These images from the Smithsonian Institution depict Nancy Knowlton's work with snapping shrimp in Panama. Knowlton found that the closing of the isthmus -- dividing the Pacific Ocean from the Caribbean -- resulted in new species of shrimp.

This interactive will present the mathematical consideration of exponentially
enriching a piece of DNA using PCR. Typically, a PCR protocol will repeat
approximately 30 cycles of denaturation, annealing, and elongation. 30 cycles of
PCR produce around 1 billion copies of the amplified region.

To create HIV-resistant immune cells with the gene editing tool CRISPR-Cas9, a specific macrophage gene must be disrupted.

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

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 toss coins to determine what traits a set of mouse parents possess, such as fur color, body size, heat tolerance, and running speed. Then they use coin tossing to determine the traits a mouse pup born to these parents possesses. Then they compare these physical features to features that would be most adaptive in several different environmental conditions. Finally, students consider what would happen to the mouse offspring if those environmental conditions were to change: which mice would be most likely to survive and produce the next generation?

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:

List the steps in eukaryotic transcription
Discuss the role of RNA polymerases in transcription
Compare and contrast the three RNA polymerases
Explain the significance of transcription factors

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

List the different steps in prokaryotic transcription
Discuss the role of promoters in prokaryotic transcription
Describe how and when transcription is terminated

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

Describe the different steps in RNA processing
Understand the significance of exons, introns, and splicing for mRNAs
Explain how tRNAs and rRNAs are processed

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

Describe the different steps in protein synthesis
Discuss the role of ribosomes in protein synthesis

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

Explain the “central dogma” of DNA-protein synthesis
Describe the genetic code and how the nucleotide sequence prescribes the amino acid and the protein sequence

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

Explain Mendel’s law of segregation and independent assortment in terms of genetics and the events of meiosis
Use the forked-line method and the probability rules to calculate the probability of genotypes and phenotypes from multiple gene crosses
Explain the effect of linkage and recombination on gamete genotypes
Explain the phenotypic outcomes of epistatic effects between genes

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

Describe the structure of prokaryotic and eukaryotic genomes
Distinguish between chromosomes, genes, and traits
Describe the mechanisms of chromosome compaction

This explanation of genetic drift is straightforward and easy to understand. Illustrations are provided to help visual learners