Understand how a gene is a stretch of DNA on a chromosome. Find out about alleles in their role as versions sequence variants of a gene. [8:18]

Khan Academy learning modules include a Community space where users can ask questions and seek help from community members. Educators should consult with their Technology administrators to determine the use of Khan Academy learning modules in their classroom. Please review materials from external sites before sharing with students.

Learn about the gene as a stretch of DNA on a chromosome. Also find out about alleles as versions or sequence variants of a gene. [8:17]

Khan Academy learning modules include a Community space where users can ask questions and seek help from community members. Educators should consult with their Technology administrators to determine the use of Khan Academy learning modules in their classroom. Please review materials from external sites before sharing with students.

This interactive will present the varying applications of the laboratory technique Polymerase Chain Reaction, also known as PCR.

Scientists from the University of Arizona are conducting Y chromosome research on native Siberians to try to determine whether there is a genetic affinity to North American native people. The rationale and direction of this research are explained here.

A graphic which communicates the beauty and intricacy of DNA, illustrating how DNA is the core to everything. [3:25]

Students construct paper recombinant plasmids to simulate the methods genetic engineers use to create modified bacteria. They learn what role enzymes, DNA and genes play in the modification of organisms. For the particular model they work on, they isolate a mammal insulin gene and combine it with a bacteria's gene sequence (plasmid DNA) for production of the protein insulin.

Students act as if they are biological engineers following the steps of the engineering design process to design and create protein models to replace the defective proteins in a child’s body. Jumping off from a basic understanding of DNA and its transcription and translation processes, students learn about the many different proteins types and what happens if protein mutations occur. Then they focus on structural, transport and defense proteins during three challenges posed by the R&D; bio-engineering hypothetical scenario. Using common classroom supplies such as paper, tape and craft sticks, student pairs design, sketch, build, test and improve their own protein models to meet specific functional requirements: to strengthen bones (collagen), to capture oxygen molecules (hemoglobin) and to capture bacteria (antibody). By designing and testing physical models to accomplish certain functional requirements, students come to understand the relationship between protein structure and function. They graph and analyze the class data, then share and compare results across all teams to determine which models were the most successful. Includes a quiz, three worksheets and a reference sheet.

See this close-up animation showing how ribosomes carry out translation to make a particular proteins. [3:04]

Observe a scientist describe the process used to extract DNA from a cell and to analyze it on a gene chip. [1:41]

See James Watson reenact his discovery of the base pairs that form the double helix structure of the DNA molecule. [1:42]

This narrated animation allows the learner to understand how six feet of DNA can be tightly packed to fit inside the nucleus of every human cell. [1:43]

Using information from molecular research, this 3-D animation shows how DNA is replicated at the molecular level. It involves an enzyme that unwinds the DNA and other enzymes that copy the two resulting strands. [1:07]

Find out about the genetic blood disorder, sickle cell anemia, in this short narration. [0:59]

A video discussing a variety of biotechnology applications that can be completed based on DNA's chemical properties. [2:44]

Learn how a standard lab technique, polymerase chain reaction, amplifies a single or several copies of a piece of DNA. [0:55]

Biology 2e is designed to cover the scope and sequence requirements of a typical two-semester biology course for science majors. The text provides comprehensive coverage of foundational research and core biology concepts through an evolutionary lens. Biology includes rich features that engage students in scientific inquiry, highlight careers in the biological sciences, and offer everyday applications. The book also includes various types of practice and homework questions that help students understand—and apply—key concepts. The 2nd edition has been revised to incorporate clearer, more current, and more dynamic explanations, while maintaining the same organization as the first edition. Art and illustrations have been substantially improved, and the textbook features additional assessments and related resources.

By the end of this section, you will be able to do the following:

Explain how the structure of DNA reveals the replication process
Describe the Meselson and Stahl experiments

By the end of this section, you will be able to do the following:

Discuss the different types of mutations in DNA
Explain DNA repair mechanisms