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Genetics Heredity Inheritance of traits Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice Hall biology (North Carolina ed., pp. 262- 285). Upper Saddle River, N.J.: Prentice Hall. Genetics Gregor Mendel Suggested that paired factors, or genes, carry inherited traits. Predicted how traits were inherited by studying pea plants Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice Hall biology (North Carolina ed., pp. 262- 285). Upper Saddle River, N.J.: Prentice Hall. Simple Dominant Traits Traits that are controlled by one pair of genes One dominant allele is all that the organism needs to show the dominant trait Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice Hall biology (North Carolina ed., pp. 262- 285). Upper Saddle River, N.J.: Prentice Hall. Recessive attached ear lobes Dominant Free Ear Lobes Tongue Roll Dominant trait Hitch hiker’s thumb Dominant Regular thumb Recessive Seed Seed shape color Flower color Flower position Pod color Pod shape purple axial (side) green inflated white terminal (tips) yellow Plant height Dominant trait round yellow tall Recessive trait wrinkled green constricted short Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice Hall biology (North Carolina ed., pp. 262- 285). Upper Saddle River, N.J.: Prentice Hall. Alleles Different forms of a gene type Organisms have two genes (alleles) for each trait. One gene (allele) from female gamete (egg). One gene (allele) from male gamete (sperm). Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice Hall biology (North Carolina ed., pp. 262- 285). Upper Saddle River, N.J.: Prentice Hall. Dominant gene (allele) Stronger of two genes Represented with capital letters Written first Example: T for tall plant height Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice Hall biology (North Carolina ed., pp. 262- 285). Upper Saddle River, N.J.: Prentice Hall. Recessive gene (allele) Weaker of two genes Can be hidden by dominant genes. Represented with lower case letters Example: t for short plant height Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice Hall biology (North Carolina ed., pp. 262- 285). Upper Saddle River, N.J.: Prentice Hall. Pure (Homozygous) Two of the same genes (alleles) for a trait Example: TT (homozygous dominant) or tt (homozygous recessive) Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice Hall biology (North Carolina ed., pp. 262- 285). Upper Saddle River, N.J.: Prentice Hall. Hybrid (Heterozygous) Two different alleles for a trait Example: Tt Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice Hall biology (North Carolina ed., pp. 262- 285). Upper Saddle River, N.J.: Prentice Hall. Genotype Combination of alleles or genes for a certain trait Example: Tt, TT, tt Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice Hall biology (North Carolina ed., pp. 262- 285). Upper Saddle River, N.J.: Prentice Hall. Phenotype Visible traits (how it looks) Determined by looking at organism Example: tall, short Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice Hall biology (North Carolina ed., pp. 262- 285). Upper Saddle River, N.J.: Prentice Hall. Genotype or Phenotype? Tt Round Black BB Smooth rr Tall Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice Hall biology (North Carolina ed., pp. 262- 285). Upper Saddle River, N.J.: Prentice Hall. In pea plants, green pods are completely dominant over yellow. What are the genotypes? Homozygous yellow gg Heterozygous green Gg Pure dominant GG Hybrid Gg Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice Hall biology (North Carolina ed., pp. 262- 285). Upper Saddle River, N.J.: Prentice Hall. In pea plants, green pods are completely dominant over yellow. Pure yellow gg Homozygous recessive gg Pure green GG Heterozygous Gg Yellow gg Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice Hall biology (North Carolina ed., pp. 262- 285). Upper Saddle River, N.J.: Prentice Hall. In guinea pigs, short hair is dominant over long hair What letter should be used for the gene for hair length? What hair length will be represented by a capital S? What hair length will be represented by a lower case s? Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice Hall biology (North Carolina ed., pp. 262- 285). Upper Saddle River, N.J.: Prentice Hall. What phenotypes would result from the following genotypes? SS ss Ss Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice Hall biology (North Carolina ed., pp. 262- 285). Upper Saddle River, N.J.: Prentice Hall. What are the phenotypes of the parent plants? If both parents are pure, what are their genotypes? Which gene or allele can each parent pass on to the offspring? What is the phenotype of the offspring? What is the genotype of the offspring? Short plant Tall plant t T T t t T All tall plants T t In pea plants, round pea pod texture is dominant over wrinkled texture. What is the genotype of the following? homozygous round heterozygous wrinkled pure dominant hybrid round Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice Hall biology (North Carolina ed., pp. 262- 285). Upper Saddle River, N.J.: Prentice Hall. In pea plants, round pea pod texture is dominant over wrinkled texture. What is the genotype of the following? pure recessive heterozygous round pure wrinkled hybrid pure round Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice Hall biology (North Carolina ed., pp. 262- 285). Upper Saddle River, N.J.: Prentice Hall. Punnett Squares Punnett squares – used to predict and compare the genetic differences that will result from a cross. Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice Hall biology (North Carolina ed., pp. 262- 285). Upper Saddle River, N.J.: Prentice Hall. Monohybrid crosses Heterozygous tall parent T t T T t T t TT Tt Tt tt t Heterozygous tall parent Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice Hall biology (North Carolina ed., pp. 262- 285). Upper Saddle River, N.J.: Prentice Hall. Generations of Inheritance tt Start by crossing homozygous parents TT P1 Short pea plant Tall pea plant Results in heterozygous offspring Tt F1 All tall pea plants TT Tt F2 3 tall: 1 short Tt tt Crossing heterozygous offspring from F1 generation results in three tall and 1 short Incomplete dominance Alleles BLEND (mix) Neither gene is dominant A third or new phenotype can be seen Think about colors of paint Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice Hall biology (North Carolina ed., pp. 262- 285). Upper Saddle River, N.J.: Prentice Hall. Red X White PINK If a red impatient is crossed with a white impatient, the resulting flowers are pink. Red and white blend like paint colors to produce pink (new phenotype). Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice Hall biology (North Carolina ed., pp. 262- 285). Upper Saddle River, N.J.: Prentice Hall. Incomplete Dominance R R W RW RW RW RW W www.nerdscience.com 11-3 Codominance Both alleles are dominant Both alleles are seen (expressed) TOGETHER There is NO “blending” Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice Hall biology (North Carolina ed., pp. 262- 285). Upper Saddle River, N.J.: Prentice Hall. Codominance Both alleles or genes are expressed Red X White Red & White Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice Hall biology (North Carolina ed., pp. 262- 285). Upper Saddle River, N.J.: Prentice Hall. Red cow crossed with white cow results in roan cattle. Roan cattle have both red and white hairs. Codominance Codominance Example: White chicken x black chicken = black and white checkered chicken Incomplete or Codominance? A white cow and a red cow produce a roan cow, one that has both white and red hairs. A red flower and a white flower produce pink flowers. A black cat and a tan cat produce tabby cats, cats where black and tan fur is seen together. Incomplete or Codominance? A blue blahblah bird and a white blahblah bird produce offspring that are silver. A certain species of mouse with black fur is crossed with a mouse with white fur and all of the offspring have grey fur. A woman with blood type A and a man with blood type B have a child with blood type AB. Blood Types (codominant) Blood type is codominant 4 different blood types Phenotype Genotype (Blood type) (Alleles or genes for blood type) A IAIA, IAi B IBIB, IBi AB IAIB O ii Charles Drew Charles Drew impacted blood donation and blood banks Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice Hall biology (North Carolina ed., pp. 262- 285). Upper Saddle River, N.J.: Prentice Hall. Three Basic Principles of Genetics The Principle of Dominance One gene for a trait may hide the other gene and keep it from being seen (expressed) in the organism Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice Hall biology (North Carolina ed., pp. 262- 285). Upper Saddle River, N.J.: Prentice Hall. When Mendel crossed a tall pea plant with a short pea plant, all the offspring plants were tall. In such crosses when only one trait was observed, Mendel called the observed trait dominant. Tall plant t T T t t T F1 All tall plants T t Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice Hall biology (North Carolina ed., pp. 262- 285). Upper Saddle River, N.J.: Prentice Hall. The Principle of Segregation The two genes for a trait separate, or segregate, during the formation of gametes (meiosis). This happens when pairs of chromosomes separate during meiosis Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice Hall biology (North Carolina ed., pp. 262- 285). Upper Saddle River, N.J.: Prentice Hall. The Principle of Independent Assortment Genes for different traits separate independently during the formation of gametes. Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice Hall biology (North Carolina ed., pp. 262- 285). Upper Saddle River, N.J.: Prentice Hall. Sex Chromosomes X and Y chromosomes Determine the sex of the offspring Females have two large XX chromosomes Males have an X and a smaller Y chromosome (XY). Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice Hall biology (North Carolina ed., pp. 262285). Upper Saddle River, N.J.: Prentice Hall. Miller, K. R., & Levine, J. S. (2005). Chapter 14: The Human Genome.Prentice Hall biology (North Carolina ed., pp. 340- 365). Upper Saddle River, N.J.: Prentice Hall. Sex Chromosomes All other chromosomes are autosomes. Human sperm contain 22 autosomes and an X or Y chromosome Human eggs contain 22 autosomes and an X chromosome Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice Hall biology (North Carolina ed., pp. 262285). Upper Saddle River, N.J.: Prentice Hall. Miller, K. R., & Levine, J. S. (2005). Chapter 14: The Human Genome.Prentice Hall biology (North Carolina ed., pp. 340- 365). Upper Saddle River, N.J.: Prentice Hall. Sex-linked Traits Most are carried on the X chromosome Also called X-linked traits Hemophilia and color blindness are recessive sex-linked traits carried on the X-chromosome Males show recessive traits more than females Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice Hall biology (North Carolina ed., pp. 262285). Upper Saddle River, N.J.: Prentice Hall. Miller, K. R., & Levine, J. S. (2005). Chapter 14: The Human Genome.Prentice Hall biology (North Carolina ed., pp. 340- 365). Upper Saddle River, N.J.: Prentice Hall. Sex-linked Traits Males get only one allele for a sexlinked trait carried on the X chromosome (nothing on Y) Females have a second X chromosome that carries another allele that can hide recessive traits Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice Hall biology (North Carolina ed., pp. 262285). Upper Saddle River, N.J.: Prentice Hall. Miller, K. R., & Levine, J. S. (2005). Chapter 14: The Human Genome.Prentice Hall biology (North Carolina ed., pp. 340- 365). Upper Saddle River, N.J.: Prentice Hall. Sex-linked Traits Females who have recessive alleles but show the dominant trait are called carriers A woman can have normal vision but carry the recessive allele for colorblindness Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice Hall biology (North Carolina ed., pp. 262285). Upper Saddle River, N.J.: Prentice Hall. Miller, K. R., & Levine, J. S. (2005). Chapter 14: The Human Genome.Prentice Hall biology (North Carolina ed., pp. 340- 365). Upper Saddle River, N.J.: Prentice Hall. Test Cross Done to determine the genotypes of organisms that show dominant traits Unknown genotype organism is crossed with a homozygous recessive (Example: tt) Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice Hall biology (North Carolina ed., pp. 262285). Upper Saddle River, N.J.: Prentice Hall. Miller, K. R., & Levine, J. S. (2005). Chapter 14: The Human Genome.Prentice Hall biology (North Carolina ed., pp. 340- 365). Upper Saddle River, N.J.: Prentice Hall. Test Cross If all offspring have the dominant trait then the genotype is probably pure (TT x tt) If some of the offspring show the recessive trait, then the genotype is heterozygous.(Tt x tt) Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice Hall biology (North Carolina ed., pp. 262285). Upper Saddle River, N.J.: Prentice Hall. Miller, K. R., & Levine, J. S. (2005). Chapter 14: The Human Genome.Prentice Hall biology (North Carolina ed., pp. 340- 365). Upper Saddle River, N.J.: Prentice Hall. Pedigree Study Method of determining the genotype of individuals by looking at inheritance patterns Miller, K. R., & Levine, J. S. (2005). Chapter 14: The Human Genome.Prentice Hall biology (North Carolina ed., pp. 340- 365). Upper Saddle River, N.J.: Prentice Hall. Human Genetics 23 pairs of chromosomes (46 total) Pedigrees are used to trace genetic traits Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice Hall biology (North Carolina ed., pp. 262- 285). Upper Saddle River, N.J.: Prentice Hall. Male Parents Female Siblings Affected male Affected female Mating Known heterozygotes for recessive allele Pedigrees illustrate inheritance Death Miller, K. R., & Levine, J. S. (2005). Chapter 14: The Human Genome.Prentice Hall biology (North Carolina ed., pp. 340- 365). Upper Saddle River, N.J.: Prentice Hall. I Female Pedigrees illustrate inheritance Male 1 2 II 2 1 3 4 5 III ? 1 2 4 3 In a pedigree, a circle represents a female; a square represents a male. IV 1 2 3 4 5 Miller, K. R., & Levine, J. S. (2005). Chapter 14: The Human Genome.Prentice Hall biology (North Carolina ed., pp. 340- 365). Upper Saddle River, N.J.: Prentice Hall. Pedigrees illustrate inheritance I 1 2 II 3 2 1 4 5 III ? 1 2 4 3 Highlighted circles and squares represent individuals showing the trait being studied. IV 1 2 3 4 5 Miller, K. R., & Levine, J. S. (2005). Chapter 14: The Human Genome.Prentice Hall biology (North Carolina ed., pp. 340- 365). Upper Saddle River, N.J.: Prentice Hall. Pedigrees illustrate inheritance I 1 2 II 2 1 3 4 5 III ? 1 2 4 3 Circles and squares that are not highlighted represent individuals that do not show trait. IV 1 2 3 4 5 Miller, K. R., & Levine, J. S. (2005). Chapter 14: The Human Genome.Prentice Hall biology (North Carolina ed., pp. 340- 365). Upper Saddle River, N.J.: Prentice Hall. Pedigrees illustrate inheritance A half-shaded circle or square represents a carrier, a heterozygous individual. Miller, K. R., & Levine, J. S. (2005). Chapter 14: The Human Genome.Prentice Hall biology (North Carolina ed., pp. 340- 365). Upper Saddle River, N.J.: Prentice Hall. Pedigrees illustrate inheritance I 1 2 II 2 1 III ? IV 1 2 1 3 4 4 3 2 5 3 4 A horizontal line connecting a circle and a square indicates that the individuals are parents, and a vertical line connects parents with their offspring. 5 Miller, K. R., & Levine, J. S. (2005). Chapter 14: The Human Genome.Prentice Hall biology (North Carolina ed., pp. 340- 365). Upper Saddle River, N.J.: Prentice Hall. Pedigrees illustrate inheritance I 1 2 II 1 III 1 ? IV 2 1 3 2 4 4 3 2 5 3 4 Each horizontal row of circles and squares in a pedigree designates a generation, with the most recent generation shown at the bottom. 5 Miller, K. R., & Levine, J. S. (2005). Chapter 14: The Human Genome.Prentice Hall biology (North Carolina ed., pp. 340- 365). Upper Saddle River, N.J.: Prentice Hall. Pedigrees illustrate inheritance I 1 2 II 1 3 2 4 5 III ? 1 2 The generations are identified in sequence by Roman numerals, and each individual is given an Arabic number. 4 3 IV 1 2 3 4 5 Miller, K. R., & Levine, J. S. (2005). Chapter 14: The Human Genome.Prentice Hall biology (North Carolina ed., pp. 340- 365). Upper Saddle River, N.J.: Prentice Hall. Pedigree Chart Simple Pedigree Nondisjunction Chromosome pairs do not separate correctly One gamete has too many the other too few Miller, K. R., & Levine, J. S. (2005). Chapter 14: The Human Genome.Prentice Hall biology (North Carolina ed., pp. 340- 365). Upper Saddle River, N.J.: Prentice Hall. Nondisjunction Examples: Trisomy 21 - Down Syndrome (extra chromosome 21) Miller, K. R., & Levine, J. S. (2005). Chapter 14: The Human Genome.Prentice Hall biology (North Carolina ed., pp. 340- 365). Upper Saddle River, N.J.: Prentice Hall. Down Syndrome XXY syndrome (Klinefelter Syndrome) Miller, K. R., & Levine, J. S. (2005). Chapter 14: The Human Genome.Prentice Hall biology (North Carolina ed., pp. 340- 365). Upper Saddle River, N.J.: Prentice Hall. Genetic Disorders Most caused by recessive alleles Cystic fibrosis Sickle-cell anemia Phenylketonuria (PKU) Tay-Sachs disease Miller, K. R., & Levine, J. S. (2005). Chapter 14: The Human Genome.Prentice Hall biology (North Carolina ed., pp. 340- 365). Upper Saddle River, N.J.: Prentice Hall. Karyotype Chart of chromosome pairs Shows unusual number of chromosomes Can detect trisomy 21 (Down syndrome) Identifies male or female Miller, K. R., & Levine, J. S. (2005). Chapter 14: The Human Genome.Prentice Hall biology (North Carolina ed., pp. 340- 365). Upper Saddle River, N.J.: Prentice Hall. Karyotype Normal Female Karyotype Female with Down Syndrome Autosomal Disorders in Humans www.nerdscience.com 14-1 Dihybrid Cross RrYy x RrYy RY Ry rY ry RY RRYY RRYy RrYY RrYy Ry RRYy RRyy RrYy Rryy rY RrYY RrYy rrYY rrYy ry RrYy Rryy rrYy rryy www.nerdscience.com 11-3 Extra Studying While all of these chapters where not used in this Power Point, you may find it useful to go and read, or re-read, the following chapters in your text book. Chapter 11: Introduction to Genetics Chapter 12: DNA and RNA Chapter 13: Genetic Engineering Chapter 14: The Human Genome Chapter 16: Evolution of Populations Underlined Chapters are covered in Power Point. Bibliography Miller, K. R., & Levine, J. S. (2005). Chapter 11: Introduction to Genetics. Prentice Hall biology (North Carolina ed., pp. 262- 285). Upper Saddle River, N.J.: Prentice Hall. Miller, K. R., & Levine, J. S. (2005). Chapter 12: DNA and RNA. Prentice Hall biology (North Carolina ed., pp. 286- 317). Upper Saddle River, N.J.: Prentice Hall. Miller, K. R., & Levine, J. S. (2005). Chapter 13: Genetic Engineering. Prentice Hall biology (North Carolina ed., pp. 318339). Upper Saddle River, N.J.: Prentice Hall. Miller, K. R., & Levine, J. S. (2005). Chapter 14: The Human Genome.Prentice Hall biology (North Carolina ed., pp. 340- 365). Upper Saddle River, N.J.: Prentice Hall. Miller, K. R., & Levine, J. S. (2005). Chapter 16: Evolution of Populations. Prentice Hall biology (North Carolina ed., pp. 392415). Upper Saddle River, N.J.: Prentice Hall.
