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DNA Mutations & Genetics

DNA Mutations & Genetics. Lewis Biology 2013. Concepts Covered this unit. Mutations (Point and Frame-shift) Diseases caused by Mutations Sickle Cell Anemia and Point Mutations Genetics and Heredity Gregor Mendel and the Pea Plants Monohybrid Crossing Alleles Mendelian Genetics

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DNA Mutations & Genetics

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  1. DNA Mutations & Genetics Lewis Biology 2013

  2. Concepts Covered this unit • Mutations (Point and Frame-shift) • Diseases caused by Mutations • Sickle Cell Anemia and Point Mutations • Genetics and Heredity • Gregor Mendel and the Pea Plants • Monohybrid Crossing • Alleles • Mendelian Genetics • Non-Mendelian Genetics • Dominance vs. Recessive • Co-Dominance • Incomplete Dominance • Multiple Alleles & Blood Typing • Sex-Linked Traits • Pedigree Analysis Chapters 10 & 12-13 are a good resource to use for this unit! Please read ahead

  3. Terms You will encounter this unit (Chapters 10 and 12 in blue book; do not use internet definitions!) Homozygous Heterozygous Crossing over Diploid Haploid Egg Homologous chromosomes Meiosis Nondisjunction Sperm Sexual reproduction Carrier Fetus pedigree • Heredity • Trait • Genetics • Gamete • Fertilization • Zygote • Pollination • Hybrid • Allele • Dominant • Recessive • Phenotype • Genotype Co-dominance Incomplete dominance Multiple allele Polygenic inheritance Sex chromosome Sex linked trait Karyotype

  4. Diseases covered this unit • Please research (and TAKE NOTES) and read ahead about the following genetic disorders: • Symptoms, causes, treatment, etc.. • 1. Klinefelter’s Disease • 2. Turner’s Syndrome • 3. Cystic Fibrosis • 4. Sickle Cell Anemia • 5. Trisomy 21 (Down Syndrome) • 6. Phenylkentonuria (PKU)

  5. Environmental or Genetic?? • The following list contains diseases that are either caused by environmental factors (smoking, diet, etc.) or because of mutated genes that are passed along by parents. Determine if each disease is caused by an environmental factor or genetic factor (mutation)—or both • Skin cancer • Lung cancer • Diabetes • PKU • Heart Disease

  6. The exam for this unit • The exam for this unit will be held between April 29-30. • Most of the material will cover: DNA, RNA, Protein Synthesis and Genetics—although older material will be on the exam. • The midterm will be weighed twice (as two test grades) • Please study ahead of time as it is comprehensive and cumulative. • As a resource, utilize Chapters 10, 12, & 13 in the Blue Glencoe Textbook

  7. Dna mutations • There are two general types of mutations • Point and Frame-Shift • Mutagen: something that causes a mutation • Point Mutations: a genetic mutation in which only one of the nitrogenous bases is substituted (changed) to another. Only one amino acid is changed • Frame-shift Mutations: a genetic mutation in which one of the bases is added or deleted. This causes the rest of the DNA sequence to shift, changing the ENTIRE DNA/AMINO ACID SEQUENCE. THIS IS THE MOST DANGEROUS MUTATION. Potentially lethal

  8. EXAMPLES OF Point Mutation • Sickle cell anemia is caused by a point mutation. • A single base is changed, causing the disease to occur • (FYI, those who have sickle cell are resistant to Malaria)

  9. Examples of Frame-shift Mutations • One of the bases in a DNA sequence is either inserted or deleted, therefore causing the entire sequence to shift. • This will change the entire DNA sequence, thusly changing the entire AMINO ACID SEQUENCE. • THIS CAN BE LETHAL • NORMAL SEQUENCE: ATC – GAT – TTA – AAG • THE A WILL BE DELETED, AND THE REST OF THE BASES WILL SHIFT TO FILL ITS PLACE • MUTATED SEQUENCE: ATC – GTT – TAA –AG…..

  10. Genetics & heredity Chapters 10 &12

  11. Father of Genetics • Gregor Mendel is the father of genetics (hence the term Mendelian Genetics). • Mendel was an Austrian monk studied heredity (how traits are passed from parent to offspring) • He was the first to be able to predict the outcome of one’s traits. • This led to the field of genetics (branch of biology that studies heredity) • He studied heredity using garden pea plants using the sex organs (yes, plants reproduce sexually..)

  12. THE BIRDS & THE BEES…WELL JUST THE PLANTS • IN PLANT FERTILIZATION, THE MALE GAMETE UNITES WITH THE FEMALE GAMETE. THIS RESULTS IN A ZYGOTE ZYGOTE

  13. TERMS & ABBREVIATIONS • Monohybrid cross: aka the ‘Punnett Square’, used to predict the traits of offspring • P1: Parent generation (mom & dad) • F1, F2, ..: Filial generations (the offspring, grandchildren etc.) • Homozygous Dominant: AA • Homozygous recessive: aa (this is the ONLY time recessive traits are shown) • Heterozygous: Aa (the dominant trait is still expressed) • Dominant: trait that is shown or expressed • Recessive: trait that is hidden or disappears in the mating • Alleles: forms of a gene

  14. …more terms Joke: You’ve got some good jeans! Haha… Get it?? • Phenotype= the Physical appearance (color, size, shape, etc.) • Genotype = the gene or allele (Aa, AA, aa) • Example: • 75% of the Offspring were Heterozygous Aa (genotype), meaning, they have Yellow eyes (phenotype) • 25% of the offspring were Homozygous recessive aa (genotype), meaning they have white eyes (phenotype)

  15. Basics of the punnett square: Try this example Alleles: Brown eyes: BB, Bb Blue Eyes: bb Problem: Mom has blue eyes, and Dad is Heterozygous for Brown eyes. Complete the Punnett Square and give the phenotype and genotype of the offspring A a a a

  16. Basics of the punnett square: answer Problem: Mom has blue eyes, and Dad is Heterozygous for Brown eyes. Complete the Punnett Square and give the phenotype and genotype of the offspring Alleles: Brown eyes: BB, Bb Blue Eyes: bb A a a Answer: Phenotype: 50% will have brown eyes 50% will have blue eyes Genotype: 50% Aa(heterozygous) 50% (homozygous recessive) a

  17. Assignment #2 • Complete the Monohybrid Cross worksheet on my website. The worksheet has been upload, you may write your answers on your own paper OR print it at home! • Do not forget the rules of Mendelian Genetics!!! • If there is a capital letter (A, B, C…), this means the gene is dominant, and will mask (cover) the recessive gene (a, b, c)

  18. Meiosis How we make gametes (sperm and eggs) …not sexual reproduction

  19. Remember… • We covered Meiosis when we talked about Mitosis. • Meiosis is a cell division of gametes… • In other words---it’s how guys make sperm, and ladies make eggs (ladies, you’re born with the eggs you have ) Guys continue Meiosis until they’re old…yuck • Meiosis is NOT SEXUAL REPRODUCTION

  20. meiosis • In Meiosis, it’s a way of taking a person’s 46 chromosomes, and dividing them in half—so that parents only pass 23 chromosomes onto their offspring. • You’re the perfect blending of both of your parents. • 46 chromosomes in dad’s sperm / 2 (meiosis) = 23 chromosomes • 46 chromosomes in mom’s eggs / 2 (meiosis) = 23 chromosomes • 23 chromosomes + 23 chromosomes = YOU 

  21. Review: Mitosis vs. Meiosis

  22. Meiosis vs mitosis

  23. Events in Meiosis • Crossing Over: Occurs in Prophase I, where the chromosomes break, and exchange genetic material • Nondisjunction: where the chromosomes fail to separate during Meiosis, this causes Trisomy 21 (Down Syndrome) Crossing over

  24. To be continued …non-mendelian genetics

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