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In this chapter

(^2020)

Molecular Genetics

chapter

Molecular Genetics

Exploration: Similarities

and Differences

Mini Investigation:

Building a DNA Model

Web Activity: DNA

Replication

Lab Exercise 20.A:

Synthesis of a Protein

Investigation 20.1:

Protein Synthesis and

Inactivation of Antibiotics

Web Activity:

Electrophoresis

Web Activity: Researchers

in Human Genetic

Disorders

Mini Investigation:

Examining the Human

Genome

Investigation 20.2:

Restriction Enzyme

Digestion of

Bacteriophage DNA

Web Activity:

Transformation of

Eukaryotes

Case Study: Gene

Mutations and Cancer

Lab Exercise 20.B:

Looking for SINEs of

Evolution

By the mid-1950s, scientists had determined that chromosomes contained DNA and

that DNA was the genetic material (Figure 1). Building on the work of other scientists,

Watson and Crick deduced the structure of this complex molecule. This knowledge laid

the basis for the field of molecular biology, which aims to understand the inheritance of

traits at the level of interactions between molecules in the cell.

A primary goal of molecular genetics is to understand how DNA determines the phe-

notype of an organism. What happens to DNA during duplication of chromosomes in

mitosis? How does the structure of DNA relate to its function? How does one molecule,

identical in every somatic cell of an organism, determine the characteristics of the many

different types of cells that are found in that organism?

Today, questions such as these continue to drive research in the fields of biology,

biotechnology, biochemistry, and medicine. We now know the sequence of all the

nucleotides that make up the genome of many organisms, including that of our own

species,Homo sapiens. This information has given scientists new ways to study the rela-

tionships between species and the mechanisms of evolution. It also allows law enforce-

ment agencies to identify individuals with incredible accuracy from minute quantities

of DNA.

Using genetic technologies, scientists can move genes from one species to another. In

fields such as agriculture, corporations have patented the genomes of these organisms

in order to profit from the advantages they offer over conventional organisms. Similar

manipulation of human cells may one day lead to treatments for previously untreat-

able debilitating diseases. The research and application of these technologies raises many

social, ethical, and legal issues that society has yet to fully resolve.

660 Chapter 20 NEL

Answer these questions as best you can with your current knowledge. Then, using

the concepts and skills you have learned, you will revise your answers at the end of

the chapter.

1. Differentiate between DNA and proteins. What cellular roles do they play?
   2.Describe the physical and chemical characteristics of DNA.
   3.What is the significance of DNA replication in your body?
   4.Write a short overview, in paragraph form, of the process of DNA replication.

STARTING Points

Career Connections:

Biological Technician; Biotechnologist