DSCI 422 Test 1

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  1. Dairyman Goals with Genetics
    • A Pregnancy
    • A live calf
    • A heifer calf
    • (want pregnancy rather than genetics)
  2. Genomic
    measures genes by looking at the individual chromosomes
  3. Darwins theories
    • Organisms Vary
    • Variation may or may not be inherited
    • Struggle for survived in nature
    • The best adapted to survival leave the most descendants
  4. Basic of Dairy Genetics
    • Select most desirable animals
    • Produce superior genotypes
  5. SNP
    • Single Nucleotide polymorphisms
    • Rung of ladder on DNA sequence
  6. Number of chromosomes a cow has
    • 60 chromosomes
    • 30 pairs
  7. Genotype vs Phenotype
    • Phenotype= what the animal looks like
    • -Genotype+Environmental
    • Genetoype= DNA build up
  8. 3 factors that control genetic gain
    • Heritability-the likelihood of a trait to be passed on
    • Selection differential-superiority of parents over the mean of the population
    • Generation interval-the time between generations
  9. Cytoplasm
    • No genetic material
    • Cell Function
  10. Nucleus
    • Genetic Material
    • Paired chromosomes
  11. Somatic Cells
    • Body Cells, 2n (cows 60)
    • Cytoplasm varies with function
  12. Gametes
    • Reproduction cells 1n (cows 30)
    • Male/Female sex cells
    • -Spermatogonia
    • -Oogonia
  13. Chromosomes in the cell nucleus contain DNA:
    the genetic code
  14. Homozygous vs. Heterozygous
    • Homozygous: identical genes at a locus
    • Heterozygous: not identical, different genes at a locus
  15. Dominant, Recessive, Additive
    • Dominant: genes with observable effects in only one member of a chromosomes pair
    • Recessive: no effect unless present in both members of a chromo, pair
    • Additive: a gene has a given + or - effect
  16. Cytogenetics
    Refers to the study of cell (cyto) genetics
  17. Chromosomes
    • Basis of genetics
    • Within the nucleus of all cells
    • Made up of DNA
  18. Centromere vs. Chromatids
    • Centromere: attaches to spindle fibers during division
    • Chromatids: arms made up of genetic material (chromatin)
  19. Centromere Position
    • Matacentric:in center
    • Submatacentric: not in middle
    • Acrocentric: close to the end
    • Telocentric: at the end or top
  20. Deoxyribnuclic acid
    A molecule that carries genetic material
  21. Sex chromosomes
    • Mammals 
    • -X and Y
    • -XX =female XY=male
    • Freemartins
    • -XX/XY chimeric
    • Birds
    • -Z and W
    • -ZZ=male ZW=female
  22. Mutation
    • Change in a functional genetic unit
    • Could be a single nucleotide
    • Biochemical polymorphism
    • A genetically determined variant of proteins
  23. The gene
    • A unit of inheritance, which does not subdivide
    • A unit of function or expression, a cistron (biochemical term)
    • The smallest unit that can undergo change, may be one nucleotide
  24. Translocations
    • A chromosome becomes broken
    • Becomes attached to another chromosome
    • May be carried through meiosis
  25. Number of different combinations of chromosomes
    • around 1.6 billion 
    • 2^30
  26. Mitosis
    • Each chromosome duplicates itself
    • Somatic cell (body cells) division
    • Daughter cells have the same number of chromosomes
    • (radiation can cause exact replication to sometimes cause genetic abnormalities
  27. Mitosis Interphase
    Mitosis Prophase
    • Interphase: Rest phase
    • chromatids duplicate near end
    • few to 100 hours
    • Prophase: chromatids shorten and thicken
    • Early-centriol divides and migrates
    • Late-Spindle fibers, 30 mins
    • (1 pair of tele centric, 1 pair of metracentric)
  28. Mitosis Metaphase
    Mitosis Anaphase
    Mitosis Telophase
    • Metaphase: chromosomes align along equatorial plane
    • 5 mins
    • Anaphase: chromosome divides at centromere
    • two arms back to one arm, 5 mins
    • Telophase: chromosomes cluster around centriol
    • Cell divides, ten minutes
  29. Mitosis Phases
    • Interphase: chromatids duplicate
    • Prophase: Shorten and thicken
    • Metaphase: Chromosomes align
    • Anaphase: Centromere divides
    • Telophase: Cell divides
  30. Meiosis
    • Cell division in which chromosome number is reduced
    • Daughter cells receive one member of the chromosome pair
    • Gametes (egg and sperm) are produced
    • Have Meiosis I and II
  31. Meiosis:
    Interphase I
    Prophase I
    Metaphase I
    Anaphase I
    Telophase I
    • Interphase: rest phase, chromatids duplicate near end
    • Prophase: chromatids shorten and thicken. Paired chromosomes attach to each other (synapsis)
    • Metaphase: Paired chromosomes align along equatorial plane
    • Anaphase: Homologus pairs separate (2n to 1n), still have two armed cromatids
    • Telophase: chromosomes cluster around centriol, two new haploid daughter cells
  32. Meiosis 
    Prophase II
    Metaphase II
    Anaphase II
    Telophase II
    • Prophase: shorten and thicken, with 1n
    • Metaphase: align along equatorial plane
    • Anaphase: centromere divides, 1n remains
    • Telophase: chromosomes cluster around centriol, Two new daughter cells
  33. Diploid vs. Haploid cells
    • Diploid-2n cells, somatic cells (body cells)
    • Haploid-1n cells, gametes (sex cells)
  34. Genetic defects 
    many are simple recessives
    • with a single SNP
    • Dominant, recessive, etc
    • will continue to occur
  35. Congenital defects
    Early embryonic death
    • Born with the defect (may or may not be genetic)
    • EED: some are repro problems, some are genetic
  36. Genetic defects may become a problem with:
    • Artificial Insemination
    • Line breeding (inbreeding)
    • If breed numbers are small
  37. Holstein Association USA genetic codes
    BD, BL, TL, MF, PO, PC, PP, RC, B/R, TR
    • BD: Bulldog
    • BL:Bovine leukocyte adhesion deficiency (BLAD)
    • TL: Tested free of BLAD
    • MF: Mule-Foot
    • PO: Observed Polled
    • PC: Tested Heterozygous Polled
    • PP: Tested Homozygous Polled
    • RC: Red Hair Color
    • B/R: Black/Red
    • TR: Tested free of Red hair color
  38. Methods to Identify Defect Carrier Animals
    • 1.Progeny Testing (mate a suspect animal)
    • 2.Biotechnology (with DNA probes look at strand of DNA that carries)
    • 3. Blood Testing
  39. Possible Measures to Eliminate genetic defects
    • 1. Cull sires that have produced genetic defect offspring
    • 2. Evaluate pedigrees of future sires
    • 3. Remove females that produce genetic defect offspring
    • 4. Progeny test prospective herd sires
    • 5. Cull other close relatives
    • 6. _______
  40. Progeny Testing
    • An animal bred to an affected animal-50% chance of identifying
    • An animal bred to a known carrier - 25% chance of identifying
    • An animal bred to its own offspring - 12.5% chance of identifying
  41. One pair of genes, two alleles A and a
    three genotypes
    Six basic crosses
    • AA, Aa, aa
    • 1. AA x AA
    • 2. AA x as 
    • 3. aa x aa
    • 4. AA x Aa
    • 5. Aa x aa
    • 6. Aa x Aa
  42. Black/Red in Holsteins
    • Three gene effects at the same allele
    • Black dominant over Black/red and over red
    • Black/red dominant over red
    • 3 alleles= B b bB
    • bB=black/red dom. over red
    • bb=red 
  43. Codominance
    • red x white = roan
    • roan x roan = 1/4 red, 1/4 white, 1/2 roan
    • F1 mating red bull to white cow (or vise-versa) will produce all roan calves

    F2 mating roan to roan 1/4 red, 1/4 white, 1/2 white
  44. Three gene pairs, additive gene effects
    • A = 6,000 lbs. milk
    • a = 4,000 lbs. milk
    • B = 5,000 lbs. milk
    • b = 3,000 lbs. milk
    • C = 2,000 lbs. milk
    • c = 1,000 lbs. milk
  45. Additive Genes
    • milk
    • fat 
    • protein
    • type
    • weight gain
    • milking speed
    • longevity
    • mastitis
    • overall health
    • many others
  46. Biochemical Polymorhpism
    when two or more phenotypes exist in the same population of a species
  47. Genomic
    biotechnology of DNA sequencing of sets of genes of the complete genomes of selected organisms
  48. Karyotype
    the number and visual of the chromosomes in the cell nuclei of an organism or species.
  49. Nucleotide
    a compound consisting of a nucleotide linked to a phosphate group. Nucleotides form the basic structural unit of nucleic acids such as DNA.
  50. Gene, Genome, Genomics
    • Gene: the functional and physical unit of heredity passed from parent to offspring.
    • Genome: The DNA comprising the complete genetic complement of an organism
    • Genomics: 1986 - a new scientific discipline of mapping, sequencing, and analyzing genomes
  51. 4 organic bases (nucleotides)
    G C A T
  52. QTL
    Qualitative Trait Loci: process enzyme taken to cut a piece of DNA to search for a certain gene
  53. Conclusions about genomics
    • Genomic predictions significantly better than parent average for all 26 traits tested
    • Gains in reliablity equivalent on average to 15 daughters with records
    • -analysis used 3,576 historical bulls
    • -Current data includes 5,285 proven bulls
    • Larger populations require more SNPs
  54. Improve what by testing genomics
    Improve accuracy
  55. Haplotype
    • something that causes embryonic death
    • 23.4% presence in haplotype of Jersey breed
    • Holstein presence is 4.5%, 4.6%, and 4.7%
    • Stretch of chromosome or DNA that is transmitted as a unit from one generation to the next
  56. Evidence of Hapolotypes
    • these haplotypes are never observed in a homozygous state in any live animals
    • Decreased conception rate was observed when a carrier sire was mated to a daughter of a carrier maternal grandsire
  57. Haplotypes impacting fertility
    certain haplotypes never appear in a homozygous condition
  58. The new normal of hapolotypes
    • due to modern genomic technology, undesirable genetic conditions are no longer considered rare
    • We expect to find them in some of our best genetic families
    • We should use the haplotype information to improve our breeds without causing undue economic hardship to the breeders of these animals
Card Set
DSCI 422 Test 1
Dairy Science 422 Test 1
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