Download UCSC MICROBIOLOGY MIDTERM 1 STUDY QUESTIONS WITH CORRECT AND VERIFIED ANSWERS 2025 and more Exams Nursing in PDF only on Docsity!
QUESTIONS WITH CORRECT AND VERIFIED
ANSWERS 2025
Compare and contrast the general structure of Bacteria, Archaea and Eukaryotic microbes - correct answers Bacteria and archaea have no nucleus, eukaryotes have a nucleus What makes viruses different from all other microbes? - correct answers they are not living, they do not evolve from a single common ancesetor, no ribosomes and more importantly they do not rely on cells for reproduction Why is rRNA (16s or 18s) sequencing used for microbial classification? What features make it a good gene to use? Why do we use sequencing for phylogenetic trees? - correct answers They are used because the 16s and 18s is conserved in bacteria, they are highly variable, the pcr primers bind to the conserved regions and they are highly researched so you can look them up in a database What is LUCA? What properties does it have? What organisms have these properties today? - correct answers luca is the last universal common ancestor, it has rna, dna amd emzymes such as dna polymerase and rna polymerase, ( has dna information storage and replication, proteins and rna transformation, limid membrane of celll) all living things have these properties today Draw a simple schematic depicting a eukaryote and prokaryote. (Hint: what is the one key feature that distinguishes them?) - correct answers
QUESTIONS WITH CORRECT AND VERIFIED
ANSWERS 2025
i discovered a novel virus and want to know where it falls in the phylogenetic tree. I amplified the genome via PCR, sequenced it, and uploaded the data into a program that makes phylogenetic trees based on rRNA. In what domain would you expect it to show up? - correct answers they would not show up on any of the domains because they do not come from luca. they would have their own domain List the various types of microorganisms and describe their defining characteristics - correct answers Bacteria- contain peptidoglycan made up of a peptide and a sugar, archaea- more closley related to humans than bacteria which contain exteramophiles( therman, chemical, and physical( pressure)) they contain pseudopeptidoglycan eukaryotic microbes- contain things such as fungi( break down plants, fillamentation, and sporulation like in yeast, algae(plants whcihc contain photosynthesis, cellulose cell wall, and are ina marine/ aquatic ecosystem Draw the steps of binary fission. What might it look like in an FtsZ knockout? - correct answers 1. genome replication, elongation, sepation, fission, separation. ftsz ring begins to form in genome replication and is then constricted like putting a rubber band on a balloon to make it 2 cells. IF the ftsz is not present in a knockout the cell will not be able to separate causing an elongated cell with 2 genomes. (lecture 2) During which phase does growth occur at the fastest rate? What limits increases in OD during stationary phase? (why doesn't the OD increase infinitely?) - correct answers 3 phases of growth, the lag stage where it is elongating( below the detection limit, in shock and growing slowly) log stage- growing exponentially( fastest rate) (homogenous)
QUESTIONS WITH CORRECT AND VERIFIED
ANSWERS 2025
Scientifically, we don't know as much about extremophiles. Why do you think this is? - correct answers we dont know much about extremophiles because they are rare and are extremely hard to find and get to. Why might NASA fund microbiology research in Antarctica? - correct answers Nasa might fund microbiology research in Antarctica to find bacteria that can withstand extreamly low temperatures which mirror those in outer space. It is possible they can modify these bacteria and find a use for them on space missions I'm growing an organism that (I've been told) is an obligate anaerobe. Using genetic engineering, I give the strain the ability to produce superoxide dismutase and catalase, and find that it is now able to grow in the presence of oxygen. Explain how this might be possible. - correct answers this might be possible by turning the obligate anerobe into an aerotolerant anerobe which can catalyze 2h2o2 into 2 h20 and o2. aerotolerant anerobe can shield themslves from the toxic o2. the superoxide dismutease enzymes shield them from the o Speculate on why cytoplasmic membrane proteins might be more abundant in prokaryotes than eukaryotes - correct answers Prokaryotes only have a cytoplasmic membrane whereas eukaryotes have the cytoplasmic membrane and membranes that surround every organelle. All membrane proteins expressed by prokaryotes must be present in the cellular membrane, whereas membrane proteins in eukaryotes can be expressed on the membrane of organelles.
QUESTIONS WITH CORRECT AND VERIFIED
ANSWERS 2025
(lecture 3)Summarize the common chemical characteristics of all cytoplasmic membranes. How are the cytoplasmic membranes of Bacteria and Archaea similar and different to each other? - correct answers One of the main differences between bacteria and archaea is that in the phospholipids of their cytoplasmic membrane, there is a difference between the connection point between the lipid and glycerol. In bacteria, there is an ester linkage, and in archaea there is an ether linkage. Furthermore, archaea also have branches on their lipids and they sometimes have a monolayer, which increase the rigidity of the membrane. All cell membrane are made up of a phsophlipids with glycerols and carbon isoprene groups with membrane proteins sandwiched between List three roles of the bacterial cytoplasmic membrane - correct answers 1. act as a diffusion barrier to separate polar and non-polar molecules
- create an ion gradient to make energy and do work such as mobility
- a platform for proteins that sense the environment and can alter the cells environment to combat it role of the cell wall is to protect from pressure, hold shape, and act as a barrier for large things Detail the steps for making a peptidoglycan cell well. - correct answers peptidoglycan( animo acid plus sugar) - n-acetylmuramic acid and n-acetylglucosamine(- charge G) are linked via transglycosylase(m) enzymes chains linked to another layer via peptide cross links. steps are
- G and m are linked
QUESTIONS WITH CORRECT AND VERIFIED
ANSWERS 2025
Detail what happens when a bacterial cell is treated with a beta lactam antibiotic (such as penicillin) or lysozyme. Does it matter if the cells are growing or not? What would change if the cells were gram positive or gram negative? - correct answers Beta- lactam antibiotics bind to the transpeptidase active site and prevents the real substrates from binding. Because of this competitive inhibition, peptidoglycan chains aren't cross-linked by prevention of new ones forming.If treated with lysozyme, the NAG/NAM connections are degraded causing the cells to round up and burst if in a hypotonic solution. This only affects growing cells. These methods only affect Gram(+) bacteria because of the cell was Gram(-), then it would have a outer membrane, which is essentially an extra layer of protection. Would a molecule 2000 daltons in size have an easier time getting through mycolic acid layer, outer membrane or cell wall? - correct answers Describe how the Gram stain can be used to diagnose bacterial meningitis. - correct answers A gram stain can be used to diagnose bacterial meningitis because there are only three types of bacteria that can cause meningitis, and one is Gram(+) and the other two are Gram(-). Doing a gram stain would narrow down which type of bacteria it is through denoting the bacterial contrast by using purple or pink. Purple if it is Gram(+) and pink if it is Gram(-), and then the antibiotic treatment can be decided from there (lecture 4) How do bacteria confine their DNA inside their cells? What makes it difficult to constrain the DNA? - correct answers Prokaryotes compact their DNA within the cytoplasm in a structure known as the nucleoid. It is highly compacted, organized DNA that is not surrounded by a lipid membrane.-If DNA stretched out, it can be much larger than the cell. Crowding in the cytoplasm can cause high pressure which is why cells require a cell wall to avoid bursting.
QUESTIONS WITH CORRECT AND VERIFIED
ANSWERS 2025
What is an advantage to having DNA in the cytoplasm without an additional nuclear membrane? - correct answers - substrate access
- coupling of transcription and translation What are the characteristics of bacteria with small or large genomes? Why? - correct answers - large genomes: live in a greater variety of environments and have a great variety of different cellular forms. they need a lot of genes to live in all of these environments and survive there and genes to adopt different cellular forms.
- small genomes: generally found in microbes that don't have as many environments and are usually in symbiosis (associated w/ another organism)=> can encode fewer functions in their genomes. What's the difference between a chromosome and a plasmid? - correct answers Chromosome: generally circular and haploid in a prokaryote and carries the necessary genetic information.
- Plasmids: pieces of DNA, generally smaller than the chromosome that have genes like chromosomes, but generally have non-essential genes; the organism can get rid of them and be okay "bonus" Where do we think transcription occurs in bacteria? What data exists to support this? (i.e. what experiment supports this conclusion?) - correct answers
QUESTIONS WITH CORRECT AND VERIFIED
ANSWERS 2025
How are magnetosomes made? Would you predict that magnetosomes are essential or non-essential for growth in the laboratory? - correct answers Magnetosomes: invaginations of CM w/ iron that act as a magnet to allow microbes to migrate along magnetic field lines and is how microbes swim down in bodies of water to get organic C and sediment at bottom and avoid O2. combined w/ flagella for locomotion. non essential for growth in the lab bc they dont need to control depth on a petri dish What are gas vesicles and how do they work? Why would an organism use gas vesicles instead of flagella (swimming?) - correct answers Gas-filled cytoplasmic structures bounded by protein and conferring buoyancy on cells. It is a passive function that does not require much energy that would keep the cell in the nutrient rich part of the water. Many structures can be observed within bacterial cells. Are they considered organelles? Why or why not. - correct answers no they are not due to not having defined functions? (lecture 5) Discuss the source of energy and carbon for each of these types of microbes, and speculate on what type of habitat they would live in: chemoheterotroph; photoheterotroph; chemoautotroph; photoautotroph. Use the web to find an example microbe of each type. - correct answers Chemoheterotroph: Energy - Chemicals Carbon - Organic Photoheterotroph:
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Energy - Light Carbon - Organic Chemoautotroph: Energy - Chemicals Carbon - Inorganic Photoautotroph: Energy - Light Carbon - Inorganic. Using Fig. 5.1, list the order of steps of creating macromolecules, structures, fueling products and building blocks. How does growth as a heterotroph or autotroph change this? - correct answers Growth metabolism begins with the type of energy and building blocks that a particular organism uses. In the end, even though organisms start with varying molecules, they end with essentially the same products. Heterotrophs begin with organic nutrients, autotrophs use light, inorganic carbon, and other inorganic energy sources. From here, they begin making fueling products (i.e. ATP, GTP, NADPH), to support the formation of building blocks (i.e. fatty acids, sugars, and amino acids). Now, they can make macromolecules (i.e. lipids, LPS, glycogen)
QUESTIONS WITH CORRECT AND VERIFIED
ANSWERS 2025
What is the difference between fermentation and respiration? Which one generates more energy? - correct answers The difference between fermentation and anaerobic respiration is that fermentation is coupled with glycolysis in that it utilizes the pyruvate produced form glycolysis to generate ATP. Anaerobic respiration uses the electrons donated by NADH to the ETC and those electrons end up on a terminal electron acceptor other than oxygen. respiration generates more energy What is a transmembrane ion gradient and why is it needed for the ATP synthase? What does proton motive force refer to? - correct answers a transmembrane ion gradient is a concentration of H+ and negatives charges on either side of the membrane. this is needed to spin the motor in atp sunthase, proton motive force refers to the force that wants to keep an equilibrum, the protons will rush towards an area with no protons similar to how water rushes into an area with no water through a leak. In lecture 4 we talked about gas vesicles and the fact that they are energetically favorable over swimming (a process that requires ATP). Using the terms and values discussed in this lecture, explain why is it energetically "expensive" to use ATP. (hint, use ΔG to explain). - correct answers it is energetically expensive to use atp due to that being the main type of energy in the cell and if you use atp you have to make more which will require the breakdown of more molecules in the cell. if the delta H is negative the reaction would be energetically favorable meaning that it wants to happen, while if the delta g is positive the cell would have to expend energy to make it happen
QUESTIONS WITH CORRECT AND VERIFIED
ANSWERS 2025
List two pathways that can generate NADH. What does it do? What does the cell use it for? List two ways it can be used / turned back into NAD+. - correct answers the TCA produces NADh as well as the final electron acceptor and fermentation. The cell uses nadh to convent to atp for the transmembrane ion gradient which uses the hydrogen which then turns back into nad+ Describe three methods by which small molecules are moved across the outer membrane. Would this apply to gram negative or gram positive cells? - correct answers 1. Transporter proteins in Outer Membrane (G-); Porins (facilitated or passive) 500 - 100kda
- Across the peptidoglycan (G+ and G-) 50kda
- Transport across the cell/cytoplasmic membrane (G+ and G-) Compare and contrast ion-coupled transport and ABC transport at the inner and outer membrane - correct answers Ion-coupled transport:
- transporters in cytoplasmic membrane
- require E (ion gradients/PMF)
- able to conc. molecules against a conc. gradient. ABC Transporters:
- transporters in cytoplasmic membrane
- ATP in ABC transporters
QUESTIONS WITH CORRECT AND VERIFIED
ANSWERS 2025
A prokaryote could use facilitated diffusion across the CM for glycerol via a glycerol transporter protein present in the CM. The transporter is not found in the OM because glycerol is too large to pass through the OM as the OM only allows the passage of small molecules, <500 Da What is the calvin cycle and what is it used for? What is RuBisCo? What are the starting and ending products? - correct answers CO2 Fixation: the way autotrophs utilize CO into 3 or 6-C molecules in the carbon cycle with the enzyme Rubisco.Rubisco catalyzes the addn. of CO2 to the 5-C compound ribulose biphosphate-> yields a 6-C compound that yields 2 molecules of 3-phosphoglycerate. Be able to describe how cells would carry out metabolism, for example, with the following: Aerobic and anaerobic respiration, or fermentation with glucose Aerobic and anaerobic respiration, or fermentation with trehalose Chemolithoautotrophic anaerobic growth with Fe2+ as an acceptor - correct answers Aerobic Respiration w/ glucose:
- respiration: SLP, ETC
- terminal e- acceptor: O Anaerobic respiration w/ glucose:
- respiration: SLP, ETC
- terminal e- acceptor: NO3- (molecules other than O2)
QUESTIONS WITH CORRECT AND VERIFIED
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- anaerobic respiration : SLP, ETC
- trehalose: polymer of glucose (glucose-glucose)
cleaved by TreA to produce 2 Glucose for glycolysis
- Trehalose transporter Fermentation with trehalose- - Respiration: SLP
- Input: Trehalose,
- transported-cleaved by TreA-> 2 glucose
- Trehalose->glucose->Pyruvate->Lactate How do molecules move between the pathways of glycolysis, the pentose phosphate pathway, and the TCA cycle? - correct answers Glycolysis produces G- 6 - P, in its 1st step, which can also be input from the PPP
- F- 6 - P also generated from PPP can be input into glycolysis
- pyruvate - > Acetyl-CoA for TCA
- OAA from glycolysis - > TCA
- Glycolysis generates precursor metabolites needed to make sugars, AA and FA-> feeds into PPP
