Discussion Questions Unit 1 Flashcards
“I was able to track down the source of the cholera epidemic in London.” Who am I?
John Snow
“Everyone thought that I was crazy to think that an abnormal protein could cause a neurological disease.” Who am I?
Stanley Prusiner
“I was able to disprove the theory of spontaneous generation just by using a Swan-neck flask.” Who am I?
Louis Pasteur
Eukaryotic cells are almost always larger than prokaryotic cells. What structures might allow for their larger size?
Membrane bound organelles: RER, Golgi, mitochondria, chloroplast
Methylene blue binds to DNA. What parts of a yeast cell (fungus) would be stained by this dye? (Hint: where do you find DNA in a eukaryote? & Which organelles have DNA)
Nucleus & Mitochondria
Colchicine is a drug that inhibits microtubule formation. Why does colchicine inhibit phagocytosis, movement of organelles within the cell, and formation of flagella and cilia? (What is cytoskeleton made of?)
No microtubules means that cells can’t build flagella and cilia which means no movemment
The smallest single-celled, free-living eukaryote known is a green photosynthetic alga, Ostreococcus tauris. What membranous organelles must this photosynthetic cell have?
Chloroplasts; Since its photosynthetic
Even though Clostridium is strictly an anaerobic bacterium, it can be isolated easily from the exposed surface of your skin. Explain how this can be. (Protective structure)
Endospores
Some bacterial toxins cause cells lining the digestive tract to secrete ions, making the contents of the tract hypertonic. What effect does this have on a patient’s water balance?
Dehydrations because the water will go towards the tract (diarrhea)
Following the bioterrorist anthrax attacks in the fall of 2001, a news commentator suggested that people steam their mail for 30 seconds before opening it. Would the technique protect people from anthrax infections? Why or why not?
No, because 30 seconds of steam is not enough to kill any bacteria
After a man infected with the bacterium Escherichia coli was treated with the correct antibiotic for this pathogen, the bacterium was no longer found in the man’s blood, but his symptoms of fever and inflammation worsened. What caused the man’s response to the treatment? Why was his condition worsened by the treatment? (CW, Gram+ or Gram-?)
Gram Negative CW contains an endotoxin called Lipid A, The antibiotic most likely attacked the CW that released Lipid A causing the patients symptoms to worsen
I have two parts that must work together for me to function. I have two forms in eukaryotes but one in prokaryotes. If I stop working, then enzymes won’t be made. What cellular structure am I?
Ribosomes
Where are ribosomes found? In Eukaryotes and Prokaryotes
Eukaryotes: found both free in the cytoplasm and attached to the endoplasmic reticulum,
Prokaryotes: only free in the cytoplasm
As protozoa if I don’t have this cellular structure then I most likely can’t perform aerobic respiration. What organelle am I?
Mitochondrion; because they produce energy
ATP
E. coli can perform aerobic respiration but doesn’t have the organelle found in animal cells. So, what structure allows bacteria to siphon electrons from NADH using oxygen as the final electron acceptor to make ATP?
Cell membrane; in E. coli it contains the electron transport chain
I protect against osmotic stress in both plants and bacteria. What cellular structure am I?
Cell wall
In 1985, an Israeli scientist discovered the single-celled microbe Epulopiscium fishelosoni. This organism is visible with the naked eye. Why did scientists initially think Epulopsicium was eukaryotic? What discovery revealed that the microbe is really a giant bacterium?
Because of its size;
Evidence:
No nucleus (microscopy image)
rRNA information (genetic)
Microbiologists announced the discovery of over 30 new species of bacteria that thrive between the teeth and gums of humans. The bacteria could not be grown in the researchers’ laboratories, nor were any of them ever observed via any kind of microscopy. If they couldn’t culture them or see them, how could the researchers know they had discovered new species? If they couldn’t examine the cells for the presence of a nucleus, how did they determine that the organisms were prokaryotes and not eukaryotes?
rRNA
They most likely looked at the genetic information since they had no microscopy evidence
A scientist who discovers a prokaryote living in a hot spring at 100°C suspects that it belongs to the archaea. Why does she think it might be archaeal? How could she prove that it is not bacterial?
Most hyperthermophiles are archaea;
she can prove it is not bacterial through rRNA
Joe Micro observed his TSA plate to determine whether he used proper aseptic technique. On his plate, he noticed two different types of colonies of bacteria yellow, shiny, opaque, small colonies growing along the edges of the plate & beige, dry, crusty growth in a single line in the middle of the plate. After looking at his lab notebook, he noted that the culture he used was beige, dry-looking growth & that he made a single streak line in the middle of the plate. What is one possible explanation for this observation?
Cross contamination
There might have been accidental contamination to create the different colonies
If you were to gram stain Mycoplasma sp., then what color would these cells be? Why?
They would be colorless (or pink) because mycoplasma lacks a cell wall (but the dye can still stain)
If you were to gram stain Archaeal cells, then what color would the cells be? Why?
They would likely appear pink (or Gram-negative) because most archaea lack peptidoglycan in their cell walls, a key component that retains the crystal violet stain in Gram-positive bacteria.
Jo Micro gram stained a bacterial sample that she was told was a 24-hour culture of a Gram negative rod-shaped bacteria. When Jo looked at her stained smear under the microscope, all she saw were purple monobacillus. What could have been the problem?
Under-decolorization; the alcohol may not have been applied long enough, causing the Gram-negative bacteria to retain the crystal violet dye, making them appear purple
Miki came home from microbiology lab with green fingers and a bad grade. When asked about this, she replied that she was doing a Gram stain but that it never worked the way the book said it should. Christina overheard the conversation and said that she must have used the wrong chemicals. What dye was Miki probably using, and what structure does that chemical normally stain?
Miki was likely using malachite green;
Malachite green is used to stain endospores
