Viruses

Structure, Properties, Reproductive cycle, Types, Importance

Reproductive cycle

Reproductive cycle

Structure and Properties

• Can only replicate inside living cells

• Protein coat/capsid

• Nucleic acid core

• Lipid envelope

• Genetic material

• DNA

• RNA

• Linear/circular

• Shape

• Helical

• Icosahedral

• Enveloped

• Complex

• Presence of envelope

• Animal viruses

• Type of reproductive cycle

• Lytic cycle

• Lysogenic

• Retroviruses

Types of

animal viruses

Importance

• Virus vs. cancer cells

• Virus as carriers or vectors for treatment

• Weapons and biological warfare

• Agriculture

• nanotechnology

Diversity of life

A system that names and organizes organisms in a logical manner is used

Biological classification

1. Assigns a universally accepted name to each organism

Biological classification

2. Place organisms in groups that have a real biological meaning

Artificial classification

• Superficial

• Uses only one or few characteristics

Natural classification

• Uses all or most characteristics

• Shows evolutionary relationships

Branches that deal with classification• Taxonomy

• Phylogeny

• Evolutionary history of a species / group of species

• Systematics

• Taxonomy + Phylogenetics

• Study of biodiversity in context of evolutionary history

Taxonomy

• Branch that deals with identification, classification, and naming or organisms

• Sorts species into broader taxonomic categories. Sorts species into closely related organisms

• Ex: Varanus mabitang, V. mabitang, Varanus sp., Varanus spp.

• Aristotle – air, land, and water dwellers

• Theophrastus – herbs, shrubs, trees

• John Ray – “species”

• Species – a group of structurally-similar organisms that pass on these similarities to their offspring

• Genus- group of close-related species

• Latin

• Carolus Linnaeus = father of modern taxonomy

Levels of Classification

• KPCOFGS

Binomial System of Classification

1. Genus Species

2. Genusspecies

3. Genus species

4. Genuz species

5. Genus species

6. Genus species

7. Genus species

8. Genus Species

9. Genus Species

10. Genus species

Schemes of Biological Classification

• Structural information

• Cytological information

• Embryological information

• Behavioral information

• Biochemical organization

• Evolutionary relationships

Plantae Animalia

Fungi Monera

prokaryotes

Eukaryotes

Prokaryotes

• Unbound nucleoid

• Simple appendages

• Circular DNA

• No membrane bound organelles

• Binary fission as reproduction

• Complex cell wall

• Ribosomes – small

• Cytoskeleton

• Smaller than eukaryotes

Structure

• Cell wall

• site of antibiotic action

• Cell membrane

• contains pigments and enzymes

• Cytoplasm

• cytoplasmic streaming

• Nucleiod region

• Ribosomes

• Flagellum

• Pili

Domain Archaea

• prokaryotic

• Membranes – branched hydrocarbon chains attached to glycerol by either linkages

• Cell walls : no peptidoglycan

• rRNA unique to Archaea

• Halophiles, hyperthermophiles

• Autotroph/ heterotroph

Domain Bacteria

• Prokaryotic cells

• Membranes – unbranched fatty acid chains attached to glycerol by ester linkages

• Cell walls: peptidoglycan

• Great deal of diversity

• rRNA unique to Bacteria

• unicellular

• Mycoplasmas, cyanobacteria, gram-positive, gram-negative

• Autotroph / heterotroph

Domain Eukarya

• Eukaryotic cells which have membranes similar to bacteria

• Some have cell walls

• Phylogeny

• Differences in the sequences of nucleotides in the cell’s ribosomal RNAs (rRNA)

LUCA

Super phylum

Reproduction

• Archaea - asexual repro: binary fission, budding, or fragmentation

• Eubacteria – asexual repro

• Protist – asexual repro. Meiosis

• Fungi - asexual or sexual

• Plantae – asexual: mitosis / sexual

• Animalia – sexual reproduction