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Review Questions

Review Questions. What are the 4 bases that make up DNA? How do they pair up? Name 2 differences between Mitosis and Meiosis: Why do we need mitosis? Why do we need meiosis?. Adenine (A), Thymine (T), Guanine (G), and Cytosine (C) A pairs with T; G pairs with C.

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Review Questions

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  1. Review Questions • What are the 4 bases that make up DNA? How do they pair up? • Name 2 differences between Mitosis and Meiosis: • Why do we need mitosis? Why do we need meiosis? Adenine (A), Thymine (T), Guanine (G), and Cytosine (C) A pairs with T; G pairs with C • Mitosis produces 2 diploid cells; Genetically the same • 1 division; produces body cells • Meiosis produces 4 haploid cells; Genetically different • 2 divisions; produces gametes • Mitosis repair the body, grow, and replace cells • Meiosis cut the number of chromosomes in half; makes more variation

  2. Phase Quiz Telophase • Write which phase the cell is in: 1) 4) 2) 5) 3) 6) Prophase Anaphase Metaphase Telophase Metaphase I

  3. Genes and Alleles

  4. Genetic Terminology • What is a gene? • Section of DNA that codes for a protein • Give you characteristics: • Hair color, eye color, height • What is an allele? • Different versions of a gene • Give you a specific type of characteristic • Blue eyes, brown eyes, green eyes • The combination of alleles for a gene is called a genotype • Your physical appearance, based on a genotype, is called a phenotype • AA Red Flower • aa White flower

  5. Dominate! • Allele are not created equal • An allele for one trait can dominate another allele for the same trait • Brown Eyes vs. Blue eyes • B = allele for brown eyes; dominate allele • b= allele for blue eyes; recessive allele BB Brown Eyes Homozygous Dominate bb Blue Eyes Homozygous Recessive Bb Brown Eyes Heterozygous

  6. Our Main Man Mendel! • Gregor Mendel father of genetics; discovered trends in heredity 30 years before other scientists! • Prior to Mendel what did people believe about inheritance? • Blending Theory all genetic traits are equally mixed in offspring • If this were true what would disappear? • Really tall, short, etc… members of a population 246 cm 73.7 cm

  7. Mendel’s Work • Secret to Mendel’s discovery is his detailed record keeping and attention to the controlled experiment • He work with Garden peas. Why? • Easy to grow • Easy to observe • Most traits (characteristics) came in sets of two • White Flowers vs. Purple flowers • Yellow seeds vs. Green seeds • Smooth seeds vs. Wrinkled seeds

  8. Crossing Peas • Mendel’s Experiment: • Make pure breed plants • Purple flowers (PP) • White flowers (pp) • Mix gametes of two pure breed plants with different traits • Purple flowers X White flowers • Parental Cross; P generation • Produced only purple flowers (Pp) • Mix gametes of offspring • Offspring= F1 generation • F1 Purple Flower X F1 Purple Flower • Produced F2 generation • 3 Purple : 1 White ratio!

  9. Mendel’s Three Theories • From the first cross all F1 flowers are purple • From F1 cross F2 ratio is 3 purple: 1 white flower • Theories • The parents must carry a pair of factors (alleles) the control the inheritance of each trait • P purple flowers • p white flowers • If you have one of each allele, one will be dominate and one recessive • Pp purple flowers • Pairs of alleles are segregated into different gametes • Gamete has either P or p

  10. What’s Your Genotype? • Comparing the phenotype of you and your parents, you can know you genotype for some simple traits • The phenotypes we will look at: • Tongue rolling dominant • Window’s Peak dominant • Cleft chin recessive • Attached earlobes recessive • Roman nose dominant • Dimples dominant

  11. Review Questions • What is the difference between a genotype and a phenotype? • What are the terms for genotypes AA, aa, and Aa? • If a red flower (RR) is crossed with a white flower (rr), what will be the phenotype and genotype of the F1? Genotype Alleles in DNA for a certain trait Phenotype The physical trait expressed by a genotype • AA homozygous dominant • aa homozygous recessive • Aa heterozygous • Phenotype Red flower Genotype Rr

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