VIROLOGY
, CHAP 1: INTRODUCTION
Are Viruses Living or Not?
Dead Characteristics:
• Not cellular: Viruses do not have cells like living organisms.
• No metabolism: They don’t carry out chemical processes for energy.
• Just chemical packets outside host: They’re inactive outside a host cell.
• Cannot grow: Viruses do not grow or change size on their own.
• Can be crystallized: Viruses can form crystals, unlike living organisms.
Alive Characteristics:
• They have genes and proteins, they multiply: Viruses contain genetic material and replicate when in
host.
• They evolve: Viruses change over time through natural selection and mutation.
• Intracellular parasites: Viruses behave like parasites, only becoming active inside host cells.
• Respond to environment: They can react to heat, chemicals, and radiation.
• Transmission: Viruses can spread from infected to uninfected hosts.
,INTRACELLULAR OBLIGATE PARASITES
• Intracellular obligate parasites are organisms that must live and reproduce inside t
a host to survive.
• They are entirely dependent on their host's cellular machinery for replication and o
essential functions because they cannot perform these on their own.
• In textbook stated that virus are non-living particles with nucleic acid genomes that
the assistance of living cells to reproduce.
• Scientist concluded that virus are alive base on the description: Intracellular parasi
microparasites that are capable of growing and reproducing inside the cells of a hos
Basic structure of VIRUS
• Viruses are infectious agents made up of nucleic acid (DNA or RNA) enclosed in a pr
called a capsid.
• Nucleic acid + capsid is nucleocapsid
• Sometimes, they have an additional outer layer called an envelope.
,
, CHAP 1: INTRODUCTION
Are Viruses Living or Not?
Dead Characteristics:
• Not cellular: Viruses do not have cells like living organisms.
• No metabolism: They don’t carry out chemical processes for energy.
• Just chemical packets outside host: They’re inactive outside a host cell.
• Cannot grow: Viruses do not grow or change size on their own.
• Can be crystallized: Viruses can form crystals, unlike living organisms.
Alive Characteristics:
• They have genes and proteins, they multiply: Viruses contain genetic material and replicate when in
host.
• They evolve: Viruses change over time through natural selection and mutation.
• Intracellular parasites: Viruses behave like parasites, only becoming active inside host cells.
• Respond to environment: They can react to heat, chemicals, and radiation.
• Transmission: Viruses can spread from infected to uninfected hosts.
,INTRACELLULAR OBLIGATE PARASITES
• Intracellular obligate parasites are organisms that must live and reproduce inside t
a host to survive.
• They are entirely dependent on their host's cellular machinery for replication and o
essential functions because they cannot perform these on their own.
• In textbook stated that virus are non-living particles with nucleic acid genomes that
the assistance of living cells to reproduce.
• Scientist concluded that virus are alive base on the description: Intracellular parasi
microparasites that are capable of growing and reproducing inside the cells of a hos
Basic structure of VIRUS
• Viruses are infectious agents made up of nucleic acid (DNA or RNA) enclosed in a pr
called a capsid.
• Nucleic acid + capsid is nucleocapsid
• Sometimes, they have an additional outer layer called an envelope.
,
