2 How do bacterial cell walls differ from plant cell walls? Plants – made of cellulose (polysaccharide)Bacteria – made of peptidoglycanArchaea – lack peptidoglycan, made of a variety of polysaccharides and proteins
3 Gram Staining-+More complex, less peptidoglycan, outer layer of lipopolysaccharidesSimpler cell wall, large amounts of peptidoglycan
4 Capsule – sticky layer of polysaccharide or protein covering the cell wall of many prokaryotes enables them to adhere to substrate or other cells (colony)prevent dehydrationprotects from host’s immune systemFimbriae – hair-like protein appendages (aka “attachment pili”)Sex pili – appendages that pull two cells together prior to DNA transfer from one cell to the other.
5 Bacteria LocomotionFlagellaSlimmer than Eukaryotic flagellaNot covered by plasma membrane as Eukaryotic flagella a Different molecular composition and Eukaryotic flagellaMechanism of propulsion is different than Eukaryotic
6 Taxis – movement towards or away from a stimulus Positive taxis – towards stimulusNegative taxis – away from stimulusExamples:ChemotaxisPhototaxis
7 Transformation – pGLO lab – genotype and Transformation – pGLO lab – genotype and possibly phenotype is changed by the uptake of foreign DNA from its surroundings.pGLOGriffins experimentTransduction – Bacteriophages (viruses) carry bacterial genes from one host cell to another (accidents during viral replication)
8 Conjugation – DNA transfer from. one bacterial cell to another Conjugation – DNA transfer from one bacterial cell to another (same or different species)Binary Fission – asexual reproduction of bacteria
9 What is the difference between and F plasmid and an R plasmid? F plasmid – contains genes that enable cell to form a “mating bridge” with a cell that does not have the plasmid.R plasmid – contains genes that make it resistant to antibioticsWhat is the difference between F+ cells and F- cells?F+ cells contain the F plasmid and therefore are donors during conjugationF- cells do not contain the F plasmid and therefore are recipients during conjugation
10 Transformation Transduction Conjugation Questions from 27.2 pg. 564What features of prokaryotes make it likely that considerable genetic variation will be added to their populations in each generation?Large population size (more likely that more individuals will have new mutations at any particular gene…adding diversity)Short generation time.Distinguish between the three mechanisms of transferring DNA from one bacterial cell to another.Transformation Transduction ConjugationIf a nonpathogenic bacterium were to acquire resistance to antibiotics, could this strain pose a health risk to people? Explain.Yes. Genes for antibiotic resistance could be transferred from the nonpathogenic bacterium to a pathogenic bacterium, which could then harm the population. (MRSA). The processes listed in #2 increase the spread of resistance genes.
11 Photoautotroph vs. Chemoautotroph Energy source is light Energy source is inorganic compounds (H2S or NH3)Photoheterotroph vs. ChemoheterotrophsEnergy source is light Energy source is organic but obtain carbon in organic form compounds and obtain carbon in organic form (animals, fungi, and most protists)
12 The role of Oxygen in metabolism 1. Obligate Aerobes – use O2 for CR, can’t live wo/it2. Obligate Anaerobes – poisoned by O2, some live by fermentation while others go through anaerobic respiration using nitrate ions or sulfate ions3. Facultative Anaerobes – use O2 if it is present but can also carry out anaerobic respiration or fermentation if neededNitrogen fixation – converting atmospheric nitrogen to ammonia (NH3) Benefit: can then use ammonia to make amino acids and nucleotides
13 Filamentous colonies – cooperation between the same species majority of cells in the colony carry out photosynthesisthere are a few cells (“heterocytes”) that carry out nitrogen fixation (have a thicker cell wall to keep O2 out)cells can’t do both because the O2 inactivates the enzymes involved in nitrogen fixation.products from both reactions get transported via intercellular connections between the cellsBiofilms – cooperation between different speciescells in colony secrete signaling molecules that recruit nearby cell.cells also produce proteins that stick the cells together and to a substrate.channels wi/biofilm allow nutrients and waste to be transportedCauses of tooth decay, damage to industrial and medical equipment, contamination of products
14 Ecological Significance of Prokaryotes: Recycling:Symbiosis:Pathogens:Bioremediation:Genetic EngineeringIdentify 2 ways Prokaryotes have affected you positively today…