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Genetics

Genetics. Genetics. the study of heredity the way in which traits of parents are passed on to offspring. Father of Genetics. Gregor Mendel Austrian monk did experiments with peas and proved that certain characteristics……. ………. Such as color and height, are passed from parent to offspring.

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Genetics

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  1. Genetics

  2. Genetics • the study of heredity • the way in which traits of parents are passed on to offspring

  3. Father of Genetics • Gregor Mendel • Austrian monk • did experiments with peas and proved that certain characteristics……..

  4. ………. • Such as color and height, are passed from parent to offspring

  5. Differences • all differences in organisms are not caused by genetics • some are caused by the environment • the conditions under which the animals are raised

  6. Parts of the cell • cell membrane - contains the cytoplasm and the nucleus

  7. Cytoplasm • protects and cushions the nucleus

  8. Nucleus • contains the genetic material

  9. Chromosomes • carry the genes • exist in pairs in all cells except sperm and egg cells

  10. Genes • single determiner of a hereditary trait

  11. Cell Division • two types • Mitosis • Meiosis

  12. Mitosis • cell division for growth • this division never ends • chromosome pairs are duplicated exactly alike

  13. Mitosis • each new cell is exactly like the old ones • asexual division • chromosomes are in pairs

  14. Mitosis • steps of mitosis • Prophase (Interphase) • Metaphase • Anaphase

  15. Steps • Telophase • Cytokinesis • ** PMATC

  16. Meiosis • cell division of reproductive cells (sperm and egg) • each new cell is not exactly like the old one

  17. Meiosis • in each new cell chromosomes are not in pairs • each new cell contains half of the original number of chromosomes

  18. Meiosis • allows for random assortment of parental genes

  19. Gamete • mature egg or sperm cell • each gamete has half the original number of chromosomes

  20. Dominant gene • in a pair, hides the effect of another gene

  21. Recessive gene • the gene which is hidden by a dominant gene

  22. Examples • of dominant genes • tongue rolling • free ear lobes • polled cattle

  23. Examples • of recessive genes • color red in Holsteins • dwarfism

  24. Symbols • dominant genes • capital letters A

  25. Symbols • recessive genes • lower case letters a

  26. Homozygous • gene pairs • one which carries two genes for a trait • both represented by capital or lower case letters

  27. Homozygous • polled - PP • horned - pp

  28. Heterozygous • gene pairs • one which carries one dominant and one recessive gene

  29. Heterozygous • Pp

  30. Genotype • genetic makeup of an animal or a given trait expressed by symbols • Ex: PP, AA, Pp, Aa, aa

  31. Phenotype • physical appearance expressed in words • Ex: polled, horned

  32. Mitosis T t Meiosis T t Mitosis t t

  33. Steps of Meiosis • Prophase I ( Interphase) • Metaphase I • Anaphase I • Telophase I

  34. Steps of Meiosis • Prophase II (Interphase) • Metaphase II • Anaphase II • Telophase II • Cytokinesis

  35. If • two heterozygous animals are mated • the number of traits being selected is six • the total number of offspring is over 16,000,000

  36. Incomplete Dominance • when one gene does not hide the effect of the other in a gene pair • result is a mixture of the two traits

  37. Incomplete Dominance • Roan coloring in cattle • RR X WW = RW • Red X White = Roan • Roan - mixture of red and white hairs

  38. Sex determination • male sex chromosomes • male mammals have two different sex chromosomes • XY • females are XX

  39. Sex determination • poultry • the female determines the sex of the offspring • female is ZW • male is ZZ

  40. Sex Linked Traits • genes which are carried only on the sex chromosomes • ex: red green color blindness • 2:25 males • 1:150 females

  41. Sex Linked Traits • hemophilia • bleeders’ disease • more common in males than in females

  42. Sex Linked Traits • barred feather pattern vs black in chickens

  43. Mutation • when a new trait is shown that did not exist in either parent

  44. Mutation • the new breed of polled Herefords • which resulted from the crossing of two horned animals

  45. Causes of Mutations • radiation (nuclear accident or x-ray) • chemicals

  46. Systems of breeding • purebreeding • inbreeding • outcrossing • grading up • crossbreeding

  47. Purebreeding • purebred is defined as a member of a breed • the animals of which possess a common ancestry • distinctive characteristics

  48. Purebreeding • is registered or eligible for registry

  49. Outcrossing • mating of animals of different families within the same breed • relatively safe system of breeding

  50. Outcrossing • unlikely that two unrelated animals would carry the same undesirable genes and pass them on

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