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Presentation on theme: "Genetics."— Presentation transcript:

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

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

51 Grading up mating of purebred sires to grade females
relatively inexpensive and is dependent upon the quality of the sire

52 Inbreeding mating of related animals
closebreeding - a form of inbreeding most intensive form animals are very closely related

53 Closebreeding sire to daughter son to dam brother to sister

54 Closebreeding was used on foundations but is not used much today
used in the development of the Quarter Horse breed

55 Closebreeding animals are more uniform
more chance for undesirable recessive gene expression

56 Linebreeding refers to the mating of animals which are more distantly related cousins, grandparents, half sibling

57 Linebreeding used favorably today because there is less chance of expression on undesirable recessive traits

58 Linebreeding less chance of genetically superior stock
considered middle of the road

59 Crossbreeding mating of animals from different breeds
often causes hybrid vigor

60 Hybrid Vigor causes crossbreds to outproduce the average of their parents some breeds cause hybrid vigor better than others

61 Hybrid Vigor breeding a British breed, Angus, to an Indian Breed< Brahman compared to an Angus X Shorthorn cross

62 Hybrid Vigor Angus X Brahman would have more hybrid vigor

63 Selection based upon type pedigree showring winnings
production records

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