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MICR 271 - Module 1 Exam Questions And Complete Answers., Exams of Nursing

MICR 271 - Module 1 Exam Questions And Complete Answers.

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2024/2025

Available from 07/06/2025

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MICR 271 - Module 1 Exam Questions And
Complete Answers
What is the difference in between bacteria, archaea, and eukaryotes? - answer Bacteria:
Single-celled organisms that can live freely or as a parasite.
Archaea: Single-celled organism without a membrane-bound nucleus or organelles.
Eukaryotes: Organism with nucleus and other membrane-bound organelles.
What is a microbe? - answer A microbe is a tiny organism that the naked eye cannot see.
Microbes involve many organisms, such as bacteria, viruses, protozoa, and other
organisms. (a microscopic form of life including bacterial, archaeal, fungal, and protozoal
cells)
What does the endosymbiont hypothesis state? What is the supporting evidence? - answer
The endosymbiont hypothesis states that eukaryotes evolved from prokaryotes. The
supporting evidence lies in the fact that mitochondria and chloroplasts have their own
DNA and replication systems, similarly to prokaryotes. A symbiotic relationship in between
the primitive archezoan cell and the alpha proteobacteria would have provided an
advantage to both.
What are the two mitochondrial symbiosis theories? - answer Archezoan scenario: Nucleus
formation in a primitive archezoan occurs before the arrival of the alpha proteobacteria.
(Unlikely because studies of protists showed early integration of mitochondria)
Endosymbiont scenario: Nucleus formation in the primitive archezoan occurred after the
integration of the alpha-proteobacteria into the archaeal ancestor.
What is phylogeny? - answer Classification of species based on genetic similarities to
determine evolutionary relationships.
What is a phylogenetic tree? - answer A picture of probable evolutionary relationships
between species, based on measured evidence in comparing rRNA sequences.
What are phylogenomics? - answer Comparison of entire genomes to determine
evolutionary ties. This approach is much more detailed than phylogenetics.
What is horizontal gene transfer? - answer Horizontal gene transfer is the passing of
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MICR 271 - Module 1 Exam Questions And

Complete Answers

What is the difference in between bacteria, archaea, and eukaryotes? - answer Bacteria: Single-celled organisms that can live freely or as a parasite. Archaea: Single-celled organism without a membrane-bound nucleus or organelles. Eukaryotes: Organism with nucleus and other membrane-bound organelles. What is a microbe? - answer A microbe is a tiny organism that the naked eye cannot see. Microbes involve many organisms, such as bacteria, viruses, protozoa, and other organisms. (a microscopic form of life including bacterial, archaeal, fungal, and protozoal cells) What does the endosymbiont hypothesis state? What is the supporting evidence? - answer The endosymbiont hypothesis states that eukaryotes evolved from prokaryotes. The supporting evidence lies in the fact that mitochondria and chloroplasts have their own DNA and replication systems, similarly to prokaryotes. A symbiotic relationship in between the primitive archezoan cell and the alpha proteobacteria would have provided an advantage to both. What are the two mitochondrial symbiosis theories? - answer Archezoan scenario: Nucleus formation in a primitive archezoan occurs before the arrival of the alpha proteobacteria. (Unlikely because studies of protists showed early integration of mitochondria) Endosymbiont scenario: Nucleus formation in the primitive archezoan occurred after the integration of the alpha-proteobacteria into the archaeal ancestor. What is phylogeny? - answer Classification of species based on genetic similarities to determine evolutionary relationships. What is a phylogenetic tree? - answer A picture of probable evolutionary relationships between species, based on measured evidence in comparing rRNA sequences. What are phylogenomics? - answer Comparison of entire genomes to determine evolutionary ties. This approach is much more detailed than phylogenetics. What is horizontal gene transfer? - answer Horizontal gene transfer is the passing of

genetic material from on organism to the next in a non-descendant nature. Why do eukaryotes have more subunits in RNA polymerase? - answer More complex structures allow for a wider range of functions. This explains the complexity of the organism. Why is it important that only bacteria can produce murein? - answer Murein forms the cell wall (PG layer) which provides added protection and is solely found in prokaryotes. What is the importance of horizontal gene transfer in the tree of life? - answer The tree of life is more like a "web" of life due to the transfer of genetic material in between the different evolutionary branches. How is the tree of life divided in between the archaeans, the prokaryotes, and the eukaryotes? - answer Prokaryotes are their own branch. The archaea and eukaryotes are closer in relationship. Why are viruses considered to be obligate intracellular parasites? - answer They require host-cell machinery to replicate and propagate. They can sometimes also incorporate themselves into genomes. Without explaining, identify the three theories surrounding how viruses came about. - answer 1. Virus-first theory

  1. Reduction theory
  2. Escape theory What is the virus-first theory? - answer Viruses evolved from self-replicating amino-acid structures (ribozymes, which have enzymatic properties) before cells came to be. What is the escape theory? - answer Asymmetrical cell division would have allowed for a section of DNA to part from the cell and protected by a protein coat could travel to other cells. There is a theory that viruses evolved from retrotransposons (sections of DNA that code for reverse transcriptase and integrase - it can be transcribed from RNA to DNA and then integrate itself in the host's genetic sequence), with self-replicating DNA and coat encoding RNA. What is the reduction theory? - answer A proto-cell invaded a host cell (kind of like mitochondria). The subsequent loss of function led to loss of material, which exited the cell to become a virus.

What is the difference in between commensal and pathogenic organisms? - answer Commensal: Symbiotic relationship with host. Pathogenic: Opportunistic relationship with the ability to cause infection. Identify two methods of genetic diversity. - answer 1. Mutations.

  1. Gene transfer and genetic recombination How du mutations lead to evolution? - answer Mutations can be spontaneous through an error in replication or repair or induced by chemical agents. These include insertions, deletions, point mutations, replacements, and inversions. Most of the time, these are harmful but they can occasionally be beneficial and confer advantage. What is the importance of horizontal gene transfer? - answer Allows gene sharing in between different organisms, which can lead to diversity and evolution. What are the different mechanisms of horizontal gene transfer? - answer 1. Transformation: Acquiring naked DNA from ECF and incorporating into the genome.
  2. Conjugation: Passing of genetic material from one bacterium to the next.
  3. Transduction: Viral implementation of True or False: Transposition is a method of HGT - answer False! Transposition is the jumping of a section of DNA from one region to another within the same organism. Horizontal gene transfer implies the transfer from one organism to another. What is an example of beneficial HGT? - answer When inflammation occurs in the intestinal tract, cells rupture and release iron. Seeing as inflammation is an immune response, normally bacteria would not survive the conditions. HGT allows for the acquiring of genes to use iron as an energy source, which makes their populations grow during

inflammation. HGT helps again in acquiring virulence genes. This positive regulation allows for further infection within the infected cells. What is the antibiotic resistome? - answer Pool of environmental resistance genes. Identify four mechanisms of antibacterial resistance. - answer 1. Target protection

  1. Target substitution
  2. Prevention of intracellular antibiotic accumulation
  3. Antibiotic detoxification What is target protection? - answer Expression of a molecule that impairs antibiotic activity and recognition. What is target substitution? - answer Alteration of the structure the antibiotic is meant to attack. What is prevention of intracellular antibiotic accumulation? - answer An increase in the number of efflux pumps on the membrane to favour release and not accumulation of antibiotics within the cell. What is antibiotic detox? - answer Ability to destroy antibiotics. What causes antibiotic resistance? - answer - Long term exposure
  • Inappropriate use.
  • Over the counter antibiotics used when not necessary
  • Antibiotics wrongly prescribed.

Discuss the evidence that supports the theory that mitochondria evolved from bacteria. - answer 1. Self replicating

  1. Own genome. Understand the nature of phylogenetic relationships and discuss why the microbial world is so diverse. - answer Evolution - Adapting to environments. HGT allows for gene transfer from one organism to the next. Discuss the hypotheses around the origin of viruses. - answer 1. Reduction theory
  2. Escape theory
  3. Virus-First theory List at least three mechanisms of horizontal gene transfer. - answer 1. Transduction
  4. Conjugation
  5. Transformation Describe how horizontal gene transfer and selective pressure can lead to antibiotic resistance. - answer Genes from already resistant strains can be passed on from one organism to the next. Selective pressure allows for better survival in species with better- adapted characteristics. Describe how human practices have led to increased antibiotic resistance and changes to broader microbial environments. - answer - Overprescription
  • Overused
  • Prolonged exposure
  • Antibiotics in water
  • Microbe changes in carbon and nitrogen cycles.