Spores in Space
Most people know of the Apollo Moon flights that brought American astronauts to the Moon in the 1970's. But few know that the crew of Apollo 12 brought back stowaway bacteria that had been a contaminant of camera equipment left almost three years on the Moon from an earlier flight. The 50-100 Streptococcus mitis stowawaybacteria had survived the scorching heat of launch, space vacuum, 3 years of radiation exposure, deep-freeze at an average temperature of only 20 degrees above absolute zero, and no nutrient, water or energy source. One way that bacteria can survive sterile life-killing conditions as found in Space is to encapsulate itself in a protective layer called a spore and go into a hibernating state. Many Earth organisms form a encapsulating spore which protects it from the outside environment when environmental conditions become too harsh for survival. Besides many bacteria (prokaryote cells), fungi (eukaryote cells) form spores and even a frog in Africa can encapsulate itself when ponds dry up, burying itself in the muddy bottom of the dry ponds in wait until rains return when the frog emerges from hibernation to live again. Scientists now know from experimental evidence that certain microbes are hardy enough to survive the hazards of space travel such as hitchhiking on a rock that might have been ejected into space following a large bolide (big rock from space!) impact. Could it therefore be possible that microbes have “hopped” between the planets or even “seeded” some planets with first life? Astrobiologists say it is a real possibility given that we now know how often planets lose material to space following frequent bolideimpacts. In fact scientists have identified rocks from Mars here on Earth and some have claimed they see evidence of the imprints of "Martian bacteria" in the microscopic pores seen under a microscope in the rocks. In this experiment we will observe how some organisms might survive the harsh conditions of outer space. You will be looking at a more complicated organism than bacteria. You will try to revive Saccharomyces cerevisiae, common baker’s yeast. What kingdom of life do yeast belong to? ______
Follow the instructions below!
1. One person from each group should bring a bag to Mr. Cypher and get a spoonful of dry (spore) yeast to take back to the group. Look at your yeast spores in your bag. Write at least threeobservations of the dry yeast below (color, smell, size, etc.).
2. Now add a little warm water to the bag and add a sugar cube. Squeeze the air out of the bag and seal it. Give the yeast in the bag a few minutes to revive itself out of hibernation and then observe what happens and write what you observe below.
3. After you have written down the changes you saw in the closed bag, open the bag slowly and observe any new changes. Carefully smell the yeast too! Has the color changed? How does the revived yeast smell compared to the dry (spore) yeast? Write what you observe then throw away the bag in the garbage can. Then turn this paper over to answer questions on the back!
Answer the following question as best you can.
1. What conditions were necessary to revive the yeast?
Scientists hypothesize that the one absolutely essential ingredient for life is liquid water. Ice is found throughout our solar system, but liquid water is far more rare. Where is liquid water known to be in our solar system?
Are they any other places you have learned where liquid water may be in our solar system?
Where is ice found in our solar system? Look at your notes about the Outer Planets!
All life must have an energy source. What was the energy source in the bag?
2. Can you guess what gas was produced in the bag? Here's a hint: all living organisms "breathe" it out during the process of respiration.
Recall from 7th Grade Life Science that respiration is a process that is involved in the digestion of food. Food is carbon based. When carbon based food is combined with oxygen the result is the gas carbon dioxide: CO2. Look at the Periodic Table on wall of the classroom. Can you find and write down the symbols for carbon and oxygen?
3. Based on what you learned in this lab, fill in the blanks in the sentence that follows. How do yeast survive the sterile conditions of being stored for long times at the supermarket or in you home? They form a ______and go into a state of ______.
Based on what you learned in this lab, what kind of organism is yeast? What kind of cell do these organisms have (prokaryote or eukaryote)?
4. What advantage might yeast have in potentially making a long exposed space flight?
5. Your yeast has a genus and species name: Saccharomyces cerevisiae. Commonly known as baker’s yeastit is used to make bread rise when baking bread. What makes the bread rise when revived yeast is folded into the batter?
6. Finally, use your imagination to do a drawing of an individual yeast cell “sleeping” inside it’s personal protective spore capsules. Yeast has DNA inside a nucleus, mitochondria (where cell respiration occurs) and all the other parts contained in “true” cells. The eu in eukaryote means true. And karyo comes from karuon or kernel or nut, like in a plant.