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Viruses definitions Flashcards

Viruses definitions
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  • Viruses

    Microscopic entities that lack cellular structure, consisting of genetic material (DNA or RNA) encased in a protein coat (capsid), and require a host cell to replicate and propagate.

  • Capsid

    A protein shell that encases a virus's genetic material, composed of subunits called capsomeres, providing protection and aiding in the delivery of the viral genome into host cells.

  • Capsomeres

    Protein subunits that assemble to form the protective outer shell (capsid) of a virus, encapsulating its genetic material.

  • Double Stranded DNA

    A molecule consisting of two complementary strands of nucleotides wound around each other in a double helix, forming the genetic blueprint for most organisms.

  • Single Stranded DNA

    A DNA molecule consisting of a single strand, often found in certain viruses, which lacks the complementary strand typical of double-stranded DNA.

  • Double Stranded RNA

    A type of RNA molecule with two complementary strands, often found in certain viruses, that can serve as a template for viral protein synthesis and replication within host cells.

  • Single Stranded RNA

    A molecule of RNA consisting of a single strand, often serving as the genetic material for certain viruses, capable of direct translation or requiring complementary strand synthesis for protein production.

  • Bacteriophage

    A virus that infects bacteria, using a complex capsid to inject its genetic material into the host, leading to either lytic or lysogenic replication cycles.

  • Phages

    Viruses that specifically infect bacteria, using them to replicate by injecting their genetic material, often leading to the destruction of the host cell.

  • Viral Envelope

    A membranous structure derived from the host cell's membrane, aiding in viral entry and evasion of the host immune system.

  • Glycoproteins

    Surface proteins on viruses that bind to host cell receptors, determining the virus's host range and facilitating entry into the host cell.

  • Host Range

    The collection of host species that a virus can infect, determined by the virus's surface proteins and their ability to recognize and bind to specific receptors on the host cells.

  • Spontaneous Assembly

    The process by which viral components self-organize into a functional virus without external guidance, similar to how cell membranes form spontaneously in an aqueous environment.

  • Lytic Cycle

    A viral replication process where the virus hijacks the host cell's machinery to produce new viruses, leading to the host cell's lysis and release of progeny viruses.

  • Lysogenic Cycle

    A viral replication process where the viral genome integrates into the host's DNA, remaining dormant and replicating with the host cell's genome, potentially switching to a lytic cycle later.

  • Virulent Phage

    A bacteriophage that exclusively replicates through the lytic cycle, leading to the destruction of the host cell by causing it to burst and release new viral particles.

  • Restriction Enzymes

    Enzymes that cut DNA at specific sequences, protecting bacteria by degrading foreign DNA, such as that from viruses.

  • Prophage

    A viral genome integrated into a bacterial chromosome, remaining dormant until triggered to enter the lytic cycle.

  • Retroviruses

    Viruses with RNA genomes that reverse transcribe their RNA into DNA, integrating it into the host's genome using the enzyme reverse transcriptase, leading to persistent infections.

  • Reverse Transcription

    The process by which RNA is converted into DNA, often used by retroviruses to integrate their genetic material into the host cell's genome.

  • Reverse Transcriptase

    An enzyme that converts viral RNA into DNA, allowing integration into the host genome, crucial for retrovirus replication.

  • Provirus

    A viral DNA integrated into the host cell's genome, allowing the virus to replicate with the host's cellular machinery.

  • HIV

    A retrovirus that targets the immune system, using reverse transcriptase to integrate its RNA genome into the host's DNA, leading to immune deficiency.

  • RNA Polymerase

    An enzyme that synthesizes RNA from a DNA template during transcription, crucial for gene expression and viral replication.

  • Positive Sense Strand

    A single-stranded RNA virus genome that can directly serve as mRNA for protein synthesis, allowing immediate translation upon entering the host cell.

  • Negative Sense Strand

    A viral RNA strand that is complementary to the mRNA needed for protein synthesis, requiring RNA polymerase to first transcribe it into a positive-sense mRNA before translation.

  • Transcription

    The process where RNA polymerase reads DNA to synthesize a complementary RNA strand, essential for gene expression and protein production.

  • mRNA

    A molecule that carries genetic information from DNA to ribosomes, where it serves as a template for protein synthesis.

  • Coding Strand

    The DNA strand with the same sequence as the mRNA, except thymine (T) is replaced by uracil (U) in RNA, used as a template during transcription.

  • Plus Strand

    A single-stranded RNA virus genome that can directly serve as mRNA for protein synthesis, facilitating immediate translation upon infection.

  • Viral RNA Polymerase

    An enzyme used by RNA viruses to replicate their RNA genome within a host cell, enabling the production of viral mRNA and proteins necessary for viral replication.

  • Smallpox

    A highly contagious and deadly viral disease caused by the variola virus, characterized by fever, malaise, and a distinctive progressive skin rash.

  • Herpes

    A DNA virus causing lifelong infections, characterized by latent and active phases, often resulting in sores or blisters on the skin or mucous membranes.

  • Chickenpox

    A highly contagious viral infection causing an itchy rash and red spots or blisters, primarily affecting children, and is preventable by vaccination.

  • West Nile Virus

    A mosquito-borne virus causing flu-like symptoms, encephalitis, or meningitis in severe cases, primarily affecting birds, humans, and other mammals.

  • Common Cold

    A viral respiratory infection caused by rhinoviruses, leading to symptoms like a runny nose, sore throat, and cough. It spreads through airborne droplets and direct contact with infected surfaces.

  • Hepatitis C

    A liver disease caused by a single-stranded RNA virus, often leading to chronic infection, liver inflammation, and potentially severe liver damage. It spreads primarily through blood-to-blood contact.

  • Rabies

    A viral disease transmitted through animal bites, causing severe neurological symptoms and often fatal if untreated.

  • Ebola

    A highly infectious RNA virus causing severe hemorrhagic fever, characterized by high mortality rates and transmitted through direct contact with bodily fluids of infected individuals.

  • Influenza

    A highly contagious viral infection affecting the respiratory system, characterized by fever, cough, and body aches, caused by RNA viruses of the Orthomyxoviridae family.

  • Polio

    A viral disease caused by an RNA virus that can lead to paralysis by infecting the nervous system, primarily affecting children and spread through contaminated water or food.

  • Viroids

    Smallest known pathogens, consisting of short, circular, single-stranded RNA, infecting plants and disrupting their growth without encoding proteins, relying on host enzymes for replication.