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Class Topics

Hand in W.S. 8.1 before the bell rings please Review Chapter 7 Test Chapter 8 – Mendelian Genetics Terms Mendel’s research Mendel’s laws

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Class Topics

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  1. Hand in W.S. 8.1 before the bell rings please Review Chapter 7 Test Chapter 8 – Mendelian Genetics Terms Mendel’s research Mendel’s laws "It has become fashionable in science education to mold K-12 students around an idee fixe of a modern scientist; formulating hypotheses, observing measuring, and discovering through hands-on investigations. What has been left unsaid is that real scientists don't actually spend very much of their day 'observing' and 'measuring.' They read! Reading for understanding of content is the core process skill of science, and there is no substitute for practice at an early age. ...-- Dr. Stan Metzenberg, "Reading: The Most Important Science Process Skill" To assess learning about genetic variation due to meiosis and about gametogenesis. Title: Biology 1/26/07 Class Topics Objectives: Thursday, January 2, 20203:07 AM

  2. Class Assignments What By When • Read 161-165 1/26/07 • W.S. 8.1 (DR/Quiz) 1/26/07 • Read 166-170 1/30/07 • W.S. “The Puzzle of Heredity” 1/30/07 • Due this class period • Due next class period • Due in the future

  3. Grade Sheet 2A – p. 157 (5 pts.)

  4. Chapter 7 Test Review • Absolutely no talking • You have 7 minutes to review your exam – do not write anything on the test • You will get your test back next class period and be given 20 minutes to adjust any answers. • I suggest you make notes • of items to study • of questions to ask

  5. Mendel’s Breeding experiments8.1 • Gregor Johann Mendel’s history • “Father” of genetics • Bred garden peas (Pisum sativum) • 1st to develop rules to predict patterns in inheritance of traits • Quantitative Data!!!! • Used very large samples • Kept careful records • Minimized errors (took time and stayed organized)

  6. Key Terms I7.1 • Heredity • Passing traits from parents to offspring • Genetics • Branch of biology that studies heredity • Gene • Unit of DNA that controls traits • Cross • Mating or breeding of two individuals

  7. Why peas?8.1 • Several traits take clearly different forms • Ex. Yellow or green seeds • Male and female parts of peas are enclosed within the same flower • Mating can be controlled as either: • Self fertilization (self-pollination) • Cross-pollination • Mendel removed the stamens (male) from the flower of on plant and dusted the pistil (female) of another • Peas are small, grows quickly, and produces many offspring • Not to mention that the offspring can be used as food!!

  8. From : http://www.people.virginia.edu/~rjh9u/monotraits.html

  9. Peas have 14 chromosomes (? Pairs) and each gene was on a different chromosome

  10. Key Terms II • Monohybrid cross • A cross that involves one pair of contrasting traits • True breeding (pure) • All offspring display the same form of the trait • P generation • 1st two individuals (mated or bred) • F1 generation • Offspring of P generation (F means filial) • F2 generation • Offspring of self-pollinated F1 generation

  11. Example of a classic Mendel’s cross • P generation • Tall crossed with dwarf (both purebreeding) • F1 generation • All tall • Self-pollinate a single example of F1 • F2 generation • 787 tall, 277 dwarf • 2.84 : 1 ratio • Close to a 3:1 ratio

  12. Math Labp. 165 • “Calculating Mendel’s ratios” • Copy the table • Calculate the ratio • State the ratio in words and then as a fraction • Answer the final question

  13. Mendel’s Theory • Historical perspective • Heredity was thought of as a blending of the two parents • Mendel determined that there were two separate “heritable factors” for each trait • Factors are called alleles (book says genes)

  14. Mendel’s hypothesis • 1. For each inherited trait, an individual has two copies of the gene – one from each parent. • 2. There are different versions of genes. • Alleles • Receive one from each parent

  15. Mendel’s hypothesis • 3. Dominant allele • Can mask the presence of another allele • Expressed whenever present • Represented by a capital letter • recessive allele • Can be masked by the presence of a dominant allele • Only expressed when contrasting allele is not present • Represented by a lowercase letter (same letter as dominant)

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