Genetics

1. Genetics The science that relates to the study of genes and the patterns of heredity

2. Heredity Imagine a puppy. The puppy has long, floppy ears like his mother has, and the puppy has dark brown fur like his father… How did the puppy get these traits? The passing of traits from parents to offspring is called heredity.

4. Each human has 46 chromosomes located in the nucleus of the cell These are divided into 23 chromosomes- a baby inherits one chromosome from each parent from each pair of chromosomes

5. Of the 46 total chromosomes, two of them are sex chromosomes. XX- female Xy- male

6. A piece of DNA on a chromosome is called a gene. Genes also come in pairs. They determine many of the characteristics of a baby.

7. Alleles, are variations of a gene, and they usually come in pairs. Alleles determine the appearance of our characteristics There are at least two alleles for every characteristic If the two alleles are the same then it is said to be homozygous for that gene If they are different then they are heterozygous

9. Gregor Mendel Gregor Mendel is known as the father of genetics He was born in 1822 He grew up on a farm and learned a lot about flowers and trees When he was 21 yrs old he joined a monastery and became a monk. As a monk he taught science and performed scientific experiments

10. Mendel spent most of his time and energy performing experiments with pea plants He was very curious as to how offspring inherited their traits He used pea plants in his experiments because peas had many desirable traits that made them easy to work with

11. Peas were a good choice because They grow quickly They come in many varieties with easy to observe traits: round, wrinkled, yellow, green, smooth bumpy, tall, short Some cross pollinate, others self-pollinate Self –pollination was important because Mendel was able to grow true- breeding plants for his experiments

12. Mendel noticed that one trait was always present in the first generation and the other one seemed to disappear He called the trait that appeared the dominant trait and the trait that seemed to fade away the recessive trait To find out what might have happened to the recessive trait, Mendel decided to perform another set of experiments

13. Brown eyes is a dominant trait, so we would write the genotype for brown eyes as BB, Bb Blue eyes is a recessive trait. The only way to show a recessive trait is to have a genotype with two recessive alleles, such as bb

14. Alleles An allele is a variation of a gene: BB, Bb, CC, Cc, cc, DD, EE, ee Some alleles are dominant and some alleles are recessive. Dominant alleles are represented by capital letters in genetics, and recessive alleles are represented by lower case letters

15. Genotype and Phenotype Genotype is the combination of alleles that code for a specific trait DD for example could be the genotype for having dimples. Phenotype is the trait that is determined by one’s genotype Brown eyes, dimples, round face, curly hair are examples of phenotypes

16. Homozygous and Heterozygous Genotypes Homozygous genotypes with either all dominant alleles or all recessive alleles DD, dd, cc, CC, EE, ee, FF, gg, GGG, ddd, DDD Heterozygous genotypes have at least one dominant allele and one recessive allele Dd, Ff, Gg, Ee, EEe, CcC, GGg, Rr...

17. Punnett Squares predict the possible genotypes of offspring in a particular cross

18. What color feathers will the offspring in the test cross below have?

19. A brown furred rabbit (Bb) mates with a white furred rabbit (bb). What is the probability that they will have a white-furred offspring?

20. Answer: The answer should be 1/2 will have the genotype bb, which will show the phenotype of white fur (a recessive trait). To show the recessive trait, the offspring must have inherited two recessive alleles, one from each parent.

21. Two brown furred rabbits with the genotypes Bb mate and produce ¼ offspring that are light furred with the genotype bb. How is this possible?

22. The ¼ offspring received one recessive allele from each parent giving them a recessive trait

23. True or false A puppy receives half its genes from its mother and half from its father

24. Incomplete Dominance

25. Codominance Human blood type is determined by codominance There are three alleles for blood type. We inherit two from our parents. iA and iB share dominance and I is recessive See chart to the side…. A person with alleles A and B is neither A or B blood type, but rather, blood type AB. A person must have two i alleles to have blood type O because O blood type is a recessive trait.

26. Type A and B individuals can be either homozygous (IA,IA, or IB, IB), or heterozygous (IA i, or IB i) A person must have two i alleles to have blood type O

27. A woman with blood type A and a man with type B blood could potentially have offspring with which of the following blood types?

28. Multiple Genes Some traits, such as hair color and skin color are determined by multiple genes, giving a wide variety in the colors produced

29. Environmental Influences

31. EYE COLOR Different eye colors are produced because of the different amounts and patterns of pigments in the iris (colored part of the eye), which is determined by one’s genetic make up The DNA inherited from one’s parents determines what color eyes they will have Right now there are three known gene pairs that control eye color

32. The bey 2 gene on chromosome 15 has a brown and blue allele On chromosome 15 the bey 1 gene contains the central brown gene On chromosome pair 19, the gey gene contains a blue allele and a green allele

33. BB Xbb All children with Bb genotype Bb X Bb Possible genotypes: BB,Bb,Bb, bb

35. A green allele is dominant to a blue allele And brown allele is dominant to both a blue and a green allele For the bey 2 gene if a person has a brown allele then they will have brown eyes In the gey gene the green allele is dominant to the blue alleles but still recessive to brown A person will have green eyes if they have a green allele on chromosome 19 and all or some blue alleles Blue eyes is produced by having only recessive genes So for a blue eyed person all four alleles have to be blue

36. If two parents have a blue and a brown gene, there eyes are brown, but they can have a blue eyed child if the child inherits a blue gene from each parent If the child inherits one blue gene and one brown gene the child will have brown eyes, because brown is dominant to blue

37. Heterochromia- condition where a person has two different colored eyes

38. What are the causes of heterochromia? Disease or injury to that affects the health of the melanocytes (cells in the eyes that produce eye colors) Wardenburg Syndrome- A mutation in certain genes that causes melanocytes to get lost on their to where they are supposed to go Chimarism (very rare!)- when two fertilized eggs fuse to form one egg, each with a different set of DNA

39. David Bowie

40. Karotype A karotype is a picture of all the chromosomes in a cell A normal human karotype has 46 chromosomes, 22 are identical pairs The other two are the sex chromosomes. Is this the karotype of a male or a female individual?

41. Genetic Disorders A genetic disorder is one that is caused by abnormalities in the genes or chromosomes While some diseases, such as cancer, are caused by genetic abnormalities in some cells, a “genetic disease” is one that is present in all cells and has been present since conception When something goes wrong with the chromosomes in processing a new human being, the code cannot be read properly and the child’s brain and body may not develop properly. When a problem results from this genetic mistake, we call is a genetic disorder.

42. Turner’s Syndrome XO Occurs 1 in every 2000 These women have only 45 chromosomes; they are missing an x chromosome They are genetically female, but do not mature sexually during puberty and are infertile They have a short stature 98% of these fetuses die before birth

43. Trisomy X A condition where a female has an extra copy of an X chromosome, typically inherited from the mother It is a random event Typically diagnosed later in life, if ever

44. Trisomy X (XXX) Sometimes there are no symptoms and symptoms vary a lot between individuals Possible symptoms: Tall stature Speech and language delays Delayed motor skills Below average intelligence Occurs 1 in 1000 births These women are fertile and capable of having normal (XX) and (XY) children

45. Super Male XYY These are males with an extra Y chromosome They tend to be taller than average More prone to acne Usually have a low mental IQ Used to be thought that these men were more likely to end up in prison, but no study was able to back this claim

46. Klinefelter’s Syndrome XXY A chromosomal condition that affects a male’s sexual development Most males with this have an extra copy of the X chromosome in each cell Because the testicles of these males do not form normally, affected males may have low levels of the hormone, testosterone, beginning during puberty A lack of this hormone can cause breast development, reduced facial and body hair, and the inability to father children (infertility)

47. Klinefelter’s Syndrome

48. Down Syndrome This individual has an extra # 21 chromosome The extra chromosome causes physical differences in appearance as well as learning challenges About half of these individuals have heart defects These children did not used to live very long due to heart defects and other ailments, but today they are able to live in to adulthood, thanks to advances in medicine

49. Down Syndrome

50. Multiple Sclerosis This is a chronic inflammatory disease of the immune system Two genes have been found to increase a person’s risk for MS, and they are found in the immune system The person’s immune system begins to attack the fatty covering around the axon of a nerve cell, called a myelin sheath, this interrupts the electrical signals necessary in the relaying of impulses from one nerve cell to another