Characteristics of life and viruses

traits unifying cellular life

• growth

• respond to environment

• cellular in structure and composition

• metabolizes

• reproduce

• hereditable traits

• homeostasis

• evolution

• common ancestry

viruses

particles composed of genetic material enclosed in protein capsuls

obligate parasites

require a host to replicate

what a virus does

1. infects cells

2. uses host molecules and organelles to replicate

   1. leaves by exosytocis or by bursting cell

traits of a virus

• heredity

• evolution

  • reproduction

Progressive hypothesis

viruses originated from genetic material that gained the ability to replicate and move from one cell to another

Regressive hypothesis

Simplification of formerly free-living organisms becoming parasitic to the point of not being able to replicate independently

Virus-first hypothesis

viruses were the earliest life forms, then they evolved into other life forms

Antibiotics

target prokaryotic cells (bacteria)

Antivirals

Targets viral replication cycle

Viruses in the human genome

- approx. 8% of human genome is from ancient viral infections

- 40% is repeat regions likely from viruses