Prokaryotes and Viruses: Structure, Diversity, and Ecological Roles in Biology

What are the main differences between viruses and bacteria?

Viruses are not considered living organisms, cannot reproduce without a host cell, and cannot make their own ATP or proteins, while bacteria are unicellular and can reproduce independently.

What are the two main types of cells based on cellular structure?

Eukaryotic cells (with organelles and a nucleus) and prokaryotic cells (without organelles and a nucleoid region).

What are the common shapes of prokaryotic cells?

Spherical (cocci), rod-shaped (bacilli), and spiral.

What is the primary component of most bacterial cell walls?

Peptidoglycan.

How do Gram-positive and Gram-negative bacteria differ in their cell wall composition?

Gram-positive bacteria have simpler walls with a large amount of peptidoglycan and stain purple, while Gram-negative bacteria have less peptidoglycan and an outer membrane, staining pink.

What are the nutritional types of prokaryotes?

Autotrophs (photoautotrophs and chemoautotrophs) and heterotrophs (photoheterotrophs and chemoheterotrophs).

What is binary fission?

A method of asexual reproduction in prokaryotes where a cell divides into two identical cells.

What are the three factors contributing to genetic diversity in prokaryotes?

Rapid reproduction, mutation, and genetic recombination.

What are the three methods of genetic recombination in prokaryotes?

Transformation (uptake of foreign DNA), transduction (gene transfer by bacteriophages), and conjugation (direct transfer between cells).

What distinguishes Domain Archaea from Domain Bacteria?

Archaea share traits with both bacteria and eukaryotes and often live in extreme environments.

What are extremophiles?

Organisms that thrive in extreme environments, including extreme halophiles, extreme thermophiles, and methanogens.

What roles do prokaryotes play in the biosphere?

They act as decomposers, form symbiotic relationships, and can be pathogenic.

What is mutualism in the context of prokaryotic relationships?

A symbiotic relationship where both organisms benefit.

What is bioremediation?

The use of prokaryotes to clean up environmental contaminants.

What is CRISPR and its significance?

A technology derived from prokaryotes used for genetic modification and gene therapies.

What is the approximate size range of prokaryotic cells?

0.5-5 µm, much smaller than eukaryotic cells (10-100 µm).

What is the significance of the Gram stain in microbiology?

It classifies bacteria based on their cell wall composition, aiding in diagnosis and treatment.

What are endospores and their function?

Metabolically inactive structures that allow prokaryotes to survive harsh conditions.

How do antibiotics affect bacteria?

Many antibiotics target peptidoglycan in bacterial cell walls, affecting mainly Gram-positive bacteria.

What is horizontal gene transfer?

The exchange of DNA between different prokaryotic species, complicating the understanding of evolutionary relationships.

What are some examples of pathogenic bacteria?

Staphylococcus, Streptococcus, E. coli, and Salmonella.

What are the ecological dependencies of certain ecosystems on prokaryotes?

Ecosystems like hydrothermal vents rely on chemoautotrophic bacteria for energy.

What is the role of nitrogen-fixing bacteria?

They convert atmospheric nitrogen into a form usable by plants, forming a mutualistic relationship.

What are the characteristics of prokaryotic genomes?

They consist of less DNA than eukaryotic genomes, typically a single circular chromosome located in the nucleoid region.

What is the significance of the classification of prokaryotes into two domains?

It reflects genetic analysis that distinguishes between Bacteria and Archaea based on evolutionary relationships.