(GMN) Genetics: Mendelian & Non Mendelian Module Overview

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What's a Mendelian?

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From pea plants to genes to genetic technology, the world of Genetics is continuing to expand. The possibilities are endless in this ever-changing field. Just a few years ago, it was impossible to imagine a world where we could predict traits of offspring. Helping families understand their genetic history was not even a possibility.

Where will Genetics take us in the next 5 years? 10 years?

In this module, you will learn terminology to help you make predictions about future outcomes. You will learn how Gregor Mendel gave us the foundation for genetics. Ultimately, you will learn how genetics relates to you, your family, and society.

Module Lessons Preview

In this module, we will study the following topics:

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Module Key Terms

  • Trait - a feature that an organism displays that is inherited
  • Genetics - the study of traits of organisms
  • Heredity - passing traits from one generation to the next
  • Self-pollinated - plants whose pollen can normally only pollinate its own eggs
  • Cross pollinated - plants whose pollen is artificially transferred to another plant
  • P generation, or parents - the two organisms whose genes produce offspring
  • F1 generation - the offspring from two parents
  • F2 generation - the offspring produced from crossing two F1 individuals
  • Principle of Dominance and Recessiveness - one trait in a pair may mask the effect of another
  • Principle of Segregation - the two traits for a characteristic separate during the formation of eggs and sperm
  • Principle of Independent Assortment - the traits for different characteristics are distributed to reproductive cells independently
  • Probability - the likely outcome a given event will occur from random chance
  • Phenotype - the external appearance of an organism; refers to the physical appearance of the individual
  • Genotype - the genetic makeup of the organism; refers to the alleles an individual receives at fertilization
  • Homozygous dominant - genotype possess two dominant alleles for a trait (TT)
  • Homozygous recessive- genotype possess two recessive alleles for a trait (tt)
  • Heterozygous - genotype possess one dominant and one recessive allele for a trait (Tt)
  • Punnett Square - a chart drawn to show the probable results of a genetic cross
  • Monohybrid cross - a cross between individuals with one pair of contrasting genes (i.e. height)
  • Dihybrid cross - a cross between individuals with two pairs of contrasting genes (i.e. height and hair color)
  • Testcross- cross used to determine if an organism is homozygous dominant or heterozygous dominant; An unknown (A?) is crossed with a homozygous recessive to determine its genotype
  • Complete dominance- a pattern of inheritance where heterozygous offspring display dominant phenotype
  • Incomplete dominance- a pattern of inheritance where one allele is not completely shown, which results in a third phenotype. (i.e. white flower crossed with a red flower results in a pink flower)
  • Lethal alleles - a genetic defect that causes 100% mortality in the offspring
  • Co-dominance - a pattern of inheritance where both alleles of a gene are expressed in a heterozygote
  • Sex-linked traits - have genes locate on a sex chromosome
  • Sex-linked inheritance - because the gene in question is on a sex chromosome, both sexes do not show the same probability for inheritance of a trait.For instance, X-linked traits would show two alleles for females (XaXa) whereas males have only one allele to show the phenotype (XaY)
  • Multiple-allele traits- are controlled by three or more alleles of the same gene
  • Polygenic traits - are controlled by two or more genes
  • Pleiotropy - one gene results in multiple phenotypes
  • Sex-influenced traits- are located on autosomes (not a sex chromosome) but express themselves differently because of the sex hormones
  • Pedigree - graphic method for mapping inheritance of genetic traits within several generations of families
  • Carrier - an individual that does not express, but carries the trait/allele for a phenotype; can pass the trait to another generation
  • Sex-linked disorders - mutations of a chromosome located on a sex chromosome; occurs more frequently in males since they only have one X chromosome; a female would need to have two defective X chromosome to show the disorder
  • Co-dominant disorder - a single dominant allele will cause some phenotypic disorder, but not life-threatening, such as sickle cell anemia
  • Dominant Allele Disorders - genetic mutations in a dominant allele causes the disorder (i.e. Huntington’s Disease)
  • Recessive Allele Disorders - genetic mutations in a recessive allele and two recessive alleles are required to express the disorder
  • Chromosomal disorders - mutations in which an entire chromosomal pair fails to separate properly in meiosis; results in one or three of the homolog (i.e. Turner Syndrome, Down Syndrome, Klinefelter’s Syndrome)

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