Comparative Study of Prokaryotic and Eukaryotic Cells

Prokaryotic and eukaryotic cells

Both have DNA, ribosomes, membranes, and similar metabolic processes.

Genetic material organization in prokaryotes

Prokaryotes have circular DNA in a nucleoid; eukaryotes have linear DNA within a nucleus.

Eukaryotic cell organelles

They contain specialized, membrane-bound organelles.

DNA packaging in eukaryotic cells

It is wrapped around histones to form chromatin within the nucleus.

Common bacterial shapes

Bacilli (rods), cocci (spheres), and spirilla (spirals).

Diplococci vs chain-forming cocci

Diplococci occur in pairs; chain-forming cocci line up sequentially.

Diplobacilli and streptobacilli

They refer to rod-shaped bacteria arranged in pairs or chains, respectively.

Spiral bacteria types

Vibrios are curved rods; spirilla are rigid spirals; spirochetes are flexible helices.

Nucleoid in prokaryotes

It's an irregular region containing the cell's circular DNA.

Plasmids

Small, circular DNA molecules that can carry antibiotic resistance genes.

Prokaryotic ribosomes

Prokaryotic ribosomes are 70S, which are smaller than eukaryotic 80S ribosomes.

Antibiotics targeting bacterial ribosomes

They bind to ribosomal subunits to inhibit protein synthesis (e.g., streptomycin targets the 30S subunit).

Bacterial cytoplasmic membrane components

Phospholipids, proteins, and sometimes carbohydrates.

Functions of the cytoplasmic membrane

It regulates transport, energy production, and maintains cell integrity.

Bacterial cell wall

It provides shape, protection, and prevents cell lysis.

Peptidoglycan

A polymer of sugars and amino acids forming the cell wall.

NAG and NAM in cell wall structure

They form repeating units that are crosslinked to provide strength.

Gram-positive cell walls

They have a thick peptidoglycan layer with teichoic acids.

Gram-negative cell walls

They have a thin peptidoglycan layer and an outer membrane containing LPS.

Lipopolysaccharides (LPS)

Complex molecules in the outer membrane that can trigger immune responses.

Periplasmic space

The area between the inner and outer membranes in Gram-negative bacteria where enzymes and nutrient processing occur.

Purpose of the Gram stain

To differentiate bacteria based on cell wall structure.

Iodine in the Gram stain

It fixes the primary stain in Gram-positive cells.

Decolorization in the Gram stain

The dye is removed from Gram-negative cells, leaving them colorless.

Counterstain function

It stains Gram-negative cells pink/red after decolorization.

Gram-positive cells appearance

Their thick cell walls retain the dye complex.

Thick cell walls

Their thick cell walls retain the dye complex.

Virus structure

Viruses have a simple structure with a genome and a protein coat, and sometimes an envelope, lacking cellular machinery.

Viral capsid function

It protects the viral genome and assists in host cell attachment.

Virus classification

As DNA or RNA viruses.

Viral envelope role

It facilitates host cell entry and can help evade the immune system.

Basic steps of viral replication

Attachment, penetration, replication, assembly, and release.

Hijacking host machinery

They use host ribosomes and enzymes to replicate their genome and produce proteins.

Bacterial cells vs viruses

Bacteria are complex, living cells; viruses are simple, acellular particles that require host cells to replicate.

Structural differences and treatment

They help target specific bacterial or viral features with appropriate drugs.

Identifying viruses in the lab

Techniques include electron microscopy, PCR, immunofluorescence, and cell culture.

Antiviral drugs

They interfere with viral entry, replication, or release.

Immune system response to viruses

Through pattern recognition, antigen presentation, and antibody production.

Vaccine protection against viruses

By stimulating an immune response that creates memory cells and antibodies.

Influenza vaccine development

High mutation rates due to antigenic drift and shift.

Key features of HIV

It is an RNA retrovirus with a high mutation rate and complex envelope proteins.

Emerging viral diseases factors

Zoonotic transfers, mutations, and environmental changes.

Zoonotic disease

An infection transmitted from animals to humans.

Biosafety measures in virology labs

Use of biosafety cabinets, PPE, and strict containment protocols.

Cryo-electron microscopy

They allow detailed views of viral structures in near-native states.

Viruses in gene therapy

As engineered viral vectors to deliver therapeutic genes.

Viral vectors in vaccines

They deliver antigens to stimulate an immune response.

Structural differences summary

Cells are complex and self-sustaining; viruses are simple, acellular, and require host cells to replicate.

Structural differences influence treatment

They determine which drugs or therapies will be effective against each pathogen.

Global factors influencing disease spread

Through travel, climate change, and urbanization, which can facilitate outbreaks.

Current challenges in microbial research

Issues like antibiotic resistance, rapid mutation rates, and complexity of pathogen structures.

Future research in infectious diseases

Through advanced technologies that offer better diagnostics, targeted therapies, and vaccines.