Biology Study Guide

Biology Study Guide for Viruses and Bacteria

I. Definitions and Matching Terminology

Virus (O): A nonliving particle that consists of genetic material (DNA or RNA) encased in a protective protein coat called a capsid. Viruses can only replicate inside a host cell, making them dependent on living organisms for survival. They are capable of infecting various forms of life, including animals, plants, and bacteria.
Bacteriophage (F): A type of virus that specifically infects bacterial cells. Bacteriophages can be utilized in phage therapy to target and destroy harmful bacteria in infections.
Lysogenic Infection (H): A type of viral infection where the viral DNA is integrated into the host cell's genome, remaining dormant and replicating alongside the host's DNA. In favorable conditions, the virus can reactivate and enter the lytic cycle.
Pili (A): Thin, hair-like appendages on some bacteria that facilitate attachment to surfaces and play a role in bacterial conjugation, allowing for horizontal gene transfer.
HIV (J): A retrovirus that targets the immune system, specifically CD4 T cells, leading to a progressive failure of the immune response and potentially resulting in AIDS.
Conjugation (K): A process of genetic exchange between bacteria where one bacterium transfers genetic material to another through direct contact, often enhancing genetic diversity and antibiotic resistance.
Endospore (D): A dormant, tough, and non-reproductive structure produced by certain bacteria, allowing them to survive extreme environmental conditions, including heat and desiccation.
Cocci (E): A term used to describe bacteria with a spherical shape, which can appear as single cells or in clusters (e.g., streptococci or staphylococci).
Decomposer (B): Organisms, including certain bacteria and fungi, that break down dead organic matter, recycling nutrients back into the ecosystem.
Spirilli (M): Spiral-shaped bacteria that can exhibit various forms of movement owing to their shape; examples include Treponema and Borrelia.
Bacillus (G): Rod-shaped bacteria that can form chains or clusters. Notable examples include Bacillus anthracis, the causative agent of anthrax.
Capsid (P): The protein shell of a virus that encloses its genetic material, composed of proteins that can influence the virus's ability to infect host cells.
Zoonotic (N): Referring to viruses or diseases that can be transmitted from animals to humans, often through direct contact or vectors, such as insects.
Prokaryotic (I): Cells that lack a nucleus and membrane-bound organelles; they are typically unicellular and include all bacteria and archaea.
Flagella (L): Long, whip-like structures that allow bacterial cells to swim, providing mobility in their environment.
Lytic Infection (C): A viral infection process that culminates in the destruction (lysis) of the host cell, resulting in the release of new viral particles.

II. Causes of Illnesses

Strep throat: A common bacterial infection caused by Streptococcus pyogenes, leading to a sore throat and fever.
Common cold: Primarily caused by viruses such as rhinoviruses, resulting in symptoms like sneezing, cough, and sore throat.
MRSA (Methicillin-resistant Staphylococcus aureus): A type of antibiotic-resistant bacterial infection that can cause severe skin infections and is a concern in healthcare settings.
Flu (influenza): A viral infection characterized by fever, cough, and body aches; caused by influenza viruses that can vary in severity each season.
Tetanus: An infection caused by the bacterium Clostridium tetani, often resulting from deep puncture wounds, leading to muscle stiffness and spasms.
Ebola: A severe viral hemorrhagic fever caused by the Ebola virus, characterized by high mortality rates and caused by bodily fluid transmission.
HIV (Human Immunodeficiency Virus): The virus that leads to acquired immunodeficiency syndrome (AIDS), necessitating long-term management with antiretroviral therapy.
Lyme disease: Caused by the bacterium Borrelia burgdorferi, transmitted through tick bites, presenting with varying symptoms, including rash and joint pain.
HPV (Human Papillomavirus): A viral infection linked to cervical cancer and other genital cancers; some strains can cause warts.
Anthrax: An infectious disease caused by Bacillus anthracis, which can affect the skin, lungs, and gastrointestinal system; often classified as a potential bioweapon.
Hepatitis: Inflammation of the liver, which can be caused by various viruses, including Hepatitis A, B, and C, leading to liver damage.
Smallpox: A highly contagious and deadly viral disease caused by the variola virus, eradicated through vaccination efforts.
Botulism: A rare but serious illness caused by Clostridium botulinum toxin, leading to paralysis; often associated with improperly canned foods.
Chickenpox: A highly contagious virus caused by varicella-zoster virus, leading to an itchy rash and flu-like symptoms.
Shingles: Reactivation of the varicella-zoster virus, causing a painful rash and occurs typically in individuals with previous chickenpox infection.
Tuberculosis: A bacterial infection caused by Mycobacterium tuberculosis, primarily affecting the lungs and requiring prolonged antibiotic treatment.
West Nile Virus: A viral infection spread by mosquitoes, which can cause neurological diseases in some individuals.

III. Coronavirus Overview

ACE-2 Receptor: Critical protein receptors located on the surfaces of respiratory cells, which facilitate entry of the SARS-CoV-2 virus into host cells.
S Protein: Spike glycoprotein on the surface of the coronavirus that plays a key role in receptor recognition and cell entry during the infection process.
Zoonotic: This term describes how viruses like SARS-CoV-2 can jump from animal hosts to humans, often influenced by environmental and genetic factors.
Cytokine Storm: A serious immune reaction where the body releases an excess of cytokines, leading to hyper-inflammation and potential organ damage, commonly observed in severe COVID-19 cases.
mRNA Vaccine: A novel type of vaccine used to prevent COVID-19, working by instructing cells to produce a harmless piece of the virus’s spike protein, triggering an immune response without using live virus.
Respiratory: Coronaviruses predominantly infect cells in the respiratory tract, leading to symptoms such as coughing, difficulty breathing, and pneumonia in severe cases.

IV. True or False Statements

False: Viruses are not classified as living cells because they cannot carry out metabolic processes independently.
True: Bacteria are considered among the first living organisms to inhabit Earth, adapting to various environments over billions of years.
False: Eubacteria are a more recent evolutionary group, and Archaebacteria are thought to have preceded them.
False: Viruses are indeed smaller than bacteria, with sizes typically ranging from 20 to 400 nanometers for viruses compared to 1 to 10 micrometers for bacteria.
True: Certain viral infections can remain dormant within a host, reactivating under specific conditions.
True: Viruses possess the ability to infect diverse organisms, including plants, fungi, and bacteria.
False: Specificity is key; viruses can only infect certain host cells that have compatible receptors.

V. Diagrams Labeling

Diagram of bacterial/prokaryotic cell:
A: Pili/pilus
B: Flagella
C: Nucleoid region/DNA
D: Plasmid
E: Ribosome
F: Cytoplasm
G: Cell membrane/plasma membrane
H: Cell wall
I: Capsule
Diagram of bacteriophage:
A: Capsid (protein)
B: DNA or RNA (genetic material)
C: Sheath
D: Tail

VI. Comparison of Archaebacteria and Eubacteria

Similarities:

Both are classified as prokaryotic cells, meaning they lack a nucleus and other membrane-bound organelles.
Both can exhibit a diverse range of cell structures, such as plasmids and capsules, aiding in their survival and environmental adaptation.

Differences:

Archaebacteria:

Believed to have evolved before Eubacteria, thriving in extreme environments such as hot springs and salt lakes.
Their cell membranes have unique lipid compositions that distinguish them from other bacteria.
They do not contain peptidoglycan, a polymer found in the cell walls of Eubacteria, providing them structural differences.

Eubacteria:

Have evolved more recently compared to Archaebacteria and occupy a wider variety of natural environments, from soil to human microbiota.
Eubacterial cell walls consist of peptidoglycan, crucial for maintaining cell integrity during osmotic pressure changes.
Examples include common pathogens like E. coli and MRSA, illustrating their diverse roles in health and disease.

VII. Virus Transmission

HIV: Primarily spread through direct contact with infected bodily fluids, including sexual contact, sharing of needles, and from mother to child during childbirth or breastfeeding.
SARS-Coronavirus: Transmitted primarily through respiratory droplets when an infected individual coughs or sneezes, highlighting the importance of personal protective measures in controlling its spread.

VIII. Lytic Virus Life Cycle Steps

Attachment: The virus binds to specific proteins on the surface of the host cell, an essential first step in infection.
Entry: Viral genetic material is injected into the host cell, either through direct fusion with the cell membrane or via endocytosis.
Replication: The host's cellular machinery is hijacked to replicate the viral genome and produce viral proteins.
Assembly: New viral particles are assembled using replicated genetic material and proteins synthesized by the host.
Lysis: The host cell becomes overwhelmed with newly formed viruses, leading to cell rupture and release of the viruses to infect additional cells.

IX. Classifications of Biological Entities

B: Size range of bacterial cells varies between 1 – 10 micrometers, making them visible under a light microscope.
BV: Both entities lack a nucleus, which is a defining characteristic of prokaryotes.
BV: Both possess DNA, although the structure and packaging differ significantly.
BV: Both groups can include pathogenic species that cause diseases in their respective hosts.
V: Viruses have a size range of approximately 20 – 400 nanometers, significantly smaller than bacteria and typically requiring electron microscopy for visualization.
V: Viruses cannot autonomously reproduce and must hijack a host's cellular machinery to replicate.
B: Bacterial infections can often be treated with antibiotics, though antibiotic resistance poses a growing challenge.
B: Unlike viruses, bacteria are living organisms that can conduct metabolic processes.
B: Bacteria can come in shapes such as Cocci (spherical), Bacilli (rod-shaped), and Spirilla (spiral).
B: Bacteria reproduce via binary fission, a form of asexual reproduction.
B: Bacteria are classified within two kingdoms: Eubacteria and Archaebacteria, indicating their diversity in biological classification.
B: Bacteria are indeed cellular organisms, exhibiting characteristics of life, such as growth, reproduction, and response to stimuli.

Sure! Here are some questions based on the assessment content:

What is a virus, and how does it differ from a living organism?
Can you explain the purpose of a bacteriophage? In what context can it be used?
What are the stages of a lytic infection, and what happens at each stage?
Define conjugation in bacteria. Why is this process significant for genetic diversity?
What are endospores, and under what conditions do bacteria form them?
How do cocci, bacilli, and spirilli differ in terms of their shapes?
What are two major diseases caused by bacterial infections, and what are their symptoms?
Describe the structure and role of the S protein in coronaviruses.
What types of cells do retroviruses like HIV specifically target?
Contrast Archaebacteria and Eubacteria in terms of their evolutionary history and structural differences.