ProtistansOnce upon a timeSlide 3Slide 4Slide 5Slide 6Slide 7Slide 8Slide 9Slide 10Slide 11Slide 12Slide 13Slide 14Slide 15Slide 16Why be Eucaryotic??Slide 18Slide 19Slide 20Slide 21Slide 22Slide 23Why sex?Needed for Sex.Slide 26Slide 27Slide 28Slide 29Slide 30Figue 27.3 – Part 1Slide 32Slide 33Slide 34Slide 35Slide 36Slide 37Slide 38Figure 27.3 – Part 2Slide 40Slide 41Slide 42Slide 43Slide 44Slide 45Slide 46Slide 47Protozoans and diseaseSlide 49Slide 50Summary – eucaryotic advances over bacteriaProtistansOnce upon a time•Protozoa = animal one celled organisms and algae = primitive plants•Then; all one celled eucaryotic organisms are protists•Now the group is all eucaryotic cells that are not plants, animals or fungiCurrent view, based on biochemistry; three domains Eukarya include protists, fungi, animals and plantsProtista have a single origin = eucaryotic cell complex enough that probably arose only once.Giardia; Giardiasis (GEE-are-DYE-uh-sis) is a diarrheal illness caused by a microscopic parasite, Giardia intestinalis (also known as Giardia lamblia or Giardia duodenalis). Once a person or animal has been infected with Giardia, the parasite lives in the intestine and is passed in feces. Because the parasite is protected by an outer shell, it can survive outside the body and in the environment for long periods of time (i.e., months).During the past 2 decades, Giardia infection has become recognized as a common cause of waterborne disease in humans in the United States. Giardia can be found worldwide and within every region of the United States. 2 million cases a year in U.S.Giardia has a nucleus but no mitochondria. Once thought to be the most primitive protozoan. However, its nucelar DNA has mitochondrial genes = lost mitochondria .Major new features: Eucaryotic =nucleus, organelles (mitochondria, chloroplast in some, other things like endoplasmic reticulum.Cytoskeleton, methods of taking in, dumping stuffAnd no cell wallAlso; cells much larger than bacterial cells.Also; totally new method of reproduction.Lots of variety;‘animal like’Plant likeFungi like Locomotion, ciliated, flagella, amoeboidHard vs soft covering; diatoms, Single cell to multicellular = all algae belong here!! (multicellular but without much division of function = almost all cells identical in abilities(sex cells the exception) algae include, red, green, yellow green, brown – based on differences in photosynthetic pigmentFigure 27.9 An AmoebaFigure 27.5 Foraminiferan Shells Are Building BlocksInvasive algae caulerpa = all one cell!Figure 27.32 A Cellular Slime MoldWhy be Eucaryotic?? Perhaps – 1. increasing abilities (metabolism, biochemical pathways, etc. required increasing amount of DNA –2. Increasing DNA required ‘chromosomes’ = DNA organization3. Nucleus required to hold DNA4. Increase in cell size required to hold nucleus, etc.5. Internal cell organization needed as simple diffusion too slow over bigger distances.Bacterial reproductionSingle circular strand of DNA makes copies. Copies separate. Cells separate.Sex is bacteria – haploid (one set of information) ring dna – one dna strand onlyBacteria – a naked circular strand of DNAEucaryotes; have DNA organized into ChromosomesMitosis –Involves DNA division, chromosome formation and the development of a ‘spindle’ spindle fibers, etc, to ‘pull’ chromosomes apart to different ends of a cell; then cell divisionTraditional cell division in euycaryotesDna in strands and two sets of information. Each makes a copyLine up in cellArms move to opposite ends of cellCell division occurs Result = two cells identical to parent cell.More information, requires more dna organization.Mitosis could work with one set of genetic information (divided into pieces)Advantage in dividing (when spaghetti strand gets too long – hard to keep track of.So chromosomes and mitosis do not require sex to existWhy sex?•“creates more variation” Is this valid or necessary?• allows more individuals to survive a disease (mutant survival vs recessives•Allows, through crossover, combination of bad genes and elimination. (bad genes often do bad things, not just inoperative)•Bigger cells, smaller population, mutation not enoughNeeded for Sex.•Probably nucleus – keep genetic material together•Diploidy•Meiosis = maintain level of genetic info.Basic sexual division - meiosis0. chromosomes make copies of selves – stay connected1. Chromosomes line up in pairs = diploid organism with two sets of information2. Division 1 = pairs split3. Pairs line up and split –4 result – 4 gametes (eggs or sperm) each haploid – have all information but only one set.5. Gametes meet, get back to diploid fertilized egg.You now have “sex” = 2 gametes come togetherNote: proctista experimented. Some have more than two sexes.Paramecium reproductionUnder certain conditions, such as overcrowding or environmental stress, Paramecium turns from strictly asexual reproduction to sexual reproduction. Sexual reproduction involves the exchange of genetic material between two individuals of different 'mating strains'. Through a process called conjugation, two paramecia line up side by side and then fuse together. All but one of the cell's micronuclei disintegrate. This micronucleus then divides* into four – one of which will be exchanged during conjugation. (* This process involves meiosis, where the diploid micronucleus divides twice to yield four haploid micronuclei. Three of these disintegrate, while one divides again to produce two swapping haploid micronuclei.)There are several “odd” ways of doing sex in protists.Origins???No neat intermediate forms. You are either a procaryote or a eucaryoteSexual, asexual, nucleus and chromosomes, or not.Things to do in transition: first steps• get rid of outer cell wall, retain cell membrane• grow in size• divide dna into chromosomes – develop apparatus for division = mitosis• develop a nuclear membrane – get endoplasmic reticulum in the processThings to do in transition – next steps• develop sex• add organelles – mitochondria and chloroplasts and ?flagella?Final Steps:Begin multicellularity = division of function between cells = intercellular communication.Figue 27.3 – Part 1Figure 27.3 – Part 1 figure 27-03a.jpgOrigin of nucleusInfolding of outer membrane.Loss of procaryote cell wall = allows intake of things by various meansMore shielding from uv light, by ozone layer =