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Simple Genetics (One Gene for One Trait)

Simple Genetics (One Gene for One Trait). Mendel ’ s Pea Plants. Tall or short. Round or wrinkled. Etc… Dominant & recessive. Purebred or Hybrid. Simple Punnett Squares. Gregor Mendel.

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Simple Genetics (One Gene for One Trait)

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  1. Simple Genetics(One Gene for One Trait) • Mendel’s Pea Plants. • Tall or short. • Round or wrinkled. • Etc… • Dominant & recessive. • Purebred or Hybrid. • Simple Punnett Squares. Gregor Mendel

  2. Gregor Mendel was a monk who worked with pea plants in the mid 1800’s. Today he is known as “Father of Genetics.” He was curious about the “factors” acting on inheritance. Are there patterns?

  3. What is Genetics? • Genetics is the branch of biology that deals with heredity. • Heredity is the passing of traits from parents to offspring. • Parents  offspring • Traits are characteristics of an organism. • Human examples: height, hair, eye color.

  4. Gene: a section/piece of DNA on a chromosome that codes for a specific trait. • Alleles = alternate forms of a gene (Ex: Blood type A/B/O). • Genes tend to come in pairs (alleles). • DOMINANT: an allele whose trait always shows up in the organism when the allele present. • (CAPITAL LETTER) • recessive: an allele hidden by dominant. • (lower case letter) • Genotype: genetic makeup; allele combinations. • (Ex: BB, Bb, bb) • Phenotype: physical appearance of an organism (Ex: Brown hair)

  5. How to make a test cross(aka Punnett Square) Parent #1 alleles Parent #2 alleles

  6. Diagrams & math can be used to predict the probability that a trait will pass from parent(s) to offspring. Punnet Squares

  7. Complete this test cross between two purebred pea plants: T T t t T = tall stem t = short stem

  8. Where are genes? • Genes & chromosomes come in pairs. Most human cells have 23 pairs of chromosomes in the nucleus containing just under 30,000 genes.

  9. CHROMOSOMES • Half from each gamete (sperm and egg). • But what about asexual reproduction???

  10. Code Conservation • All species on Earth use the same chemical code (GTCA). Biodiversity comes from SNP’s along a gene sequence.

  11. Terms Must Know Challenge Central Dogma Co-dominance Dihybrid cross Diploid Haploid Histones Gametes Locus (Loci) Mutagen Pedigree chart Purines (A & G) Pyrimidines (T & C) • Allele • Chromosome • DNA (GTCA) • Dominant • Gene & Genetics • Genotype • Heterozygous • Heredity • Homozygous • Hybrid • Meiosis • Mutation • Offspring • Phenotype • Probability • Punnett Square (Cross) • Purebred • Recessive • Traits

  12. Challenge Mendel’s Dihybrid cross • We can look at two traits simultaneously using a dihybrid cross. • Consider shape & color in peas • R: round r: wrinkled • Y: yellow y: green • Cross two heterozygotes RrYy x RrYy • Try in your notes now!

  13. RY Ry ry rY RY Ry ry rY

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