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Genetics Notes Who is Gregor Mendel? Principle of Independent Assortment –

Genetics Notes Who is Gregor Mendel? Principle of Independent Assortment – Inheritance of one trait has no effect on the inheritance of another trait. “ Father of Genetics ”. Genetics – study of how traits are passed from parent to offspring.

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Genetics Notes Who is Gregor Mendel? Principle of Independent Assortment –

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  1. Genetics Notes Who is Gregor Mendel? Principle of Independent Assortment – Inheritance of one trait has no effect on the inheritance of another trait “Father of Genetics”

  2. Genetics – • study of how traits are passed from parent to offspring

  3. Traits are determined by the genes on the chromosomes. A gene is a segment of DNA that determines a trait.

  4. You are a Homo Sapien. (true or false)

  5. Chromosomes come in homologous pairs, thus genes come in pairs. • Homologous pairs – • matching genes – one from female parent and one from male parent

  6. Alleles – different genes (possibilities) for the same trait – ex: blue eyes or brown eyes

  7. Genotype – • gene combination for a trait (e.g. RR, Rr, rr) • Phenotype – • the physical feature resulting from a genotype (e.g. tall, short) • Homozygous genotype – • gene combination involving 2 dominant or 2 recessive genes (e.g. RR or rr); also called pure  • Heterozygous genotype – • gene combination of one dominant & one recessive allele    (e.g. Rr); also called hybrid

  8. Dominant and Recessive Genes • Gene that prevents the other gene from “showing” – • dominant • Gene that does NOT “show” even though it is present – • recessive • Symbol – • Dominant gene – upper case letter – T Recessive gene – lower case letter – t

  9. Incomplete dominance • occurs in the heterozygous or hybrid genotype where the 2 alleles blend to give a different phenotype • Example: Flower color in snapdragons (type of flower) shows incomplete dominance whenever a red flower is crossed with a white flower to produce pink flowers

  10. Both genes of a pair are the same is called – • homozygous or purebred • One dominant and one recessive gene is called– • heterozygous or hybrid

  11. Used to predict the possible gene makeup of offspring – • Punnett Square

  12. When both alleles are expressed – • Codominance Example: In certain chickens black feathers are codominant with white feathers. Heterozygous chickens have black and white speckled feathers.

  13. Behavior • is anything an animal does in response to a stimulus. • Stimulus • is an environmental change that directly influences the activity of an organism • What is considered a living fossil? • Horseshoe Crab

  14. Sex – linked Traits • Genes for these traits are located only on the X chromosome (NOT on the Y chromosome) • X linked alleles always show up in males whether dominant or recessive because males have only one X chromosome

  15. Examples of recessive sex-linked disorders: • colorblindness – • inability to distinguish between certain colors

  16. hemophilia – • blood won’t clot

  17. Mutations • Mutation – • sudden genetic change (change in base pair sequence of DNA) • Can be : Harmful mutations Beneficial mutations Neutral mutations • Mutations can occur in 2 ways: • chromosomal mutation or gene/point mutation

  18. Chromosomal mutation: • less common than a gene mutation • more drastic – affects entire chromosome, so affects many genes rather than just one • caused by failure of the homologous chromosomes to separate normally during meiosis • chromosome pairs no longer look the same – too few or too many genes, different shape

  19. Down’s syndrome – (Trisomy 21) 47 chromosomes, extra chromosome at pair #21

  20. Automatic responses • Involves no conscious control • Innate Behavior • behaviors that animal is born with. • Learned Behavior • When behavior changes due to practice or experience

  21. Having an extra set of chromosomes is fatal in animals, but in plants it makes them larger and hardier.

  22. Gene or Point Mutation • most common and least drastic • only one gene is altered

  23. Examples: Recessive gene mutations: Sickle cell anemia – red blood cells are sickle shaped instead of round and cannot carry enough oxygen to the body tissues – heterozygous condition protects people from malaria

  24. Detecting Genetic Disorders • picture of an individual’s chromosomes – karyotype • amniotic fluid surrounding the embryo is removed for analysis – amniocentesis Female with Down’s syndrome

  25. According to science life began as what? • Bacteria • According to science, what is the definition of life? • Anything made up of cells • What Kingdom are Homo sapiens in? • Aminalia

  26. Things to study • All terms-you do not have to study the different time frames • The basics of evolution

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