Podcast
Questions and Answers
Which of the following characteristics is NOT used to classify viruses?
Which of the following characteristics is NOT used to classify viruses?
- The method of viral release from the host cell (correct)
- The presence or absence of an envelope
- The shape of the capsid
- The type of host they infect
During viral replication, which step involves the viral genome being inserted into the protein capsid?
During viral replication, which step involves the viral genome being inserted into the protein capsid?
- Synthesis
- Attachment
- Assembly (correct)
- Entry
An enveloped virus contains glycoprotein spikes. What is their primary biological function?
An enveloped virus contains glycoprotein spikes. What is their primary biological function?
- To aid in the synthesis of viral proteins.
- To protect the viral genome from degradation.
- To facilitate attachment to host cells. (correct)
- To promote the release of new viral particles.
A researcher identifies a newly discovered virus with a single-stranded RNA genome that utilizes reverse transcriptase. Based on this information, to which group does this virus likely belong?
A researcher identifies a newly discovered virus with a single-stranded RNA genome that utilizes reverse transcriptase. Based on this information, to which group does this virus likely belong?
Bacteriophages are used as a model to study viruses. What characteristics of bacteriophages make them useful for this purpose?
Bacteriophages are used as a model to study viruses. What characteristics of bacteriophages make them useful for this purpose?
A virus that enters a host cell via endocytosis and has a DNA genome will most likely undergo uncoating and replication in which cellular location?
A virus that enters a host cell via endocytosis and has a DNA genome will most likely undergo uncoating and replication in which cellular location?
Which of the following characteristics would most likely be associated with a naked virus?
Which of the following characteristics would most likely be associated with a naked virus?
If a mutation occurred in the gene encoding hemagglutinin in the influenza virus, what is the most likely consequence?
If a mutation occurred in the gene encoding hemagglutinin in the influenza virus, what is the most likely consequence?
Which of the following viral entry mechanisms involves the direct interaction between viral glycoproteins and host cell membrane receptors, leading to the merging of the viral envelope with the host cell membrane?
Which of the following viral entry mechanisms involves the direct interaction between viral glycoproteins and host cell membrane receptors, leading to the merging of the viral envelope with the host cell membrane?
An enveloped virus uses its surface glycoproteins to bind to a host cell. After entry via membrane fusion, where in the host cell does the viral genome get released?
An enveloped virus uses its surface glycoproteins to bind to a host cell. After entry via membrane fusion, where in the host cell does the viral genome get released?
A researcher is studying a newly discovered enveloped virus. They observe that the virus buds from the endoplasmic reticulum (ER) of the host cell. What can they infer from this observation?
A researcher is studying a newly discovered enveloped virus. They observe that the virus buds from the endoplasmic reticulum (ER) of the host cell. What can they infer from this observation?
A scientist observes that a particular virus exhibits a high rate of antigenic drift. Which of the following is the most likely mechanism driving this phenomenon?
A scientist observes that a particular virus exhibits a high rate of antigenic drift. Which of the following is the most likely mechanism driving this phenomenon?
Consider a mutation in the Spike protein of SARS-CoV-2 that prevents it from binding to its receptor on human cells. What is the most likely outcome of this mutation?
Consider a mutation in the Spike protein of SARS-CoV-2 that prevents it from binding to its receptor on human cells. What is the most likely outcome of this mutation?
Flashcards
What are viruses?
What are viruses?
Infectious agents containing either DNA or RNA, but not both. They are not cells and require a host to replicate.
What is a viral capsid?
What is a viral capsid?
A protein shell enclosing the viral genome.
Envelope & Glycoproteins
Envelope & Glycoproteins
Envelope: A lipid layer surrounding some viruses, derived from the host cell membrane; Glycoproteins: Protein spikes on the envelope surface, aiding in attachment to host cells.
Viral Shapes
Viral Shapes
Signup and view all the flashcards
Viral Replication Steps
Viral Replication Steps
Signup and view all the flashcards
Direct Viral Entry
Direct Viral Entry
Signup and view all the flashcards
Viral Membrane Fusion
Viral Membrane Fusion
Signup and view all the flashcards
Viral Endocytosis
Viral Endocytosis
Signup and view all the flashcards
Viral Synthesis Locations
Viral Synthesis Locations
Signup and view all the flashcards
Viral Release Mechanisms
Viral Release Mechanisms
Signup and view all the flashcards
Viral Budding
Viral Budding
Signup and view all the flashcards
Key Viral Surface Molecules
Key Viral Surface Molecules
Signup and view all the flashcards
Antigenic Drift
Antigenic Drift
Signup and view all the flashcards
Study Notes
- Viruses are infectious agents that need a host to replicate
Virus Classification
- Viruses can be classified based on whether they have DNA or RNA as their genetic material
- DNA viruses include 7 families
- RNA viruses include 12 families
- Viruses can be enveloped or naked
- The structure of viruses includes dsDNA, ssDNA, dsRNA, and ssRNA classification
Viral Structure
- Viruses have a capsid, which is a protein shell that surrounds the nucleic acid (viral genome)
- Some viruses have an envelope, which is a lipid bilayer derived from the host cell membrane
- An enveloped virus consists of glycoproteins, a helical capsid, a matrix protein, and an envelope
Viral Shapes
- Viral shapes can be helical, polyhedral, or complex
Viral Genomes
- Viral genomes contain genes that:
- Ensure replication of the viral genome
- Code for capsid proteins
- Ensure packaging of the genome into the capsid
- Alter the structure and function of the host
- Enveloped viruses have genes that code for glycoprotein spikes
Viral Replication Steps
- There are 5 viral replication steps:
- Attachment
- Entry/Uncoating
- Synthesis
- Assembly
- Release
Bacteriophages
- Bacteriophages are viruses that infect bacteria
- They are used as a model to study viruses and follow the same 5 steps as other viruses
Animal Virus Cell Entry
- Animal viruses enter cells through direct penetration
- Animal viruses enter cells through Membrane Fusion
- Viral glycoproteins remain in the cytoplasmic membrane
- Animal viruses enter via Endocytosis
- Cytoplasmic membrane of host engulfs the virus
Synthesis and Assembly
- DNA genomes can be synthesized in the nucleus of the cell
- RNA genomes can be synthesized in the cytoplasm of the cell
- If a virus also contains an envelope, the building blocks need to be synthesized
- Assembly/Packaging of nucleocapsid:
- DNA- usually this occurs in the nucleus
- RNA- usually this occurs in the cytoplasm
Release From the Cell
- Naked viruses can be released through exocytosis or lysis
- Enveloped viruses are released through budding
Case Studies- Influenza and SARS-CoV2
- Influenza is an enveloped RNA virus (many pieces of RNA)
- Has two important molecules on its surface: Hemagglutinin and Neuraminidase
- Undergoes antigenic drift, where surface molecules change through mutation, and antigenic shift
- SARS-CoV2 is an enveloped RNA virus (one ssRNA, like mRNA)
- The main molecule present it the Spike protein (glycosylated)
- There are variants that undergo either drift or shift
Role of Viruses in Cancer
- Viruses are involved in about 15% of cancers
- Variety of mechanisms:
- Integrate viral DNA into the host genome
- Activate oncogenes, which increases replication and transcription, while preventing apoptosis
- HPV is involved in cervical and other cancers; vast majority of cervical cancers are linked to HPV
- Available to everyone up to the age of 26
Prions
- Prions are protein infectious particles that consist of ONLY proteins
- Cause progressive neurodegenerative diseases and are very stable
- Diseases caused by prions are known as transmissible spongiform encephalopathies (TSEs)
Pathophysiology of Prions
- Prions are infectious misfolded proteins
- There are 3 types of prion occurrence:
- Sporadic (random?)
- Genetic
- Acquired (eating)
- Fatal Familial Insomnia (FFI) results from a slow conversion/accumulation of PrPSc
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
Learn about virus classification based on genetic material, including DNA and RNA types. Explore viral structures like capsids and envelopes and understand the functions of viral genomes in replication and host interaction. Different viral shapes and their characteristics will also be discussed.
