Chapter 3 Eukaryal Microbes The morphology of typical eukaryal cells What do eukaryal cells look like Defined by presence of a membrane bound nucleus Usually larger than bacterial archaeal cells Usually contain intracellular compartments organelles May possess a cell wall Complex internal cytoskeleton The morphology of typical eukaryal cells The nucleus Double membrane structure containing linear chromosome DNA Nucleolus non membrane bound exists within nucleus and is the site of ribosome synthesis Spatial separation means transcription occurs in the nucleus because DNA is transcribed into RNA and DNA is located in the nucleus translation occurs in cytoplasm because this is where the ribosomes are located The morphology of typical eukaryal cells The mitochondria and chloroplasts A role in cell metabolism Use electron transport chains to produce ATP chemiosmosis Chloroplasts use the ATP they produce to fix carbon into organic compounds often glucose The morphology of typical eukaryal cells The mitochondria and chloroplasts A role in cell metabolism Both organelles are semi autonomous Each has their own DNA ribosomes transcription machinery and can replicate independently of the rest of the cell The morphology of typical eukaryal cells The plasma membrane Phospholipid bilayer with embedded proteins that allow molecule transport facilitated diffusion active transport cell expends energy no energy required from cell The morphology of typical eukaryal cells The cell wall A role in cell support Eukaryal cells can broadly be separated into those with and those without cell walls Cell walls can vary widely between the domains The morphology of typical eukaryal cells The cytoskeleton complex internal structure includes microtubules and microfilaments contributes to cell shape by exerting outward pressure on the plasma membrane involved in intracellular trafficking and cell division The morphology of typical eukaryal cells Motion can be achieved by cilia or flagella VERY different in structure from bacterial fimbria and flagella Diversity of eukaryal microbes What are the different types of eukaryal microbes Phylogenetic trees based on rRNA gene sequences show types and relatedness of organisms Diversity of eukaryal microbes Eukaryal microbes Model organisms Four extensively studied eukaryal microbes fungi protozoa slime molds and algae heterotrophic must acquire energy from the environment and autotrophic means that they are photosynthetic and can acquire their energy from light Diversity of eukaryal microbes Eukaryal microbes Model organisms Fungi Saccharomyces cerevisiae Diversity of eukaryal microbes Eukaryal microbes Model organisms Protozoa Giardia lamblia Diversity of eukaryal microbes Eukaryal microbes Model organisms Slime molds Diversity of eukaryal microbes Eukaryal microbes Model organisms Algae Chlamydomonas Heterotrophic cell walls of chitin used to make bread beer wine Easy cheap tool to study eukaryotic structures gene expression As a whole protozoa is a BROAD category some heterotrophic some heterotrophic some photosynthetic variable cell walls different reproduction strategies different reproduction strategies Giardia is interesting because it is genetically old it lacks mitochondria and it causes human disease Model for studying ecology cell motility and cell cell communication Some types can fuse many cells into a continuous multinucleate giant cell Some algae are single celled but many are multicellular All are photosynthetic with cellulose cell walls Chlamydomonas has two flagella good for studying eukaryal flagella Chlamydomonas is also studied because of its ease of growth and durability They are photosynthetic It is generally thought that life started 4 5 to 4 bya but eukaryotes appeared around 2 1 to The origin of eukaryal cells How did eukaryal microbes originate 1 6 bya How why did eukaryotes evolve The origin of eukaryal cells Endosymbiotic theory How did organelles develop Basic idea is that one primitive microbe ingested another forming a symbiosis Interactions between eukaryal microbes and everything else What harmful and beneficial roles do eukaryal microbes play Diseases caused by eukaryal microbes can cause significant human diseases Protozoa Plasmodia causes malaria It infects red blood cells causing them to lysis which in turn causes fever Trypanosoma cause african sleeping sickness and is transmitted by insects Toxoplasma can cause toxoplasmosis Animals carry it and can transmitted to humans Typically it is not a big deal unless a pregnant woman is infected early on in pregnancy Fungi are less likely to cause disease but can do so in immunocompromised individuals Interactions between eukaryal microbes and everything else Diseases caused by eukaryal microbes ex athletes foot oral thrush Interactions between eukaryal microbes and everything else Diseases caused by eukaryal microbes famine mid 1800 s Interactions between eukaryal microbes and everything else Beneficial roles of eukaryal microbes Protozoa and fungi can cause significant disease in plants potato blight and the great Irish Many eukaryal microbes are primary producers providing energy especially in aquatic ecosystems or biodegraders recycling nutrients Some algae produce large amounts of oxygen through photosynthesis Some eukaryal microbes can degrade cellulose recycling plant matter better than animals can Termite gut conatins a protist that digests cellulose because they cannot do it on their own Conclusion Eukaryal microbes exhibit great diversity and are key to energy production and nutrient cycling on this planet Chapter 4 Archaea Distinctive properties of Archaea How do we know that Archaea is a distinct domain of life Archaeons look like bacteria Prokaryotes don t have membrane bound organelles However genetic analyses show them to be different They live in some of the most inhospitible extreme for humans on Earth Hypothermal vents are an example of where archaea can be found Distinctive properties of Archaea Phylogeny Comparisons of rRA gene sequences can establish phylogenetic trees If organisms are close together they are closely related and their DNA is realtively similar Woese The first organisms termed archaeons were the methanogens a group of microbes and Fox began these studies in the 1970s capable of producing methane Live in anaerobic environments and use carbon dioxide Distinctive properties of Archaea Phylogeny conditions Distinctive properties of Archaea Structure