Microbiology Final Exam Questions

Prokaryotic and Eukaryotic Features

• Ribosomes are present in all prokaryotic organisms.
• Prokaryotic ribosome subunits total 70S (50 + 30), while eukaryotic ribosome subunits total 80S (60 + 40).

Bacterial Growth Phases

• During the log phase, bacterial populations double under optimal conditions.

Enzyme Activity

• Noncompetitive inhibitors bind to the allosteric site of enzymes, halting their reactions.

Fungal Infections

• Candida albicans is the causative agent of yeast infections like thrush.

Virus Structure

• The capsid is the outer protein coat of a simple virus particle.
• Some viruses have an envelope composed of phospholipids derived from the host cell membrane.

Viral Life Cycle

• In the lysogenic cycle of animal viruses, uncoating occurs between penetration and biosynthesis phases.

Sterilization Techniques

• Gamma radiation is used to sterilize disposable prepackaged gloves.

Hepatitis and Food Safety

• Hepatitis A can be contracted from eating raw tomatoes or green onions in restaurants.

Meningitis Causative Agents

• Bacteria causing meningitis attach and multiply in the upper respiratory system.

Immune Response

• Helper T cells are crucial for activating both humoral and cell-mediated immune functions.
• Plasma cells produce antibodies and release them into the bloodstream.

Chemical Mediators

• Histamines and leukotrienes stimulate inflammation.

Genetic Competence

• Cells are termed competent when their cell walls allow foreign DNA to enter.

Enzyme Functions

• RNA polymerase is responsible for assembling free nucleotides to create RNA.

Obligate Intracellular Parasites

• Rickettsias and Chlamydias are similar to viruses as they must live inside host cells.

Antibiotic Discoveries

• Alexander Fleming discovered penicillin, which remains the least effective antibiotic due to increased resistance.

Bacterial Structures

• Fimbriae assist in attachment, whereas pili facilitate bacterial conjugation (sex).

Viral Antigen Variation

• New strains of influenza arise via antigenic shifts.

Infection and Disease

• Septicemia refers to blood poisoning, characterized by the presence of bacteria in the blood (bacteremia).

Defense Mechanisms

• The first line of defense includes skin and mucous membranes; the second line involves white blood cells and inflammatory responses; third line comprises lymphocytes and antibodies.

Antibody Types

• IgG: Long-lasting immunity, can cross the placenta, monomer.
• IgA: Most abundant, found in secretions.
• IgM: First antibody response, pentamer structure.
• IgD: Found on B-cells, helps initiate immune response.
• IgE: Involved in allergic reactions, found on basophils.

White Blood Cell Rankings

• Neutrophils are the most abundant, followed by lymphocytes, monocytes, eosinophils, and basophils.

Fungal Dimorphism

• Medically important fungi can exist as both yeast-like and filamentous forms.

Systemic Mycoses

• Fungi causing systemic mycoses thrive as saprophytes in soil.

Syphilis Stages

• The three stages are primary (chancre sores), secondary (rash), and tertiary (gummas), with only the primary and secondary stages being infectious.

Treatment of Diseases

• Vaccination (DTaP) is effective against tetanus; if unvaccinated, tetanus immune globulin is required.

Pathogen Identification

• Streptococcus mutans is responsible for cavities, while Clostridium tetani causes tetanus.
• Treponema pallidum is the causative agent of syphilis.

Vector Transmissions

• Diseases like malaria (Anopheles mosquito), Chagas disease (kissing bug), West Nile virus (mosquito), and sleeping sickness (tsetse fly) are transmitted by specific vectors.

Reverse Transcription

• Reverse transcriptase converts DNA back into RNA.

Bacterial Immunity Mechanisms

• Beta-lactamase enzymes confer resistance to penicillin, demonstrating a mechanism for bacterial survival against antibiotics.

Infection Definitions

• Intoxication involves illness due to bacterial toxins ingested with food, while infection refers to illnesses caused by live bacterial pathogens that grow in the body.