Virology Lecture 3 Flashcards (Processes of Hijacking Host Cells)

Flashcards covering key vocabulary related to the process of viruses hijacking host cells, including viral structure, replication stages, host cell molecular biology, and host defenses.

Capsid

The protein shell that protects the nucleic acid genome of a virus from nucleases.

Nucleocapsid

The structure consisting of a virus's capsid and its genome.

Capsid protein

A protein coded for by viral genes, essential for assembling infectious virus particles.

Viral receptor-binding protein

A protein used by viruses for attachment to the host cell, coded by viral genes.

Viruses

Parasitic entities that are dependent on a host cell for replication.

Replication

The process of making copies of nucleic acids (DNA or RNA).

Transcription

The process of synthesizing RNA from a DNA template.

Translation

The process of synthesizing proteins from processed messenger RNA (mRNA).

Eucaryotic host cells

Cells in which DNA replication and RNA transcription occur in the nucleus, and translation occurs in the cytoplasm.

Central dogma of molecular biology

The fundamental concept that genetic information flows from DNA to RNA to Proteins (DNA → RNA → Proteins).

Protein-coding sequences (Genes)

Segments of DNA in the genome that contain instructions for making proteins.

Non-protein-coding sequences

Segments of DNA in the genome that do not directly code for proteins, including introns, promoters, enhancers, telomeres, and non-coding RNAs.

Introns

Non-protein-coding sequences that are removed from pre-mRNA during RNA splicing.

Promoters

Larger nucleotide sequences that mark the start of the transcription process for a gene.

Enhancers

Short nucleotide sequences that increase the rate of transcription for a gene in the genome.

Telomeres

Repetitive DNA sequences at the ends of eukaryotic chromosomes that protect genetic information.

DNA polymerases

Enzymes that synthesize double-stranded DNA during replication by copying in the 3′ → 5′ direction and synthesizing in the 5′ → 3′ direction.

Primases

Cellular proteins involved in initiating DNA synthesis by synthesizing RNA primers.

Ligases

Cellular proteins that seal the gaps between DNA fragments during replication.

RNA polymerases

Enzymes that synthesize RNA from a DNA template during transcription.

Transcription factors

Proteins that initiate and regulate the transcription of genes by binding to DNA.

RNA splicing

The process where non-coding introns are removed from pre-mRNA, and coding exons are joined together.

Initiation (translation)

The crucial first step in eukaryotic translation where the ribosome assembles at the start codon, important for viruses.

Posttranslational processing of proteins

Modifications made to a protein after its synthesis, which serve many functions.

Viral replication

The process by which viruses hijack host cells, taking over their genetic machinery and resources to produce more viruses.

Attachment (viral)

The first step in viral hijacking, where specific viral proteins bind to corresponding receptor molecules on the host cell membrane.

Specificity (viral infection)

The lock-and-key interaction between viral proteins and host cell receptors that determines which types of cells a virus can infect.

Entry (viral) / Penetration (viral)

The process where the virus gains access past the host cell membrane.

Membrane Fusion

A method of viral entry where enveloped viruses fuse their lipid membrane directly with the host cell's membrane, releasing the viral core into the cytoplasm.

Enveloped viruses

Viruses that possess an outer lipid layer (envelope) which they can use for membrane fusion during entry.

Endocytosis (viral entry)

A method of viral entry where the host cell forms a vesicle around the virus, engulfing it and transporting it into the cell's interior.

Genetic Injection

A method of viral entry used by bacteriophages, where only the genetic material is injected into the host cell while the empty capsid remains outside.

Bacteriophages

Viruses that exclusively infect bacteria.

Uncoating (viral)

The process where a virus sheds its protein coat (capsid) to release its genetic material (DNA or RNA) into the host cell.

Replication and biosynthesis (viral)

The core

Viral protein production

The process where the viral genetic material instructs the host cell's machinery to produce viral proteins instead of host proteins.

Genome replication (viral)

The process where the virus forces the host's cellular machinery to make thousands of copies of the viral genome.

DNA viruses

Viruses whose DNA genome replicates in the cell's nucleus.

RNA viruses

Viruses whose RNA genome typically replicates in the cytoplasm.

Assembly (viral) / Maturation (viral)

The process where newly synthesized viral proteins and replicated genomes are gathered and assembled into new, immature virus particles.

Release (viral) / Egress (viral)

The final stage where new, infectious viruses leave the host cell to find and infect other cells.

Lysis (viral)

A method of viral release where viruses cause the host cell to burst, releasing new viruses and killing the cell.

Budding (viral)

A method of viral release used by enveloped viruses, where they acquire their outer membrane by pushing out from the host cell's plasma membrane, potentially allowing the host cell to survive.

Molecular Hurdles (host cell)

Barriers within eukaryotic cells designed to prevent viral infections.

RNA-dependent RNA polymerase

An enzyme essential for replicating viral RNA genomes, which is encoded by some viral genomes but absent in host cells.

Actin remodeling

A host cell barrier that affects every stage of a viral replication cycle, involving changes to the cytoskeleton.

Monocistronic RNAs

Eukaryotic messenger RNAs (mRNAs) that typically code for only one protein.

Alternative (differential) splicing

A viral strategy to produce multiple proteins from a single pre-mRNA molecule.

Segmented genomes

A viral strategy where the genome is divided into multiple RNA molecules, allowing complex gene expression.

Polyprotein

A viral strategy where a single, large protein is translated and then cleaved into multiple functional proteins.

RNA polymerases (viral)

Enzymes in RNA viruses that often lack proofreading ability, leading to higher mutation rates and genetic diversity.

Antiviral drug development

The process of creating drugs that target essential processes for viral replication without being toxic to the host organism.