The invisibly small world of the cell comes to life as students look at plant and animal cells through a microscope. Students create wet-mount slides of onion skin, elodea leaf, and human cheek cells. They learn some of the gross differences between plant and animal cells (cell walls are present in plant but not in animal cells), and even some of the differences between different plant cells (chloroplasts are found in the leaves but not in the roots). It is suggested that this lesson take place after students learn the parts of a cell and their functions. Resources for good cell diagrams are provided in the Sources section. This lesson may be used in conjunction with the Pond Water activity for students to get a sense of the diversity of microscopic life, both single celled and multi-celled.
Submitted by irene on Thu, 2006-07-27 12:56.
Mars Exploration Rovers: This special-effects image combines a model of the Mars rover Opportunity and 46 photogrpahs that Opportunity took of "Burns cliffs" near the edge of "Endurance Crater". Image courtesy of NASA/JPL-Caltech/Cornell.
In the summer of 2003, NASA’s Jet Propulsion Laboratory launched two Mars Exploration Rovers - Spirit and Opportunity - towards Mars. They landed on January 3rd and 4th, 2004. Their primary scientific goal was to study the geology of Mars and search for signs of water. Although they were expected to last only 3 months, they have been vigorously sending back data for over 2 years and are still going strong! In this activity, students receive simulated Martian soils and are given the task of designing 3 tests to determine whether the soil sample contains something alive or something that was once alive. They may use any of the tools from the previous lessons – agar plates, tests for organic molecules, microscopes, or something of their own design. This assignment allows students an opportunity to demonstrate what they have learned throughout the unit, both about scientific experimentation and about the special characteristics of living things.
Can describe the necessary characteristics of life.
Can categorize objects as alive or not alive using self-generated data.
Can demonstrate that all living things will grow and reproduce when provided with the proper nutrients and environmental conditions.
Can demonstrate that living things are made of organic molecules.
Can test for the presence of protein, glucose and starch.
Can design an experiment.
Can make observations and keep track of data over several days.
Can interpret the results of an experiment.
Submitted by irene on Wed, 2006-07-26 18:40.
All known life is made out of a small group of chemical compounds called organic molecules. Common organic molecules include proteins, glucose, starch, lipids, and nucleic acids. This lesson plan asks students to conduct tests for proteins, glucose, and starch. At the beginning of the activity, they choose 3 items to test: one known to be “never alive”, one known to be “once was alive”, and one mystery item. In addition, each station includes a positive control. By the end of the experiment, students should be familiar with some of the major organic molecules and should recognize that living things, and substances derived from them, are made of organic molecules. In addition, this is a chance to bring in topic surrounding nutrition, health, and digestion. Since our bodies are made up of organic molecules, we need each of these molecules as nutrients in our food.
Submitted by irene on Tue, 2006-07-25 15:24.
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.