Year 12 Genetics and Evolution

Reminder: There are three key areas to this topic:

• The source of variation, including meiosis and mutations
• Dihybrid crosses and the inheritance of two traits at once
• Population genetics

 One of the best animations of meiosis I’ve seen!
Here is an extended version (with no narration) placing meiosis in the context of sexual reproduction. (It has a fantastic sequence on fertilisation and mitosis, although takes some artistic licence...)

Another great meiosis clip which covers how it results in variation too.

MEIOSIS AND MUTATIONS

• Stages of meiosis - Beautifully coloured animation with a quiz.
• Meiosis - Nice animation with stage names and controllable slider. Step-through or narrated.
• Mitosis and Meiosis Comparison 1 and Comparison 2 - Animation is the same for both, but quiz differs.
• BBC Biology: Meiosis - Revision bite on meiosis, including a step-through animation and a video which clearly shows crossing over. Test at the end.
• Special features of meiosis - Shows crossing over in closer detail as well as highlights the reduction division
• Crossing over interactive - Click through the stages to see how crossing over creates new combination of alleles (using colours, rather than letters, to represent alleles)
• Crossing Over Causes Genetic Variation - Simple animation showing how crossing over reshuffles alleles and results in unique gametes.
• Meiosis tutorial - Tutorial, diagrams, text, animations, quiz. Pretty long, I guess.
• Independent assortment - The importance of independent assortment in bringing about variation. Animation and text.
• Random orientation of chromosomes during meiosis - Another animation of independent assortment. A pretty one.
• Independent assortment and gamete diversity - An animated and narrated or step-through tutorial and a quiz. Good coverage.
• Independent Assortment Causes Genetic Variation - Simple animations to show how different assortments in each meiotic division of identical cells by meiosis can result in different sets of chromosomes in gametes.
• Evolution 101: Genetic variation - Click through the pages to review how variation comes about, including through mutations and meiosis.
• Genetics and adaptations - Mutations - Includes gene mutations,chromosome mutations, non-disjunction mutations, mutagens and polyploidy. Step-through interactives to help show you the different types.Too much depth for 2011’s Year 12, but still worth bearing in mind.

GENETICS CROSSES

• BBC Science: What is inheritance? - The revision bite that reminds you about inheritance and genetics, from inherited characteristics, through monohybrid crosses and the difference between expected and actual results to sex determination. Of course, there is a test bite at the end.
• BBC Biology: The dihybrid cross - The all-important dihybrid cross. One page overview, then a challenging test.
• Virtual Mouse – genetics - Time limited gizmo (5 minutes?) so work fast! Leads you through the thinking behind inheritance and alleles using a coin-toss model, how genotypes affect phenotypes, and you actually get to breed virtual mice! Also does dihybrid crosses using an online simulator.
• Drag-and-drop genetics cross practice problems - Practise a genetic cross on this interactive webpage. Just stick with this on page, then try the practice problems 1, 2 and 4 on this site.
• Genetics Practice Problems - An excellent way to check if you really know how to do those crosses. Do Monohybrid, Test cross and Dihybrid cross only. The rest can wait till next year.
• Mendelian genetics at The Biology Project - Monohybrid crosses, dihybrid crosses, and sex-linked inheritance. Do these when you are well and truly confident. You need to do your working on a separate sheet of paper.
• Dihybrid inheritance - How independent assortment results in 4 different phenotypes when looking at the inheritances of two traits at once. Uses round/wrinkled yellow/green peas. Interactive.
• Pedigree Problems - Notes on how to spot dominant or recessive conditions, (and whether something is X-linked or not). Not great, but there’s not a lot out there!

EVOLUTION & NATURAL SELECTION

• Genetic drift - Animated tutorial and quiz about drift in plants.
• Natural selection - Animated tutorial and quiz about selection of Darwin’s finches.
• Gene flow - Shows how migration can introduce new alleles to a population.
• Natural selection - Step-through or narrated animation of natural selection of butterflies includng (Batesian mimicry and) stabilising, directional and disruptive selection.
• BBC Science: Survival of the fittest - Evidence for and mechanisms of evolution.
• BBC Biology: Natural selection & speciation - Superb resource for this often difficult topic, including some thoughtful and highly relevant questions and answers. Supported by built-in video clips. (Speciation not needed at Y12 in 2011)
• Nowhere to Hide - Simple interactive where bugs come in two colours: green and orange, and get eaten by birds. You can change the colour of the background and see how that affects the proportion of the population that is each colour of bug
• Evolution in action - Interactive: Change the colour of the background and see what happens to a population of….things. Can keep going with this for ages. Experiment with rapid changes and slow changes to the background colour.
• Peppered moth simulation - Peppered moth simulation with a bluejay. Simulates lichen forest and sooty forest with stationary and moving moths. Can you, as the bluejay, find enough moth to not starve?
• Evolution 101: Natural selection - Click through the pages to review natural selection including how it leads to adaptation and clarifying misconceptions.
• Evolution 101: Genetic drift – Good notes and a model of sampling showing how drift can quickly result in the loss of variation from a population. Some mention of bottleneck and founder effect also.
• Mechanisms of Evolution - A maybe not so good animation depicting the effects of genetic drift, gene flow, mutations, non-random mating, and natural selection on allele frequences in a fish population.
• Founder effect or bottleneck? - Weird animation. The text and narration describe a bottleneck, but the animation is definitely showing founder effect.
• Simulation of genetic drift - What it says. Shows how alleles can be lost or fixed in small populations, but tend not to fluctuate so wildly in large ones. Comes with a short quiz to check understanding.

Year 11 DNA replication and cell division

THE STRUCTURE OF DNA AND DNA REPLICATION

• Genes and Inheritance  - A fairly comprehensive review of Year 11 Genetics. Mouseover specific terms to be reminded of definitions. Each page has a quiz at the end to check your understanding. Some interesting applications of inheritance with respect to genetically inherited diseases. A complete quiz at the end.
• Tour of the basics of genetics - Animations to remind you of the structure of DNA and how it works.
• Structure of DNA  - A narrated video to watch. Nice because it shows how the actual atoms in the molecule are arranged. Very complex in the vocab, so at best, just watch the pictures.
• DNA workshop: DNA replication (& protein synthesis) - Interactive animations to review the processes of DNA replication (and protein synthesis). Get involved; it doesn’t take long!
• DNA replication – This animation includes more of the nitty gritty of replication, showing the enzymes that are involved. e.g. helicase, polymerases, ligase.

HOW SCIENTISTS MADE THEIR DISCOVERIES ABOUT DNA

This isn't examined at any level, but it's still interesting!

• Meselson-Stahl experiment: DNA replication - How scientists found out that DNA replicates by unzipping and copying complementary strands.
• Decoding DNA - The science involved in decoding DNA – finding the sequence. More for 13BIO, but interesting nevertheless.
• DNA from the beginning - A huuuuuuge resource including text, animations, and a lot of the science behind the knowledge. Use the menus down the side to navigate through some of the main points of the genetics topic. Of the three main sections, Classical Genetics and Molecules of Genetics are the most relevant.

MITOSIS
Don't worry about the names of stages, just watch what the chromosomes are doing.

Here's a clip of mitosis in 3 dimensions. The narration is complex but the animation is good.

• Mitosis -Narrated and/or step-through animation of mitosis with a quiz at the end.
• Cells Alive - mitosis - Compare a diagram of mitosis with photographs of an actual real cell dividing.
• Mitosis and the cell cycle - Narrated animation and a quiz. Animation is nice but the text level is high.
• Mitosis and cytokinesis - Narrated animation and a quiz. Animation is nice but the text level is high.
• BBC Science: Cell division - Cell division by mitosis, including stages, and then a test.
• Mitosis: Interactive Java Tutorial - Very detailed description of mitosis, and an animation to boot. Not particularly interactive.
• Genetics Review: Mitosis - Brief diagram and text reminder of the names of the stages of mitosis for Year 13.
• Mitosis and cytokinesis - Animation of these processes in a plant cell. High level text. 
• Cell division and cancer - Extra for experts. A somewhat long but good review of cell structure including specialisation, as well as cell division by mitosis (with an animation; no stage names). Includes what happens when cell division goes out of control i.e. cancer. Self-check tests throughout. 

MEIOSIS

Best animation I have seen of the first division, but doesn't feature much detail on the second division.

• Stages of meiosis - Beautifully coloured animation with a quiz.
• Meiosis - Nice animation with stage names and controllable slider. Step-through or narrated.
• Mitosis and Meiosis Comparison 1 and Comparison 2 - Animation is the same for both, but quiz differs.
• Special features of meiosis - Shows crossing over in closer detail as well as highlights the reduction division
• Crossing over interactive - Click through the stages to see how crossing over creates new combination of alleles (using colours, rather than letters, to represent alleles)
• Random orientation of chromosomes during meiosis - Another animation of independent assortment. A pretty one.
• Independent assortment and gamete diversity - An animated and narrated or step-through tutorial and a quiz. Good coverage.

MITOSIS VS MEIOSIS: COMPARISONS

• How Cells Divide: Mitosis vs Meiosis - A brilliant side-by-side animation comparison of these two cell divisions which highlights the differences between them. Stages are named and described but can be ignored for Year 11 and 12. If the flash doesn’t work for you, try the text-only link here.
• Comparison of meiosis and mitosis - Another superb animation of meiosis vs mitosis. This one you can fast forward and rewind easily.