Problem 10 - Biology Concepts and Applications

Question

Bacteriophages can multiply by ___ a. prokaryotic fission c. a lysogenic pathway b. a lytic pathway d. both b and c

Step-by-Step Solution

Answer

d. both b and c

Step 1: Understanding the Context

Bacteriophages, also known simply as phages, are viruses that infect bacteria. They have specific pathways they use to multiply and replicate within the host.

Step 2: Pathway Options

Consider the multiplication pathways given in the options. The 'prokaryotic fission' listed in option a is a method used by prokaryotic cells to reproduce. However, it is not applicable to viruses like bacteriophages, which require different processes.

Step 3: Lytic Pathway

The lytic pathway involves a bacteriophage injecting its genetic material into a bacterial host, using the host’s machinery to produce new phage particles, and eventually causing the bacterial cell to burst, releasing new phages. This is option b.

Step 4: Lysogenic Pathway

In the lysogenic pathway, the bacteriophage integrates its DNA with the host's DNA and remains dormant. It replicates along with the host cell's DNA until certain conditions trigger it to enter the lytic cycle. This is option c.

Step 5: Analyzing the Options

After reviewing, bacteriophages can multiply using both the lytic (b) and lysogenic (c) pathways, depending on their life cycle and environmental conditions.

Step 6: Final Decision

Since bacteriophages can use both pathways, the most accurate choice among the provided options is d, combining both b and c since both pathways are valid for bacteriophage multiplication.

Key Concepts

Lytic Pathway

The lytic pathway is one of the main ways bacteriophages reproduce inside host bacteria. Once a bacteriophage attaches to a bacterial cell, it injects its genetic material, usually DNA, into the host. This DNA then hijacks the cell’s machinery to produce viral components instead of the host’s usual products.

These newly formed viral parts assemble into complete bacteriophage particles. Eventually, the accumulation of these new virions causes the bacterial cell to burst, or lyse. This process releases many new bacteriophages that can go on to infect other bacteria.

**Key characteristics of the lytic pathway:**

• Rapid multiplication of phages
• Leads to destruction of host cells
• Results in the release of new bacteriophage particles

This pathway tends to occur under favorable conditions for viral replication, ensuring that the bacteriophages can quickly spread and infect new hosts.

Lysogenic Pathway

In contrast to the lytic pathway, the lysogenic pathway doesn't immediately lead to the destruction of the host cell. Instead, the genetic material of the bacteriophage integrates into the bacterial host's genome, forming what is known as a prophage.

The prophage is replicated along with the host's DNA every time the bacterial cell divides, allowing the viral genome to be passed on to future generations of the host. This integration allows the viral DNA to remain dormant until triggered by certain environmental factors, like stress or UV light, to enter the lytic cycle.

**Characteristics of the lysogenic pathway include:**

• Integration of viral DNA into host genome
• Viral genome replicates alongside host DNA
• Does not immediately kill the host cell
• Can switch to lytic pathway under certain conditions

This pathway is a form of viral stealth, allowing the phage genes to persist quietly within a population until conditions favor active replication.

Prokaryotic Fission

Prokaryotic fission, also known as binary fission, is a type of asexual reproduction used by prokaryotic organisms like bacteria. This is fundamentally different from how bacteriophages multiply.

During prokaryotic fission, a bacterial cell duplicates its DNA and then divides into two identical daughter cells. This process ensures rapid population increase, especially under optimum environmental conditions.

**Key elements of prokaryotic fission:**

• Exclusively asexual and simple form of reproduction
• Results in genetically identical copies
• Efficient method for rapid growth

While prokaryotic fission is a crucial aspect of bacterial multiplication, it's important to note that bacteriophages, being viruses, do not reproduce in this manner. They require a host cell to complete their viral replication cycles.