Quiz #2 - Chapters 3 and 7
What evidence exists that supports the endosymbiotic theory?
-mitochondrial DNA and chloroplast DNA are highly related to their bacterial counterparts by both DNA sequence and chromosomal structure -mitochondrial land chloroplast ribosomes are structurally similar to bacterial ribosomes, rather than the ribosomes of their host cell -binary fission of mitochondria and chloroplasts resemble the binary fission of bacteria (instead of mitosis like eukaryotic cells)
.Label the parts of the prokaryotic cell.
A - Fimbriae B - Ribosome C - Nucleoid D - Flagellum E - Cell Wall F - Plasma Membrane
Explain how the ABC transporter system works.
ABC transporters utilize the energy of ATP binding and hydrolysis to energize the translocation of various substrates across membranes
Which of the following slides is a good example of staphylococci?
Answer D
Provide some examples of bacterial structures that might be used as antibiotic targets and explain why.
Antibiotics are the chemicals released by the microbes that inhibit the growth of other microbial species. Antibiotics can also be synthesized in the laboratories. The first synthetic antibiotics are sulphonamides. Streptomyces is also used as an antibiotic. Any structural features that are specific only to the bacteria or any pathogen are the good targets of antibiotics. Because, they would only affect the microbe but not the host cell.
Microorganisms can thrive under many different conditions, including high-temperature environments such as hot springs. To function properly, cell membranes have to be in a fluid state. How do you expect the fatty acid content (saturated versus unsaturated) of bacteria living in high-temperature environments might compare with that of bacteria living in more moderate temperatures?
Bacteria in moderate temperatures you would expect to see unsaturated fatty acid content because lipids containing unsaturated fatty acids are liquid at room temperature. Bacteria in high temperatures you would expect to see saturated fatty acid content because lipids containing saturated fatty acids are solid at room temperature
What is the molecular formula for this monosaccharide? (Count the C, H and O atoms in each to confirm that these two molecules have the same formula, and report this formula.)
C6 H10 O5
List and draw 3 major morphologies of prokaryotic cells.
Coccus (round), Bacillus (rod), Spirillum (spiral)
Heating a protein sufficiently may cause it to denature. Considering the definition of denaturation, what does this statement say about the strengths of peptide bonds in comparison to hydrogen bonds?
Denaturation = resulting in loss of its higher-order structure (secondary and tertiary structure without the loss of the primary structure) and its biological function: Peptide bonds are stronger than hydrogen bonds, they can withstand more because of chemical linking bonds
How are fimbriae and pili similar? How are the different?
Fimbriae and pili are structurally similar Similar (They both are used to attach itself to surfaces and other cells); Differences (Fibriae are often short and bristle-like; pili are longer and less numerous)
What is a flagellum made of and what drives its "motor"?
Flagella are structures used by cells to move in aqueous environments. Bacterial flagella act like propellers. They are stiff spiral filaments composed of flagellin protein subunits that extend outward from the cell and spin in solution. Purposeful movement toward a chemical attractant, like a food source, or away from a repellent,
Describe and draw the structural differences between gram-positive and gram-negative cell walls.
Gram-positive: has a thicker cell wall consisting in many layers of peptidoglycan and embedded teichoic acid external to the plasma membrane Gram-negative: has a thin cell wall with fewer peptidoglycan layers and an outer membrane containing LPS
Why was the work of Snow so important in supporting the germ theory?
He conducted studies to track the source of cholera outbreaks. He ultimately demonstrated that cholera was transmitted via drinking water. This represented the first known epidemiological study and resulted to the first known public health response to an epidemic. Overall, it was important in supporting the germ theory because it showed that disease is not only transmitted through air but also through contaminated items.
Draw the structure of a phospholipid bilayer and label the parts.
Hydrophilic head (made of phosphate & glycerol), hydrophobic tails (made of saturated & unsaturated fatty acids).
What would the results of Pasteur's swan-neck flask experiment have looked like if they supported the theory of spontaneous generation?
If the results of his experiment supported spontaneous generation then both the flask with swan neck and it broken off would have had shown organism growth from some "life force" even if the swan neck had not been exposed to air
What is the direction of water flow for a bacterial cell living in a hypotonic environment? How do cell walls help bacteria living in such environments?
In a hypotonic medium, the solute concentration inside the cell exceeds that outside of the cell, so water will move by osmosis into the cell. This causes the cell to swell and potentially lyse, or burst. The cell wall helps protect the cell from changes in osmotic pressure. It is made from peptidoglycans that help resist changes by maintaining the shape integrity of the cell before it lyses.
The causative agent of botulism, a deadly form of food poisoning, is an endospore-forming bacterium called Clostridium botulinim. Why might it be difficult to kill this bacterium in contaminated food?
It's difficult to kill this bacterium because endospores allow some bacterial cells to survive long periods without food or water, exposure to chemicals, extreme chemicals, and radiation.
Describe the three major functions of the cytoplasmic membrane
Keep organelles in and toxic substances out of the cell Have receptors and channels that allow specific molecules in and out Site of energy generator
For gram-negative bacteria describe the location and function of: lipopolysaccharides (LPS); Porins; and Periplasm
LPS are found in the outer membrane of gram-negative cells. It functions as an endotoxin in infections that involve gram-negative bacteria. Porins - Porins form large water-filled channels which allow the diffusion of hydrophilic molecules into the periplasmic space. Periplasm is the gel-like matrix that occupies the periplasmic space between the cell wall and the plasma membrane
Why are mitochondria and chloroplasts unable to multiply outside of a host cell?
Mitochondria are unable to live on their own because most of the genome of the mitochondria and chloroplasts has been transferred to the host cell's nucleus.
What are monosaccharides, disaccharides, and polysaccharides?
Monosaccharides: simple sugars, building blocks for synthesis of polymers Dissarcharides: two monosaccharides molecules that are chemically bonded Polysaccharides: called glycans, polymers composed of hundreds of monosaccharide monomers
What were the differences in mortality rates due to puerperal fever that Ignaz Semmelweis observed? How did he propose to reduce the occurrence of puerperal fever? Did it work?
Mortality rates due to puerperal fever when mothers gave birth in hospitals staffed by physicians and students =10-20% Mortality rates due to puerperal fever when mothers gave birth with the help of a midwife = 1% He suggested that the number of puerperal fever cases could be reduced if physicians and medical students simply washed their hands with chlorinated lime water before and after examining every patient. When this practice was implemented, the maternal mortality rate in mothers cared for by physicians dropped to the same 1% mortality rate observed among mothers cared for by midwives. This demonstrated that handwashing was a very effective method for preventing disease transmission.
Describe the three systems known for transporting substances through the membrane.
Passive Transport (molecules moving from a higher concentration to a lower concentration with the concentration gradient) Facilitated Diffusion (structure to ferry molecules across the membrane) Active Transport (cells move molecules across their membrane against concentration gradients)
Explain in your own words Pasteur's swan-neck flask experiment.
Pasteur placed chicken broth in a swan-neck flask. The broth was boiled to sterilize it and denature any present microbes. The curve of the flask prevented allowed air to enter the flask but prevented bacterial and fungal spores from entering the flask. The broth could have sat indefinitely with no signs of contamination. However, when the neck of the flask was broken off, it was exposed to air and bacteria and the broth became contaminated and spoiled.
What is peptidoglycan? (general chemical components and overall function)
Peptidoglycan is made of long chains of alternating molecules (NAG & NAM), sugars, and amino acids. It's overall function is to provide structural strength and is also involved in binary fission.
Describe the structure of a typical phospholipid. Are these molecules polar or nonpolar?
Phospholipids contain both hydrophobic hydrocarbon chains and polar head groups, making them amphipathic( hydrophilic portion of the phospholipid is often referred to as a polar "head," and the long hydrocarbon chains as nonpolar "tails." )and capable of forming uniquely functional large scale structures. The cell membrane is a phospholipid bilayer that is unique in that it both attracts and repels polar molecules. Each phospholipid has a polar phosphate head that attracts water and other polar molecules. (Hydrophilic means, "water loving") As well as two nonpolar fatty acid tails that repel water and other polar molecules. (Hydrophobic means, "water repelling".) The phospholipids form a double-layered membrane with the fatty acid tails in the middle away from the water inside and outside the cell. This nonpolar region inside the cell membrane is a barrier to most polar molecules. They are repelled by this nonpolar layer and cannot pass through it without help.
Explain why prokaryotes tend to survive and adapt more rapidly to extreme and dynamic environmental conditions than eukaryotes.
Prokaryotes tend to reproduce faster and therefore their mutation rate is higher. Another feature that increases mutation rate is the haploid nature of prokaryotes.
Name at least two ways that prokaryotic flagella are different from eukaryotic flagella
Prokaryotic flagella are formed of flagellin protein while Eukaryotic flagella are formed of tubulin protein. Prokaryotic flagella are smaller in size and narrower while Eukaryotic flagella are larger in size and thicker.
.How did the explanation of Virchow and Remak for the origin of cells differ from that of Schleiden and Schwann?
Schleiden and Schwann believed there were similarities between plant and animal tissues and formed through crystallization. Virchow and Remak believed cells come from other cells by the process of cell division.
What existing evidence supports the theory that mitochondria are of prokaryotic origin?
The endosymbiotic theory supports the statement that mitochondria are prokaryotic origin. The mitochondria multiplies similar to how bacteria (prokaryotes) multiply during binary fission. According to the endosymbiotic theory, mitochondria and chloroplasts are each derived from the uptake of bacteria. These bacteria established a symbiotic relationship with their host cell that eventually led to the bacteria evolving into mitochondria and chloroplasts.
Identify which hydroxyl group in the linear structure undergoes the ring-forming reaction with the carbonyl group.
The last hydroxyl group (on the right) undergoes ring-forming reaction with the carbonyl group These ring structures result from a chemical reaction between functional groups on opposite ends of the sugar's flexible carbon chain, namely the carbonyl group and a relatively distant hydroxyl group. Glucose, for example, forms a six-membered ring
Explain how endospores provide an advantage to organisms capable of forming them. How long can endospores last (and remain viable)?
They allow some bacterial cells to survive long periods without food or water, as well as exposure to chemicals, extreme temperatures, and radiation. They can persist in a dormant state for extended period of time, up to thousands of years. When living conditions improve, endospores undergo germination, and reenter a vegetative state and become metabolically active again and resume normal functions of growth and cell division.
What is the function of an endospore and how is an endospore formed?
They are to essentially protect the bacterial genome in a dormant state when the conditions are unfavorable. They are formed from sporulation and when there is a lack of nutrients.
Explain why the experiments of Needham and Spallanzani yielded in different results even though they used similar methodologies.
They had different results because Needham did not boil the broth for long enough.
How do bacterial flagella respond to a chemical gradient of an attractant to move toward a higher concentration of the chemical?
When a chemical gradient of an attractant exists, the length of runs is extended, while the length of tumbles is decreased. This leads to chemotaxis: an overall forward directional movement toward the higher concentration of the attractant.
Why are carbon, nitrogen, oxygen, and hydrogen the most abundant elements in living matter and, therefore, considered macronutrients?
account for about 99% of the dry weight of cells -light elements capable of forming strong bonds=produce molecules -essential to function of many biochemical reactions -necessary for the formation of the structures & enable functions of organism
