Applied Human Genetics

Lab 5: Follow the instructions and complete the assignment below. Submit your answers through the Lab 5 Assignment on Blackboard.

Lab 5 1

Lab 5: Solvents and cells

Part 1: Chemistry of Molecules Read/watch the provided resources and take notes, applying the information to what we learned this week. CO2 and Soda: https://www.youtube.com/watch?v=HFCeV5BVBh0 Dissolving M&Ms: https://www.youtube.com/watch?v=umJmRaG6v80 When you are finished, answer the following questions: 1. You are having a debate with a friend about the science behind the Diet Coke and Mentos phenomenon. Your friend thinks that since the volume of matter after the experiment (the big mess) seems to be more than what was originally present in the individual components (soda/Mentos) before they were combined, that the “explosion” is the result of carbon dioxide being produced (made) by the reaction. Is this true? Does the amount of carbon dioxide increase through this reaction? Use what you’ve learned this week to verify or debunk your friend’s argument.

2. During the M&Ms experiment, why did the scientist emphasize that each of the treatments in this experiment needed to be stirred the same say, for the same length of time?

3. For the M&M experiment, name and describe the chemical property that is demonstrated by both the sugar and the candy coloring in the shell of an M&M that permits dissolution in the water, but not in the oil.

4. In your own words discuss this quote. Was Jamf mistaken in his understanding of the relative strengths of ionic and covalent bonds? Explain why/why not (in your own words!).

 

5. The scientific field of organic chemistry is based entirely on studying the chemical structure and reactivity (bonds and chemical reactions) of carbon containing molecules. Based on what you learned in class this week, discuss why carbon is so important that entire fields of study are dedicated to understanding and applying it.

 

 

 

 

Lab 5: Follow the instructions and complete the assignment below. Submit your answers through the Lab 5 Assignment on Blackboard.

Lab 5 2

Part 2: A Picture is Worth a Thousand Words This unit we learned about cells, their structure, and how they carry out the processes of life. We know that there are size restrictions that prevent living cells from being too small or too large. However, the rules that govern cell size may be more complex than scientists originally thought. The existence of ultra-small living cells has been debated for two decades. This debate was settled in February of 2015, when researchers from the U.S. Department of Energy’s National Laboratory at UC Berkeley obtained the first microscopy images of ultra-small bacteria- about as small as life can get. Follow this youtube link to view the research images/reconstructed videos of the cell structure: https://www.youtube.com/watch?v=ofNrtg-FpSc; primary article may be provided upon request. This part of the lab will focus on a popular media ScienceDaily article that summarizes the researchers’ findings. However, before we investigate these ultra-small nanobes, it is important that we fully comprehend the history and scientific impact behind this debate. For this, you’ll need to read the following extract: “In 1996, researchers published a description of a meteorite that fell from Mars, which sparked a long and complicated debate over the existence of what they called ‘nanobacteria’, later also described as nanobes. Various teams argued over whether life, theoretically, could live to be that size, but the debate didn’t really get anywhere because no one really had any evidence for either side. One side said all the things needed for life – DNA, RNA, proteins and solvents – couldn’t actually fit inside a cell that small, while others said life could be that small, but just in a starved, inactive state. Researchers argued over the theoretical limit for how small a cell could get in diameter and volume, and one team even reported finding some marine nanobes, but lacked direct microscopic evidence to prove they fit inside the size range to classify them as such. But now, such bacteria found in some Colorado groundwater have been imaged, and these things are undeniably tiny – several times tinier than several estimates for the lower size limit of life on Earth, in fact. And as difficult as it is to see them, the researchers think they could actually be quite common.” http://www.sciencealert.com/new-images-reveal-the-tiniest-known-life-forms-on-earth Next, click the link to read the article describing researchers’ findings and use this information, along with what you learned this week to answer the provided questions. https://www.sciencedaily.com/releases/2015/02/150227181339.htm When you are finished, answer the following questions: 6. The image at the beginning of the ScienceDaily article shows and describes the visible structure of the cell, and the authors state: “The cell has a very dense interior compartment and a complex cell wall.” As you remember from your readings, not all cell types contain a cell wall. What kinds of cells, other than bacteria, would you expect to possess a cell wall? List the

 

 

Lab 5: Follow the instructions and complete the assignment below. Submit your answers through the Lab 5 Assignment on Blackboard.

Lab 5 3

functions that this structure provides for these organisms. How do organisms that don’t have a cell wall execute these same functions? 7. The image at the beginning of the ScienceDaily article shows and describes the visible structure of the cell, and the authors state: “The darker spots at each end of the cell are most likely ribosomes.” Of all the different structures that could exist within a cell, why do you think that the authors think that these are ribosomes? (Hint: think about the types of cellular structures that are/aren’t found within bacteria, and what ribosomes do, and the importance of that job, within a cell.)

8. Interestingly, the ScienceDaily article states: “images also revealed dividing cells, indicating the bacteria were healthy and not starved to an abnormally small size.” This statement implies that in order for cells to divide they must be “healthy”. Discuss the requirements that a “healthy” eukaryotic cell must meet before it will under cell division. What are the consequences if a eukaryotic cell divides even if these requirements are not met? 9. The ScienceDaily authors state: “About 150 of these bacteria could fit inside an Escherichia coli cell and more than 150,000 cells could fit onto the tip of a human hair”. To provide you with some context so that you can really understand this statement: the spherical diameter of a

typical Escherichia coli cell is 1.3 m (micrometers), and the spherical diameter of these new

ultra-small bacteria is ~0.23 m. Compare the SVR of these new ultra-small bacteria to that of a typical E. coli cell (Hint: you need to calculate the SVR for each), which organism has a larger SVR, does this make sense in the context of the size of the cell? 10. Throughout the ScienceDaily article, the researchers studying these tiny bacteria acknowledge the challenges that such small cells face when it comes to performing the basic functions of life, and the additional challenges that limit our ability to study such small organisms. This makes sense, considering that previously calculated theoretical minimum diameter of a cell was established (and generally accepted by respected scientists and experts

in the field) to be 0.250-0.30 m. The authors say, “There isn’t a consensus over how small a free-living organism can be, and what the space optimization strategies may be for a cell at the lower size limit for life.” Why, before this, did scientists think that living cells couldn’t be much smaller than this lower limit (why is it that when a cell is too small, that it “can’t” survive)?

11. Choose another statement/quote from this article (or the other summary or the original research paper) and discuss how it relates to the material that we learned this week. Be sure to use specific examples (and your own words).