Ch. 19 - Viruses

Campbell - Campbell Biology 12th Edition

Urry12th EditionCampbell BiologyISBN: 9785794169850Not the one you use?Change textbook

Urry 12th Edition

Ch. 19 - Viruses

Problem 6

Chapter 19, Problem 6

Redraw Figure 19.8 to show the replicative cycle of a virus with a single-stranded genome that can function as mRNA (a class IV virus).

Verified step by step guidance

Begin by drawing the virus particle, which includes a protein coat (capsid) surrounding a single-stranded RNA genome. Label this as the 'Class IV virus'.

Illustrate the virus attaching to a host cell. This is typically shown by the virus binding to specific receptors on the host cell's surface.

Depict the entry of the viral RNA into the host cell. This can occur through direct injection or endocytosis, where the virus is engulfed by the cell membrane.

Show the viral RNA being used directly as mRNA by the host cell's ribosomes. This step involves the translation of viral proteins necessary for replication and assembly.

Finally, illustrate the assembly of new virus particles within the host cell. The newly synthesized viral RNA and proteins come together to form new virions, which are then released from the host cell to infect other cells.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above.

Video duration:

38s

Was this helpful?

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Class IV Virus

Class IV viruses are single-stranded RNA viruses whose genomes can directly function as mRNA. This means that upon entering a host cell, their RNA can be immediately translated by the host's ribosomes into viral proteins, facilitating rapid replication and infection processes.

Viral Replicative Cycle

The viral replicative cycle involves several stages: attachment, entry, replication, assembly, and release. For a Class IV virus, the cycle begins with the virus attaching to the host cell, followed by entry where the viral RNA is released into the cytoplasm, serving as mRNA for protein synthesis, leading to the assembly of new virions and their release from the host cell.

mRNA Functionality

mRNA, or messenger RNA, is crucial for protein synthesis as it carries genetic information from DNA to ribosomes, where it is translated into proteins. In the context of Class IV viruses, the viral RNA itself acts as mRNA, bypassing transcription and directly engaging the host's ribosomal machinery to produce viral proteins necessary for replication.

Recommended video:

Guided course

06:04

Functional Groups

Related Practice

Textbook Question

To cause a human pandemic, the H5N1 avian flu virus would have to

a. Spread to primates such as chimpanzees.

b. Develop into a virus with a different host range.

c. Become capable of human-to-human transmission.

d. Become much more pathogenic.

Textbook Question

A bacterium is infected with an experimentally constructed bacteriophage composed of the T2 phage protein coat and T4 phage DNA. The new phages produced would have

a. T2 protein and T4 DNA.

b. T4 protein and T2 DNA.

c. T2 protein and T2 DNA.

d. T4 protein and T4 DNA.

Textbook Question

RNA viruses require their own supply of certain enzymes because

a. Host cells rapidly destroy the viruses.

b. Host cells lack enzymes that can replicate the viral genome.

c. These enzymes translate viral mRNA into proteins.

d. These enzymes penetrate host cell membranes.

views