micro 303
Horizontal gene transfer (HGT) makes the concept of species in bacteria more difficult because
Genes are not always inherited vertically so the capabilities of a species do not always reflect its ancestry
Looking for something fun to do, you decide to compare the relatedness of Gram-positive and Gram-negative bacteria species to their collective last common ancestor. The genetic sequence for which of the following structures/proteins could be a useful root sequence?
the Z ring Histones and 80s rRNA are not found in bacterial cells so their last common ancestor would not have it. LPS is only found in gram-negative cells, so it is unlikely to be found in gram-positive cells' ancestors. Gas vesicles are not found in all bacteria, so this would not a good structure to compare the relatedness of gram-positive and gram negative bacteria. The Z ring is a cytoplasmic structure that is found when bacteria cells undergo binary fission and is common among almost all bacteria.
Which bacteriophage(s) contain double-stranded DNA and can go thought a lytic cycle?
λ and T4
All of the following are true about evolutionary relatedness of organisms EXCEPT...
Cyanobacteria are related to mitochondrion because of their Gram-negative cell wall
Major cellular differences between Archaea and Bacteria are
Promoter start sites (pribnow box in Bacteria vs. TATA box in Archaea
In which category of organisms can bacteria exchange DNA via horizontal gene transfer?
Proteobacteria (bacteria) Euryarcaeota (archea) Crenarchaeota (archea)
Which of the following steps is not included when Gram staining bacteria in order to differentiate them from their background?
Rinsing cells with Methyl Red
Which is NOT a function of the nucleus in Eukaryotes
an area for post-translational modification of protein
A main difference between transcription and translation in eukaryotes and bacteria is that
The process of transcription and translation occur simultaneously in bacteria
In DNA replication the role of Primase is to
Create RNA Primers that DNA polymerase uses
If you consider all types of viruses (dsDNA, dsRNA, ssDNA, ssRNA) what structure/enzyme is required by all of them to be able to replicate the virus?
-Ribosome
what are the 4 types of bacteria motility
4 types of motility are swimming, swarming, twitching, and gliding
What is the Shine-Dalgarno sequence?
A short conserved nucleotide sequence upstream of the AUG start codon that serves to align the mRNA on the bacterial small ribosomal subunit The Shine-Dalgarno sequence specifies the initiation site in prokaryotes which helps recruit the ribosome to the mRNA. This aligns the ribosome with the start codon. TATA-binding protein is involved in transcription, not translation.
The two strands in a DNA double helix get their specificity and thermal stability from
A:T and G:C hydrogen bonds across the helix Van der Waals/Hydrophobic interactions between stacked bases
What discovery allowed us to finally characterize microbes, despite them being discovered by Thonis Philipszoon in the 17th century?
Agar
Your friends want to have a big glucose factory, which he believes will help him make big money. You, as a hardworking biology major student and a good friend, what enzymes would you remind your friends to have before he starts his business?
Amylase, maltase, glucose
Which of the following best summarizes the evidence that mitochondria and chloroplasts evolved from bacteria and cyanobacteria respectively?
Analysis of the 16S rRNA of the ribosomes in chloroplasts and mitochondria reveals similar sequences to those found in the 16S rRNA of bacteria and cyanobacteria. - correct - Your answer
Which of the following is false about the role of the promoter in transcription?
Archaea and bacteria have similar promoters.
16S rRNA are used when comparing the evolutionary relationship between organisms as the sequence is highly conserved. Which feature of 16S rRNA can explain why the gene is highly conserved between organisms?
Because 16S rRNA is a part of the ribosome participating in protein synthesis in all organisms
Which of the following statements about bacterial cell structure is not true?
Beta-lactam antibiotics such as penicillin targets the beta linkages in the peptidoglycan to induce cell lysis
Keratinase is not found in
Bioremediation at sewage plants
Streptokinase is a useful treatment for
Blood clots
How is Archaea translation similar to Eukarya translation?
Both Archaea and Eukarya have methionine as their first amino acid Eukarya don't have coupled transcription and translation, only have monocistronic mRNA, have caps on their 5' ends, and have an 18S small subunit rRNA. However, they both share methionine as their first amino acid, which is the correct answer.
Which of the following characteristics are similar across prions and viruses?
Both are disease-causing agents
Which of the following prevents oxidative damage by regulating hydrogen peroxide at a cellular level
Catalase
Which of the following prevents oxidative damage by regulating hydrogen peroxide at a cellular level?
Catalase
How does a standard Gram staining process differentiate between Gram-positive and Gram-negative bacterial cell walls?
Crystal violet is retained by the thick layer of peptidoglycan in Gram-positive cell walls, while the layer of peptidoglycan in Gram-negative cell walls is too thin to retain the dye.
Which of the following microbes were most essential to the evolution of eukaryotes and subsequently most organisms?
Cyanobacteria
Transcription into mRNA by host enzymes
Class I and VII (+/-) dsDNA
Synthesis of the (-) strand to dsDNA intermediate and then transcription to mRNA
Class II (+) ssDNA
Used directly as mRNA
Class IV (+) ssRNA
Transcription of the (-) strand by viral enzymes into mRNA
Class V (-) ssRNA
Reverse transcription to dsDNA intermediate and then transcription to mRNA
Class VI (+) ssRNA retrovirus
DNA takes its double-helix shape due to ___________ and is stabilized by ________________.
Complimentary base-paring using hydrogen bonds; Van der Waal forces in base-stacking
What does a Gram-negative bacterium have in its cell wall that Gram-positive bacterium does not?
Core polysaccharide
An bacterium comes into contact with a negative chemical stimulus. In which way will its flagella rotate to productively move the bacterium?
Counterclockwise, this is the fastest most productive form of movement
What is the main difference between DNA and RNA according to their pentose sugar structure?
DNA does not have an OH attached to its 2' position
Which of the following is NOT a reason why DNA is used to store hereditary information instead of RNA?
DNA has thymine which is more table than uracil.
Bacterial sigma factors are important to
Direct RNA polymerase to the promoter
What is a unique feature of Qβ that neither T4 or λ possess?
During translation, the ribosome purposely reads through a stop codon 5% of the time Qβ has too small of a genome to contain the complex sensing mechanism for a lytic/lysogenic cycle decision, only λ can make that choice between these 3 phages. Qβ has a positive-strand ssRNA genome that can be directly used as template mRNA. It may be tempting to say it encodes an independent RNA-driven replicase, but this is not true. It uses many auxiliary proteins from the host cell to operate. In class we discussed that occasionally the coat protein stop sequence is missed by the modified replicase to continue translating a longer polypeptide with a function critical to the finished virion.
In an environment where a microbe must be smaller than 10 μm to evade protozoa attraction, which of the following microbes would most likely survive?
E. coli
The SARS-CoV-2 virus is a single-stranded, (+) strand RNA virus. Therefore it must
Encode its own RNA-dependent, RNA polymerase
Animal viruses can enter cells in a manner that is unique to animal cells. This method is by
Endocytosis
If the CII protein of the &lamda; bacteriophage had a frameshift mutation, the λ virus would not longer be able to
Enter the lysogenic phase
A major difference between enveloped viruses and naked viruses is...
Enveloped viruses have a membrane made of a lipid bilayer with embedded proteins Both enveloped and naked viruses contain capsids. The genome of viruses can be dsDNA, ssDNA, dsRNA, or ssRNA. Enveloped viruses are surrounded my a membrane (envelope) that is composed of a lipid bilayer and proteins. Viroids are naked infectious RNA particles. "All of the above" doesn't work because some of the statements are incorrect.
In the process of a virus infecting a cell, the virus binds to the cell, invaginates, forms an endosome, and the cell absorbs nutrients from the endosome. What kind of cell is this and which step comes next in the viral infection pathway?
Eukaryotic; Gene Expression Process being described is the endocytic route of a virus entering a cell, entry process is only found in eukaryotic cells
Give an example of a phylogenetic group in the Archaea. List one distinguishing characteristic
Euryarchaeota many of which are methanogens
A research group has developed a new antibiotic that kills the enzyme that synthesizes lipid A. This antibiotic would be most effective against
Gram-negative bacteria
A notable difference between the cell walls of Gram-negative and Gram-positive is that
Gram-negative cells contain O-polysaccharide
Which of the following is true regarding the peptidoglycan layer in Gram-positive or Gram-negative bacteria?
Gram-positive cells can have amino acid interbridges between peptides In the peptidoglycan layer, Gram-positive bacteria have amino acid interbridges between peptides, while Gram-negative have direct linkages between the peptides.
Which cellular transport system uses PEP(phosphotransferase) to get its energy in order to function?
Group Translocation
Which of the following statement(s) is/are true regarding the structures of DNA and RNA. I. DNA has a narrower/deeper major groove that makes it more rigid for protein access, because it lacks 2'OH II. In eukaryotes, both 5' and 3' end of a mRNA imparts stability to the mRNA III. Archaea and bacteria both have 16S small subunit rRNA which is different from eukarya IV. tRNA must be charged with the correct amino acid for translation. The first charged amino acid in bacteria is methionine
II and III
DNA uses the nucleotide thymine to base pair with adenosine. RNA is transcribed using uracil instead of thymine. How does this prevent mutations from being passed on to later generations?
In DNA, cytosine can spontaneously mutate into uracil, which can be identified as a mutation and corrected through base excision repair Mutations in DNA can be easily found by repair mechanisms that find uracil in the strand. Uracil is a spontaneous mutation of cytosine.
Which is a reason why staining is used in bright-field microscopy?
Light that is aimed at the sample is absorbed by the pigmentation of stain creating a contrasted image against white background
You have isolated a new protozoan that has an unusual inclusion. You think the inclusion is actually an organelle that carries out the conversion of H+ to hydrogen gas. What evidence would convince you that this inclusion should be grouped with mitochondria and chloroplasts?
It has ribosomes and 16S rRNA
Carl Woese's use of 16S rRNA was very beneficial in his studies of evolutionary relationships due to all of the following reasons EXCEPT..
It is a very small molecule which made it simple and easy to work with.
Which of the following statements is INCORRECT regarding the 16S rRNA?
It is frequently exchanged via horizontal gene transfer
If you wanted to examine the morphology of a bacterium and determine its Gram stain reaction, you would use a
Light microscope
A leaf of a tomato plant has a stoma that is 7.5 micrometers wide. Which of the following microorganisms would be able to penetrate the stoma and get inside the plant?
Many (but not all) bacteria and all viruses
Which characteristic and description correctly matches their phylogenetic group in Archaea?
Methanogens reproduce by asexual reproduction and are abundant in the environment
Prior to technology to sequence RNA, what evidence did scientists have for the theory that mitochondria evolved from bacteria?
Mitochondria divide by binary fission
Observation of a bacterium on a solid surface shows that it is capable of motility. However, electron microscopy indicates a lack of flagella on the surface of the bacterium. It is most likely
Motile by pili using twitching motility
A microbe exhibiting chemotaxis should do which of the following when a positive stimulus is introduced into the environment?
Move toward the positive stimulus in a series of runs of random direction, runs toward the positive stimulus last longer than runs away from the stimulus
A mutation in a bacterial cell's offspring has damaged and ultimately destroyed the cell's Type IV pili. What will this mutation affect the most?
Movement
Microbes impact the medical field through the use of vaccines. Which of these vaccination milestones occurred first?
People in India and China variolating against smallpox
The chemical modification of a glucose molecule as it is transported across a cell membrane
Occurs s a result of being transported via group translocation
You discovered a strange microorganism. You want to first examine the motile microorganism in its natural state and then to determine the structure of the protein that forms the pili. What kinds of microscopes you should use?
Phase Contrast Microscope and X-Ray Crystallography
Which of the following microscopes do not require you to stain the organisms in order to see them under the microscope
Phase-contrast microscope
Which of the following statements about taxis is INCORRECT
Pili move cells by swimming
The cause of some infectious neurological illnesses such as Mad Cow Disease and Chronic Wasting Disease were found to not have a DNA or RNA component to them. The disease is spread by prions which are
PrP molecules that are proteins that fold abnormally and then cause host PrP to take on the abnormal shape. - correct - Your answer
You are studying a completely novel (new) microbe and observe it to have the following characteristics. Which can you use to justify placing the organism into a domain?
Presence of ether-linked lipids in the cell membrane
Which of the following is NOT a difference between prions and virusesPrions are acellula
Prions are acellular
If you compare the Qβ bacteriophage to λ bacteriophage, the major difference between them is
Qβ has a ssRNA genome
A mutation changes the first A in the Pribnow box to a guanine in a bacterial promoter region of a gene. What effect will this have on the transcription of this gene
RNA Polymerase will have a lower affinity for the promoter and transcribe at a lower rate
Select all that are true about the structure of DNA and RNA
RNA has a 2' hydroxyl, DNA does not. RNA uses uracil, DNA uses thymine. DNA is double-stranded and RNA is single or double-stranded. DNA has a wider and shallow groove for protein access and flexibility (less rigid) for easier storage. Function dictates structure. DNA and RNA have different structures due to their different functions. If degradation happens in DNA, you know that uracil is not supposed to be there in DNA and it can be removed, that is why DNA uses thymine. DNA is kept for a long time, whereas RNA is much shorter lived.
Which of the following is NOT a true example of structure dictating function?
RNA uses uracil because its life span is much longer than DNA and it has more time to become stabilized.
What is the correct order of the steps involved in transcription-
Recognition, Formation of open complex, Elongation, Termination
During which stage do enveloped viruses obtain their membrane
Release
A major difference between the Rho-independent and Rho-dependent termination processes in prokaryotic cells is that:
Rho-dependent termination involves a Rho protein that can bind to an open sequence of RNA, while hydrolyzing ATP as it walks down the strand, causing termination
Based on size what is the correct order of the following?
Ribosome < Average Virus < Average Prokaryote < Average Eukaryote
A microbe using chemotaxis changes its direction of motion by
Rotating flagella clockwise to enter tumble, then proceed in a random direction by rotating counterclockwise In chemotaxis, microbes either run in a straight line or tumble. Tumbling causes the microbe to point in a random direction. Microbes move in a desired direction by lengthening runs in the desired direction and shortening runs away from the desired direction. There is no reverse gear.
The repeatable two-dimensional crystalline structure found in many Bacteria and Archaea, but is not found in any Eukaryotes is the
S layer proteins
You are conducting an experiment studying an exceptionally rare disease that involves the Golgi. You will need to mutate as many organisms as possible to create any that will have the mutation you are looking for. Which of the following would be the most suitable model organism to choose?
S. cerivisiae (brewer's yeast) a eukaryote S. cerivisae (brewer's yeast) is the most suitable answer. The disease involves the Golgi which is only found in eukaryotes, excluding E. coli and M kandleri. The question states that you must mutate as many organisms as possible. This will be much faster, easier and cost- effective with brewer's yeast.
What is a MAJOR difference between prokaryotes and eukaryotes in the process of translation?
Shine-Dalgarno sequence
Which of the following is a reason that the 16S rRNA sequence is useful in comparing the evolutionary relationships between organisms?
The 16S rRNA sequence is very similar in all bacteria, therefore detection of small differences in this sequence would allow for distinction of species
f you were looking for another molecule besides the 16S rRNA gene to do phylogenetic classification, a good candidate would be.
The 23S rRNA gene that is 2904 nucleotides long, The 5S rRNA while universal, is too small for useful comparisons, maltose permease, transpeptidase and ompA are not universal to all bacteria and archaea. The 23S rRNA is both large enough and universal so that it could be used for phylogenetic classification.
While they are both phages, the lambda phage and T4 phage differ because...
The T4 phage is lytic and cannot integrate into the host genome; the lambda phage is lysogenic and can integrate into the host genome
You create a pool of mutants such that each one changes one base pair in the coding region of in the gene glutamate synthase. About 33% of the changes do not cause a detectable change in the activity of the enzyme. This is because
The genetic code is redundant and many times a change in the 3rd base of the codon still codes for the same amino acid.
A mutation in an enzyme only allows a bacteria to make unsaturated fatty acids for the cell membrane. The effect on the bacterial cell is...
The maximum growth temperature would decrease
What is the special problem of (-) single stranded RNA viruses?
They need to be transcribed into a (+) strand before making mRNA
Which of the statements about microorganisms/microbes is/are true?
They provide useful tools in biology as model organisms and thus have major implications in research
Which of the following characteristics is unique to only bacteria
Use of f-met in translation
You have two vials of subviral entities and are convinced that vial A contains prions and vial B contains a virus. which of the following observations would support your suspicions?
Vial B is shown to contain double-stranded DNA
When does the λ virus make the decision to become Lytic?
When reading the cell as healthy with degraded cll protein
Which type(s) of RNA have a secondary structure?
mRNA rRNA tRNA
Working in a microbiology lab, your supervisor brings you a novel bacterium that needs to be classified. You are under specific instruction to not kill the living microbe because of a limited sample size. Which microscope is the best option
phase-contrast microscopy