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Heredity. An introduction. YOUR Traits…. YOUR Traits…. YOUR Traits…. YOUR Traits…. YOUR Traits…. YOUR Traits…. YOUR Traits…. YOUR Traits…. YOUR Traits…. YOUR Traits…. Less desirable traits…. Polydactyly (6+ fingers/toes; autosomal dominant),
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Heredity An introduction
Less desirable traits… • Polydactyly (6+ fingers/toes; autosomal dominant), • Marfan syndrome (connective tissue disorder; an autosomal dominant disorder that has been linked to the FBN1 gene on chromosome 15) • Tay-Sachs disease (TSD, fatal in its most common variant known as Infantile Tay-Sachs disease; fatty acid deposits in brain nerve cells; autosomal recessive.) • Huntington's disease (autosomal dominant neurological disorder, cell death in brain 8/100,000)
Less desirable traits • Neurofibromatosis (autosomal dominant; causes tumors to grow along types of nerves, can affect the dev. of non-nervous tissues such as bones and skin. Type I, chrom. 17, (1/3000); Type II, chrom. 22, (1/40,000) • Hypertrophic cardiomyopathy (HCM, disease of the myocardium (the muscle of the heart) a portion of the myocardium is hypertrophied (thickened) without any obvious cause; most famous as a leading cause of sudden cardiac death in young athletes; a cause of sudden unexpected cardiac death in any age group and as a cause of disabling cardiac symptoms.)
Neurofibromatosis • Joseph Merrick “The Elephant Man”
History • Hippocrates • Ancient Greece (400 B.C.) • Pangenesis • particles from throughout body are passed to sperm or egg; also, changes in the body are passed on • Problem with it: • 1) Particles from somatic cells don’t make up gametes • 2) Changes in somatic cells (body) don’t affect gametes
History • Blending Hypothesis • Early 19th century • Hereditary materials from m/f blend, or mix. • Problem with it: • “Mixing” isn’t true, original traits can show up again later.
History • Gregor Mendel (1866) • Monk, lived & worked in an abbey in Brunn, Austria. Had attended U. of Vienna; knew physics, mathematics, chemistry. Worked in garden. • Studied peas. Curious as to why certain traits kept appearing on peas.
History • Concluded these things: • 1. Inheritance controlled by “factors” passed from parents to offspring. • 2. Principle of Dominance/Recessiveness • 3. Law of Segregation • Pair of factors is separated during gamete formation (anaphase) • 4. Law of Independent Assortment • Factors separate independently during gamete formation(metaphase)
Terms: • P generation: parents • F1 generation: offsp. of P’s • F2 generation: offsp. of F1 gen.
Terms: • Hybrid (Cross): offsp. of two diff.varieties • Monohybrid Cross: Crossing one trait • Dihybrid: two traits Tri… • Allele: alt. forms of same gene • Homozygous: identical alleles for same char. • Heterozygous: 2+ diff. alleles for same char.
Terms: Phenotype: the expressed traits of an org: (what it looks like)
Terms • Genotype (the genetic makeup of an org.)
This is how Mendelcontrolled his crossesto produce a new generation…
The F1 generations were all heterozygous for the trait being observed. The original P generations were pure homozygousfor the traits. Ex: The P gen. for flower color was PP x pp. The F1 was Pp x Pp.
Terms: Consider the genotypes TT Tt tt • Dominant allele (in Heterotroph., allele that determines phenotype [T]) • Recessive allele (in Het., allele that has no noticeable affect on phen. [t])
Terms: • Punnett Square • Tool used to predict offspring ratiosTry this: Show why there are about ½ males and ½ females born to humans…
