pair • Alleles separate in the sex cells during meiosis and results with one allele is being donated by each parent for the traits they carry

3. Mendel- the Father of Genetics • Gregor Mendel, 1856, Austrian monk studied how traits were transferred to offspring • Studied pea plants and 7 traits • Used scientific method and mathematics to predict offspring traits

4. Genetics in a Garden • When plants always produce the same traits generations and generation they are called purebreds • He noticed when he crossed purebreds with different traits they always produce one of the traits by one parent. He called these hybrids • For example: crossed purebred tall pea plants with purebred short pea plants and always got tall plants

5. Dominate and Recessive traits • Cross pollination techniques allowed Mendel to cross the tall and short purebreds • The result was always tall plants • Mendel called the tall form the Dominate factor while the short form was called Recessive factor • In the first generation the short trait disappeared , while the tall trait dominated over the short

6. Probability helps make prediction • Punnett square is a tool to help predict the possible outcomes of traits • Mendel used capital letters to represent each allele that were dominate (TT) representing tall purebred . • He used small letters for the same alleles that were recessive(tt) short plants • Two alleles that are the same are called homozygous (both above are homozygous)

7. Probability helps make prediction • Heterozygous refers to an organisms with 2 different alleles Tt • Tt represents a crossbred plant with one allele (Tall) and one allele (short) • The offspring is tall because the tall allele dominates over the short

8. Probability helps make prediction • Genotype is the genetic make up of an organism • TT, tt and Tt represents the genetic make up of pea plants dealing with tall and short plants • Actual alleles present in an organisms • Phenotype represents the actual appearance of the offspring • TT would appear tall, Tt would appear tall, tt would appear short

9. Making a Punnett Square • On the top of square, one parent has both alleles above the square, one each in each section • The vertical side has one parent has both alleles, one each in each section • Each square in grid is filled with one allele from each parent • Probability of offspring can be calculated

11. Principles of Heredity • 1. traits are controlled by alleles on chromosomes • 2. An allele’s effect is dominant or recessive • 3. When a pair of chromosomes separates during meiosis, the different alleles for a trait move into separate sex cells

12. Genetics since Mendel • When 2 homozygous parent show intermediate phenotypes it is called Incomplete Dominance • Occurs when some pure white flowers cross with pure red flowers and phenotype of offspring is pink • When cross the pink flowers, the result was some pink, white and red flowers on 2nd generation

13. Multiple alleles • Some traits are determined by more than 2 alleles A trait that is controlled by more than two alleles is said to be controlled by multiple alleles Traits controlled by multiple alleles produce more than three phenotypes Blood type is determined by 3 alleles A, B, O blood alleles O is recessive homozygous OO AB both A and B is expressed A blood type could be AA, or AO B blood type could be Bb or BO

14. Polygenic Inheritance • Groups of gene pairs acts together to produce a trait • Effect of many genes acting on a trait effect a wide variety of phenotypes • Eye color, height, skin color are examples

15. Human genes and mutations • Chromosomes disorders can occur because of wrong numbers of chromosomes produced during meiosis • Down syndrome is a result of 3 copies of chromosome 21

16. Recessive Genetic Disorders • In order for a recessive disorder to show up, both parents may have the hidden recessive gene but not shown in one or either parent • Cystic fibrosis is homozygous recessive disorder • Disorder produces thick mucus in lungs that make it hard to breath

17. Gender Determination • Females are designated XX(both alleles for sex are the same) • Males XY (X or Y alleles can be donated )

18. Sex-linked Disorders • Sex linked gens is an allele on a sex chromosome • Color blindness is a recessive disorder caused on X allele • Female would be color blind if both X alleles are present • Male will be color blind if the X allele is present • Males most generally are color blind

19. http://www.youtube.com/watch?v=yEIM4jmK1F0&feature=related

20. Sex linked Disorders • Dominate sex linked disorders are rare and result when a person inherits at least on dominant sex linked allele • Vitamin D rickets is an example where kidneys can’t absorb adequate amounts of phosphorus leading to soft bones, teeth

21. Pedigrees Trace Traits • Represent a tool to follow traits of family • Squares represent male • Circles represent females • Affected traits are colored in • You can follow traits thru family history and compare if it is a sex linked

22. Advances in Genetics • Genetic engineering is the experimenting with biological and chemical methods to change the DNA that makes up a gene • Help in medicine, genetic crops have been completed with genetic engineering

23. Recombinant DNA: inserting a useful segment of DNA from one organism into bacterium • Insulin for diabetics is a result of recombinant DNA • Gene Transfer: replace abnormal genetic material with normal genetic material • Genetically Engineered Plants: finding the genes that produce desired traits in one plant and inserting those into a different plant