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Mendelian Heredity CH12 pg 267. Sexual Reproduction. Combining of a sperm cell and an egg cell from two individuals The offspring of this "cross" will have characteristics from both "parents“ hybrid. Self – Pollination Contrasting traits, easy to grow and reproduce.
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Sexual Reproduction • Combining of a sperm cell and an egg cell from two individuals • The offspring of this "cross" will have characteristics from both "parents“ • hybrid
Self – PollinationContrasting traits, easy to grow and reproduce
Mendel’s Laws of Heredity • Law of Dominance - One factor (trait) in a pair may mask the effect of the other.
Mendel’s Laws of Heredity • Law of Segregation - The two traits for a characteristic separate during the formation of eggs and sperm.
Mendel’s Laws of Heredity • Law of Independent Assortment - The traits for different characteristics are distributed to reproductive cells independently. pg272
Using Punnett Squares • Punnett Square • Model that predicts the likely outcomes of a genetic cross with the alleles taken from the parents • Shows all the genotypes that could result from a given cross
How to for Punnett Square • Capital letter • Dominant trait • Letter represents trait (B for brown) • Dominant always written first in sequence (Bb) • Lower case letter • recessive trait • same letter as dominant trait (b for blond)
Monohybrid Cross • Contrasting traits (purple vs white flower) • Homozygous Cross (PP or pp) • Heterozygous Cross (Pp) • Paternal alleles across the top • Maternal alleles down the left side
Monohybrid Cross • Phenotype • Genotype
Using Probability • Likelihood that a specific event will occur • Probability = # of one kind of possible outcomes total # of all possible outcomes • Probability of a specific allele in a gamete • Represented as a fraction or ratio
Probability in a Heterozygous Cross • Flipping a coin/ possible alleles • Both parents have Pp, How do you know? P p P p
Using a Pedigree • Several generations • Determine genetic disorders or diseases that can be inherited • Pedigrees can help answers questions about the three factors of inheritance • Sex-linked Genes • Dominant or Recessive • Heterozygous or Homozygous
Many Genes, Many Alleles • Polygenic Inheritance • Several genes affect characteristic • Relative greenness or brownness, blue eyes are recessive
Many Genes, Many Alleles • Incomplete Dominance • Intermediate between traits • Snapdragon (red and white = pink)
Many Genes, Many Alleles • Multiple Alleles • 3 or more possible alleles, only to alleles for a gene can be present • Complex dominance • Blood types and Labrador coat color
Many Genes, Many Alleles • Codominance • Both Alleles for the same gene are fully expressed
Genes affected by the Environment • Nutrients and temperature • Personality and behavior
Genes Linked Within Chromosome • Genes that are close together are less likely to be separated than genes that are far apart