BIOL 1000 Chapter Notes - Chapter 21: Lipid A, Boiling Point, Euryarchaeota
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I need help on this microbiology question:
Contrary to our favorite science fiction books and movies, the chances of us finding another planet with a civilization comparable to, or even more advanced than our own, seems highly unlikely. But, through your work as a microbiologist at NASA, you have been able to help change our views as to what forms of life we should be looking for on planets in our solar system and around neighboring stars. Instead of radio signals or errant transmissions, we have begun looking for planets that have environments similar to those capable of sustaining life as we know it here on Earth. To determine what we could find out there, you have begun studying different unique and atypical environments found here on Earth. Although the harsh conditions of hot springs or undersea sulfur vents seem incompatible with most forms of life, organisms known collectively as "extremophiles" have still managed to survive and adapt to these extreme conditions. You believe extremophiles may help you gain insight into the potential metabolic requirements, processes, and challenges of extraterrestrial life. Thus far in your search, you have identified some prokaryotic cells that have evolved to survive in the extreme conditions of sulfur vents on the sea floor. These vents are found at great depths, where the crushing pressure and lack of light and oxygen are prohibitive to many forms of life. Bacteria that are not considered extremophiles reside in most ecological niches on this planet. There are some common criteria for the environment that would sustain these bacteria. Availability of water, pH that lies between 5 and 9, temperatures that will remain steady and below boiling; these are some of the characteristics that bacteria will require in their environment if they are to succeed. But in the environment of the ocean floor vents, not only is the pH of the water very low, but also the water temperature is unusually high due to the geologic activity that fuels the vents. Organisms that are adapted to such harsh conditions have necessarily evolved enzymes able to function beyond average optima, as well as a chemosynthetic metabolism capable of using vent organic and inorganic compounds as energy sources.
Part A - Comparable Earth Environments to Be Found on Another Planet
You identify the prokaryotic cells you've found as a species of bacteria. These bacteria appear to be living off of nutrients and sulfur compounds released from the vents on the sea floor. Over time, the bacteria must have evolved extreme metabolic and enzymatic capabilities to allow them to tolerate and even benefit from the extreme depths, the lack of oxygen, the low pH of the surrounding waters, high temperatures due to volcanic releases, and the unique nutrient source of the vents.
Choose the characteristics and their impact on enzyme activity that are not correct from the following statements. (more than one may be chosen)
| Archaea are able to tolerate highly acidic pH environments and have proteins that will not denature in the low-pH environments that the bacteria are found in. |
| Archaea are able to colonize water that is at or above the boiling temperature due to high levels of disulfide bridges that maintain the three-dimensional structure of the enzyme. |
| Archaea are only able to survive exceedingly well at high temperatures due to the amount of activation energy required by their enzymes. |
| Archaea are able to grow in extremely shady or low-light conditions that allow for optimal enzyme activity. |
QUESTION 1
Which of the following statements about the bacterial cytoplasmic membrane is false?
| a. | It resists attachment of the bacterial chromosome to its inner surface. | |
| b. | It contains a protein complex that drives ATP synthesis. | |
| c. | It is asymmetric. | |
| d. | It consists of relatively equal amounts of phospholipids and proteins. |
1 points
QUESTION 2
Which of the following statements regarding Mycobacteria is false?
| a. | The genome has relatively low Guanine (G) and Cytosine (C) content. | |
| b. | The cytoplasmic membrane is surrounded by a polymer (peptidoglycan) consisting of alternating N-Acetylglucosamine (NAG) and N-Acetylmuramic (NAM) acid units. | |
| c. | It infects approximately one-third of the global human population. | |
| d. | It has a Gram-positive cell wall with an additional waxy lipid layer of mycolic acid. |
1 points
QUESTION 3
Which of the following outer membrane porins enables Mycobacteria to adapt to acidic and intracellular environments, and shows homology to outer membrane porin A?
| a. | OmpATb. | |
| b. | OmpA. | |
| c. | MspA. | |
| d. | Lipid A. |
1 points
QUESTION 4
Based on your understanding of bacterial membranes, which of the following is not likely to be found in an E. coli outer membrane?
| a. | Membrane-anchored enzymes. | |
| b. | Mycolic acid. | |
| c. | Lipopolysaccharide. | |
| d. | Porin channels. |
1 points
QUESTION 5
Based on the conclusions of this paper, which of the following statements would the author most likely disagree with?
| a. | Some archaeon do not contain all of the genes essential for life. | |
| b. | The membrane structures of prokaryotes show far greater diversity than those of eukaryotes. | |
| c. | As demonstrated in this definitive report, scientists have a great understanding of the majority of basic functions and evolution of bacterial membranes. | |
| d. | The outer membrane (and its associated components) of archaea, Gram-negative bacteria, and Gram-positive bacteria likely evolved independently of one another. |
1 points
QUESTION 6
Which of the following is not true for Gram-negative, acid-fast, and archaeal membranes?
| a. | They modify their lipid content in response to environmental changes. | |
| b. | They have co-evolved the same outer membrane composition and structure. | |
| c. | They all have a cytoplasmic membrane. | |
| d. | Membrane transport proteins regulate nutrient uptake and waste removal. |
1 points
QUESTION 7
Compared to Mycobacteria, Gram-negative bacterium contain:
| a. | More mycolic acid. | |
| b. | Pores of increased length. | |
| c. | Less peptidoglycan. | |
| d. | 50-fold-lower numbers of porins. |
1 points
QUESTION 8
Archaea are found to survive in strongly acidic lakes compared to bacteria and Eukaryotes. Which of the following supports this claim according to the study?
| a. | The presence of L-glycerol ether linked lipids in Archaea membranes. | |
| b. | The presence of D-glycerol ether linked lipids in Archaea membranes. | |
| c. | The presence of L-glycerol ester linked peptidoglycans in Archaea membranes. | |
| d. | The presence of L-glycerol ester linked lipids in Archaea membranes. |
1 points
QUESTION 9
Based on your understanding of the symbiotic relationship between Nanoarchaeum equitans and Ignicoccus, which of the following below is not true?
| a. | The membrane lipids of N. equitans are synthesized by Ignoccocus. | |
| b. | In exchange for membrane lipids, N. equitans provide Ignicoccus with many essential cytoplasmic enzymes. | |
| c. | N. equitans lack enzymes capable of catalyzing lipid biosynthesis. | |
| d. | Intraperiplasmic vesicles produced by Ignicoccus allow for lipid transfer to N. equitans. |
1 points
QUESTION 10
What is the role of hydrogen bonds in bacteria, as mentioned in the article?
| a. | They mediate transmembrane electron flow. | |
| b. | They mediate lipid biosynthesis. | |
| c. | They help to stabilize the cytoplasmic membrane. | |
| d. | They are responsible for the selective permeability of the cytoplasmic membrane. |