Patterns of heredity

1. Patterns of heredity By: Worsey, Mauzey, Vexler, Yu

2. Vocab • Karyotype: Photograph of chromosomes grouped in ordered pairs • Sex Chromosomes: the 23rd chromosomes that determine ones sex • Autosomes: all chromosomes excluding the sex chromosomes • Pedigree: a chart showing relationships with in a family • Sex-linked genes: genes found on the sex chromosomes • Nondisjunction: when homologous chromosomes fail to separate • DNA Finger Print: analyzes DNA sections that have little or no function but vary widely from one individual to another

3. Key concepts Questions • How is sex determined? • All human egg sells carry a single X chromosome. However, half of all sperm cells carry an X chromosome and half carry a Y chromosome. This ensures that about half the zygotes will be 46, XX and half will be 46, XY. • How do small changes in DNA cause genetic disorders? • By changing a sequence of DNA, it changes the structure of the proteins produced, causing a serious genetic disorder. • Why are sex linked disorders more common in males than females? • Males have just one X chromosome, so all X-linked alleles are expressed in males, even if they are recessive.

4. Key concepts continued • What is non disjunction and what problems does it cause? • If nondisjunction occurs, abnormal numbers of chromosomes may find their way into gametes, and a disorder of chromosomes may result. • What is the goal of the human genome project? • The Human Genome Project is an ongoing effort of analyze the human DNA sequence. • What is gene therapy? • In gene therapy, an absent or faulty gene is replaced by a normal, working gene.

5. Pedigree Review I II III

6. Pedigree Questions • Is the trait dominant or recessive? • Label the pedigree. “H” is the dominant allele, and “h” is recessive. • If the first daughter of generation II married a man heterozygous for the trait, what would be the genotype and phenotype of their children?

7. Pedigree Info • Squares are males, and circles are females. • Filled in shapes mean they have the trait. • Horizontal lines mean they are married. • Vertical lines are offspring. • The oldest generation is on the top of the pedigree. • The youngest generation is on the bottom. • If a person has died from the trait, a slash is put through the shape. • The oldest offspring are located on the left, and youngest on the right. • Generations are labeled by Roman numerals.

8. Sex-linked trait info Affected by trait Unaffected by trait X^h Y Male X^H Y X^H X^H X^h Female X^hX^h X^h Y X^h Males = XY Females = XX Males have just one X chromosome. Thus all X-linked alleles are expressed in males, even if they are recessive. Show the Punnett square for an unaffected male and a affected female. If the trait is dominant.

9. Karyotypes Normal Male Male with Down Syndrome

10. Blood groups • This table shows the relationship between genotype and phenotype for the ABO blood groups. It also shows which blood types can safely be transfused into people with other blood types.

12. Sex Chromosome Disorders Turner’s Syndrome Klinefelter’s Syndrome Caused by nondisjunction in males Extra X chromosomes Normally sterile (interferes with meiosis) • Caused by nondisjunction in females • They only inherit one X chromosome • Sterile

13. Questions • A normal human diploid zygote contain • 23 chromosomes • 46 chromosomes • 44 chromosomes • XXY chromosomes • A chart that traces the inheritance of a trait in a family is called a Traits that are caused by the interaction of many genes are said to be polygenic • pedigree • Karyotype • genome • Autosome • Traits that are caused by the interaction of many genes are said to be polygenic • Polyploid • Linked • Polygenic • Autosomal • An example of a trait that is determined by multiple alleles is • Huntington disease • ABO Blood Groups • Down Syndrome • hemophilia • Most sex-linked genes are found on the • Y chromosome • O Chromosome • YY Chromosomes • X Chromosome

14. Questions Continued • Hemophilia is a genetic disorder that is • Sex-linked • Sex influenced • Fairly common • More common in women than in men • The parental pair that could produce females with colorblindness is • Homozygous normal vision mother, father with colorblindness • Colorblind mother, normal vision father • Heterozygous normal vision mother, normal vision father • Heterozygous normal vision mother, color blind father • A common genetic disorder characterized by bent and twisted blood cells is • Cystic fibrosis • Hemophilia • Sickle cell disease • Muscular dystrophy • The technique that takes advantage of repeated DNA sequence that do not code for proteins is • DNA fingerprinting • DNA sequencing • Genetic engineering • Rapid sequencing • The process of attempting to cure genetic disorders by placing copies of healthy genes into cells that lack them is known as • Gene therapy • DNA fingerprinting • Rapid sequencing • The Human Genome project

15. Answers • A normal human diploid zygote contains 23 chromosomes • A chart that traces the inheritance of a trait in a family is called a pedigree • Traits that are caused by the interaction of many genes are said to be polygenic • An example of a trait that is determined by multiple alleles is ABO blood Groups • Most sex-linked genes are found on the XChromosome • Hemophilia is a genetic disorder that is sex-linked • The parental pair that could produce females with colorblindness is Heterozygous normal-vision mother, father with colorblindness • A common genetic disorder characterized by bent and twisted blood cells is sickle cell disease • The technique that takes advantage of repeated DNA sequence that do not code for proteins is DNA fingerprinting • The process of attempting to cure genetic disorders by placing copies of healthy genes into cells that lack them is known as gene therapy