Oct7LecNotes - October 7th Lecture Notes (ppt) Routine...

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October 7 th Lecture Notes (ppt) Routine Class Matters ~ Reading assignments for Today: Chp 9 Intro Essay through 9.8 and 9.11 through 9.24. For October 21 st it’s Chp 13 Intro essay through 13.9 Our goal is to provide the background information needed to examine evolution. REMEMBER NO CLASS AGAIN UNTIL OCT 21 st !! After fall break we’ll tackle evolution ~ make note of days off around fall break (ppt) Mendel’s Laws Mendel is considered the “father” of genetics, particularly predictive breeding experiments. Try to imagine 150 years ago and how much we’ve learned about the nature of life since then. Gregor Mendel—why would anyone have thought selective breeding would work? o He reached his conclusions based on observations (e.g. Domestication started 1,000’s of years ago). (ppt) Mendel’s Laws See Figure 9.2C from your text and review the breeding experiment Mendel carried out [highlighted during class referring to Figure 9.2C]. Note the incorporation of a ‘Control’. P1 = parents F1 = first generation offspring F2 = second generation offspring (ppt) Mendel hypothesized (see Figure 9.2D) there were alternative forms [different alleles on homologous chromosomes] of genes [however, no one actually knew about genes or alleles at the time]. We now know these entities are called alleles (e.g. note the different expression (alleles) trait color on Figure 9.2D). (ppt) See Figure 9.3A for summary of what Mendel concluded What does the Law of Segregation state? From his experimental data Mendel deduced his “law of segregation,” that an organism has two genes (alleles) for each inherited characteristic, one from each parent If the two alleles of an inherited pair differ, then one determines the organism’s appearance and is called the dominant allele Purple would be the dominant allele in Figure 9.3A The other allele has no noticeable effect on the organism’s appearance and is called the recessive allele White would be the recessive allele in the example portrayed on Figure 9.3A 1
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th Lecture Notes (ppt) Mendel’s Law of Segregation (see Figure 9.3B)~ 1. Mendel’s law of segregation predicts that allele pairs separate from each other during the production of gametes (mitosis or meiosis?) 2. Do you understand what’s going on here? Is PP found in haploid or diploid cells? a. PP is found in diploid cells because you have two alleles present for a given trait. Haploid cells have only one allele present for a given trait. 3. Do you see how one gets a 1:2:1 ratio of genotypes and a 3:1 ratio of phenotypes ? a. What is the definition of Genotype? [see Lab folder for help] b. What is definition of Phenotype? [see Lab folder for help] c. What is the definition of Homozygous? [see Lab folder & below for help] d. What is definition of Heterozygous? 2 P plants Gametes Genetic makeup (alleles) Gametes F 1 plants (hybrids) F
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This note was uploaded on 10/21/2009 for the course BIO G 109 at Cornell.

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Oct7LecNotes - October 7th Lecture Notes (ppt) Routine...

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