Bio: chapter 19

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What is the primary function of the capsid in a virus?

To produce toxins that harm the host cell
To facilitate the division of the virus
To provide a lipid membrane for the virus
To protect the viral genome from the host cell (correct)

What is the term for the units that make up the viral capsid?

Genomic particles
Nucleic acids
Capsomers (correct)
Viral proteins

Which of the following is a characteristic of viruses?

Acellular structure (correct)
Ability to divide by themselves
Large size compared to cells
Classification in a specific kingdom

What is the function of the envelope in a virus?

To provide an external lipid membrane for the virus (A) Signup and view all the answers

What is the term for the viral genome?

Nucleic acid genome (B) Signup and view all the answers

What is the primary characteristic that distinguishes viruses from cells?

Ability to divide (C) Signup and view all the answers

What is the meaning of the Latin root for the word 'virus'?

Poison (A) Signup and view all the answers

What occurs as a result of the lytic cycle?

The host cell dies, and new phages are released. (D) Signup and view all the answers

What is the term for the coexistence of a phage with its host cell?

Lysogeny (D) Signup and view all the answers

What is the purpose of the protein tailpiece in the phage?

To attach the phage to the host and inject the phage DNA (A) Signup and view all the answers

What is the term for a phage that reproduces only by the lytic cycle?

Virulent phage (A) Signup and view all the answers

What is the advantage of a bacterial mutant with surface proteins that cannot be recognized by a particular type of phage?

It tends to survive and thrive (D) Signup and view all the answers

What is the term for the integrated viral DNA in the host cell's chromosome?

Prophage (C) Signup and view all the answers

What is the name of the viruses that infect bacteria?

Bacteriophages (D) Signup and view all the answers

What is the function of restriction enzymes in bacteria?

To identify and cut foreign DNA (A) Signup and view all the answers

Why is the bacterium's own DNA not cut by restriction enzymes?

Because it is methylated (C) Signup and view all the answers

What are the 'spacer' sequences in CRISPRs derived from?

Phage DNA (C) Signup and view all the answers

What is the role of CRISPR-associated (Cas) proteins in the CRISPR-Cas system?

To identify and cut phage DNA (A) Signup and view all the answers

What happens when a phage infects a bacterial cell with the CRISPR-Cas system?

The phage DNA is integrated between two repeat sequences (A) Signup and view all the answers

What is the purpose of the CRISPR-Cas system in bacteria?

To defend against viruses (A) Signup and view all the answers

What are CRISPRs composed of?

Clustered regularly interspaced short palindromic repeats (C) Signup and view all the answers

What happens to the phage DNA if the phage is identified?

It is cut and destroyed (D) Signup and view all the answers

What is the function of the phage-related RNA in the CRISPR-Cas system?

To act as a homing device to detect invading phages (A) Signup and view all the answers

What is the significance of the membranous envelope in animal viruses?

It provides protection from the host's immune system (D) Signup and view all the answers

What is the difference between bacteriophages and animal viruses?

Animal viruses have a membranous envelope (B) Signup and view all the answers

What triggers the transcription of the CRISPR region?

The attempt of the phage to infect the cell (D) Signup and view all the answers

What is a key variable used to classify viruses that infect animals?

The presence or absence of a membranous envelope (C) Signup and view all the answers

What is the result if a cell survives a phage infection?

The cell blocks any attempt of the same type of phage to re-infect it (A) Signup and view all the answers

What is the primary mechanism by which retroviruses, such as HIV, copy their RNA genome?

Reverse transcriptase (B) Signup and view all the answers

What is the term for the viral DNA that is integrated into the host genome?

Provirus (A) Signup and view all the answers

What is the primary way in which viral infections cause symptoms?

Release of hydrolytic enzymes from lysosomes (D) Signup and view all the answers

What is the role of a vaccine in preventing viral illnesses?

Stimulating the immune system to mount defenses (A) Signup and view all the answers

Why are viral infections not treated by antibiotics?

Antibiotics are ineffective against viruses (B) Signup and view all the answers

What is the factor that determines the level of damage a virus causes?

The infected tissue's ability to regenerate (D) Signup and view all the answers

What is the term for the diseases caused by viral infections in animals?

Viral diseases (C) Signup and view all the answers

What is the result of HIV infection in humans?

Acquired immunodeficiency syndrome (AIDS) (C) Signup and view all the answers