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Questions and Answers
Viruses are classed as non-living because they do not carry out ___.
Viruses are classed as non-living because they do not carry out ___.
metabolism
The largest known viruses are called ____, measuring 400 nanometers in diameter.
The largest known viruses are called ____, measuring 400 nanometers in diameter.
mimiviruses
The smallest known viruses are ____ that measure 20 nanometers in diameter.
The smallest known viruses are ____ that measure 20 nanometers in diameter.
circoviruses
The protein shell of a virus is called a ___.
The protein shell of a virus is called a ___.
One step in the viral reproductive cycle is ____, where the viral genome enters the host cell.
One step in the viral reproductive cycle is ____, where the viral genome enters the host cell.
The process of ____ involves the release of new viruses from the host cell.
The process of ____ involves the release of new viruses from the host cell.
Viruses can have a broad or narrow host ____, which determines which organisms they can infect.
Viruses can have a broad or narrow host ____, which determines which organisms they can infect.
The viral component that integrates into the host genome carries the enzyme ____.
The viral component that integrates into the host genome carries the enzyme ____.
Viruses are classified as 'non-living' because they do not have the ability to carry out ___.
Viruses are classified as 'non-living' because they do not have the ability to carry out ___.
The viral genetic material can either be ___ or RNA.
The viral genetic material can either be ___ or RNA.
The process of viral infection involves several steps, including attachment, entry, integration, synthesis, assembly, and ___.
The process of viral infection involves several steps, including attachment, entry, integration, synthesis, assembly, and ___.
Bacteria can acquire ___ resistance through various mechanisms, posing a challenge in clinical settings.
Bacteria can acquire ___ resistance through various mechanisms, posing a challenge in clinical settings.
The viral assembly may occur spontaneously or may require additional ___ for help.
The viral assembly may occur spontaneously or may require additional ___ for help.
Viruses are considered obligate ___ because they can only replicate inside a host cell.
Viruses are considered obligate ___ because they can only replicate inside a host cell.
The host range of a virus describes the different types of ___ that the virus can infect.
The host range of a virus describes the different types of ___ that the virus can infect.
The two stages of bacteriophage life cycles are the lytic cycle and the ___ cycle.
The two stages of bacteriophage life cycles are the lytic cycle and the ___ cycle.
Which characteristic is true for all viruses?
Which characteristic is true for all viruses?
What distinguishes mimiviruses from other viruses?
What distinguishes mimiviruses from other viruses?
What is a key factor in the evolution of bacteria?
What is a key factor in the evolution of bacteria?
Which step is part of the viral reproductive cycle?
Which step is part of the viral reproductive cycle?
What describes the typical size of circoviruses?
What describes the typical size of circoviruses?
Which option accurately refers to how viruses infect eukaryotic cells?
Which option accurately refers to how viruses infect eukaryotic cells?
What role does integrase play in a viral life cycle?
What role does integrase play in a viral life cycle?
What is the primary reason antibiotic resistance is a concern in bacteria?
What is the primary reason antibiotic resistance is a concern in bacteria?
What factor contributes significantly to the evolution of bacteria?
What factor contributes significantly to the evolution of bacteria?
Which mechanism do viruses use to enter host cells during infection?
Which mechanism do viruses use to enter host cells during infection?
What is the function of the enzyme integrase in some viruses?
What is the function of the enzyme integrase in some viruses?
Which type of virus is characterized by its ability to cause a broad range of infections across different species?
Which type of virus is characterized by its ability to cause a broad range of infections across different species?
What biological structure aids in the assembly of new viruses within a host cell?
What biological structure aids in the assembly of new viruses within a host cell?
Which of the following statements about viruses is incorrect?
Which of the following statements about viruses is incorrect?
In the context of viral reproduction, what does the term 'lysis' refer to?
In the context of viral reproduction, what does the term 'lysis' refer to?
What describes a characteristic of mimiviruses compared to other viruses?
What describes a characteristic of mimiviruses compared to other viruses?
Which factor primarily drives the evolution of bacteria?
Which factor primarily drives the evolution of bacteria?
What is the primary method through which a virus typically gains entry into a host cell?
What is the primary method through which a virus typically gains entry into a host cell?
What characterizes a virus with a narrow host range?
What characterizes a virus with a narrow host range?
Which component is responsible for packaging the viral genome?
Which component is responsible for packaging the viral genome?
Which of the following steps is involved in the lytic cycle of a bacteriophage?
Which of the following steps is involved in the lytic cycle of a bacteriophage?
How do bacteria primarily acquire antibiotic resistance?
How do bacteria primarily acquire antibiotic resistance?
Which of the following is true about the influenza virus?
Which of the following is true about the influenza virus?
What process describes the release of new viruses from a host cell through cell rupture?
What process describes the release of new viruses from a host cell through cell rupture?
What is the first step in the HIV life cycle?
What is the first step in the HIV life cycle?
During which phase is the HIV RNA converted into DNA?
During which phase is the HIV RNA converted into DNA?
What occurs immediately after the reverse transcription step in the HIV life cycle?
What occurs immediately after the reverse transcription step in the HIV life cycle?
Which method is primarily responsible for the release of new viruses in the HIV life cycle?
Which method is primarily responsible for the release of new viruses in the HIV life cycle?
What is synthesized during the transcription and translation phase of the HIV life cycle?
What is synthesized during the transcription and translation phase of the HIV life cycle?
During which phase of the HIV life cycle is the genetic material of the virus integrated into the host cell's DNA?
During which phase of the HIV life cycle is the genetic material of the virus integrated into the host cell's DNA?
What is the primary purpose of the reverse transcription step in the HIV life cycle?
What is the primary purpose of the reverse transcription step in the HIV life cycle?
Which method is typically employed by HIV to exit the host cell once new viruses are assembled?
Which method is typically employed by HIV to exit the host cell once new viruses are assembled?
In the HIV life cycle, what is the first event that allows the virus to begin the infection process?
In the HIV life cycle, what is the first event that allows the virus to begin the infection process?
What are the new virus particles primarily composed of during the assembly phase of the HIV life cycle?
What are the new virus particles primarily composed of during the assembly phase of the HIV life cycle?
During which phase of the HIV life cycle is the synthesis of viral components carried out?
During which phase of the HIV life cycle is the synthesis of viral components carried out?
Flashcards
What are viruses?
What are viruses?
Viruses are non-living particles composed of nucleic acid (DNA or RNA) enclosed within a protein coat called a capsid. They lack the ability to carry out metabolism, use energy, maintain homeostasis, or reproduce independently. To survive, viruses must infect and hijack a host cell's resources.
Why are viruses called obligate parasites?
Why are viruses called obligate parasites?
Viruses are classified as obligate parasites because they require a host cell to replicate and survive. They don't have their own machinery to make copies of themselves.
Describe the viral reproductive cycle.
Describe the viral reproductive cycle.
The viral reproductive cycle involves several steps: attachment (virus binds to host cell), entry (viral genome enters host), integration (viral genome integrates into host DNA), synthesis (viral components are made), assembly (new viral particles are assembled), and release (new viruses are released).
What are the lytic and lysogenic cycles?
What are the lytic and lysogenic cycles?
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How do bacteria become antibiotic resistant?
How do bacteria become antibiotic resistant?
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How does the high mutation rate in bacteria impact their evolution?
How does the high mutation rate in bacteria impact their evolution?
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Why is antibiotic resistance a concern?
Why is antibiotic resistance a concern?
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What steps can be taken to combat antibiotic resistance?
What steps can be taken to combat antibiotic resistance?
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Study Notes
Lecture 7: The Genetics of Viruses & Bacteria
- Viruses: Non-living particles composed of nucleic acid and protein.
- Viruses are obligate parasites.
- Viruses don't carry out metabolism, use energy, maintain homeostasis, or reproduce independently.
- Mimiviruses: Largest known viruses, measuring 400 nanometers in diameter and containing over 900 proteins encoded by 1,200,000 nucleotides.
- Circoviruses: Smallest known viruses, measuring 20 nanometers in diameter, with a genome of 1,700 nucleotides encoding two proteins.
- Viral Structure:
- Genome: DNA or RNA
- Capsid: Protein shell, rod-shaped or polyhedral.
- Capsomeres: Protein subunits forming the capsid.
- HIV: A virus that destroys the immune system by invading and killing T-cells (CD4).
- Transmitted through blood, vaginal fluid, and breast milk.
- Estimated 40 million people worldwide live with HIV/AIDS.
- Estimated 2.1 million new infections in 2019.
- An estimated 103,800 people are living with HIV in the UK in 2019.
- HIV Life Cycle:
- Binding: HIV binds to CD4 and co-receptors on a T-cell.
- Fusion: The virus fuses with the host cell membrane.
- Reverse Transcription: The single-stranded HIV RNA is converted into double-stranded HIV DNA.
- Integration: HIV DNA is inserted into the host cell's DNA.
- Transcription and Translation: The synthesis of viral components.
- Assembly: Formation of new virus particles.
- Release: New viruses are released, typically by lysis or budding.
- Opportunistic Infections in AIDS: Infections taking advantage of a weakened immune system. Examples include Cryptococcal meningitis, Toxo (toxoplasmosis), CMV (cytomegalovirus), and more.
- Bacterial reproduction and mutation: Bacteria reproduce through binary fission, where a cell divides into two daughter cells.
- Mutations can occur in bacteria, leading to antibiotic resistance.
- Mutation rate is low, but high rate of replication produces many bacteria with mutations, some resistant to antibiotics.
- Mutations can occur in bacteria, leading to antibiotic resistance.
- Bacteria:
- Diverse species
- High mutation rate drives evolution
- Acquire antibiotic resistance
- Important clinical cases
- Horizontal Gene Transfer: transfer of genetic material between bacteria.
- Transformation: Uptake of genetic material from the environment
- Transduction: Transfer by a bacteriophage
- Conjugation: Direct transfer via a sex pilus
- Antibiotic Resistance: Intrinsic (inherent) or acquired (develops over time) resistance.
- Mechanisms to make bacteria resistant:
- Mutation, horizontal gene transfer, pump antibiotics out of the cell
- Mechanisms to make bacteria resistant:
- Clinical Importance of Antibiotic Resistant Bacteria :
- At least 2 million people infected with antibiotic resistant bacteria
- At least 23,000 deaths annually due to these infections
- Further complications from resistant infection
Vaccines
- Vaccines contain a harmless variant or derivative of a pathogen to stimulate the immune system.
- Vaccines help prevent infections but don't always cure them once they occur.
- Edward Jenner was an important contributor to the development of vaccines.
- Conducted successful early vaccination experiment
Host Range
- Viruses can have a broad or narrow host range.
- Viral infection within eukaryotes are sometimes limited to specific tissues.
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