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BIO305: Genetics

Unit 2: Mitosis and Meiosis  

Unit 1 gave you a foundation of Mendel’s discoveries on which to build. As we move through the genetic concepts of this unit, we will also discuss some of the history that led Mendel’s work to be applied to the chromosome. In this unit, you will learn how Mendel and subsequent work by other scientists led to the concept of genes and chromosomes through investigations of mitosis and meiosis.
 

Mitosis is the cell replication that results in two daughter cells that are identical to each other and to the parent cell. Every cell in your body has the ability to undergo mitosis, and most replicate tens of times before dying. Mitosis is a multistep process that can lead to cancer when errors occur. Almost all cancers are cells undergoing uncontrollable mitosis; cancer cells are immortal.

 
On the other hand,
meiosis is the cell replication that results in four unique daughter cells that are different from each other as well as from the parent cell. Meiosis is also a multistep process, and it leads to the production of germ cells: sperm and egg cells. If meiosis goes awry, it can result in genetic defects but more likely in miscarriage.

 
As a result, it is important that researchers and physicians fully understand mitosis and meiosis, the two fundamental replication cycles, and that they are able to find out how to control each step in order to help prevent disease.

Unit 2 Time Advisory
This unit should take you approximately 14 hours to complete:
 
☐    Subunit 2.1: 0.25 hours
 
☐    Subunit 2.2: 1 hour
 
☐    Subunit 2.3: 5.25 hours
☐    Introduction: 1.75 hours
 
☐    Subunit 2.3.1: 2 hours
 
☐    Subunit 2.3.2: 1.5 hours

☐    Subunit 2.4: 5 hours
☐    Subunit 2.4.1: 1 hour
 
☐    Subunit 2.4.2: 1.5 hours
 
☐    Subunit 2.4.3: 1.25 hours
 
☐    Subunit 2.4.4: 0.25 hours
 
☐    Subunit 2.4.5: 0.25 hours
 
☐    Subunit 2.4.6: 0.75 hours

☐    Subunit 2.5: 2.5 hours

Unit2 Learning Outcomes
Upon successful completion of this course, you will be able to:
- explain Mendel’s observation with the movement of chromosomes during cell division; - predict the number of unique daughter cells after cell division; - explain the significance of crossing over; - compare and contrast as well as discuss mitosis and meiosis; - compare and contrast as well as discuss female and male meiosis; - compare and contrast as well as discuss oncogenes and proto-oncogenes; - explain how oncogenes and inactivated tumor suppressor genes contribute to cancer development; and - explain why mutations may lead to the development of cancer.

2.1 Locus and Alleles   - Reading: The Saylor Foundation’s “Chromosomes, Chromatids, Loci, and Alleles” Link: The Saylor Foundation’s “Chromosomes, Chromatids, Loci, and Alleles” (PDF)
 
Instructions: Read this article for an overview of the proper definition and use of the following terms: chromosome, chromatid, locus, and allele.
 
Reading this article should take approximately 15 minutes.

2.2 Chromosome   - Lecture: Khan Academy’s “Chromosomes, Chromatids, Chromatin, etc.” Link: Khan Academy’s “Chromosomes, Chromatids, Chromatin, etc.” (YouTube)
 
Instructions: Watch this lecture for a quick review of chromosomal structure.
 
Watching this lecture and pausing to take notes should take approximately 30 minutes.
 
Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

  • Web Media: YouTube: The Saylor Foundation: Lynn Carpenter’s “Chromosome History” Link: YouTube: The Saylor Foundation: Lynn Carpenter’s “Chromosome History” (YouTube)
     
    Instructions: Watch this video for an introduction to the concept of a chromosome.
     
    Watching this video and pausing to take notes should take approximately 30 minutes.

2.3 Mitosis and Cancer   - Reading: National Center for Biotechnology Information’s Genes and Disease: “Cancers” Link: National Center for Biotechnology Information’s Genes and Disease: “Cancers” (HTML)
 
Instruction: Study the sections entitled “Cancers” and “Diseases.” Click on the hyperlink for each disease to learn about the genetics of cancer. Note that the photomicrograph on the main page shows a dividing HeLa cell, the first human cell line that was established and cultured. HeLa cells are cervical adenocarcinoma cells that originate from a patient without her informed consent. HeLa cells are sold worldwide.
 
Reading these sections should take approximately 1 hour.
 
Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

  • Reading: Massachusetts Institute of Technology: Professor Leona Samson’s “Lecture 33: Chromosome Anomalies II” Link: Massachusetts Institute of Technology: Professor Leona Samson’s “Lecture 33: Chromosome Anomalies II” (PDF)
     
    Instructions: Select the PDF links to “Lecture 33: Chromosome Anomalies II,” and download the first of the three PDF files: “PDF 1 of 3 – 3.1MB.” Read these lecture notes carefully. These lecture notes give a brief introduction to cancer genetics, including a description of the molecular changes in aflatoxin B that lead to the interaction with DNA. This text is technical, so please plan to read it several times for a full understanding.
     
    Reading these lecture notes should take approximately 30 minutes.
     
    Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

  • Web Media: YouTube: The Saylor Foundation: Lynn Carpenter’s “Mitosis” Link: YouTube: The Saylor Foundation: Lynn Carpenter’s “Mitosis” (YouTube)
     
    Instructions: Watch this video to learn about the process of mitosis.
     
    Watching this video and pausing to take notes should take approximately 15 minutes.

2.3.1 Oncogenes and Inactivated Tumor Supressor Genes   - Reading: Massachusetts Institute of Technology: Professor Leona Samson’s “Lecture 33: Chromosome Anomalies II” Link: Massachusetts Institute of Technology: Professor Leona Samson’s “Lecture 33: Chromosome Anomalies II” (PDF)
 
Instructions: Select the PDF links to “Lecture 33: Chromosome Anomalies II,” and download the second and third files: “PDF 2 of 3 – 1.9 MB” and “PDF 3 of 3 – 3.8 MB.” Read these lecture notes carefully. These lecture notes review the phases of the cell cycle. These notes also describe a laboratory test that is used to determine the carcinogenicity of substances. This text is technical, so please plan to read it several times for a full understanding.
 
Reading these lecture notes should take approximately 30 minutes.
 
Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

  • Reading: Massachusetts Institute of Technology: Professor Leona Samson’s “Lecture 34: Genetics of Cancer I” Link: Massachusetts Institute of Technology: Professor Leona Samson’s “Lecture 34: Genetics of Cancer I” (PDF)
     
    Instructions: Select the PDF link to “Lecture 34: Genetics of Cancer I,” and read these lecture notes. These lecture notes describe the conversion of proto-oncogenes to oncogenes. These lecture notes also outline pathways that result in lost cell cycle control through the actions of oncogenes and inactivated suppressor genes. This text is technical, so please plan to read it several times for a full understanding.
     
    Reading these lecture notes should take approximately 1 hour and 30 minutes.
     
    Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

2.3.2 Mutations May Cause Cancer   - Reading: Massachusetts Institute of Technology: Professor Leona Samson’s “Lecture 35: Genetics of Cancer II” Link: Massachusetts Institute of Technology: Professor Leona Samson’s “Lecture 35: Genetics of Cancer II” (PDF)
 
Instructions: Select the PDF link to “Lecture 35: Genetics of Cancer II,” and read these lecture notes. These lecture notes discuss gene mutations that are linked to cancer. They also outline how these mutations disturb cell cycle control. This text is technical, so please plan to read it several times for a full understanding.
 
Reading these lecture notes should take approximately 1 hour and 30 minutes.
 
Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

2.4 Meiosis   2.4.1 Mitosis and Meiosis   - Lecture: Khan Academy’s “Mitosis, Meiosis, and Sexual Reproduction” Link: Khan Academy’s “Mitosis, Meiosis, and Sexual Reproduction” (YouTube)
 
Instructions: Watch this lecture for a comparison of mitosis and meiosis.
 
Watching this lecture and pausing to take notes should take approximately 30 minutes.
 
Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

  • Web Media: YouTube: The Saylor Foundation: Lynn Carpenter’s “Meiosis” Link: YouTube: The Saylor Foundation: Lynn Carpenter’s “Meiosis” (YouTube)
     
    Instructions: Watch this video for an overview of the process of meiosis.
     
    Watching this video and pausing to take notes should take approximately 30 minutes.

2.4.2 Meiosis and Fertilization   - Reading: Boundless: Biology: “Chapter 16, Section 3: Chromosomal Behavior in Meiosis and Fertilization” Link: Boundless: Biology: “Chapter 16, Section 3: Chromosomal Behavior in Meiosis and Fertilization” (HTML)
 
Instructions: Read about the following concepts: “Chromosomes in Human Cells,” “Chromosomes over the Human Life Cycle,” and “Three Types of Sexual Life Cycle” by clicking on the arrow on the right side of each concept heading. Compare meiosis and mitosis. Note that meiosis gives rise to unique daughter cells, and haploid cells cannot go through meiosis.
 
Reading this material should take approximately 1 hour and 30 minutes.
 
Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

2.4.3 Stages of Meiosis   - Reading: The Saylor Foundation’s “Recombination, Chiasmata, and Genetic Variation” Link: The Saylor Foundation’s “Recombination, Chiasmata, and Genetic Variation” (PDF)
 
Instructions: Read this article, which provides an illustrated example of the process of recombination. Recombination eventually leads to genetic variation within a population.
 
Reading this article should take approximately 15 minutes.

  • Reading: Delta State University: Dr. John Tiftickjian’s “Genetics and Tetrad Analysis” Link: Delta State University: Dr. John Tiftickjian’s “Genetics and Tetrad Analysis” (HTML)
     
    Instructions: Read this article, which covers homologous chromosomes, the process of crossing over, and how this will ultimately provide genetic variation. The simple bread mold Neurospora crassa provides a unique system for scientists to study the process of crossing over. One reason is that researchers can see that crossover events are recorded by the order of spores they produce.
     
    Reading this article should take approximately 1 hour.
     
    Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

2.4.4 Meiosis I and Reducational Division   - Reading: The Saylor Foundation’s “Meiosis I and the Role of Reductional Division” Link: The Saylor Foundation’s “Meiosis I and the Role of Reductional Division” (PDF)
 
Instructions: Read this article, which illustrates the process of meiosis I and how it relates to reductional division.
 
Reading this article should take approximately 15 minutes.

2.4.5 Meiosis II and Equational Division   - Reading: The Saylor Foundation’s “Meiosis II and the Role of Equational Division” Link: The Saylor Foundation’s “Meiosis II and the Role of Equational Division” (PDF)
 
Instructions: Read this article, which illustrates the process of meiosis II and how it relates to equational division.
 
Reading this article should take approximately 15 minutes.

2.4.6 Female vs. Male Meiosis   - Reading: Palomar College: Dennis O’Neil’s “Cell Reproduction and Conception” Link: Palomar College: Dennis O’Neil’s “Cell Reproduction and Conception” (HTML)
 
Instructions: Read the “Meiosis” and “Conception” sections of this article. Note that environmental clues are instrumental in germ cell differentiation.
 
Reading these sections should take approximately 45 minutes.
 
Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

2.5 Comparison of Mitosis and Meiosis   - Lecture: Yale University: Professor Stephen C. Stearns’ Principles of Evolution, Ecology, and Behavior: “Lecture 2: Basic Transmission Genetics” Link: Yale University: Professor Stephen C. Stearns’ Principles of Evolution, Ecology, and Behavior: “Lecture 2: Basic Transmission Genetics” (Adobe Flash)
 
Instructions: Watch this lecture on basic transmission genetics. This lecture is technical, so please plan to pause, take notes, and view the lecture several times for a full understanding.
 
Watching this lecture and pausing to take notes should take approximately 2 hours.
 
Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

  • Web Media: YouTube: The Saylor Foundation: Lynn Carpenter’s “Genetic Variation” Link: YouTube: The Saylor Foundation: Lynn Carpenter’s “Genetic Variation” (YouTube)
     
    Instructions: Watch this video, which addresses genetic variation.
     
    Watching this video and pausing to take notes should take approximately 30 minutes.