Chapter 17 - The Simpler Genetic Systems of Viruses, Bacteria, and Archaea

Viruses

Nonliving particles that require living cells to replicate

Host Range

The number of species and cells a virus can infect

Capsid

Protein coat that varies in shape and complexity found in all viruses

Viral Envelope

A lipid bilayer derived from the host cell found in many viruses that infect animal cells.

Viral Reproductive Cycle

Attachment to the surface of the host cell, entry of the viral genome into the host cell, synthesis of viral components, viral assembly, and release of new viruses into the environment

Lytic Cycle

New phages are made, and then the bacterial cell is lysed

Lysogenic Cycle

The integrated phage DNA is replicated along with the DNA of the host cell

Prophage

Integrated phage DNA in the lysogenic cycle

Emerging Viruses

Arise via mutations in pre-existing viruses and have a greater probability of causing infection

Prokaryotic Genome

Consists of a single, usually circular chromosome composed of DNA and proteins within a nucleoid region

Plasmids

Exist separately from the main chromosome and provide growth advantages

Degradative plasmids

Enable digestion and utilization of an unusual substance

Fertility plasmids (F factors)

Allow bacteria to transfer genes to each other

Binary Fission

Rapid production of new cells through cell division

Strains

Lineages of the same species that have genetic differences

fertility plasmid

Contains genes required for conjugation and may also carry genes that confer a growth advantage

Bacterial Transformation

Living bacterial cells import a strand of DNA (typically derived from a dead bacterium)

Competence factors

Facilitate binding, uptake, and incorporation of DNA

Transduction

A phage picks up a piece of DNA from the bacterial chromosome and transfers it to another bacterium

Horizontal Gene Transfer

An organism incorporates genetic material from another organism without being the offspring of that organism