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Genetics Cornell notes

Genetics Cornell notes. EQ: How did Mendel influence Genetics? E 4.2 Explain how genotypic variation occurs and results in phenotypic diversity. Who is Gregor Mendel?. A scientist from a Monastery in Austria

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Genetics Cornell notes

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  1. Genetics Cornell notes EQ: How did Mendel influence Genetics? E 4.2 Explain how genotypic variation occurs and results in phenotypic diversity.

  2. Who is Gregor Mendel? • A scientist from a Monastery in Austria • Studied how traits are inherited or passed down from generation to generation. • He was not the first to study traits, but he was the most successful. • Has been called the “Father of Genetics”

  3. What happened to Mendel’s Peas? • Mendel grew garden peas and studied the characteristics of garden peas that occurred in two specific forms, called traits. • The traits that Mendel examined included: • seeds that were round or wrinkled • seeds that were Yellow or Green • pods that were smooth or constricted • pods that were Yellow or Green • stems that were long or short

  4. What are the dominant traits in each parental cross? • Tall stems • Axial flowers • Inflated pod • Green pod • Round seed • Coloured seedcoat • Yellow seed

  5. How are traits determined? After an F1 (first generation) was crossed with another F1 (first generation), both ended up round and wrinkled seeds were produced. Traits are determined by two different alleles, one dominant and one recessive.

  6. How are genetics passed down? Inheritance: the transmission of traits from parent to offspring. Traits are controlled bygenes. SO what is GENETICS? Genetics: The study of how traits are inherited.

  7. What are Alleles? One FORM of a gene (there can be more than one form) Body cells have 2forms or ALLELES for a single gene (you got one from Mom and one from Dad) • One may be dominantor recessive.

  8. What is dominant and recessive? A Dominant trait: will always be expressed and will “hide” a recessive trait. A Recessivetrait: can only be expressed if there are NO dominantalleles present.

  9. Example:R= dominant r = recessive • Generally, dominant alleles are represented with a capital letter, and recessive alleles are represented with a lower case letter.

  10. Example: Eye color—Brown color is dominant and blue is recessive. A person can have a brown allele and a blue allele but still have brown eyes because the brown allele is dominant and “hides” the blue allele.

  11. Each organism is represented by TWOletters, one for each allele.Example:A baby boy has brown eyes, what are the possible genotypes?

  12. What are the differences between Homozygous and Heterozygous? “Purebred” or Homozygous species have two alleles of thesame trait. Example: BB or bb. Species with two different alleles or two different forms of the gene would be a “hybrid”. Example: Bb

  13. What is the difference between Genotype and Phenotype? The GENETICalleles found within an organism are called a GENOTYPE. Example: BB or Bb or bb The PHYSICAL trait that shows, regardless of genotype is called a PHENOTYPE. Example: Blueor Brown Eyes.

  14. What is Probability? Predicts thechance that something will happen Example: the probability of throwing heads or tails on a coin is 50% (1/2 chances)

  15. Steps for using the Punnett Square: • One parent’s alleles (genotype) go along the top • The other parent’s alleles go down the side. • Fill in the squares like doing the communicative property of multiplication. B b B b BB Bb Bb bb

  16. Steps for using the Punnett Square: Let’s say the parents are Bb and Bb (the same genotype). What would be their phenotype? Brown Eyes B b So you would predict: ¼offspring to be BB, or Brown Eyes 2/4 or 1/2 to be Bb, or Brown Eyes and ¼to be bb or Blue eyes B BB Bb b Bb bb

  17. How is sex determined within an individual? These are the 23rd pair of chromosomes that determine the biological sexof the individual. male female

  18. Is it a female or male? Female x male

  19. What are the main concepts of the Law of Segregation? • A gene can exist in more than one form or allele. • Organisms can inherit two alleles for each trait. • When sex cells are produced, allele pairs separate that leaves each cell with a single allele for a trait. • When the two alleles of a pair are different, one is dominant and the other is recessive.

  20. What are the main concepts of the Law of Independent Assortment? Allele pairs will separate independently during the formation of sex cells. • Traits are given to offspring separately of one another.

  21. Summary: 1. Who is Gregor Mendel? 2. Define the terms: Allele: ____________________________ Genotype: _________________________ Phenotype: ________________________ 3. A heterozygous round seeded plant (Rr) is crossed with a homozygous round seeded plant (RR). What percentage of the offspring will be homozygous (RR)? ____________ 4. A homozygous round seeded plant is crossed with a homozygous wrinkled seeded plant. What are the genotypes of the parents? __________ x __________

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