The Single Cell: Viruses, Bacteria, & Protists

Why are levels of organization important? What do you notice as the levels go from atom to organism? Once at the organism level how do we organize?

Structure: Viruses, Bacteria, & Protists

DNA or RNA  DNA viruses : - Herpes simplex virus (HSV) What is a Virus? Classification on basis of nucleic acid  RNA viruses : - influenza virus ½ to 1/100 the size of the smallest bacteria

Structure of a Virus?  Envelope – additional layer surrounding the capsid  Capsid - a shell of protein surrounding nucleic acid Proteins determine the viruses shape: Polyhedral - papilloma virus helical - tobacco mosaic virus with projections - HIV Polyhedral head w/cylindrical tail w/ leg fibers Envelope Lipid bilayer Capsid Genetic material

Kingdom Archebacteria Prokaryote Extreme environment No free O 2 High salt or sulfur concentration Some produce methane What are Bacteria ?

Kingdom Eubacteria Human pathogens Decomposers Symbiotic living Prepare food Make antibiotics What are Bacteria ?

Structure of Bacteria Prokaryotic cells lack a nucleus and membrane bound organelles Common shapes among prokaryotes are spheres, rods, & spirals

Unicellular, multicellular, colonial Eukaryotic Aquatic environments Kingdom Protista All organisms that are neither animals, plants, bacteria or fungi are called 'protists' What are Protists ?

Plant like Protists - Algae Live in fresh or salt water Reproduction & metabolism similar to plants What are Protists ? Animal like Protists - Protozoa Aquatic All are single celled Metabolism similar to animals Grouped according to how they move Ciliate Flagellate Pseudopod Sporazoan Fungus like Protists – plasmodium, slime mold, downy mildew Behavior & metabolism similar to fungus

Reproduction: Viruses, Bacteria, & Protists

Viral Repr o ducti o n Lytic Cycle The viruses attaches to a host cell and deposits its DNA The viral DNA instructs the host cell to use its own enzyme raw material & energy to only make new viruses The new viruses burst from the host cell – killing it – & are able to go infect other cells Attachment Entry Replication Assembly Release

Viral Repr o ducti o n Lysogenic Cycle The viral DNA is integrated into the host cells chromosome - provirus Every time the host cell replicates it also replicates the viral DNA Once activated, the provirus enters the lytic cycle replicates and kills the host cell Attachment Entry Provirus formation Replication Assembly Release

Most prokaryotes have a single, circular, double-stranded DNA chromosome condensed in the nucleoid region of the cytoplasm Bacterial Reproduction Many bacteria have an additional small ring of DNA – The Plasmid – prokaryotes can survive without the plasmid the genes for essential functions are on the chromosome. Plasmids sometimes contain genes for resistance and other special issues

Prokaryotes reproduce mostly asexually via binary fission, making DNA almost continuously Bacterial Reproduction ASEXUAL No cell cycle like seen in Eukaryotes No mitosis or meiosis Translation and transcription occur simultaneously Allows for rapid response to Environment – ADAPTATION

Conjugation, one cell directly transfers DNA to another Resulting in a bacterium with a new genetic composition Bacterial Reproduction SEXUAL

Plant Like Protist Reproduction Asexual & Sexual Conjugation occurs when two filaments form conjugation tubes. The contents of one cell passes through the tube an fuses with a cell from the other filament. Fertilization occurs and a zygote is formed. Fragmentation occurs when a filament breaks apart and each piece develops into another organism. Spirogyra (haploid) (diploid) Alternation of generations Sexual and asexual reproduction occurs during alternating periods in the life cycle of the plant like protist.

Multiply asexually by fission. The cell divides into two individuals. Animal Like Protist Reproduction Paramecium undergoing fission. Fungus Like Protist Reproduction Plasmodium - Reproduces by haploid spores Slim molds are haploid their entire life & reproduce by cell division

Metabolism: Viruses, Bacteria, & Protists

Do viruses need energy? Do viruses produce waste? Do viruses need to “eat”? Do viruses have a metabolism?

Heterotrophic Bacteria Use organic molecules as a food source Obtain nutrients from living organisms Unable to produce organic molecules Parasites Parasites – Saprophytes Saprophytes – Feed on dead organisms or organic waste Break down nutrients locked in body tissues of dead organisms Excretes waste thru cell wall

Autotrophic Bacteria Use sunlight to make organic molecules Photosynthetic autotrophs Photosynthetic autotrophs – Contain chlorophyll Excretes waste thru cell wall Make organic molecules from inorganic ones Chemosynthetic autotrophs Chemosynthetic autotrophs – Obtain energy needed to make food from Chemicals like sulfur & nitrogen Excretes waste thru cell wall

Plant like Able to perform photosynthesis contain chlorophyll Not all are green. Diatoms & dinoflagellates have yellow to brown chloroplasts. There are brown algae & red algae Release waste thru cell wall Animal like Heterotrophic – feed on other organisms or dead organic matter. Some are parasitic Have specialized organelles used to release waste Protists Heterotrophic Plasmodium Eats as it moves Mildew Feed on dead organisms Releases waste thru cell membrane Fungus like

Gas Exchange: Viruses, Bacteria, & Protists

Do viruses need oxygen or carbon dioxide? Why is gas exchange important?

Obligate aerobes – require oxygen Mycobacterium tuberculosis – the organism that causes the lung disease tuberculosis Obligate anaerobes – require NO oxygen Treponema pallidum – the bacterium that causes syphilis Bacteria Metabolism

Prokaryotes used infolded regions of the plasma membrane to perform many metabolic functions, including cellular respiration and photosynthesis. Respiratory membranes in aerobes Thykaloid membranes in photosynthetic bacteria Heterotroph Autotroph Bacteria Metabolism

Protists Metabolism Protists are eukaryotic cells Have many specialized organelles including mitochondria or chloroplasts used in cellular respiration Protists are aerobic – they require oxygen Paramecium

Homeostasis: Viruses, Bacteria, & Protists

What is HOMEOSTASIS? Why is it important? How do VIRUSES maintain homeostasis?

The cell wall maintains the shape of the cell, protects the cell, and prevents the cell from bursting in a hypotonic environment Bacteria Homeostasis When life gets rough some bacteria can form resistant endospores Endospores contain a bacterium’s DNA and a small amount of cytoplasm Endospores are encased in a tough outer covering that resists drying out and extreme temperatures

Star-shaped contractile vacuoles are used to balance the amount of water in the cell. Two nuclei contain the genetic information. Amoebas can grow to very large sizes. Some species are 5 mm long! They can survive by having many nuclei within their single cell. If you would keep Euglenoids in the dark they start feeding on organic matter and may loose their chloroplast. Sometimes classified as animal like other times classified as plantlike Protist Homeostasis Because the kingdom protista contains such a variety, several homeostatic behaviors exist

Are viruses alive ? How do characteristics of viruses compare to that of living organisms? What are the characteristics of life? M a i n t a i n H o m e o s t a s i s M e t a b o l i s m R e p r o d u c t i o n C e l l u l a r o r g a n i z a t i o n G e n e t i c i n f o r m a t i o n

Are viruses alive ? How do characteristics of viruses compare to that of living organisms? U s e h o s t c e l l ’ s m e t a b o l i s m No cell organization U n a b l e t o r e p r o d u c e w i t h o u t a h o s t c e l l H a s g e n e t i c m a t e r i a l Homeostasis?