Virology and Nucleic Acids Flashcards

Vocabulary flashcards covering viral structure, nucleic acid differences, replication cycles, viral infection types in animal cells, and viral treatments from the lecture notes.

Viral Genome

The nucleic acid core of a virus that contains instructions to take over the host cell and build new copies of itself through molecular hijacking.

Acellular

Describing an entity that lacks a cellular structure, containing no organelles, ribosomes, or plasma membrane, as observed in viruses.

Micron

An abbreviated term for micrometer, defined as one millionth of a meter ($1/1{,}000{,}000$\,meters). Viruses are about $100\times$ smaller than bacteria.

Capsid

The outer shell made of protein coat that protects the core nucleic acid of a virus.

Envelope

A lipid membrane surrounding the protein capsid in certain viruses.

Spike

A glycoprotein structure projecting from the viral surface that functions to attach the virus to specific host cell surfaces.

Host Range

The specific set or type of host cells that a virus is capable of infecting.

Two Types of Nucleic Acids

The primary genetic structures in biological systems: Deoxyribonucleic Acid (DNA), which carries genetic information and is double-stranded with deoxyribose, and Ribonucleic Acid (RNA), which is single-stranded with ribose and involved in protein synthesis.

Deoxyribonucleic Acid (DNA)

A double-stranded nucleic acid forming a double helix joined by hydrogen bonds between nitrogenous bases (Thymine, Cytosine, Adenine, Guanine) and containing deoxyribose sugar to carry genetic information.

Ribonucleic Acid (RNA)

A single-stranded nucleic acid containing ribose sugar and nitrogenous bases (Uracil, Cytosine, Adenine, Guanine) involved in protein synthesis.

Lytic Cycle

A viral replication cycle in which the virus enters the host cell, hijacks host ATP and enzymes to replicate components, assembles new viral particles, and destroys the host cell by lysis.

Lysogenic Cycle

A viral replication cycle in which viral DNA coexists with the host cell by integrating into the host chromosome, replicating alongside daughter cells, and later exiting the chromosome under stress to enter the lytic cycle.

DNA Viruses

Viruses with double-stranded genomes that rarely mutate, maintain their identity, can carry out DNA replication, and remain active in the nucleus of the host cell (e.g., Herpes simplex virus, Varicella-zoster virus, Epstein-barr virus).

RNA Viruses

Viruses with single-stranded genomes that cannot perform DNA replication on their own and require host cell nuclear enzymes (e.g., Rhinoviruses, Influenza, Rotaviruses).

Retrovirus

A type of virus containing reverse transcriptase that converts its single-stranded RNA into DNA, allowing it to mutate and replicate within host cells (e.g., Human Immunodeficiency virus, Hepatitis B).

Reverse Transcriptase

An enzyme carried by retroviruses that allows them to convert their viral RNA genome into DNA.

Retrovirus Cycle

The replication process where a retrovirus converts its RNA to DNA via reverse transcriptase, integrates into the host chromosome as a provirus, transcribes mRNA, and forms new viral particles that exit the host cell.

Latent Infection

An infection where viral DNA becomes part of host DNA and enters a dormant state with no immediate significant harm, which can later reactivate due to a trigger (e.g., Herpes simplex, Varicella-zoster).

Persistent Infection

An animal cell infection where viruses are slowly produced and released for a long period without immediately killing the host cell (e.g., Retroviruses, Hepatitis B, Rubella).

Virulent / Lytic Infection

An infection in animal cells where viral replication causes rapid cell death through cell lysis (e.g., Influenza, polio).

Cancerous Infection

An infection where viral DNA integrates into the cell's genome, altering host cell function and triggering uncontrolled cell division to form tumors (e.g., Papilloma virus, Hepatitis B).

Vaccines

Preventative treatments containing non-infectious virus particles that stimulate the body to produce antibodies, preparing the immune system for future pathogen exposures.

Herd Immunity

The protection from a pathogen provided to unvaccinated individuals in a population when a sufficiently high percentage of people are vaccinated.

Antiviral Drugs

Therapeutic medications used to treat viral infections by preventing the virus from attaching to, entering host cells, or replicating.

Gene Therapy

A medical procedure using modified viruses as vectors to introduce new, useful genes into a patient's genome to treat conditions like Cancer, Cystic fibrosis, Hemophilia, and Diabetes.