I. Classical Genetics. 1. What makes these parakeets so varied in color?

Transcription

1 1. Classical Genetics a. Mendel i. Mendel s Laws ii. Advanced Genetic Principles b. Modern Genetics i. Scientists ii. Nucleic Acids DNA/RNA Function iii.replication iv.protein Synthesis v. Mutations (gene and chromosomal) vi.biotechnology vii. Genetic Engineering I. Classical Genetics 1. What makes these parakeets so varied in color? 1

2 2. The color of these parakeets is an example of a trait 3. What determines our traits? Genesgenes 4. We're missing a very important step in this process though, known as the central dogma of genetics: (For now just keep this flow in mind. We'll come back to this throughout this unit.) 5. Who is Gregor Mendel? a. What was Mendel's contribution to genetics? "Father of genetics" Worked with pea plants (took meticulous notes) Developed laws of inheritance 2

3 Unit 8 Genetics Notes.notebook c. How did Mendel carry out his experiments? Mendel crossed two PURE STRAINS (P generation or parents) of pea plants with purple and white flowers and discovered that the FIRST FILIAL GENERATION (1st offspring) were ALL purple i. What happened to the white flower trait? Covered up by dominant purple trait How do we know? it reappears in the next generation d. What did Mendel conclude from his experiments? i. Biological inheritance is determined by "factors" that are passed from one generation to the next. e. With modern genetic advances, we now know these "factors" are genes f. There are different forms (versions) of a gene, and some are dominant and some are recessive Alleles 3

4 f. Vocabulary Checkpoint: 1. Label the following: Nucleus, cell, chromosome, DNA, gene A. B. C. D. E. 1. Traits: 2. Alleles: 3. Dominant allele: Look back at Mendel's pea plants and give three examples of traits he observed What are the alleles for the three traits you chose? 4. Recessive allele: Which of the alleles for each of the 3 traits you chose are dominant? 6. 1) Label the Sex Chromosomes & the Autosomes: Autosomes (all except sex) Sex Chromosomes XX Female XY Male 4

5 6. What is a genotype? Genetic makeup (alleles) P = dominant allele (uppercase) p = recessive allele (lowercase) 7. What is a phenotype? physical appearance purple or white flowers 8. do we express genotypes? PP = Homozygous Dominant pp = Homozygous Recessive Pp = Heterozygous 9. What is a phenotype determined by? Genotype (nature) + Environment (nurture/gene expression) 10. Homozygous "Same alleles" a. Homozygous dominant PP (purple) b. Homozygous recessive pp (white) 11. Heterozygous "different alleles" c. Heterozygous Pp (purple) (hybrid) 12. When will a recessive allele show up in a phenotype? only when there are 2 recessive alleles Homozygous recessive pp = white (1 recessive allele must come from each parent 5

6 recessive alleles will always be masked by dominant alleles (Mendel crossed a pure PP (purple) plant with a pure pp (white) plant, all F1 were Pp (purple)) (sex cells =n) during gametogenesis, chromosomes separate (segregate) so that offspring receive one copy from each parent (Mendel: pea pods in F1 generation were all dominant (green), but recessive yellow reappeared in F2 generation chromosomes assort independently during gametogenesis, giving different traits an equal opportunity of occurring together. (Mendel: observed the following combinations of traits: Green round seeds, Green wrinkled seeds, Yellow round seeds, Yellow wrinkled seeds) SsYy x SsYy SY= round, yellow seeds Sy = round, green seeds sy = wrinkled, yellow seeds sy = wrinkled, green seeds F1 all SsYy 6

7 Unit 8 Genetics Notes.notebook 14. What is a test cross? 15) Two Exceptions to the Basic Rules of Genetics: a) Codominance: Both alleles are dominant Heterozygous- will see both traits ex. Red + white (red and white spotted) b) Incomplete Dominance (Intermediate Inheritance): Neither allele is completely dominant Heterozygous - Intermediate or blended ex. Red + white (pink) 7

8 Why is gene expression (especially in humans) more complicated than Mendel's laws? 17. Polygenic traits many genes control one trait usually see continuous distribution for example, height or skin color 8

9 Unit 8 Genetics Notes.notebook a. Multiple alleles: More than two allele options (Please note that an offspring will still inherit one allele from each parent, however there are more than two variations b. Blood types: IA and IB are codominant, i (o) is recessive 18. Pleiotropy: 9

10 Epistasis - one gene affects the expression of another 10

11 Light vs. Dark ENVIRONMENT affects gene expression in these seeds 11

12 50% chance XY- Male 50% chance XX- Female Disorders that occur because of mutations on the autosomes Autosomal recessive AA= normal Aa= normal (carrier) aa= affected Autosomal Dominant AA=Affected Aa= Affected aa= Normal 12

13 "Family tree" that follows the inheritance of a particular trait Male Female Affected individuals Needs to be inherited from both parents in order to express the trait ex. aa 13

14 Only need one allele to express the trait ex. AA or Aa Disorders occur because of mutations on the X chromosome Females can be carriers, males can not, because they only have 1 X There are some disorders on the y chromosome, but it is MUCH smaller, so not as many 14

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