General Biology 116 – Introductory Virology, Classification & Evolution

These flashcards review key points from Dr. Stern Cardinale’s introductory lecture on course logistics, memory strategies, biological classification, evolution, and fundamental virology concepts including viral structure and replication cycles.

Which type of memory is also called working memory?

Short-term memory (STM)

Define taxonomy.

The science of naming, describing, and classifying organisms

Define phylogeny.

The evolutionary history of a species or group of species

What is a taxon?

A grouping of organisms at any rank in the classification hierarchy

What is the broadest category in the modern Linnaean hierarchy?

Domain

How is evolution defined in this course?

A change in allele frequency from generation to generation

State two requirements for natural selection to occur.

Heritable phenotypic variation and differential reproductive success (beneficial traits increase in frequency)

What does a phylogenetic tree depict?

Hypothesized evolutionary relationships (patterns of descent), not phenotypic similarity

Name the three domains in the three-domain system.

Bacteria, Archaea, and Eukarya

Are viruses placed on the Tree of Life?

No—they are not included because they are non-cellular

How are viruses described with respect to cellular organization and lifestyle?

Subcellular, intracellular parasites

List two cellular characteristics viruses lack.

They lack metabolic processes and organelles such as nucleus or cytoplasm

What two main components make up a basic virus particle?

Capsid and genome

Typical viral size falls in what range?

About 20–300 nm (with exceptions)

What kinds of genetic material can viruses possess?

DNA or RNA; single-stranded or double-stranded; linear, circular, or segmented

Define a capsid.

The protein coat (made of capsomeres) that encloses the viral genome and aids in host attachment

What is a viral envelope?

A phospholipid bilayer surrounding some capsids, derived from the host membrane and containing viral glycoproteins

Define host range.

The species or tissue types that a particular virus can infect, usually narrow

List the four general steps of a typical viral replication cycle in eukaryotes.

Attachment, entry, genome replication & gene expression, assembly, and exit

What characterizes the lytic cycle of a bacteriophage?

Viral replication that culminates in host cell lysis and horizontal transmission

What characterizes the lysogenic cycle?

Viral genome integrates as a prophage, replicates with the host, enabling vertical transmission without immediate host death

What is a temperate phage?

A phage capable of switching between lytic and lysogenic cycles (e.g., phage λ)

Name one bacterial defense against phage infection mentioned in the lecture.

Restriction enzymes that cut foreign DNA

How many main viral replication cycles were summarized in lecture?

Two – lytic and lysogenic

Which option in the practice question is true of BOTH lytic and lysogenic cycles?

Option B: Only lysogenic involves vertical transmission (the statement about vertical transmission distinguishes the two)

Why are viruses often said to "break all the rules"?

They show extreme diversity in size, morphology, and genome type, with many exceptions to general patterns