Bacterial Structure and Viral Replication Quiz

Basic Unit: Prokaryotic cells without a nucleus.
Cell Wall: Composed of peptidoglycan; differences between Gram-positive (thick wall) and Gram-negative (thin wall plus outer membrane).
Cell Membrane: Phospholipid bilayer; contains proteins for transport and communication.
Cytoplasm: Gel-like substance where cellular processes occur; contains ribosomes and genetic material.
Genetic Material: Circular DNA (chromosome) and plasmids (small circular DNA).
Flagella and Pili: Structures for movement (flagella) and attachment (pili).
Capsule: Gel-like layer outside the cell wall providing protection and aiding in adhesion.

Attachment: Virus binds to host cell receptors.
Entry: Virus or its genetic material enters the host cell.
Replication:
- DNA viruses: Use host machinery to replicate DNA.
- RNA viruses: Often replicate in the cytoplasm using viral RNA-dependent RNA polymerase.
Assembly: New viral particles are assembled from replicated components.
Release: New viruses exit the host cell, often causing cell damage or death (lysis) or budding off without destroying the cell.

DNA Structure: Circular DNA in bacteria; can exchange genetic material through transformation, transduction, or conjugation.
Gene Expression: Transcription (DNA to mRNA) followed by translation (mRNA to protein).
Mutations: Changes in DNA sequence that can lead to variability and adaptation.
Plasmids: Extra-chromosomal DNA that can confer advantageous traits like antibiotic resistance.

Mechanisms:
- Mutation in target genes (e.g., alteration of ribosomes).
- Enzymatic degradation of antibiotics (e.g., beta-lactamase).
- Efflux pumps that expel antibiotics from the cell.
- Biofilm formation that protects communities of bacteria from antibiotics.
Causes: Overuse of antibiotics, incomplete courses of treatment, and use in livestock.
Implications: Increased morbidity, mortality, and healthcare costs; need for new antibiotics and alternative treatments.

Types of Pathogens: Bacteria, viruses, fungi, protozoa, and helminths.
Infection Process:
- Entry (through skin, mucous membranes, etc.).
- Colonization and persistence in the host.
- Evasion of host immune response.
Virulence Factors: Molecules produced by pathogens that enhance their ability to cause disease (e.g., toxins, adhesion factors).
Immune Response: Pathogens trigger innate and adaptive immune responses; successful pathogens often evade these defenses.
Transmission: Various modes including direct contact, airborne, vector-borne, and fomite transmission.

Prokaryotic cells lack a nucleus and are the basic unit of bacteria.
The cell wall is made of peptidoglycan; Gram-positive bacteria have a thick wall, while Gram-negative bacteria have a thinner wall with an additional outer membrane.
A phospholipid bilayer forms the cell membrane, housing proteins that facilitate transport and communication.
Cytoplasm is a gel-like medium for cellular processes, containing ribosomes and genetic material.
Bacterial genetic material consists of circular DNA (chromosomes) and plasmids, which are small, circular DNA molecules.
Flagella provide locomotion, while pili assist in attachment to surfaces.
The capsule is a protective gel-like layer outside the cell wall that aids bacterial adhesion and defense.

Viruses attach to specific receptors on host cells to initiate infection.
Viral entry occurs when the virus or its genetic material penetrates the host cell.
DNA viruses replicate by utilizing the host's cellular machinery, while RNA viruses commonly replicate in the cytoplasm with the help of viral enzymes.
Replicated viral components are assembled into new viral particles.
New viruses exit the host cell either by lysis, causing cell damage, or through a budding process that allows for cell survival.

Bacterial DNA is circular and can undergo genetic exchange through mechanisms like transformation, transduction, and conjugation.
Gene expression starts with transcription (conversion of DNA to mRNA) and is followed by translation (conversion of mRNA to protein).
Mutations can alter DNA sequences, contributing to genetic variability and adaptability in bacteria.
Plasmids provide additional genetic advantages, such as conferring antibiotic resistance.

Resistance mechanisms include mutations in target genes, enzymatic breakdown of antibiotics, efflux pumps expelling antibiotics, and biofilm formation that protects bacterial communities.
Overuse of antibiotics, failure to complete treatment regimens, and use in livestock contribute to the development of antibiotic resistance.
Impacts of antibiotic resistance include increased illness, higher mortality, escalating healthcare costs, and the urgent need for new antibiotics and alternative therapies.

Pathogen types include bacteria, viruses, fungi, protozoa, and helminths.
The infection process encompasses entry through barriers such as skin and mucous membranes, colonization, and evasion of the host immune defenses.
Virulence factors, such as toxins and adhesion molecules, enhance a pathogen's ability to cause disease.
Pathogens activate both innate and adaptive immune responses, with successful pathogens often adept at evading these defenses.
Transmission modes include direct contact, airborne routes, vector-borne dissemination, and fomites (inanimate objects).