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In this video Paul Andersen explains how to run the student's t-test on a set of data. He starts by explaining conceptually how a t-value can be used to determine the statistical difference between two samples. He then shows you how to use a t-test to test the null hypothesis. He finally gives you a separate data set that can be used to practice running the test.

How does a Killer T Cell Kill its target? Our new film captures the behaviour of cytotoxic T cells - the body's 'serial killers' - as they hunt down and eliminate cancer cells before moving on to their next target.

HIV is a disease of the gut, a concept that's easy to lose sight of with all the attention paid to sexual transmission and blood measurements of the virus and the CD4+ T cells it infects and kills. But the bottom line is that about two thirds of all T cells reside in the lymphoid tissue of the gut, where the virus spreads after exposure, even before it shows up in blood.

DNA has a double helix structure. If untwisted, DNA looks like two parallel strands. Each strand has a linear sequence of A, C, G, and T. The precise order of the letters carries the coded instructions. One strand is a complementary image of the other: A always pairs with T, and C always pairs with G.

This set of mini cases on the ecology of eastern cottontail rabbits is designed to give students practical experience using statistics in a scientific context. Given a dataset and experimental design, groups of students are asked to play the part of a wildlife management researcher to determine the results for each study. Students practice the scientific process and gain experience making hypotheses and predictions, choosing an appropriate statistical test, interpreting and displaying results, and presenting data to others. Students choose between four basic, commonly used, statistical tests (t-test, one-way ANOVA, linear regression, and Chi-square test), and justify their choices. This activity was developed for undergraduate level students and is applicable to biology courses, particularly those dealing with ecology or management. The case is designed for student groups, but could be modified into clicker questions or individual assignments.

An overview of the immune system, concentrating on the roles played by B and T lymphocytes, and the antigen-presentation system.

4:42 At least one entire class of dinosaurs seems to have had feathers -- including velociraptors, and probably T. rex. Find out how we know, and how we even know what color some of them were!

Immune cell maturation details

Published on Feb 19, 2015 View full lesson: http://ed.ted.com/lessons/what-does-t... Beneath your ribs, you'll find, among other things, the pancreas -- an organ that works a lot like a personal health coach. Emma Bryce explains how this organ controls your sugar levels and produces a special juice that releases the nutrients from your food to help keep you in the best possible shape. Lesson by Emma Bryce, animation by Tremendousness.

HPV is considered one of the most common sexually transmitted infections, and it affects both men and women! Is it dangerous, and can it be prevented? Get your official DNews t-shirt here: http://www.forhumanpeoples.com/collec... Read More: Genital HPV Infection - Fact Sheet http://www.cdc.gov/std/hpv/stdfact-hp... "Human papillomavirus (HPV) is the most common sexually transmitted infection in the United States. Some health effects caused by HPV can be prevented with vaccines." Time To Rethink 'Girls-Only' Approach To HPV Vaccine? http://www.futurity.org/hpv-vaccines-... "Encouraging parents to have their sons get the human papillomavirus (HPV) vaccine-rather than just trying to get more girls vaccinated-could ultimately protect more people for the same price, according to a study by a mathematician."

Every second of your life you are under attack. Bacteria, viruses, spores and more living stuff wants to enter your body and use its resources for itself. The immune system is a powerful army of cells that fights like a T-Rex on speed and sacrifices itself for your survival. Without it you would die in no time. This sounds simple but the reality is complex, beautiful and just awesome. An animation of the immune system.

We see color because of specialized light-sensing cells in our eyes called cones. One type, L-cones, sees the reds of strawberries and fire trucks; M-cones detect green leaves, and S-cones let us know the sky is blue. But vision scientists have now discovered that not all cones sense color (see video).

CRISPR still has a long way to go before it can be used safely and effectively to repair-not just disrupt-genes in people. That is particularly true for most diseases, such as muscular dystrophy and cystic fibrosis, which require correcting genes in a living person because if the cells were first removed and repaired then put back, too few would survive. And the need to treat cells inside the body means gene editing faces many of the same delivery challenges as gene transfer-researchers must devise efficient ways to get a working CRISPR into specific tissues in a person, for example. CRISPR also poses its own safety risks. Most often mentioned is that the Cas9 enzyme that CRISPR uses to cleave DNA at a specific location could also make cuts where it's not intended to, potentially causing cancer.

Animation of the central Dogma 10 minutes

Transgenic glow in the dark cloned cats

Hank tells us about the team of deadly ninja assassins that is tasked with protecting our bodies from all the bad guys that want to kill us - also known as our immune system.

10:47 animation with text

Students who used longhand remembered more and had a deeper understanding of the material

Teacher site with detailed instructions for using Google for online science notebooks.

A dynamic 3D computer animated video takes you "inside" for a close-up look at how we're made. Watch as the mysteries of the Human Genome are literally "unraveled." 3D modeling and animation created by Bill Baker, Bakedmedia, Inc. and Mike Fisher for the National Human Genome Research Institute.