Acellular Life & Viruses - Vocabulary Flashcards (Lecture Notes)

Vocabulary flashcards covering core concepts from acellular life, viruses, viral structure, notable viruses, life cycles, HIV/AIDS, prions, viroids, and plant/pathogen examples based on the provided lecture notes.

virus

A non-cellular infectious entity containing RNA or DNA in a protein coat; reproduces only in living cells and depends on the host for biosynthetic machinery; causes diseases in plants and animals and does not follow cell theory.

acellular

Lacking cellular organization; viruses are acellular infectious agents.

virion

A complete, mature virus particle capable of infecting a host.

capsid

Protein coat around the genome, built from capsomeres; determines virus shape and protects the genome.

capsomere

Protein subunit of the capsid; the number of capsomeres is specific to each virus (e.g., 162 in herpes, 252 in adenovirus).

envelope

Lipid membrane outside the capsid derived from the host cell; contains viral glycoprotein spikes and is absent in naked viruses.

naked virus

A virus lacking an envelope; generally more resistant to antibiotics than enveloped viruses.

genome

The viral genetic material (RNA or DNA), which can be single- or double-stranded and may mutate.

nucleocapsid

The combination of the viral genome and the capsid.

Tobacco mosaic virus (TMV)

A plant virus that infects tobacco; first virus crystallized by W. Stanley in 1935; is filterable.

bacteriophage

Viruses that infect bacteria; typically have a head and tail; discovered by Twort (1915) and d’Herelle (1917).

retrovirus

A virus that uses reverse transcription to convert RNA into DNA and integrates into the host genome.

reverse transcriptase

Enzyme that converts viral RNA into DNA, enabling integration into the host genome.

polio virus

RNA virus with about 32 capsomeres; causes poliomyelitis; transmitted through contaminated water/feces; discovered by Landsteiner (1908).

glycoprotein spike

Envelope-embedded spikes that recognize and attach to host cells.

gp120

HIV envelope attachment glycoprotein used to bind the CD4 receptor.

gp41

HIV envelope fusion glycoprotein that mediates fusion with the host cell membrane.

matrix protein

Protein between the envelope and capsid in HIV; helps organize and coordinate assembly.

HIV

Human immunodeficiency virus; a retrovirus that infects helper T-lymphocytes; envelope with spikes; genome encodes reverse transcriptase, protease, and integrase; 100–150 nm diameter with ~72 spikes; two main types (HIV-1 and HIV-2).

AIDS

Acquired immunodeficiency syndrome; advanced HIV infection with loss of helper T-lymphocytes and increased susceptibility to opportunistic infections.

ART

Antiretroviral therapy; combination drug treatment to control HIV; not a cure and may be costly with daily pills.

viral load

The amount of virus present in the body; used to monitor HIV infection and treatment response.

ELISA

Enzyme-linked immunosorbent assay; screening test for HIV antibodies; PCR is more sensitive/accurate.

PCR

Polymerase chain reaction; nucleic acid amplification technique; more authentic than ELISA for detecting HIV.

World AIDS Day

December 1; international day of awareness and support for those living with HIV/AIDS; symbol is the red ribbon.

Red Ribbon

Symbol of solidarity with AIDS patients and those living with HIV/AIDS.

HIV-1 and HIV-2

Two species of HIV; HIV-1 is more common and pathogenic; HIV-2 is less widespread outside Africa.

influenza virus

An enveloped RNA virus in the orthomyxovirus family; genome length ~12,000–15,000 nucleotides with 6–8 segments; shapes range from round to filamentous.

orthomyxoviruses

Virus family including influenza viruses; characterized by segmented genomes and enveloped virions.

leaf curl virus

Plant virus disease causing curling and vein darkening; major threat to cotton; vector is the whitefly Bemisia tabacii (Bemisia tabacii) and was reported in Multan in 1985.

Bemisia tabacii

Whitefly vector for leaf curl virus.

H5N1

A common form of bird (avian) influenza.

PSTVd

Potato spindle tuber viroid; first viroid discovered in 1971; a circular, single-stranded RNA plant pathogen without a protein coat.

prions

infectious protein particles lacking nucleic acid; smaller than viruses; cause diseases like CJD, KURU, and Fatal Familial Insomnia; very resistant to UV and heat; always fatal and untreatable.

viroids

Very small, circular, single-stranded RNA plant pathogens without a protein coat; ribozymes with catalytic activity; replication by RNA polymerase II; Hepatitis D is the only known human disease linked to viroids.

PSTVd discovery

Potato spindle tuber viroid was first discovered in 1971 by Theodor Diener.

lytic cycle

Phage life cycle that results in host lysis and release of new phages; rapid replication and destruction of the bacterial cell.

lysogenic cycle

Phage life cycle where viral DNA integrates into the host genome as a prophage and can be induced to enter the lytic cycle.

induction

Process by which a prophage exits the lysogenic state and begins the lytic cycle.

bacteriophage size

Typically 24–200 nm in diameter.

host range

The spectrum of host species a virus can infect; attachment specificity often determines host range (e.g., polio in humans/primates; rabies in mammals).