Bio ch 19

Obligate Intracellular Parasites

Viruses that can only reproduce within a host cell

Viral Genome

Consists of either double- or single-stranded DNA or RNA

Capsids

Protein coats made of identical subunits in viruses

Viral Envelopes

Membranes cloaking capsids, derived from host cell membranes

Spike Protein

Virally encoded proteins embedded in the envelope

Lytic Cycle

Viral reproduction strategy involving host cell lysis

Bacteriophages

Viruses infecting bacteria with elongated capsid heads

Prophage

Integrated viral DNA in a dormant state within host cell

Lysogenic Cycle

Virus integrates into host genome, pausing infection

Host Range

Limited range of host cells a virus can infect

Lock-and-Key Fit

Specific receptor-virus protein interaction for host cell entry

Viral Budding

Enveloped viruses escaping host cell by budding process

Viral Host Specificity

Viruses attacking specific tissues or cell types

Viral Mechanisms

Viruses modifying host cell machinery for viral replication

Viral Entry Strategies

Various ways viruses enter host cells

Viral Replication Steps

Attachment, penetration, replication, assembly, release

Viral Genome Strands

Plus strand serves as coding strand, minus strand does not

Viral Protein Functions

Proteins that alter host cell replication/transcription/translation

Viral Exit Strategies

Different methods viruses use to exit host cells

Protease

Enzyme that cleaves TATA-binding portion of transcription factor

Splicing Blocker

Protein in Influenza virus inhibiting splicing

Endonuclease

Enzyme cleaving 5' caps off host cell mRNAs

Translation Factor Cleaver

Protease cleaving certain translation initiation factors

Adenovirus Effect

Inhibits p53 and Rb to drive host cell into S phase

DNA Polymerase

Enzyme in some DNA viruses for DNA replication

RNA Polymerase

Enzyme in all RNA viruses for RNA replication

Shared Life Property

Nucleic acids store hereditary info in prokaryotes and eukaryotes

Order and Complexity

Arrangement of biological molecules in prokaryotes and eukaryotes

Energy Processing

Metabolic reactions in prokaryotes and eukaryotes

Evolution Capacity

Ability to evolve in prokaryotes and eukaryotes

Non-Virus Particle

Single-stranded DNA plus protein composition

Virus Particle Exclusion

Protein plus lipid envelope without genome

Virus Particle Requirement

Genome needed for any known virus particle

Negative Strand Virus

Influenza virus with non-coding genome

Retrovirus

HIV virus with reverse transcription into DNA

Reverse Transcriptase

Enzyme in retroviruses for RNA to DNA conversion

Provirus

Integrated viral DNA in host genome

Mutation Impact

High mutation rate in RNA viruses due to proofreading lack

Zoonosis

Disease transmissible from animals to humans

Viral Disease Emergence

New diseases from existing viruses due to host changes

Viral Recombination

Influenza strains reassort to form new virus types

1918 Pandemic Cause

Recombination of fowl and human flu strains

Immunity Impact

Less sickness from flu with age due to prior exposure

Factory Farming Effect

Increased susceptibility to infection from close animal contact

Recombinant Viruses

Viruses with mixed genome fragments from different species, leading to epidemics

RNA Virus Mutation

Higher mutation rates due to lack of proofreading during genome replication

Lysogenic Bacteriophage

Virus type inserting gene into host genome

Innate Immunity

Immediate defense against pathogens, lacks specificity and memory

Adaptive Immunity

Develops slowly, specific to pathogens, with memory for future encounters

COVID-19

Disease caused by SARS-CoV-2, highly contagious

Non-structural Proteins

Enzymes or regulatory proteins in viruses like proteases

Accessory Proteins

Alter cell environment for easier virus replication, suppress immunity

Viral Genome Sequencing

Comparing new virus sequences to known ones for analysis

Positive Sense Virus

Viral genome serves as messenger RNA

Open Reading Frame

Start and stop codons for amino acid sequence in viral protein

Coronavirus Particle

Structure containing RNA genome, capsid, envelope, and spike protein

Viral Fusion and Entry

Conformational changes in spike protein for membrane fusion

Vaccine Function

Tricks immune system to prepare for pathogen exposure

Live Vaccine

Uses weakened virus for strong immune response

Inactivated Vaccine

Uses killed virus for safer but weaker immune response

Subunit Vaccine

Uses specific viral pieces for targeted immune response

Viral Vector Vaccine

Uses modified virus vector for immune protection delivery

mRNA Vaccine

Triggers immune response by protein production

Antiviral Medication

Treats viral infections by inhibiting viral DNA synthesis or assembly

Protease Inhibitor

Blocks viral particle assembly, used in treating HIV

Nucleoside Analogue

Stops accurate viral genetic material replication, rendering new particles noninfectious

AZT

Modified nucleoside analog treating HIV by interfering with viral DNA synthesis