Biology Chapter 6 Virus Flashcards

Questions and Answers

Identify the different environments in which some viruses can replicate.

Bacterial cells, Animal cells, Human cells

Which of the following activities are not characteristics of viruses?

Maintain homeostasis (correct)

Metabolize food (correct)

React to environmental factors

Replicate independently (correct)

The cause of viral infections remained unknown for many years longer than other types of infections due to which of the following reasons?

The symptoms of viral infections were not severe.

Viruses reproduce quickly.

The techniques used to observe other pathogens were useless with viruses. (correct)

Viruses are not visualized by light microscopes. (correct)

Which of the following describes viruses?

Non-living, infectious agent Signup and view all the answers

Which term best describes viruses?

Ultramicroscopic Signup and view all the answers

Which of the following relate to all viruses?

Acellular, Nucleic acid, Capsid Signup and view all the answers

Many animal viruses will acquire which of the following from the host cell's membrane?

Envelope Signup and view all the answers

The viral envelope is compositionally different from a non-infected host cell because of the presence of which of the following?

Viral proteins Signup and view all the answers

Which of the following are reliant on the viral capsid?

Adsorption, Penetration Signup and view all the answers

Poliovirus and adenovirus have a capsid arranged in a symmetrical polygon structure called a(n)

icosahedron Signup and view all the answers

Viral glycoproteins are present in the host membrane but not in the viral envelope.

False Signup and view all the answers

Which type of capsids are composed of multiple protein types and nonsymmetrical shapes?

Complex Signup and view all the answers

Why must living cells carry a larger genome than viruses?

They must be able to carry out metabolic processes that sustain independent life. Signup and view all the answers

Which of the following describes bacteriophages?

Polyhedral capsid head, Complex, Flexible tail Signup and view all the answers

In terms of numbers, how many genes can be found in some viruses?

~9 to 100s Signup and view all the answers

What is common to replicase and reverse transcriptase?

They are preformed viral proteins. Signup and view all the answers

Which are the criteria used in classifying viruses into families?

Genetic makeup, Structure, Chemical composition Signup and view all the answers

What term is used to describe when a virus initially 'sticks' to the host cell?

Absorption Signup and view all the answers

Which of the following best explains why viruses have so few genes?

Viruses do not have metabolic pathways. Signup and view all the answers

Which preformed enzyme is involved in the synthesis of DNA from RNA in retroviruses, such as HIV?

Reverse transcriptase Signup and view all the answers

What functions do capsid proteins perform for naked viruses?

Protection, Attachment Signup and view all the answers

Which term describes the tissue specificities of animal viruses for certain body cells?

Tropisms Signup and view all the answers

Which of the following viral structures must be specific for adsorption?

Spike proteins Signup and view all the answers

The two main processes by which viruses penetrate host cells are engulfment, also known as __

endocytosis and direct fusion Signup and view all the answers

The process of penetration occurs when viruses are taken into the cell followed by engulfment in a vesicle called a(n) __

endosome Signup and view all the answers

Tropisms are tissue specificities of animal viruses for certain body cells, e.g., the hepatitis B virus targets the _____

liver & salivary Signup and view all the answers

Identify all the methods that a virus can use to gain entry into an animal cell.

Fusion of the viral envelope and the cell membrane Signup and view all the answers

In which way do enveloped viruses leave their host cell?

Budding Signup and view all the answers

What is a simple translation of cytopathic?

Cell disease Signup and view all the answers

What is a name given to a disease-causing agent composed only of protein?

Prion Signup and view all the answers

Using a microscope, you observe some cells which have multiple nuclei because a virus has caused normal cells to fuse together. What is this observation called?

Cytopathic effect Signup and view all the answers

AAV can only replicate in cells infected with?

Adenovirus Signup and view all the answers

Study Notes

Virus Characteristics and Structure

Viruses can replicate in various environments including bacterial, animal, and human cells.
Viruses are considered non-living infectious agents characterized by their ultramicroscopic size.
They lack the ability to metabolize food, maintain homeostasis, replicate independently, or respond to environmental changes.
Viral structures include an acellular composition that comprises nucleic acids and a protective capsid.

Viral Genomes and Classification

Viral genomes generally consist of approximately 9 to several hundred genes.
Criteria for virus family classification include genetic makeup, structural characteristics, and chemical composition.

Viral Entry and Penetration

Viruses enter host cells through absorption and employ spike proteins for specific adsorption.
Two main mechanisms for penetration include endocytosis and direct fusion, facilitating the engulfment of viruses into the cells.
Enveloped viruses escape host cells by a process known as budding.

Viral Proteins and Enzymes

Capsid proteins provide protection and facilitate attachment in naked viruses.
Preformed enzymes like replicase and reverse transcriptase play essential roles in viral replication; the latter synthesizes DNA from RNA in retroviruses.

Virus Host Interactions and Effects

Tropisms refer to the tissue-specific preferences of viruses, such as the affinity of hepatitis B for liver and salivary cells.
Cytopathic effects occur when viruses induce the fusion of normal cells, resulting in multinucleate cells.

Unique Viral Agents

Prions are disease-causing agents composed solely of protein, distinct from conventional viruses.
AAV (Adeno-Associated Virus) requires co-infection with adenoviruses to replicate.

Viral Structures

Complex capsids have multiple protein types with non-symmetrical shapes.
The viral envelope is different from the host cell membrane due to the presence of viral proteins, which includes specific glycoproteins.

Important Viral Concepts

Viruses possess a capsid vital for adsorption and penetration into host cells, while naked viruses rely significantly on their capsid for these functions.
The process of viral absorption marks the initial attachment phase, which is crucial for successful infection.

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Test your knowledge of viruses with these flashcards from Biology Chapter 6. Learn about their replication environments and characteristics that differentiate them from living organisms. Perfect for students studying microbiology or preparing for exams.