Lab 6 Cell Division, Mitosis, and Meiosis
Introduction: Connecting Your Learning
All cells, including those in the human body, have a cell cycle. This cycle involves preparing for cell division and eventually dividing. Coupled with cell division is nuclear division. Nuclear division, either mitosis or meiosis, is the process by which the nucleus of a cell divides. Mitosis results in two identical daughter cells; each containing the same number of chromosomes as the parent cell. (In humans, this is 46.) In comparison, meiosis results in four daughter cells, each containing half the number of chromosomes as the parent cell (23 in humans). Meiosis is essential to sexual reproduction and the inheritance of genes. This lab examines cell division, nuclear division, and the concepts associated with the study of inheritance or genetics.
Resources and Assignments
Multimedia Resources Virtual Microscope
Required Assignments Lesson 7 Lab 6
Laboratory Materials None
Focusing Your Learning
Lab Objectives
By the end of this lesson, you should be able to:
1. Describe the molecular structure of DNA. 2. Identify and describe the stages of mitosis, meiosis, and cell division. 3. Distinguish between cell division and mitosis. 4. Identify the stages of mitosis in onion root tip cells, observed under a
microscope. 5. Explain the process of crossing over.
Background Information
Deoxyribonucleic acid (DNA) is an important component that determines who an individual is and what he or she looks like. But DNA is much more complex than simply defining the external features of an individual. DNA is responsible for controlling the complex processes involved in living organisms.
DNA is composed of a coiled double helical strand of nucleotides that are bonded together in a specific pattern. The backbone of the double helix is composed of linked deoxyribose sugars and phosphorus atoms, and cross-links form between two nitrogenous bases. The four nitrogenous bases consist of Adenine (A), Guanine (G), Cytosine (C), and Thymine (T). An image of a DNA molecule is seen below. Note that the sugar-phosphate backbones are the blue ribbons, and the nitrogenous bases are the cross-links seen in shades of green and orange.