My Science Box

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.

Summary
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.

Objectives
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.

Vocabulary
Characteristic
Agar
Nutrients
Yeast
Organic molecule
Protein
Biuret solution
Carbohydrates
Glucose
Benedict’s solution
Starch
Iodine
Microscope

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

Cystic Fibrosis
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.

Summary
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.

Objectives
Reinforce and assess students understanding of real world genetics issues.

Protein synthesis comic strip: Created by teachers from the Science STARTS/Delta Sierra Science Program summer institute

Summary
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.

Objectives
Reinforce and assess students’ understanding of the central dogma of molecular biology.

Vocabulary
DNA
Genetic code
Nucleotide
Base pair
RNA polymerase
Messenger RNA
Transfer RNA
Amino acid
Ribosome

Summary
This is an alternative assessment activity in which students pull apart a rotting log as an example of a microhabitat that can be explored in the classroom. As they dissect the log and discover the myriad of bizarre creatures on and inside the log, the notes the students keep can be used as an assessment of many of the major concepts in this unit. Another use for this lab is as an engaging way introduce a very special organism-organism relationship, symbiosis. Termites have a symbiotic relationship with the protozoa in their gut. The protozoa that digest the cellulose in the wood for the termites, can be extracted from the termites’ gut and observed under a microscope. One of my students who witnessed the extraction and then saw the protozoa proclaimed “That was the coolest thing I have ever seen. Ever.” Finally, if you are just fascinated by termites and want to become completely enamoured, try putting a termite on a line drawn by a Bic pen…