Introduction

Module 9 – Genetics

Introduction

At this point in the course, we have discussed genetic material in some detail. You know the location of the genetic information in the cell, and where the genetic information of eukaryotes and prokaryotes can be found. In addition, we have examined the structure of the DNA molecule, examined how it is packaged into chromosomes in the cell, and how those chromosomes are passed from one cell to another through the cell cycle, and mitosis and meiosis. We also talked about how genetic diversity can be accomplished through the processes of crossing over and independent assortment in meiosis. In this module, we will begin our work in understanding the basics of genetics. Genetics is the study of “genes” and inheritance. One of the earliest scientists working in this field was Gregor Mendel. We’ll look at his work with pea plants and the information that his work with plants elucidated.

Interestingly, at the time of Mendel’s work, DNA had not been identified as the genetic material. The structure and the whereabouts in the cell of DNA were completely unknown. In addition, mitosis and meiosis had yet to be defined. Mendel was in essence experimenting with how genetic material was passed along without knowing what the genetic material was, what it looked like, or where it was found in the cell.

In this module, focus your efforts on understanding the basics of Mendelian genetics. Apply some of the things you have learned through your work in this course (like the definition of a gene, the structure of DNA, and the process of gene expression) to examine how traits are inherited. By the end of this module, you should be able to perform genetic crosses when given the genetic information of the parents and the trait in question. You should be able to determine possible gametes from the parental genotypes, perform a cross (through the use of parental genotypes, produce a Punnett Square) and you should be able to analyze the offspring in terms of the expected genotypic and phenotypic ratio of the offspring.

Spend some time thinking about exceptions to the rule(s). When might you see inheritance patterns in offspring that do not follow normal Mendelian genetics? Examine situations where multiple alleles, codominance, and incomplete dominance play a role in a genetic cross 1 .

Learning Outcomes

This module addresses the following Course Learning Outcomes listed in the Syllabus for this course:

  • Demonstrate knowledge of biological principles.
  • Demonstrate knowledge of scientific method.
  • Communicate scientific ideas through oral or written assignments.
  • Interpret scientific models such as formulas, graphs and tables.
  • Demonstrate problem solving methods in situations that are encountered outside of the classroom 1 .

Module Objectives

Upon completion of this module, the student will be able to:

  • Define terms related to Mendelian genetics (all bolded terms within the text).
  • Describe normal Mendelian Genetics.
  • Complete Punnett Squares and determine expected genotypic and phenotypic ratios of offspring.
  • Describe crossing over and independent assortment as related to Mendelian genetics.
  • Describe inheritance patterns outside of normal Mendelian genetics patterns.
  • Use genetic information to determine phenotypes.
  • Define sex-linked traits.
  • Perform 1 and 2 trait crosses.
  • Perform a cross involving a sex-linked trait.
  • Define the terms allele, complete dominance, incomplete dominance, and codominance.
  • Perform crosses dealing with genes that demonstrate variations of dominance.
  • State the genetic disorders covered in the reading for this module and describe the cellular events that cause each disorder.
  • Discuss genetic testing and be able to perform pedigree analysis 1 .