2-9 - Eukaryotic Microbial Cells.pdf

2-9: Eukaryotic Microbial Cells Lecture Overview: • Brief overview of the internal structure of eukaryotic cells. Prominent varieties of eukaryotic microbes • Textbook: Chapter 1 (I), Chapter 2, Chapter 18. Cell structure overview: prokaryotic cells & eukaryotic cells o Eukaryotic cells contain se...

2-9: Eukaryotic Microbial Cells Lecture Overview: • Brief overview of the internal structure of eukaryotic cells. Prominent varieties of eukaryotic microbes • Textbook: Chapter 1 (I), Chapter 2, Chapter 18. Cell structure overview: prokaryotic cells & eukaryotic cells o Eukaryotic cells contain several conserved membrane-bound compartments. Prokaryotic cells do not. o These internal structures are key to complexity and organization. DNA-RNA relates to DNA processes o Discrete functions in dedicated compartments Textbook, Fig. 1.4 Eukaryotic compartments: Nucleus Defining characteristic of eukaryotic cells Separates genetic material (DNA) from the rest of the cell Transcription/translation uncoupled – ribosomes outside of the nucleus Proteins related to DNA replication, transcription, etc. must be translocated into nucleus Textbook, Fig. 2.42 Eukaryotic compartments: Mitochondria Almost universal amongst eukaryotes (a few protists lack mitochondria) Vary in number, shape between different eukaryotes/cell types/tissues Energy center of the cell – site of respiration, ATP production Contain own genomes, ribosomes Evolved from an Alphaproteobacterium Textbook, Fig. 2.42 Eukaryotic compartments: Golgi Complex & Endoplasmic Reticulum UPS + Can Post of Cell Involved in modifying & sorting proteins (and other molecules, such as lipids) to be secreted from cell or translocated to other parts of the cell. One important modification is glycosylation – many eukaryotic proteins have glycans (sugars) added Proteins & other molecules packaged into vesicles and trafficked around the cell (and secreted from the cell) Wikipedia Some other eukaryotic compartments/components Cytoskeleton: Dynamic protein filament network involved in cell shape, transport within cell, cell movement and more Vacuoles: Membrane bound compartment, often for storing nutrients and/or waste. Lysosomes are specialized vacuoles found in many animal cells that contain enzymes to break down incoming nutrients Chloroplasts: Found in phototrophs (like plants and algea) – contain the machinery for photosynthesis Vesicles: Small, membrane bound compartments used extensively to traffic materials around the cell, into/out of cells and between organelles Cell Wall: Some eukaryotes have one (plants, fungi), others don’t (animals). Much diversity in structure. Cell structure of a eukaryotic microbe Saccharomyces cerevisiae Model yeast organism (we’ll come back to this in a few slides) Relatively small/simple eukaryote, but still contains considerable internal compartmentalization Compared to E. coli (model bacterium): - Cells ~20x larger than E. coli. - E. coli lacks this internal compartmentalization Walker and Stewart, Beverages, 2016 Microbial eukaryotes: much diversity o All eukaryotes are descendants of the last eukaryotic common ancestor (LECA) and share some common aspects of their cell biology (cytoskeleton, nucleus, mitochondria, etc.) o Many different lineages branched off long ago, and there is remarkable diversity. Differences even show up in cell biology (e.g. plants contain cell walls and chloroplasts & animals don’t) o Microbial eukaryotes present in all 5 “supergroups” of Eukarya o Despite this ecological/morphological diversity, eukaryotes have limited metabolic diversity compared to prokaryotes – most are obligate aerobes and use either photosynthesis or organic compounds for energy Microbial eukaryotes: much diversity 5 “supergroups” (clusters of related phyla) Note transfer of chloroplast “secondary endosymbiosis” Textbook, Fig 18.3 Algae o Definition is highly variable. Photosynthetic organisms that are not plants. Some definitions include bacteria as well (cyanobacteria, AKA “blue-green algae”) o Includes microbes (microalgae) and non-microbes (macroalgae – e.g. seaweed). Typically aquatic. o Tens or hundreds of thousands of species (or more) of algae on the planet – many are single-celled eukaryotes. o Many uses/applications (pigments, foods, fertilizers, more) o A lot of interest in using algae for biofuels One acre algae growth pond https://www.orlandosentinel.com/ Fungi o A kingdom of life that includes both microbes (e.g. yeast) and nonmicrobes (e.g mushrooms) o Microbial group most-closely related to animals. o Mostly non-motile. Chitin (polysaccharide) cell walls a defining feature o Some (rare) Fungi are pathogens of plants or animals (incl. humans) Candida albicans is an opportunistic fungal pathogen. § Commonly found in healthy individuals § Most common cause of “yeast infections” in women § Can cause serious infections in the immunocompromised Meurman et al, Topics & Trends in Applied Microbiology, 2007 Yeast: model organisms & industrial applications o Yeast are single-celled fungi -- Saccharomyces cerevisiae is an important model yeast (like E. coli is for bacteria) o Some aspects of biology are conserved between yeast and animals o Yeast have been used as a model system for many aspects of eukaryotic genetics and cell biology o Yeast also convert carbohydrates to CO2 + alcohol via fermentation o Very heavily used in baking & to make alcoholic beverages, etc Amoeba o Single-celled eukaryotic organisms that use pseudopods for locomotion o Change shape as pseudopods form – these are temporary projections that stick out from cell - use these as “arms” to crawl across surfaces o Inhabit many environments including fresh water and soil pseudopods o Amoebozoa is a diverse phylum of eukaryotes. o Eukaryotes from different lineages can have the characteristics of an “amoeba” www.Wikipedia.com Some “p” words that can relate to eukaryotic microbes… Protist/protozoa: o Historical term used to describe a eukaryotic microbe that isn’t a plant, animal or fungus. o Used in a generic sense and doesn’t refer to a specific taxonomical group o Traditionally one of the kingdoms of life…that view is a bit outdated Plankton o “Drifters”. Diverse organisms (not just microbes, not just eukaryotes) that can’t propel themselves - drift in water or in the air Parasite: o Specific type of symbiotic relationship (we’ll come back to this) o Also a generic term for some types of eukaryotic microbes pathogens