In this 8 minute video, Paul Andersen describes how life could have formed on our planet through natural processes. The progression from monomers, to polymers, to protocells and finally to cells is described. The Miller-Urey experiment is described in detail as well as characteristics of the latest universal ancestor.

Also included are worksheets, a concept map, a slideshow, and transcript of the video.

Transcript added from YouTube subtitles. You can use this to write your own worksheet or quiz.

Using the signal transduction pathway for the cholera toxin to understand activation and inhibition.

The purpose of this video lesson is to expand the student's knowledge about enzymes by introducing the antioxidant enzymes that are intimately involved in the prevention of cellular damage and eventual slowing of the aging process and prevention of several diseases. Students will learn that natural antioxidant enzymes are manufactured in the body and provide an important defense against free radicals. The topic of free radical action is introduced, covering how they are constantly generated in living cells both by ''accidents of chemistry'' and also by specific metabolic processes.

This activity is designed to help students understand the structures and functions of the cell by building a model.

This 14-minute video lesson provides an overview of B cells (B lymphocytes) and how they are activated and produce antibodies. [Biology playlist: Lesson 53 of 71].

This 13-minute video lecture provides an introduction to what cancer is and how it is the by-product of broken DNA replication. [Biology playlist: Lesson 13 of 71].

This 10-minute video lesson discusses how cytotoxic T-Cells get activated by MHC-I/antigen complexes and then proceed to kill infected cells. [Biology playlist: Lesson 56 of 71].

This 19-minute video lesson looks at diffusion and osmosis. [Biology playlist: Lesson 36 of 71].

This 13-minute video lesson provides an overview of glycolysis. [Biology playlist: Lesson 24 of 71].

This 21-minute video lesson provides an introduction to helper T-Cells and their role in activating B cells. [Biology playlist: Lesson 55 of 71].

This 14-minute video lesson presents an introduction to cellular respiration, glycolysis, the Kreb's Cycle, and the electron transport chain. [Biology playlist: Lesson 21 of 71].

This 27-minute video lesson looks at the phases of Meiosis. [Biology playlist: Lesson 11 of 71].

This 21-minute video explains the phases of mitosis. [Biology playlist: Lesson 10 of 71].

This 12-minute video lesson looks at how professional antigen presenting cells present parts of engulfed pathogens on MHC II complexes (major histocompatibility complexes). [Biology playlist: Lesson 54 of 71].

This 11-minute video lesson provides a review of B cells, CD4+ T cells and CD8+ T cells. [Biology playlist: Lesson 57 of 71].

All living beings are made up of cells. Some of them are made up of only one cell and others have many cells. Also in: Dutch | French | Hungarian | Spanish

CK-12’s Life Science delivers a full course of study in the life sciences for the middle school student, relating an understanding of the history, disciplines, tools, and modern techniques of science to the exploration of cell biology, molecular biology, genetics, evolution, prokaryotes, protists,fungi, plants, animals, invertebrates, vertebrates, human biology, and ecology. This digital textbook was reviewed for its alignment with California content standards.

CK-12’s Life Science delivers a full course of study in the life sciences for the middle school student, relating an understanding of the history, disciplines, tools, and modern techniques of science to the exploration of cell biology, genetics, evolution, prokaryotes, protists, fungi, plants, the animal kingdom, the human body, and ecology. This digital textbook was reviewed for its alignment with California content standards.