BBC Nature - History of life on Earth SAPS Student Resources Homepage Frontpage Slideshow | Copyright © 2006-2010 JoomlaWorks, a business unit of Nuevvo Webware Ltd. SAPS Student Resources Homepage Find out where a career in biology might take you with this collection of case studies - 10 biologists take us through their daily routine, share their advice and tell us how they got into their current job. Find out more Are you planning to do an extended project on a topic in biology? See the project ideas
The Genetics of Resistance to HIV Infection Evolutionary biologists have developed many techniques to analyze how male and female mating preferences have co-evolved. These studies combine animal behavior, sensory biology, phylogenetics, and neurobiology to observe the effects of male trait biases based on female receiver systems; that is, the “attractiveness” of the male trait to potential female mating partners. In this case study you will learn about the mating calls of Physalaemus frogs, and how the calls have evolved over time. You also will see how scientists use molecular information to develop an evolutionary tree based on sequence homology. Before beginning this case study, you may want to review these related materials: • Evolution and Phylogenetics Video • Evolution and Phylogenetics Online Text • Genomics Online Text
Timeline: The evolution of life - life - 14 July 2009 Read full article Continue reading page |1|2|3|4 There are all sorts of ways to reconstruct the history of life on Earth. Pinning down when specific events occurred is often tricky, though. For this, biologists depend mainly on dating the rocks in which fossils are found, and by looking at the "molecular clocks" in the DNA of living organisms. There are problems with each of these methods. Modern genetics allows scientists to measure how different species are from each other at a molecular level, and thus to estimate how much time has passed since a single lineage split into different species. These difficulties mean that the dates in the timeline should be taken as approximate. 3.8 billion years ago? This is our current "best guess" for the beginning of life on Earth. , and was probably based on RNA rather than DNA. At some point far back in time, a common ancestor gave rise to two main groups of life: bacteria and archaea. 3.5 billion years ago 3.46 billion years ago 3.4 billion years ago
WELCOME to DOC BROWN'S SCIENCE Biology Chemistry Physics gcse igcse A level HOMEPAGE docbrown chemhelp iphone ipad notepad notebook netbook epad tablet android NOT apps GCSE Bitesize: Darwin's theory of evolution Virtual Microscope Beagle Voyage 26 December 1831 - to - 27 February 1832 Crossing the Atlantic Ocean: H.M.S. Beagle leaves Plymouth Harbor A tour of the Madeira and Canary islands Landfall at the Cape Verde islands The weather was now quite fine and the Beagle was ready to set sail on 26 December. "Never, I believe, did a vessel leave England better provided, or fitted for the service she was destined to perform, and for the health and comfort of her crew, than the Beagle. The Beagle arrived near Madeira Island, its first port-of-call, on 4 January 1832. Capt. "This was a great disappointment to Mr. H.M.S. Darwin made detailed observations of a cuttle-fish that populated the tide pools around the island, and was fascinated by their ability to change colors. Darwin's Discovery: It was on Santiago that Darwin made his first curious discovery. The Beagle left Santiago on 7 February and sailed towards Brazil, stopping for one day St.
What is DNA and how does it work? Human Evolution Evidence Scientists have discovered a wealth of evidence concerning human evolution, and this evidence comes in many forms. Thousands of human fossils enable researchers and students to study the changes that occurred in brain and body size, locomotion, diet, and other aspects regarding the way of life of early human species over the past 6 million years. Millions of stone tools, figurines and paintings, footprints, and other traces of human behavior in the prehistoric record tell about where and how early humans lived and when certain technological innovations were invented. Exciting scientific discoveries continually add to the broader and deeper public knowledge of human evolution.
For Teachers - Origami DNA Origami DNA Type: Classroom activity Age level: 10 years + Topic area: DNA, DNA structure Description: A practical activity for the classroom that allows the students to create an origami model of DNA, demonstrating its double helix structure. Two templates are available as PDFs; a standard template with the base pairs already coloured or a blank template where the students have to colour the four bases A, C, T and G and mark them in the correct location on the template. Running the activity: To run this activity each student will require: one template and one instruction sheet. If you choose to use the blank template, you will need to provide students with colouring-in pencils or pens to complete the base pairs. Credits: Concept and content: Alex BatemanGraphics: Preeti Deshpande Support Links: DNA Origami activity downloads A paper based activity where students can make an origami double Helix. Origami DNA instructions Origami DNA template only Instructions for using blank template Related items:
The Origin and Evolution of Life the basic outline of the origin of life is believed to be: formation of earth 4.6 bya formation of monomers (simple amino acids, sugars, etc) formation of polymers (proteinoids, nucleic acids, etc) lipid synthesis for membranes (phospholipids) formation of a protobiont RNA is believed to be the first information molecule; DNA likely came later 3 different scenarios exist regarding how life began: tidal pools, with drying and rewetting, offered an excellent medium to accumulate monomers and polymerize them; then form coascervates which would have been precursors of protobionts panspermia - a cosmic origin of life where organisms from other planets seeded earth via a meteor undersea thermal vents, which provide the necessary energy and catalysts for life's origins one scenario: required 60°C heat, produced polymers of 100 amino acids (MW > 10,000) this may have occurred in tidal pools where periodic drying occurred adding polymers to water forms larger structures an early life form would have required: