Prokaryote vs Eukaryote 1 st division Prokaryotes Found

Prokaryote vs. Eukaryote

• 1 st division

Prokaryotes • Found in bacteria and archaea kingdoms • Characteristics include q 1 -10μm(micrometer-one millionth of a meter) q lack a true nucleus so keep DNA in nucleoids q no membrane bound nucleus or organelles q many are anaerobic so they do not require O 2 q Unicellular q Have a cell wall(peptidoglycan)

Eukaryotes • Found in protists, plants, fungi, and animal kingdoms • Characteristics include q 100 -1000 μm q Presence of a nucleus q Presence of membrane bound organelles Ex: mitochondria is an organelle that gives energy q most are aerobic so they require O 2 for cellular respiration q most are multicellular

Summary chart • Prokaryotes – 1 -10 μm – Lack a true nucleus – No membrane bound organelles or nucleus – Many are anaerobic – Unicellular – Have a cell wall • Eukaryotes – 100 -1000 μm – Presence of a nucleus – Has membrane bound organelles – Most are aerobic – Mostly multicellular (pluricellular)

Viruses • Debate over whether viruses are “alive” v Arguments that they are not-living • Cannot live independently (require a host or remain dormant) (parasites of living cells!!) • Not Cellular v Arguments that they are living • Contain genetic material (RNA and DNA) • Reproduce

Classifying viruses 1) Classification based on capsid • protein coat that surrounds the genetic material of a virus § Spherical § Cylindrical § Crystalline

2) Classification based on diseases they cause • Viruses that affect humans are divided into 21 groups based on the differences in their genome and replication methods

How viruses replicate (no cellular division) 1) The Lytic Cycle • kills host cell • 5 -step process: – Virus binds itself to host cell (attachment) – Injects the viral 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) which can go infect other cells.

The Lytic Cycle • • • 1. Attachment 2. Entry 3. Replication 4. Assembly 5. a) Lysis b) Release

How viruses replicate (cont’d) 2) The Lysogenic Cycle • Viral RNA becomes part of the cells chromosomes. It does not take over the cell but the RNA gets copied with the cell. The onset of disease can be postponed until the virus goes into its lytic cycle b)Process – Attachment – Entry – Viral DNA becomes part of the host cell’s chromosomes (provirus formation)

The Lysogenic Cycle 1. 2. 3. Attachment Entry Provirus Formation

Viral disease • Cyclical symptoms can be explained by the replication method of a virus ex. cold sores • appear during the lytic cycle • disappear during the lysogenic replication cycle (Virus is always in a person, never goes away so always susceptible to cold sores)

Virus working for us Virus use in biotechnology: 1) Gene therapy i) addition of a specific gene into the virus ii) virus can deliver and force organism to replicate that gene iii) “typos” corrected ex. Parkinsons

2) Bacteriophages § viruses attack bacteria (45 min = 200 new viruses)

3) Reovirus (Respiratory Enteric Orphan Virus) § kills cancer cells -head, neck, lung, liver cancers - few side effects

Prions • Protein 1) Do not contain RNA or DNA (not a virus) • Becomes harmful when it changes its molecular shape -because they can cause several deadly brain diseases such as: Creutzfeld-Jakob disease Mad-cow disease in bovine