2. MICROBIOLOGY - ALCAMO LECTURE: CRITERIA FOR PROKARYOTES & EUKARYOTES

3. Introduction - Cells All living organisms have cells Basic unit of structure Large organisms – many cells Cells are organized into: –Tissues – stomach lining –Organs – esophagus, stomach, intestines –Systems – digestive system

4. MICROORGANISMS One or a few cells take care of all functions

6. Prokaryotic Cell: No nuclear membrane No other internal membranes (no organelles) Only has a cell membrane Examples – bacteria, cyanobacteria

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8. PROKARYOTES - They are very small cells - They have a very thin cell wall: -Shape -Protection - They have a cell membrane: - Lines the cell wall - Regulates molecular traffic - They have a nucleoid or nuclear region where their one, looped molecule of DNA resides

9. PROKARYOTES - Their cytoplasm is a soup of chemicals (including free ribosomes), where all cell activities take place -They may contain a flagella – a long hair- like appendage made of protein and responsible for motion in MO’s -May have one or many -Made of protein flagellin -Movement is chemically driven - chemotaxis

11. Eukaryotic Cell: Has a nuclear membrane Has other membrane bound organelles: mitochondria Golgi bodies endoplasmic reticulum Examples – animals, plants, fungi, protozoa, unicellular algae

13. EUKARYOTES - They are larger cells than the prokaryotes - They may have a 3 layer cell wall: -Shape -Protection -They have a cell membrane: -Lines the cell wall -Regulates molecular traffic -They have a nucleus with a nuclear membrane: - Double stranded DNA (chromosomes) - RNA

15. . - They have a cytoplasm – Soup of chemicals containing membrane bound organelles for all cell activities -They may have a flagella – -cable-like -Made of tubulin protein -Arranged in a microtubule array of 9 doublets around 2 singlets

16. Prokaryotic vs. Eukaryotic Cells CharacteristicProkaryotesEukaryotes NucleusAbsentPresent with nuclear membrane OrganellesAbsentPresent in a variety of forms DNA StructureSingle closed loop Naked strand with no protein Multiple chromosomes Protein associated with DNA ChlorophyllWhen present – dissolved in cytoplasm When present –contained in chloroplasts RibosomesSmaller and free in cytoplasm Larger and often bound to membranes Cell wallsPresent and complexPresent /absent and simple ReproductionFission – no mitosisMitosis ExamplesBacteria, CyanobacteriaFungi, protozoa, plants, animals, humans

18. Classification of Organisms -Eukaryotes - all multicellular organisms and unicellular organisms (except 2) Examples: mammals, fish, plants, fungi, algae and protozoa -Prokaryotes – (the other 2) only bacteria and cyanobacteria

19. Microorganism Size Micrometer – unit of length most commonly used (1/1,000,000 of a meter) MO’s range in size from almost visible protozoa (100um) down to incredibly small viruses (0.01 um) Most bacteria are 1 – 5 um in length

21. Bacteria Prokaryotes and one of the most abundant organisms on earth Can affect us positively (digest sewage, extract N from air for plants, break down dead and decaying matter) Can be harmful to us (produce toxins in our bodies, infect plants and animals, etc) Are able to live under almost any conditions (arctic ice, hot springs, ocean trenches, acidic conditions, no oxygen)

22. Small Bacteria Rickettsiae barely seen with light microscope Transmitted by arthropods such as ticks and lice Can cause Rocky Mountain spotted fever and typhus fever

23. Small Bacteria Chlamydiae – even smaller than rickettsiae and can’t be seen with light microscope –One species causes the gonorrhea-like disease known as chlamydia Mycoplasmas – smallest known bacteria and do not have cell walls –Can cause one form of pneumonia and one type of sexually transmitted disease

24. Cyanobacteria Used to be known as blue-green algae, but are more closely related to bacteria They are prokaryotes and have light trapping pigments for photosynthesis Many are blue, but some are black, green or red (Red Sea) Inhabit freshwater and marine environments (ponds turn green, need algicide in pools)

25. Protozoa Single celled microscopic eukaryotes Some cause diseases such as malaria and sleeping sickness Come in many shapes and sizes and some are capable of photosynthesis Classified according to how they move (flagella, cilia, cytoplasmic extensions called pseudopodia)

26. Cilliate Amoeba

27. Fungi Primary decomposers of organic matter in the world Can cause human diseases such as athlete’s foot Used to be classified as plants but: –Don’t do photosynthesis – must obtain preformed food –Cells have different cell wall

28. Fungi Eukaryotic organisms – 2 groups: –Yeasts – unicellular, ~ size of large bacteria Play a vital role in fermentation of beer and wine and production of bread –Molds – long chains of cells seen as fuzzy masses

29. Yeast Mold

30. Unicellular Algae The term algae refers to any plant-like organisms that practice photosynthesis and differ structurally from land plants Two important algae for microbiology: –Diatoms –Dinoflagellates

31. Diatoms Eukaryotic marine organisms They are photosynthetic – make carbohydrates – passed on to other marine organisms when they are eaten Cell walls are impregnated with silicon dioxide (glasslike) When they die their remains accumulate on the sea floor as diatomaceous earth (used to produce filters)

32. Dinoflagellates Photosynthetic eukaryotes Important in the world’s food chains They can also produce periodic red tides in the oceans

33. Viruses Neither prokaryotes nor eukaryotes They are non-cellular, do not grow, do not show any nutritional pattern Only observable activity is replication, which can only be done inside a living cell They are just a fragment of DNA or RNA inside of a protein sheath Cause many human diseases – flu, polio, hepatitis, chickenpox