Prokaryote vs. Eukaryote

Prokaryote vs. Eukaryote 1st division Life Prokaryotes Eukaryotes Bacteria Archea Protist Fungi Plants Animals

Prokaryotes Prokaryotes (bacteria and archea) Lack a true nucleus Keep DNA in nucleoids No membrane bound organelles Many are anaerobic Do not require O2 Unicellular

Eukaryotes Eukaryotes (protists, plants, fungi, animals) Presence of a nucleus Presence of membrane bound organelles For example Mitochondria to give energy Most are aerobic Require O2 for cellular respiration Most are pluricellular

Summary chart Prokaryotes Eukaryotes Lack a true nucleus No membrane bound organelles Many are anerobic Unicellular Eukaryotes Presence of a nucleus Has membrane bound organelles Most are aerobic Mostly pluricellular

But where do viruses fit in? Debate over whether viruses are “alive” A) Non-living arguments 1. Cannot live independently (require a host or remain dormant) 2. Not Cellular B) Living arguments 1. Contain genetic material (RNA and DNA) 2. Reproduce

Classifying viruses Classification based on 1. Capsids Protein coat that surrounds the genetic material of a virus Spherical Cylindrical Crystalline

Classifying viruses 2. Diseases they cause Viruses that affect humans are divided into 21 groups based on the differences in their genome and replication methods

Going viral (how viruses replicate) Virus replication (No cellular division) 1. The Lytic cycle Kills host cell Process Virus binds to host (attachment) Injects the genetic material into the host cell (entry) The host replicates the viral genetic material (replication) New viral particles are assembled (assembly) The host cell breaks (lysis) and releases new viral particles (release)

The lytic cycle 1. Attachment 2. Entry 3. Replication 4. Assembly 5.a) Lysis 5. b) Release

Virus replication 2. the Lysogenic cycle As the viral RNA becomes part of the cells chromosomes, the onset of disease can be postponed until the virus goes into its lytic cycle Process Attachment Entry Viral DNA becomes part of the host cell’s chromosomes (provirus formation)

The lysogenic cycle Attachment Entry Provirus Formation

Viral disease Cyclical symptoms can be explained via the replication method of a virus E.g cold sores Appear during the lytic cycle Disappear during the lysogenic replication cycle

Virus working for us Virus use in biotechnology ability to direct the activity of the hosts cell DNA Addition of a specific gene into the virus Virus can deliver and force organism to replicate that gene

Prions Prions Protein Do not contain RNA or DNA (not a virus) Becomes harmful when it changes its molecular shape Cause several deadly brain diseases Creutzfeld-Jakob disease Mad-cow disease in bovine