Ch4 Eukaryotic Cell (pt2) AND Ch 5 Viruses and Prions (pt1)

Q: What are multicellular parasitic worms categorized under Domain Animalia called?

A: Helminths

Q: What is the adult body size range for macroscopic adult helminths?

A: From $1\,\text{cm}$–$2\,\text{cm}$ up to $15\,\text{ft}$, $20\,\text{ft}$, or $25\,\text{ft}$ in length.

Q: Why are macroscopic helminths included under the scope of microbiology?

A: Because microscopic stages (eggs, embryonic forms, or larvae) exist within their life cycles.

Q: Do all helminth species exist as parasites?

A: No; vast numbers inhabit soil or aquatic environments harmlessly, while microbiology focuses exclusively on pathogenic/parasitic species.

Q: What body organ system is traversed or inhabited by the majority of helminth parasites during their life cycle?

A: The gastrointestinal (GI) tract.

Q: What primary phylum of helminths is characterized by dorsoventrally flattened, often ribbon-like body structures?

A: Phylum Platyhelminthes (Flatworms)

Q: What sub-group of Platyhelminthes consists of tapeworms with segmented bodies?

A: Cestodes

Q: What is the head structure of a tapeworm equipped with suckers, barbs, or hooks used strictly for anchoring to the host's intestinal lining?

A: Scolex

Q: Does the scolex of a tapeworm consume or chomp host tissue?

A: No; it serves strictly as an anchoring mechanism.

Q: How do tapeworms acquire nutrients from their host?

A: They absorb pre-digested nutrients directly through a protective outer cuticle from the host's intestinal contents.

Q: What body region located directly behind the scolex continuously generates new tapeworm segments?

A: The neck region

Q: What are the individual body segments of a tapeworm, each containing both male and female reproductive organs?

A: Proglottids

Q: What are highly mature, egg-packed distal segments that break off from the tapeworm and pass out in host feces?

A: Gravid proglottids

Q: What appearance do gravid proglottids take when passed in stool or seen around an animal's tail?

A: Wiggling grains of rice.

Q: What is the most common tapeworm infection in humans, and how is it acquired?

A: Pork tapeworm infection, acquired by consuming undercooked infected pork containing tissue cysts or ingesting food/water contaminated with pork manure fertilizer.

Q: What sub-group of Platyhelminthes consists of leaf-shaped, unsegmented flatworms with anterior suckers that target organ-specific tissues?

A: Trematodes (Flukes)

Q: Which group of trematodes represents one of the leading global Neglected Parasitic Infections (NPIs)?

A: Blood flukes

Q: What primary phylum of helminths is characterized by unsegmented, cylindrical (round) body cross-sections?

A: Phylum Nematoda (Roundworms)

Q: What common nematode infects domestic pets, livestock, and humans?

A: Ascaris

Q: What nematodes target domestic pets such as dogs and cats?

A: Heartworms

Q: What is the most common helminthic infection in the United States, typically affecting elementary and preschool children?

A: Pinworms

Q: Where does the adult female pinworm deposit eggs at night?

A: In the perianal region.

Q: What nematode larvae develop in soil and bore directly through bare skin?

A: Hookworms

Q: Which organ system is the most extensively developed in all helminths to support high egg production?

A: The reproductive system.

Q: What type of helminth life cycle is completed entirely within a single host organism (e.g., pinworms)?

A: Simple life cycle

Q: What type of helminth life cycle requires multiple sequential host species to complete development?

A: Complex life cycle

Q: What is the host organism in which a parasite reaches adulthood, undergoes sexual maturation, and mates?

A: Definitive host

Q: What is the host organism harboring larval development or larval maturation stages prior to definitive host transmission?

A: Intermediate host

Q: What is an intermediate vehicle that transfers a parasite without essential developmental changes occurring?

A: Transport host

Q: What is the primary ingestion route for acquiring helminth infections?

A: Ingestion of eggs or larvae via the fecal-oral route (contaminated food, water, or poor animal husbandry).

Q: How do larval blood flukes infect humans in open water bodies?

A: By boring directly through intact skin during swimming, bathing, or washing.

Q: How do larval hookworms infect human hosts?

A: By boring directly through the bare skin of feet in contaminated soil.

Q: What standard prevention methods reduce helminth transmission?

A: Handwashing, proper meat cooking temperatures, USDA meat inspection screening, freezing meat, and boiling municipal/unfiltered water.

Q: Why are over-the-counter worm cleanses or detoxes unnecessary for average individuals with standard sanitation?

A: Sanitation infrastructure prevents most exposures, and misuse of anthelmintics contributes to widespread drug resistance.

Q: What are acellular infectious particles that lack cellular structures and are excluded from the three domains of life?

A: Viruses

Q: What organization standardizes modern scientific taxonomy for viruses?

A: International Committee on Taxonomy of Viruses (ICTV)

Q: How high does the formal taxonomic hierarchy extend for viruses?

A: Up to the rank of Order (does not utilize domain-level ranks).

Q: What size range defines the ultramicroscopic scale of viral particles?

A: Between $20\,\text{nm}$ and $400\,\text{nm}$.

Q: What microscope types are required to visualize viruses?

A: Electron microscopes (Transmission Electron Microscope [TEM] or Scanning Electron Microscope [SEM]).

Q: What is the relative size hierarchy among eukaryotic cells, prokaryotic cells, and viruses?

A: Eukaryotic Cells > Prokaryotic Cells > Viruses.

Q: What term describes biological entities that require internal invasion of a compatible host cell to replicate or perform metabolic processes?

A: Obligate intracellular parasites

Q: What metabolic capabilities do virions possess outside of a living host cell?

A: Zero metabolic activity, zero independent replication, and zero protein synthesis (they exist in an inert state).

Q: What fundamental rule governs the nucleic acid composition of virions?

A: They contain either RNA or DNA, but never both simultaneously.

Q: How does the size of a viral genome compare to human and bacterial genomes?

A: Viral genomes carry only a few dozen to a few hundred genes, compared to $\sim 4,000$–$6,000$ in E. coli and $\sim 20,000$–$30,000$ in humans.

Q: What configuration forms can viral nucleic acid genomes take?

A: Double-stranded (ds) DNA, single-stranded (ss) DNA, single-stranded (ss) RNA, or double-stranded (ds) RNA (linear, circular, continuous, or segmented).

Q: What is the protective protein shell completely enclosing the central nucleic acid core of a virus?

A: Capsid

Q: What are the individual repeating protein subunits that assemble to form a capsid shell?

A: Capsomeres

Q: What capsid morphology features capsomeres arranged in a spiral tube (e.g., Ebola virus)?

A: Helical capsid

Q: What capsid morphology features a regular 20-sided geometric sphere composed of triangular protein facets?

A: Icosahedral capsid

Q: What term describes a minimalist viral assembly consisting solely of a nucleic acid core enclosed by a capsid shell?

A: Nucleocapsid (Naked virus)

Q: What additional outer flexible membrane composed of a phospholipid bilayer surrounds the nucleocapsid in select animal viruses?

A: Envelope

Q: Where do enveloped viruses derive their lipid envelope from?

A: Host cell membranes (plasma membrane, nuclear membrane, or Golgi apparatus) during viral exit.

Q: What glycoprotein projections embedded in capsids or envelopes mediate host cell recognition and receptor attachment?

A: Spikes (Peplomers)

Q: What is a fully assembled, structurally complete, infectious viral particle outside a host cell called?

A: Virion

Q: What initial replication step involves viral spikes or capsid proteins binding strictly to matching host membrane receptors?

A: Adsorption (Attachment)

Q: What term describes the limit of host organisms, tissues, or cells that a virus can infect based on receptor compatibility?

A: Host range

Q: What penetrative mechanism involves the host cell plasma membrane engulfing an entire viral particle into a membrane vacuole?

A: Endocytosis

Q: What penetrative mechanism occurs exclusively in enveloped viruses when the viral envelope merges directly with the host plasma membrane?

A: Direct fusion

Q: What step involves the enzymatic removal of the viral capsid to liberate viral nucleic acid into the host cytoplasm?

A: Uncoating

Q: Where do most DNA viruses translocate within the host cell for genome replication and transcription?

A: Host cell nucleus

Q: Where do most RNA viruses undergo genome replication and protein synthesis within the host cell?

A: Host cell cytoplasm

Q: What drives the spontaneous self-assembly of capsomeres around replicated viral genomes during assembly?

A: Intrinsic thermodynamic properties of capsomere proteins (requiring no cellular energy input).

Q: What release mechanism involves naked virions accumulating until the host cell ruptures and explodes?

A: Lytic release (Lysis)

Q: What release mechanism involves nucleocapsids pushing against host membranes, pinching off to acquire an envelope without immediate cell destruction?

A: Budding (Exocytosis)

Q: What are virus-induced, observable structural damages and microscopic alterations in host cells called?

A: Cytopathic Effects (CPEs)

Q: What gritty microscopic structures represent dense, compacted masses of viral particles or damaged organelles within host cells?

A: Inclusion bodies

Q: Detection of what specific inclusion bodies in central nervous tissue provides a definitive diagnostic marker for Rabies?

A: Negri bodies

Q: What CPE involves the fusion of multiple adjacent infected host cell membranes into a single giant multinucleated mass?

A: Syncytium (plural: Syncytia)

Q: What pediatric respiratory pathogen is named directly for its ability to induce cell fusion in host tissue?

A: Respiratory Syncytial Virus (RSV)

Q: What persistent viral state occurs when viral double-stranded DNA integrates directly into linear host chromosomal DNA?

A: Provirus state

Q: What process converts a normal host cell into a malignant cancerous cell following proviral integration or oncogene insertion?

A: Transformation (Oncogenesis)

Q: What proportion of human cancers possess direct viral triggers or causes?

A: Approximately $20\%$

Q: Which viruses are strongly associated with human cellular transformation and cancer development?

A: Human Papillomavirus (HPV), Epstein-Barr Virus (EBV), and Hepatitis B Virus (HBV).

Q: What persistent viral state occurs when a viral genome remains inside target cells (like sensory neurons) without integrating into host DNA, alternating between inactive and active phases?

A: Chronic latent state

Q: What environmental or physical factors trigger viral reactivation from a latent state?

A: Stress, sleep deprivation, fever, immunosuppression, UV radiation, or hormonal fluctuations.

Q: What disease is caused by the reactivation of latent Varicella-Zoster Virus (Human Herpesvirus 3) later in life?

A: Shingles (Herpes Zoster)

Q: What viruses establish latency in sensory nerve roots to produce recurrent fever blisters or genital lesions upon reactivation?

A: Herpes Simplex Viruses (HSV-1 and