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Mendel and the Gene idea. The Father of Genetics. Gregor Mendel (1822-1884 ) Austrian Monk Studied inheritance in pea plants Responsible for the laws of inheritance . Mendel’s Work. cross-pollinate (hybridize) two contrasting, true-breeding pea varieties

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Presentation Transcript
the father of genetics
The Father of Genetics
  • Gregor Mendel
    • (1822-1884)
    • Austrian Monk
    • Studied inheritance in pea plants
    • Responsible for the laws of inheritance
mendel s work
Mendel’s Work
  • cross-pollinate (hybridize) two contrasting, true-breeding pea varieties
  • The true-breeding parents are the P generation, and their hybrid offspring are the F1 generation.
  • Mendel would then allow the F1 hybrids to self-pollinate to produce an F2 generation.
review hopefully
Review (hopefully)
  • Mendel’s true breeding pea plants were homozygous for the trait that was being investigated
review hopefully1
Review (hopefully)
  • Dominant
  • Recessive
  • Homozygous
  • Heterozygous
  • Punnett Square
law of segregation
Law of Segregation
  • Alternative versions of genes account for variations in inherited characters
    • alleles
law of segregation1
Law of Segregation
  • For each character, an organism inherits two copies of a gene, one from each parent
law of segregation2
Law of Segregation
  • If the two alleles at the a locus differ, then one, the dominant allele, determines the organism's appearance; the other, the recessive allele, has no noticeable effect on appearance
law of segregation3
Law of Segregation
  • The two alleles for a heritable character segregate during gamete formation and end up in different gametes
law of independent assortment
Law of Independent Assortment
  • Alleles assort into gametes independently of each other
  • Genes are packaged into gametes in all possible allelic combinations
  • One allele for each gene
more complex than mendelian genetics
More Complex than Mendelian Genetics
  • Complete Dominance
    • Pea plants
    • Genotypes of the heterozygote and the homozygous dominant are indistinguishable
more complex than mendelian genetics1
More Complex than Mendelian Genetics
  • Incomplete Dominance
    • Neither allele is completely dominant
more complex than mendelian genetics2
More Complex than Mendelian Genetics
  • Codominance
    • Alleles affect the phenotype in separate distinguishable ways
more complex than mendelian genetics3
More Complex than Mendelian Genetics
  • Pleiotropy
    • Multiple phenotypic effects
human disorders
Human Disorders
  • Cystic fibrosis
    • strikes one of every 2,500 whites of European descent.
    • One in 25 people of European descent is a carrier for this condition.
    • mucus coats of certain cells to become thicker and stickier than normal.
    • This mucus buildup in the pancreas, lungs, digestive tract, and elsewhere causes poor absorption of nutrients, chronic bronchitis, and bacterial infections.
    • Without treatment, affected children die before five, but with treatment, they can live past their late 20s or even 30s.
human disorders1
Human Disorders
  • Tay-Sachs disease
    • lethal recessive disorder
    • It is caused by a dysfunctional enzyme that fails to break down specific brain lipids.
    • The symptoms begin with seizures, blindness, and degeneration of motor and mental performance a few months after birth.
    • Inevitably, the child dies after a few years.
    • Among Ashkenazic Jews (those from central Europe), this disease occurs in one of 3,600 births, about 100 times greater than the incidence among non-Jews or Mediterranean (Sephardic) Jews.
human disorders2
Human Disorders
  • Sickle-celldisease
    • one of 400 African-Americans.
    • substitution of a single amino acid in hemoglobin
    • deform red blood cells into a sickle shape.
    • About one in ten African-Americans has sickle-cell trait.
human disorders3
Human Disorders
  • Achondroplasia
    • a form of dwarfism
    • one case in 25,000 people.
    • Heterozygous individuals have the dwarf phenotype.
    • Those who are not achondroplastic dwarfs, 99.99% of the population, are homozygous recessive for this trait.
human disorders4
Human Disorders
  • Huntington’s disease
    • a degenerative disease of the nervous system.
    • dominant lethal allele has no obvious phenotypic effect until an individual is about 35 to 45 years old
    • deterioration of the nervous system is irreversible and inevitably fatal
    • Any child born to a parent who has the allele for Huntington’s disease has a 50% chance of inheriting the disease and the disorder
    • In the United States, this devastating disease afflicts one in 10,000 people.