Problem 1 - Campbell Biology

Question

\(\begin{equation} \begin{array}{l}{\text { Which of the following characteristics, structures, }} \\ {\text { or processes is common to both bacteria and }} \\ {\text { viruses? }} \\ {\text { (A) metabolism }} \\ {\text { (B) ribosomes }} \\\ {\text { (C) genetic material composed of nucleic acid }} \\ {\text { (D) cell division }}\end{array} \end{equation}\)

Step-by-Step Solution

Answer

Option (C) genetic material composed of nucleic acid.

Step 1: Understand Characteristics of Bacteria

Bacteria are single-celled organisms with structures like cell walls, plasma membranes, and ribosomes. They have a metabolism, meaning they can convert nutrients into energy, and they reproduce through cell division.

Step 2: Understand Characteristics of Viruses

Viruses are much simpler structures that cannot carry out metabolism on their own and lack organelles such as ribosomes. They require a host cell to replicate and do not undergo cell division.

Step 3: Analyzing the Options

Option (A) metabolism: Only bacteria have metabolism. Option (B) ribosomes: Only bacteria have ribosomes. Option (D) cell division: Only bacteria reproduce by cell division. Option (C) genetic material composed of nucleic acid: Both bacteria and viruses have genetic material made of nucleic acids.

Step 4: Conclusion

The characteristic common to both bacteria and viruses is having genetic material composed of nucleic acids. This genetic material is either DNA or RNA in both types of organisms.

Key Concepts

Bacterial Structure

Bacteria are tiny, single-celled organisms that have a rather complex structure compared to viruses. They possess a sturdy cell wall that provides protection and shape. Inside, there's a plasma membrane that encloses the cytoplasm. The cytoplasm contains ribosomes, which are essential for protein synthesis. Bacteria also have genetic material in the form of a single, circular chromosome located in a region called the nucleoid. Additionally, some bacteria have plasmids, which are smaller, extra-chromosomal DNA molecules.

• Cell Wall: Provides protection and structural support.
• Plasma Membrane: Encloses the cellular components.
• Ribosomes: Sites of protein synthesis.
• Genetic Material: Single circular chromosome and sometimes plasmids.

This detailed structure enables bacteria to carry out many functions that viruses cannot.

Viral Structure

Viruses are much simpler in structure than bacteria and lack many of the cellular components found in bacterial cells. A virus is essentially a small package of genetic material (either DNA or RNA) enclosed within a protein coat called a capsid. Some viruses also have an additional lipid envelope surrounding the capsid. Unlike bacteria, viruses do not have a cell membrane, cytoplasm, or organelles like ribosomes.

• Capsid: Protein coat that encases the genetic material.
• Genetic Material: Either DNA or RNA.
• Lipid Envelope: Found in some viruses, surrounding the capsid.

The simplicity of the viral structure means viruses cannot perform many functions by themselves and must rely on infecting a host cell to replicate and propagate.

Genetic Material

Both bacteria and viruses have genetic material composed of nucleic acids, which is critical for storing and transmitting genetic information. However, the form of their genetic material can differ. Bacterial genetic material typically consists of a single, circular DNA chromosome and sometimes additional plasmids. In contrast, the genetic material of viruses can be either DNA or RNA and can be single or double-stranded.

• Bacterial DNA: Usually a single, circular chromosome plus plasmids.
• Viral Genetic Material: Can be DNA or RNA, single or double-stranded.

In both cases, the nucleic acids serve as the blueprint for the organism's replication and functions.

Metabolism

Metabolism refers to the chemical processes that occur within a living organism to maintain life. Bacteria have a fully functioning metabolism, which allows them to convert nutrients into energy, build cellular components, and reproduce. They can survive independently and have various metabolic pathways, including respiration and fermentation.

• Bacterial Metabolism: Includes processes like respiration and fermentation.
• Energy Conversion: Bacteria can convert nutrients to energy.

Viruses, on the other hand, do not have a metabolism. They lack the necessary cellular machinery and must hijack the host cell’s metabolic processes to reproduce. Without a host cell, viruses are inert and cannot carry out any metabolic activities.

Cell Division

Cell division is the process by which a cell replicates to produce two daughter cells. Bacteria reproduce through a type of cell division called binary fission, where the bacterial cell duplicates its genetic material and splits into two identical cells. This method is efficient and allows bacteria to multiply rapidly under favorable conditions.

• Binary Fission: Method of bacterial reproduction.
• Rapid Multiplication: Enables fast bacterial population growth.

Viruses do not undergo cell division. Instead, they replicate by infecting a host cell and using the host’s machinery to produce new virus particles. This replication process involves the virus attaching to the host cell, injecting its genetic material, and reprogramming the host to produce viral components, which are then assembled into new viruses.