Clip: "The Code of Life"

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Fruitflies as a Tool For Understanding Human Genetic Diseases


Overview | Why This Science Matters | Explore This Topic
Links & Resources | Meet the Scientist: Ethan Bier
Teacher Resources


The growth and survival of living things depends on how the information in double-stranded DNA is transcribed into RNA, the single-stranded messenger molecule, and translated into a sequence of amino acids to synthesize specific proteins.

Why This Science Matters

Understanding the relationship between our DNA and how we function is of great medical importance. Once we know how a genetic device involved in a critical biological process works, we can try to figure out how to fix it when things go wrong as in disease. It is also very important to understand how slight variations in the DNA sequence between different individuals can impact our health, such as making us more or less susceptible to diseases such as cancer, autoimmune diseases, or neurodegenerative diseases.

These subtle differences can help us tailor preventative medical programs to address the potential risks of specific individuals. They may also lead to the development of treatments for disease by mimicking naturally arising variations, which protect against specific ailments. Finally, as is generally case for advances in science, the more we know about ourselves and our origins, the richer we become and the better prepared we will be for the accelerating change of our future.

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Explore This Topic

In this lesson, UCSD Biology Professor Ethan Bier explains the transcription and translation of DNA, the "Central Dogma of Biology," and how errors in this process and mutations in DNA can produce non-functional proteins that cause problems for an organism.

The following questions accompany this lesson. The answers are given below each question. Using your mouse, click and drag to highlight the area below the question to reveal the answers.

1) What is a gene?

A: The basic unit of heredity composed of DNA, deoxyribonucleic acid.

2.) Describe the differences between DNA and RNA:

A: DNA is a double helical molecule that stores the genetic information of all living things. It consists of two complementary strands of nucleotide bases, the information-storing units of the gene (similar to the 1s and 0s of a computer code). RNA, ribonucleic acid, is a single stranded molecule similar to DNA that carries genetic information from DNA in the cell's nucleus to the ribosome, the protein-synthesizing portion of the cell. The information from the RNA is used as a template to make proteins.

3.) What is transcription and how does it differ from translation?

A: Transcription is the synthesis of a single-stranded copy of RNA from a copy of a DNA molecule. Translation is the conversion of a base sequence of DNA and RNA (the 1s and 0s of a computer code) into a sequence of amino acids in a protein.

4.) What are the four nucleotide bases and how are they responsible for mutations?

A: The four bases, or subunits, of DNA are A, C, G, and T. The four bases of RNA are A, C, G, and U. A mutation is an alteration in the base sequence of a gene.

5.) What are amino acids and how many exist?

A: Amino acids are the subunits of proteins. There are 20 amino acids.

Extra Credit: Go to the links and resources below that provide information about genetic testing and the Human Genome Project. In two columns, write down all of the benefits of both and the drawbacks of both. Then form an opinion. What do you think about genetic testing and the Human Genome Project?

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Links and Resources

The Coiled Spring: How Life Begins by Ethan Bier (Cold Spring Harbor Laboratory Press, 2000) See Chapter One: The Central Dogma of Biology. The book also provides some interesting profiles of famous biologists (including many UCSD biologists) and their research.

What is a Gene? Web site for elementary and middle school students from Kid's Health

University of Utah Genetic Science Learning Center (experiments, online and hands on activities, group activities, genetic disorders, careers in genetics, genetic news). (Link for Students)

DNA Learning Center: Cold Spring Harbor Laboratory

Your Genes, Your Health

Peeking and Poking at DNA: Scientific American

Your Genes, Your Choices (Ethical Issues about the Human Genome Project), AAAS

A Question of Genes: Inherited Risks: 1997 PBS documentary about genetic testing features short video clips and resources for educators

Database of human genes, fly genes and human genetic diseases: Created and maintained at UCSD for scientists. Using this database, scientists can compare the similarity of the nucleotide base sequences from humans and fruit flies.

Genetics and The Human Genome Project: Links and resources from the University of Kansas Genetics Education Center

Ask the Experts (about DNA) Scientific American

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