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AP Biology Exam Review

AP Biology Exam Review. Heredity and Evolution – 25%. Heredity and Evolution. Heredity – 8% Molecular Genetics – 9% Evolutionary Biology – 8%. Heredity. Meiosis and gametogenesis Eukaryotic chromosomes Inheritance patterns. Asexual vs. Sexual Reproduction.

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AP Biology Exam Review

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  1. AP Biology Exam Review Heredity and Evolution – 25%

  2. Heredity and Evolution • Heredity – 8% • Molecular Genetics – 9% • Evolutionary Biology – 8%

  3. Heredity • Meiosis and gametogenesis • Eukaryotic chromosomes • Inheritance patterns

  4. Asexual vs. Sexual Reproduction • Asexual reproduction: binary fission, regeneration, vegetative propagation, budding • Sexual reproduction: result of gametic fusion, gametes formed from meiosis, promotes genetic recombination (variety) • Meiosis: process of gametic nuclear transfer

  5. Sexual life cycles • Remember: Asexual life cycles do not require the fusion (fertilization) of sperm and egg.

  6. Meiosis overview • Each “normal” 2N (diploid) cell has 2 sets of chromosomes, one from each gamete. • Gametogenesis: specialized cells (spermatocyte, oocyte) undergoing meiosis to produce gametes with some combination of the 2 chromosome sets

  7. Important vocabulary • Homologous chromosomes: pair of like chromosomes, having similar length, centromere position, gene loci • Linkage group: genes that are linked on the same chromosome (linked loci) • Locus (pl. loci): site on chromosome where gene is located on the chromosome

  8. Meiosis

  9. Meiosis

  10. Crossing over • Genetic variation in meiosis result of crossing over when chromosomes aligned in tetrad formation • Breaks linkage groups (genes found on the same chromosome)

  11. Oogenesis

  12. Spermatogenesis

  13. Pine life cycle

  14. Eukaryotic chromosome Allele: alternative form of the same genes Chromosome: condensed double helix (DNA)

  15. EukaryoticDNA packing • Nucleosomes: “beads on a string” (beads = histones) • Chromatin: condensed nucleosomes • Looped chromatin on protein scaffolding • Chromosomes

  16. Mendel’s work • Law of independent assortment • Law of segregation • Dominant vs. recessive phenotype • Used peas because of fast generations, easily recognizable characteristics, two alleles

  17. Inheritance patterns • Mendelian inheritance: AA & Aa = dominant phenotype; aa = recessive phenotype • Codominance: Aa = shows both A and a equally

  18. Incomplete dominance • Intermediate inheritance • AA = dominant • Aa = half way between AA and aa • aa = recessive phenotype

  19. Inheritance patterns • Hybrid: mixed genes between two species • Pleiotropy: ability of one gene to affect many different genes

  20. Epistasis • Expression of one gene determines the expression of another gene

  21. Polygenic inheritance • Many genes affecting a phenotype • Leading to many possible phenotypes of a trait

  22. Multiple alleles

  23. Test cross • If Mendelian inheritance, AA and Aa genotypes are indistinguishable. • Crossing dominant phenotype with aa. 100% dominant = PP; 1:1 = Pp

  24. Sex-linked • Sex-linked: gene loci on sex chromosome (X or Y)Ex: hemophilia, color blindness • First discovered in 1910 by Thomas Hunt Morgan • Autosomal: gene loci on non-sex chromosome

  25. Sex linkage • Look for inheritance patterns that deviate from 3:1 or 1:1. • Also look for disorders affecting mostly males.

  26. Recombination frequencies

  27. X-inactivation & Barr bodies

  28. Nondisjunction

  29. Nondisjunction disorders

  30. Human pedigrees • Square = male • Circle = female • Colored in = affected

  31. Molecular Genetics – 9% • RNA and DNA structure and function • Gene regulation • Mutation • Viral structure and replication • Nucleic acid technology and application

  32. DNA structure • Nucleotide: nitrogen base, deoxyribose sugar, phosphate group • Nitrogen bases: adenine, thymine, cytosine, guanine • Joined 5’ – 3’ (phosphodiester bonds) • Sugar-phosphate backbone

  33. RNA structure • Nucleotide: nitrogen base, ribose, phosphate group • Nitrogen bases: uracil, adenine, guanine, cytosine • Single stranded • Joined 5’-3’ • In eukaryotes: RNA produced in nucleolus of nucleus. • tRNA, rRNA, mRNA

  34. Griffith experiment Avery did a follow-up experiment and coined “transformation.”

  35. Phage

  36. Hershey and Chase

  37. DNA replication models

  38. Meselson and Stahl

  39. Origin of replication

  40. DNA elongation

  41. DNA synthesis • Leading strand: made continuously • Lagging strand: Okazaki fragments

  42. DNA priming • Necessary for starting DNA synthesis

  43. Okazaki fragments

  44. Telomeres • Necessary to preserve DNA through successive rounds of DNA replication

  45. Controlling gene expression • Gene expression = transcription • RNA transcript is translated into amino acid polymer. • Operons are examples of prokaryotic gene expression control. • Methylation is an example of eukaryotic gene expression control.

  46. One enzyme, one protein (controlling gene expression) • Beadle and Tatum

  47. Overview • Transcription: DNA  RNA • Translation: RNA  amino acid polymer (peptide)

  48. Transcription • Initiation • Elongation • Termination

  49. DNA  RNA • A  U • T  A • C  G • G  C

  50. RNA processing • Removing introns that interrupt the express-able code (exons) • Also adding poly-A tail and 5’-CAP

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