Inspired by observations of finches on the Galapagos Islands, Charles Darwin came up with an idea that is perhaps the most influential idea in all of science - natural selection. In this classic activity, students learn about natural selection by becoming birds foraging for food on an island (a large area of the schoolyard or classroom). The prey (beans) vary in their coloration such that some blend into the environment better than others. The birds vary in the type of beak they have (plastic forks, spoons and knives). Each season, any prey that survives has a baby bean the same color as the parent. In addition, the most successful birds has a baby with the same beak trait while the least successful birds die (and are reincarnated as the babies of the successful birds). Over several generations, the bird and bean populations shift depending on the environment. Well camouflaged beans survive and reproduce. Birds with beaks that can easily capture beans survive and reproduce. In this way, students model natural selection in 2 species and get a very good idea of how natural selection works.
Submitted by irene on Sat, 2006-07-22 11:42.
Students create DNA models from beads and wire that may be used as earrings, pendants, Christmas ornaments, and/or key chain pulls. This project is simple enough that a good substitute could lead the students through it since the content should be taught beforehand. More importantly, this is just one of many possible 3D DNA models you could have your students build. Be creative! Use gumdrops, Styrofoam, marshmallows, Legos, grapes, wood, aluminum cans, etc. Better yet, have your students design a model independently.
Submitted by irene on Fri, 2006-07-14 10:28.
Sickle Cell Anemia
Sickle-shaped red blood cellsSickle cell disease is a disorder that affects the red blood cells. Red blood cells use a protein called hemoglobin to transport oxygen from the lungs to the rest of the body. Normally, red blood cells are round and flexible so they can travel freely through the narrow blood vessels.
Patients with sickle cell disease have a mutation in a gene that codes for part of the hemoglobin protein. As a result, hemoglobin does not form properly, causing red blood cells to be oddly shaped. These irregularly shaped cells get stuck in the blood vessels and are unable to transport oxygen properly, causing pain, frequent infections, and damage to the organs. Patients with sickle cell disease only survive to be 20 to 30 years old. About 1 in 500 babies born in America has the disease.
The normal hemoglobin nucleic acid sequence looks like:
T A C C A C G T G G A C T G A G G A C T C
A T G G T G C A C C T G A C T C C T G A G
Submitted by irene on Fri, 2006-07-14 06:33.
Cycstic fibrosis breathing apparatusCystic fibrosis is a genetic disease that affects many different parts of the body. There are approximately 30,000 Americans with cystic fibrosis. The most serious problem is the production of extremely thick, sticky mucus that clogs up the bronchial tubes in the lungs and the passageways in the pancreas (remember, the pancreas makes digestive juices that help break down food). This causes malnutrition, diabetes, lung infections, and difficulty getting enough oxygen to the body. Most people with cystic fibrosis die in their 20s or 30s from lung failure.
Submitted by irene on Fri, 2006-07-14 06:26.
The following are a series of real world genetics problems that relate to the genetic disorders cystic fibrosis and sickle cell anemia. They may be used to give students practice with Mendelian genetics and molecular biology or at the end of the unit to assess their understanding of various concepts.
Reinforce and assess students understanding of real world genetics issues.
Submitted by irene on Fri, 2006-07-14 06:13.
In this long term computer based simulation, students play with a fabulous FREE software program called Biologica developed by the Concord Consortium. It offers an in depth, virtual experience exploring Mendelian inheritance patterns in dragons. Activities increase in complexity from initial modules introducing dragons and their chromosomes to later activities that require problem solving skills and the integration of many levels of prior knowledge. In the program, you can manipulate dragon chromosomes, breed dragons, explore pedigrees, and more. There are fantastic puzzles along the way: Which gametes should you select to breed a purple, fire breathing, boy dragon? What happens if you change the DNA sequence? Can you figure out the genotype of invisible dragon parents from the phenotypes of their offspring?
Submitted by irene on Thu, 2006-07-13 21:44.
Variation in a population is the raw material on which natural selection works. How do scientists measure and quantify variation in traits? We use garden snails as a model organism in order to describe and measure several different traits. Groups are given a small population of snails and must devise an objective way to measure a trait of their choosing (length, mass, speed, color intensity, stripes, withdrawal reflex reaction time, number of pennies it can carry, etc.). There are many ways to extend this activity. For instance, scientific protocols may be traded between groups, hypotheses may be made concerning what individuals will survive better in different environments, and snails may be tagged and released into one or more environments and the populations monitored over time. A long term open-ended project such as this provides a natural extension and assessment opportunity for both evolution and ecology concepts.
Submitted by irene on Thu, 2006-07-13 21:13.
DNA adding tapeSummary
In this CSI activity, students solve a mystery using “DNA” taken from the scene of the crime. This write up describes how to collect a “DNA sample” (student invented DNA sequence on adding machine tape) from the culprit and from each person in the class, then run the DNA on a “gel” that covers the floor of the classroom, a hallway, or gymnasium. Naturally, the CSI aspect can become as elaborate as you wish by including additional “clues” such as fingerprints, a ransom note written in a specific type of ink, cloth fibers, eyewitness accounts and more. Since both DNA fingerprinting and paper chromatography (see Sources for lesson plans) rely on the same principles – separating molecules by size – a crime scene in which there is both a note written in a specific type of water-based ink as well as a DNA sample that may compared to the students’ DNA draws some interesting parallels conceptually between these two CSI techniques.
Submitted by irene on Thu, 2006-07-13 20:47.
Protein synthesis comic strip: Created by teachers from the Science STARTS/Delta Sierra Science Program summer institute
Let your creative juices flow. The process of translating nucleic acids into amino acids becomes a tale of suspense, drama and adventure as you come up with a Marvel Comics style adventure story that is an analogy for protein synthesis. Draw comparisons between DNA and a secret message written in code. Compare ribosomes to factories churning out products. Students will surprise you with the crazy analogies they can come up with and the elegant stories they can spin.
Reinforce and assess students’ understanding of the central dogma of molecular biology.
Submitted by irene on Mon, 2006-07-10 21:11.
Example secret DNA code
Kids love secret codes and secret messages. In this activity, kids first discover how codes work by reading and writing secret messages written in Morse code. Next, they make up their own secret codes and trade messages written in their self-created code. Finally, students learn how DNA codes for a “secret” protein message in a two step coding system – the genetic code. Since each of the 20 amino acids has a one letter abbreviation, student can discover the secret protein “messages” encoded in a DNA strand. Several secret DNA messages are provided for students to decode under the assessments section. For homework, students can be challenged to write a secret message to a friend using the genetic code.
Can explain how DNA codes for a sequence of amino acids.
Can begin to explain some of the differences between DNA and RNA.
Can begin to describe the process of transcription and translation.
Submitted by irene on Mon, 2006-07-10 19:57.