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What happens during the lytic cycle of bacteriophages?
What happens during the lytic cycle of bacteriophages?
Temperate viruses always cause immediate cell death after infection.
Temperate viruses always cause immediate cell death after infection.
False
What is the primary role of T4 lysozyme during the bacteriophage infection process?
What is the primary role of T4 lysozyme during the bacteriophage infection process?
To form a small pore in the peptidoglycan layer of the bacterial cell wall.
The lytic cycle is characterized by the ____ of the host cell.
The lytic cycle is characterized by the ____ of the host cell.
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Match the following terms with their definitions:
Match the following terms with their definitions:
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Which structure surrounds the genome of a virus?
Which structure surrounds the genome of a virus?
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Viruses possess a metabolism and can replicate themselves independently.
Viruses possess a metabolism and can replicate themselves independently.
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What type of viral genome can be integrated into a host’s genome?
What type of viral genome can be integrated into a host’s genome?
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Viruses can infect bacteria, which are specifically called __________.
Viruses can infect bacteria, which are specifically called __________.
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What determines the size range of viruses?
What determines the size range of viruses?
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Match the following terms to their descriptions:
Match the following terms to their descriptions:
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Animal viruses are known to use DNA or RNA for their genomes.
Animal viruses are known to use DNA or RNA for their genomes.
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What is the first phase of the viral life cycle?
What is the first phase of the viral life cycle?
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What is the primary function of uptake ABC transporters?
What is the primary function of uptake ABC transporters?
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Planktonic growth refers to microorganisms that are attached to a surface.
Planktonic growth refers to microorganisms that are attached to a surface.
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What defines the stationary phase in a batch culture?
What defines the stationary phase in a batch culture?
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Organisms that thrive in extremely high temperatures, such as hot springs, are called __________.
Organisms that thrive in extremely high temperatures, such as hot springs, are called __________.
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Match the types of microbes with their temperature requirements:
Match the types of microbes with their temperature requirements:
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Which of the following describes a biofilm?
Which of the following describes a biofilm?
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Acidophiles are microbes that thrive in alkaline environments.
Acidophiles are microbes that thrive in alkaline environments.
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What is the key characteristic of mesophiles?
What is the key characteristic of mesophiles?
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What is the main function of alarmones like ppGpp and pppGpp in bacteria?
What is the main function of alarmones like ppGpp and pppGpp in bacteria?
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The stringent response has no effect on the synthesis of macromolecules.
The stringent response has no effect on the synthesis of macromolecules.
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What happens to tRNA when amino acids become limited?
What happens to tRNA when amino acids become limited?
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The protein associated with the ribosome that starts producing alarmones under stress is called _____ .
The protein associated with the ribosome that starts producing alarmones under stress is called _____ .
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Match the following components to their roles in the stringent response:
Match the following components to their roles in the stringent response:
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What triggers the stringent response in bacteria?
What triggers the stringent response in bacteria?
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Ribosome production immediately resumes when conditions improve after a stringent response.
Ribosome production immediately resumes when conditions improve after a stringent response.
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Name one environmental condition that can lead to a stringent response.
Name one environmental condition that can lead to a stringent response.
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What is the role of a conjugation pilus in bacteria?
What is the role of a conjugation pilus in bacteria?
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F+ cells lack the F plasmid.
F+ cells lack the F plasmid.
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What term describes cells possessing an integrated F plasmid?
What term describes cells possessing an integrated F plasmid?
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Cells without the F plasmid are referred to as ______ cells.
Cells without the F plasmid are referred to as ______ cells.
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Which of the following statements about DNA transfer via conjugation is true?
Which of the following statements about DNA transfer via conjugation is true?
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Environmental DNA is typically full-length coding DNA segments.
Environmental DNA is typically full-length coding DNA segments.
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What facilitates the digestion of ssDNA fragments during recombination?
What facilitates the digestion of ssDNA fragments during recombination?
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What type of bacteria are more prominent in breastfed infants compared to bottle-fed infants?
What type of bacteria are more prominent in breastfed infants compared to bottle-fed infants?
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C-section births result in infants having a microbiome more similar to that of their biological mother compared to vaginal births.
C-section births result in infants having a microbiome more similar to that of their biological mother compared to vaginal births.
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What is the hygiene hypothesis?
What is the hygiene hypothesis?
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Lack of microbial diversity leads to an immune system that is less effective at discerning what is ________ and what is not.
Lack of microbial diversity leads to an immune system that is less effective at discerning what is ________ and what is not.
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Match the following factors with their impact on microbiota:
Match the following factors with their impact on microbiota:
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Which group is less likely to develop immune disorders according to the discussed trends?
Which group is less likely to develop immune disorders according to the discussed trends?
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The incidence of inflammatory bowel disease (IBD) has decreased since the 1950s.
The incidence of inflammatory bowel disease (IBD) has decreased since the 1950s.
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What role does early parental transmission of microbiota play in an individual’s life?
What role does early parental transmission of microbiota play in an individual’s life?
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Study Notes
Learning Objectives
- Learning objectives are provided for the final General Microbiology exam at the University of Ottawa.
- Mastering these objectives will help in answering applied questions.
- Synthesis and contextualization of knowledge are essential.
Bacteria
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Cell Morphologies and Arrangements:
- Bacteria exhibit various shapes (cocci, bacilli, spirochetes).
- Cell arrangements include diplococci, tetrads, streptococci, staphylococci, and streptobacilli.
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Bacterial Cell Structures:
- A typical bacterial cell contains a cell membrane, chromosomal DNA (nucleoid), plasmids, ribosomes, and a cell wall.
- Some prokaryotic cells possess flagella, pili, fimbriae, and capsules.
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Cell Walls:
- The cell wall provides shape, rigidity, and protection against osmotic pressure.
- Cell walls consist of peptidoglycan.
- Gram-positive, gram-negative, and acid-fast bacteria have different cell wall structures.
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Cytoplasmic Membrane:
- Separates intracellular from extracellular environments.
- Contains proteins for transport, energy production (respiration), sensing, and secretion.
- Composed of a lipid bilayer with integral and peripheral proteins.
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Cytoplasm:
- Contains DNA (nucleoid), RNA, proteins, and ribosomes.
- Includes other structures like inclusion bodies, magnetosomes, and cytoskeleton.
- Nucleoid is the region where the chromosomonal DNA is concentrated.
- Plasmids are extra-chromosomal DNA which carries non-essential genetic information.
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Endospores:
- Specialized structures of some bacteria for survival under harsh conditions.
- Complex structures; resistant to desiccation, heat, radiation, and chemicals.
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DNA:
- Contains dipicolinic acid (DPA) and is enriched in Ca2+.
- Fimbriae and Pili:
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- Fimbriae are used for attachment
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- Pili are used for exchange of genetic material
- Flagella:
-
- Used for cell motility
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Thylakoids and Carboxysomes:
- Unique to photosynthetic bacteria.
- Thylakoids are extensively folded intracellular membranes.
- Carboxysomes are polyhedral bodies that contain the enzyme rubisco for CO2 fixation.
- Gas vesicles are protein-bound gas-filled structures that help with buoyancy.
- Holds transport proteins in place, creates a proton motive force, and transports polar/ charged molecules.
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Archaea:
- Archaea are a domain of life distinct from bacteria and eukaryotes.
- Different physical/chemical structure/function in comparison to bacteria and eukaryotes.
- Cell walls lack peptidoglycans.
- Unique lipids with ether linkages.
- Many differences in their genetic and genomic structure
-
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Structures:
- Pseudo-murein, S-layer, and hami
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Structures:
Viruses
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General structure and composition:
- All viruses have a genome (DNA or RNA) enclosed in a protein coat (capsid).
- Some viruses have an additional envelope derived from the host cell membrane.
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Genomes:
- May be DNA or RNA, linear or circular, single-stranded or double-stranded.
- Viral Replication (life cycles):
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Lytic:
- Virus replicates rapidly, lyses the host cell to release new viruses.
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Lysogenic:
- Viral genome integrates into host cell's DNA and can remain dormant.
- Virus can transition to lytic cycle under certain conditions.
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Viral Entry:
- Virus must attach to specific receptors on the host cell.
-
- Virulent viruses enter host cells while temperate viruses can insert their genome into the host's genome
- Viral Replication:
- Host genome (metabolism) is rechanneled to produce viral components.
- Viral mRNA takes over host cell's machinery to make new virus.
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Viral Assembly and Release:
- New viral particles assemble.
- Virus progeny leaves host cell by budding or cell lysis.
Microbial Metabolism
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Catabolism and Anabolism:
- Catabolism is the breakdown of complex molecules into simpler ones to release energy.
- Anabolism is the building up of complex molecules from simpler ones using energy released from catabolism.
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Energy Carriers:
- ATP, NADH, FADH2, PEP are crucial in energy transfer.
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Chemotrophs and Phototrophs:
- Chemotrophs obtain energy from chemical reactions.
- Phototrophs obtain energy from light.
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Organotrophs and Lithotrophs:
- Organotrophs use organic compounds as an electron source.
- Lithotrophs use inorganic compounds as an electron source.
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Autotrophs and Heterotrophs:
- Autotrophs make their own organic compounds from inorganic sources (CO2).
- Heterotrophs obtain organic compounds from other organisms.
Microbial Growth
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Growth Phases:
- Lag phase, log phase, stationary phase, death phase.
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Environmental Factors:
- Temperature, pH, osmotic pressure, and oxygen requirement influence growth.
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Microbial Biofilms:
- Surface-attached communities of microorganisms producing an extracellular matrix.
- Provide protection and enhanced persistence
Microbial Genetics and Genomics
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Sexual and Asexual Reproduction:
- Asexual reproduction creates genetically identical copies.
- Sexual reproduction leads to genetic variation through recombination.
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Horizontal Gene Transfer:
- Transformation, transduction, and conjugation.
- Transfer of genes between bacteria, often by plasmids
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Operons:
- Cluster of genes transcribed together; important in metabolic pathways.
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Regulation:
- Activator and repressor proteins and two-component systems control gene expression in response to environmental cues.
- Sigma factors are major players in the regulation by choosing what genes are transcribed
- Global Control Systems (regulons): Coordinate gene expression in response to a wider array of conditions.
- Chromosomal Islands: Code for non-essential genes associated with virulence, antibiotic resistance, or metabolic capabilities.
Microbial Symbiosis with Humans
-
Diversity and Dynamics of Microbial Populations:
- The human microbiome (many species, some are commensals (harmless for the host)).
- The microbial composition is affected by factors like diet, medications, and age
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Dysbiosis:
- An imbalance in the gut microbiota leading to illness,
- Role of Commensal Microbiota: -Essential for nutrient digestion, vitamin synthesis and immune system training
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Impact of microbiota on disease:
- Links between gut microbiota and diseases such as inflammatory bowel disease (IBD)
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Mechanisms of microbial colonization:
- Adherence, biofilm formation, and immune barriers play a role
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Microbiota and human health and diseases:
- Impact of a healthy, balanced microbiota on maintaining wellness
Host-Pathogen Responses
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Virulence Factors
- Microbial products that facilitate colonization, invasion, and damage to host tissues or systems.
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Mechanisms of Pathogenesis
- Virulence factors are mechanisms used by pathogens to cause infections or diseases
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Cellular and Systemic Mechanisms of Action:
- Microbial toxins (endogenous or exogenous), and their impact on cellular structures or signalling pathways.
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Secretion Systems (particularly T3SS):
- Special pathways that bacteria use to transport effector proteins into host cells.
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Effectors:
- Proteins secreted by a pathogen that interfere with host cellular processes.
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Description
Test your knowledge on the lytic cycle of bacteriophages and their infective processes. This quiz covers key concepts such as T4 lysozyme function, viral genome integration, and the characteristics of viral infections. Perfect for students studying microbiology and virology.
