Viruses Chapter 10.17
What you need to know! The components of a virus. The differences between lytic and lysogenic cycles.
What’s a Virus? Not a living cell but an infectious particle Obligate intracellular parasite Contains: 1.nucleic acids 2.protein coat
Viruses are Tiny
Protein Coats-Capsids Capsids are made from proteins called capsomeres Capsids have many different shapes depending on the virus: Rod shape, Helical, Polyhedral, Icosahedral
Tabacco Mosaic Virus Helical capsid with RNA
Adenovirus Respiratory virus in animal Polyhedral capsid with glycoprotein spikes
Influenza virus Membrane envelope from host studded with glycoproteins
Bacteriophages Viruses that infect bacteria icosahedral shape of a phage resembles a lunar landing probe
Viral Reproduction Viruses are obligate intracellular parasites Isolated viruses cannot reproduce They lack the ribosomes and enzymes for making proteins Viruses can only infect limited range of host
Lytic Cycle Virus infects host cell Cell constructs virus Cell dies and releases the virus
Lysogenic Cycle Virus infects host cell Virus nucleic acid hides inside host DNA A stimulus triggers the virus into the Lytic Cycle
Protists Chapter 28
Characteristics Protists are eukaryotes Can be unicellular, colonial, or multicellular Predecessor to other eukaryotes: plants, fungi, and animals. Fossils date back 2.1 billion years excretion)
Specifics Types: 1.Absorptive, protists (fungus-like) 2.Protozoa - ingestive, animal-like protists 3.Algae - photosynthetic, plant-like protists. Important Structures: Flagella: Protists have a flagella or cilia during some time in their life cycles. The eukaryotic flagella are extensions of the cytoplasm with a support of a microtubule system (made from tubullin) Cilia are shorter and more numerous than flagella.
*Lifestyle Many protists are symbiots that inhabit the body fluids, tissues, or cells of hosts. These symbiotic relationships span the continuum from mutualism to parasitism (malaria, giardia)
*Evolution Endomembrane system of eukaryotes (nuclear envelope, endoplasmic reticulum, Golgi apparatus, and related structures) may have evolved from in-folding of plasma membrane. Mitochondria and chloroplasts were incorporated through endosymbiosis
Euglena Freshwater microscopic algae, single celled autotrophic organism (phytoplankton) Contractile vacuole: bladder-like, pulsing structure that pumps out excess water that enters the cell due to the cell being hyperosmotic in fresh water Eyespot: detection of light direction Flagellum: movement toward light source
Amoebas Pseudopods: extensions of the cytoplasm Capturing prey, locomotion Heterotrophic Movement by pseudopods (false feet): bulging out of plasma membrane followed by cytoplasm
Paramecium Coordinated movement through ciliates Complex organelles: contractile vacuole for osmoregulation (pumping out water), oral groove (mouth), anal pore (duh)