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Vibrio harveyi is a marine bacteria that emits light only at high population density. The bacterial bioluminescence is controlled by a system called quorum sensing. In this system, signaling molecules are secreted, and when they bind to cell surface receptors, they turn on many genes, including those that produce bioluminescence.

Stem Cell Overview Article with embedded Video 7:53 Discusses gene expression/differentiation 2 minute segments -Pluripotent stem cells in early embryo CDX2 OCT3/4, Inner cell mass start- 1:50 - Characteristics of Stem Cells: differentiation, abilities of stem cells,  1:55- 3:17 - Stem Cells in the Adult Body: red blood cell hematopoetic stem cells, differentiation, small intestine crypts,  3:20-5:35 - Embryonic Stem Cells in Culture: ES pluripotent cells ES cells, treat to neural lineages, culture conditions, study differentiate into lineages 5:40- 7:53

In this audio slide show, Dr. Dana Dolinoy of Duke University explains the role that the epigenome, a sort of second genome, plays in regulating the expression of our genes. As Dolinoy notes, we can no longer say with certainty whether genetics or the environment have a greater impact on our health, because the two are inextricably linked through the epigenome.

Almost every cell in the human body has the same DNA sequence. So why is a heart cell different from a brain cell? Cells use their DNA code in different ways, depending on their jobs - just as the orchestra in this video can perform one piece of music in many different ways. The combination of changes in gene expression in a cell is called its epigenome.

Graham Williams at the University of Huddersfield, UK, has a different way - to look for modifications to the twins' DNA that have come about as a result of their lifestyles. Such epigenetic changes occur when a chemical group known as a methyl group attaches to a gene and modifies the way it is expressed. This happens as a body is influenced by a person's environment, lifestyle and disease.

Epigenetics refers to heritable changes in gene expression caused by non-genetic mechanisms, thus by alterations other than in the DNA sequence. Epigenetic changes can persist throughout an organism's lifetime and be passed on to multiple generations. Site offers 4 part "crash course" in epigenetics

9:30 video Hank & his clone Circus Hank explain the power of epigenetics, which studies the factors that determine how much or whether some genes are expressed in your body.

The following sequence of activities is designed to help your students continue their investigation into how characteristics of living things are passed on from generation to generation. This time we are looking at multifactorial traits and how the genes and environment play a role in the final expression of the trait.

1:30 A short film about DNA microarrays, and how they are used to show dynamic gene expression levels.

Almost every cell in the human body has the same DNA sequence. So why is a heart cell different from a brain cell? Cells use their DNA code in different ways, depending on their jobs - just as the orchestra in this video can perform one piece of music in many different ways. The combination of changes in gene expression in a cell is called its epigenome

This site has you covered, no matter what you teach. Each science subject is divided into major topics and resources are neatly categorized and numerous.

Sure, we know insufficient serotonin levels get a bad rap when it comes to depression, but that's like blaming one person in a full-scale riot. Depression isn't caused by only one factor. In fact, study co-author Elyse Aurbach says we're probably not getting to the core of why people are depressed because "the brain is immensely complex." In this study, the research team conducted eight experiments (four on animal brains, four on brains of the deceased human kind) of varying sample sizes - from 20 to 90 brains in each - and found that the brains of deceased humans who'd been depressed had increased levels of hippocampal FGF9 and that live animals with increased FGF9 levels demonstrated depressive, anxious behavior. "This is not just a correlation," study leader Huda Akil of the University of Michigan says. Less really may be more, at least when it comes to FGF9.

Explore some examples of specialized plant and animal cells with the Amoeba Sisters! This video explains how specialized cell structure suits their function.

Teacher website with great worksheets and links

2 min video clip showing experimental process

Interactive media book with areas to learn, explore, and analyze microarray data