Viruses, Bacteria, & Protists The Single Cell: Viruses, Bacteria, & Protists

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

Viruses, Bacteria, & Protists Structure: Viruses, Bacteria, & Protists

What is a Virus? DNA or RNA ½ to 1/100 the size of the smallest bacteria DNA or RNA Only contains instructions for making a copy of the virus. No genes for protein synthesis, viruses don’t process any food or water, they aren’t aerobic or anaerobic they have no metabolism Some viruses have only four genes Classification on basis of nucleic acid DNA viruses: - Herpes simplex virus (HSV) RNA viruses: - influenza virus

Structure of a Virus? Proteins determine the viruses shape: Envelope Lipid bilayer Capsid Genetic material Envelope – additional layer surrounding the capsid Capsid - a shell of protein surrounding nucleic acid Proteins determine the viruses shape: Polyhedral - papilloma virus The protein arrangement also determines what cell can be infected by the virus and how the virus infects the cell. with projections - HIV helical - tobacco mosaic virus Polyhedral head w/cylindrical tail w/ leg fibers

What are Bacteria? The Extremists! Kingdom Archebacteria Prokaryote Extreme environment No free O2 High salt or sulfur concentration Some produce methane These are bacteria with a twist, the reason they get their own kingdom is because of the environment where they live, The archaebacteria are prokaryotes that live in extreme environments where there is no free oxygen like deep on the ocean floor near the volcanic vents, in sulfur springs or in the dead sea or great salt lake in Utah. There are even archaebacteria that live in swamps or even in the gut of some animal that produce methane The Extremists!

What are Bacteria? Can be found just about anywhere Kingdom Eubacteria Human pathogens Decomposers Symbiotic living Prepare food Make antibiotics These are the bacteria we are familiar with. The ones that give us strep throat, streptococcus pyrogenes, the ones that live in our guts and help us digest food, E. coli, and there are may that work as decomposers. Bacteria can be found on just about all surfaces. Only 1% are harmful. Can be found just about anywhere

Structure of Bacteria Prokaryotic cells lack a nucleus and membrane bound organelles The definition of prokaryote is not membrane bound organelles. They have no mitochondria or chloroplast to produce food or energy instead Prokaryotes us parts of their plasma membrane that are folded inward inside the cell to perform metabolic activities like cellular respiration and photosynthesis. Common shapes among prokaryotes are spheres, rods, & spirals

Unicellular, multicellular, colonial What are Protists? Kingdom Protista All organisms that are neither animals, plants, bacteria or fungi are called 'protists' Unicellular, multicellular, colonial Eukaryotic Aquatic environments The most diverse kingdom. Protists are put into three groups

What are Protists? Plant like Protists - Algae Live in fresh or salt water Reproduction & metabolism similar to plants Animal like Protists - Protozoa Aquatic All are single celled Metabolism similar to animals Grouped according to how they move Pseudopod Ciliate Sporazoan Green algae prefer fresh water, there are also red and brown algae and a lot of them live in salt water. Algae are responsible fro producing more than 70% of the oxygen we breath Some algae are multicellular like kelp Some are singled celled but live in colonies like the volvox Algae are also very important as the foundation of may aquatic food webs Flagellate Fungus like Protists – plasmodium, slime mold, downy mildew Behavior & metabolism similar to fungus

Inside story “A Typical Bacteria Cell” page 503 of green text book Divide page 23 in half On the top half draw a bacteria cell label plasmid, chromosome, cell wall, plasma membrane, pilus, ribosomes, and flagellum Below your picture draw a VINN diagram to compare and contrast prokaryotic cells and Eukaryotic cells

Describe three advantages to 3-13-12 Warm- up Describe three advantages to being a Eukaryotic cell.

Viruses, Bacteria, & Protists Reproduction: Viruses, Bacteria, & Protists

Viral Reproduction 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 The recognition and attachment of the virus to the receptor site is like two pieces of a puzzle fitting together. Each virus can usually attach to only a few kinds of cells

Viral Reproduction 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 Not all viruses kill the host cell – at least not right away Attachment Entry Provirus formation Replication Assembly Release

Bacterial Reproduction Most prokaryotes have a single, circular, double-stranded DNA chromosome condensed in the nucleoid region of the cytoplasm 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

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

Bacterial Reproduction SEXUAL Conjugation, one cell directly transfers DNA to another But the thing that is so special about the plasmid is that the bacteria can share their special powers with other bacterial cells no matter if they are the same or different species. The plasmid replicates independently of the chromosome and can be transferred thru conjugation, just like in protists. This is the main way antibiotic resistance has increased. Resulting in a bacterium with a new genetic composition

Plant Like Protist Reproduction Asexual & Sexual Fragmentation occurs when a filament breaks apart and each piece develops into another organism. Spirogyra 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. Some algae reproduce asexually, but some can reproduce either asexually or sexually, and some have different stages where they reproduce sexually in one stage and asexually in another. (haploid) (diploid) Alternation of generations Sexual and asexual reproduction occurs during alternating periods in the life cycle of the plant like protist.

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

Warm up Define homeostasis. In what types of situations would an organism require a homeostatic mechanism.

Viruses, Bacteria, & Protists Metabolism: Viruses, Bacteria, & Protists 22

Do viruses need to “eat”? Do viruses need energy? Do viruses need to “eat”? Do viruses produce waste? Do viruses have a metabolism? HOST CELL DOES IT ALL!

Heterotrophic Bacteria Use organic molecules as a food source Parasites – Unable to produce organic molecules Obtain nutrients from living organisms Excretes waste thru cell wall 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 Photosynthetic autotrophs – Use sunlight to make organic molecules Photosynthetic autotrophs – Contain chlorophyll Excretes waste thru cell wall Make organic molecules from inorganic ones Cyanobacteria – usually blue/green, can be red or yellow, found in ponds, streams & moist areas of land. Colonial, composed of chains of independent cells Chemosynthetic autotrophs – Obtain energy needed to make food from Chemicals like sulfur & nitrogen Excretes waste thru cell wall NITROGEN FIXATION

Protists Animal like Plant like Fungus like Heterotrophic – feed on other organisms or dead organic matter. Some are parasitic Have specialized organelles used to release waste 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 Fungus like Green algae prefer fresh water, there are also red and brown algae and a lot of them live in salt water. Algae are responsible fro producing more than 70% of the oxygen we breath Some algae are multicellular like kelp Some are singled celled but live in colonies like the volvox Algae are also very important as the foundation of may aquatic food webs Heterotrophic Plasmodium Eats as it moves Mildew Feed on dead organisms Releases waste thru cell membrane

Viruses, Bacteria, & Protists Gas Exchange: Viruses, Bacteria, & Protists 27

Why is gas exchange important? Do viruses need oxygen or carbon dioxide? HOST CELL DOES IT ALL!

Bacteria Metabolism Obligate aerobes – require oxygen Mycobacterium tuberculosis – the organism that causes the lung disease tuberculosis Obligate anaerobes – require NO oxygen There is a wide range of oxygen need in bacteria, some have to live in an oxygenated environment like the bacteria that causes tuberculosis, other bacteria like the one that causes syphilis require an oxygen free environment. And then there are some that can live in either or have a certain percentage of oxygen required. 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 Autotroph Heterotroph

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

Viruses, Bacteria, & Protists Homeostasis: Viruses, Bacteria, & Protists

What is HOMEOSTASIS? Why is it important? How do VIRUSES maintain homeostasis? They DON’T! The Host Cell does it for them!!

When life gets rough some bacteria can form resistant endospores Bacteria Homeostasis The cell wall maintains the shape of the cell, protects the cell, and prevents the cell from bursting in a hypotonic environment When life gets rough some bacteria can form resistant endospores The Gram + cells have a plasma membrane with a bunch of peptidoglycan stacked on top. Balloon demo The Gram – cells have a plasma membrane a small amount of peptidoglycan and then another membrane 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

Protist Homeostasis Because the kingdom protista contains such a variety, several homeostatic behaviors exist 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 Amoebas can grow to very large sizes. Some species are 5 mm long! They can survive by having many nuclei within their single cell. Star-shaped contractile vacuoles are used to balance the amount of water in the cell. Two nuclei contain the genetic information.

Cellular organization Are viruses alive? What are the characteristics of life? Reproduction Genetic information Maintain Homeostasis How do characteristics of viruses compare to that of living organisms? Metabolism Cellular organization

NO Are viruses alive? How do characteristics of viruses compare to that of living organisms? No cell organization Has genetic material Once the virus drops off its genetic material it uses the metabolism of the host cell to make new viruses. A typical lytic cycle takes about 30 minutes and produces about 200 new viruses The host cell is destroyed Unable to reproduce with out a host cell Use host cell’s metabolism Homeostasis?

Turn to page 523 in the Green text book On the top half of the next odd page of your BIN draw a picture of the paramecium Be sure to draw ALL of the organelles Draw a food particle as it is consumed by the paramecium and trace it’s path thru the digestive system of the protist Next to your drawing describe how the food is taken in by the paramecium and where in the digestive system the goes and what happens to the food at each point along the way. Draw a contractile vacuole doing it’s job in your paramecium Below your drawing explain why the job of the contractile vacuole is so important. 8. Describe how bacteria deal with unfavorable environmental conditions.