Eukaryotic Structures 2025 PDF

Eukaryotic Structures General Microbiology, Spring 2025 Part 1: Eukaryotic cellular envelope and outer structures List the major components of the cell wall in various eukaryotes (Cellulose, pectin, chitin) List the major components of the plasma membrane and describe functions Sphingol...

Eukaryotic Structures General Microbiology, Spring 2025 Part 1: Eukaryotic cellular envelope and outer structures List the major components of the cell wall in various eukaryotes (Cellulose, pectin, chitin) List the major components of the plasma membrane and describe functions Sphingolipids and sterols Lipid rafts Compare and contrast the plasma membrane of eukaryotes and bacteria Compare and contrast the cell wall of eukaryotes and bacteria Describe the composition of the glycocalyx and its functions List the two external structures used for movement Explain how flagella in eukaryotes differ from flagella in bacteria The microbial eukaryote display large amounts of morphological diversity Larger than bacteria Vary in size Eukaryotic cells have organelles that perform specific functions Compartmentalization independent control coordination of cellular processes. Large membrane surfaces greater respiratory and photosynthetic activity.  Some eukaryotes have a cell wall Algae Protists Most (Cysts) fungi cellulose and Multiple layers Rigid pectin. of chitin structure inorganic Composition substances – varies: silica or calcium cellulose, carbonate. chitin, or glucan. Eukaryotic plasma membrane is a bilayer containing, phospholipids, sphingolipids and sterols Sphingolipid Sterols Pack closely together Affect fluidity and permeability The lipid bilayer is asymmetric and contains lipid rafts Lipid composition differs Composition is the same Microdomains of different lipids Cellular processes: Signal transduction Assembly and release of virus particles Endocytosis Integral membrane proteins, lipids, and carbohydrates form a glycocalyx Functions Strengthens the cell surface Helps with cell adhesion May contribute to cell-to-cell recognition. External Structures include cilia and flagella Cilia Short hair-like structures composed of microtubules Beating motion with two distinct phases: Effective stroke – pulls through fluid Recovery stroke Flagella Long whiplike structures composed of microtubules Flagella undulate ATP powers the movement of both cilia Which of the following statements is false? A. At higher temperatures, sphingolipids and cholesterol levels in eukaryotic membranes most likely increase. B. Eukaryotes use ATP to drive flagellar and cilia movement while bacteria and archaea use a proton motive force C. Bacteria contain peptidoglycan in their cell walls while eukaryotes do not. D. Some types of bacteria and eukaryotes lack cell walls. Part 2: Internal organization of the eukaryotic cell List and differentiate the major components of the cytoskeleton (actin, intermediate filaments, microtubule) List and describe the functions of major organelles Determine the destination of proteins based on the location of ribosomal translation Compare and contrast bacterial/archaeal ribosomes and eukaryotic ribosomes Cytoskeleton is a network of interconnected filaments 1. Actin filaments 2. Microtubules 3. Intermediate filaments Cytoskeleton is a network of interconnected filaments Actin Filaments are: Dynamic Composed of an actin protein Functions: Change cell shape Amoeboid movement Endocytosis Cytoskeleton is a network of interconnected filaments Intermediate filaments Assembled from multiple proteins Example is Keratin Fungi and plants lack IFs. Cell junctions Cytoskeleton is a network of interconnected filaments Microtubules Dynamic α-tubulin and β- tubulin Functions: spindle apparatus Form tracks which organelles and vesicles move along. Organelles: Rough Endoplasmic Reticulum synthesizes large quantities of proteins Rough Endoplasmic Reticulum (RER) Membrane is continuous with nuclear membrane Studded with ribosomes Organelles: Smooth Endoplasmic Reticulum synthesizes large quantities of lipids Smooth Endoplasmic Reticulum (SER) Lacks ribosomes Organelles: Golgi Apparatus packages and prepares materials for secretion Golgi Apparatus Composed of a flattened, sac-like cisternae The cisternae have two faces: Cis: closest to ER Trans: farthest from the ER. Other Functions: Participates in development of the cell Organelles: Storage Vacuoles involved in intracellular digestion and storage of materials Storage Vacuoles (similar to lysosomes in animal cells) Found in fungal and protist cells Also called phagocytic vacuoles Functions Intracellular digestion Storage of calcium ions, Nucleus stores DNA and site of RNA synthesis Nucleus Exclusively found in eukaryotes Double membrane vesicle Eukaryotic chromosomes are composed of chromatin – a complex of DNA and proteins. Eukaryotic Ribosomes are larger than bacterial and archaeal ribosomes Ribosomes 60S and 40S subunits Free ribosomes produce non-secreted and non- membrane proteins ER bound ribosomes produce secreted and membrane proteins Botryococcus braunii, is an algae that excretes high levels of hydrocarbons that is similar to crude oil. What type of organelle would you expect to be found in high levels in the cells of this organism? A.Phagocytic vacuole B.Smooth endoplasmic reticulum C.Rough endoplasmic reticulum D.Nucleus Part 3: DNA containing organelles List organelles that contain DNA Describe the general structure of mitochondria and its main function Describe the general structure of chloroplast and its main function Describe the endosymbiotic theory. List evidence that supports the endosymbiotic theory Mitochondria contains DNA and is the site for ATP synthesis Mitochondria The number of mitochondria vary based on the organism. Mitochondria contains DNA and is the site for ATP synthesis Mitochondria The number of mitochondria vary based on the organism. Similar to gram-negative bacteria, mitochondria have two lipid membranes Cristae: folds of the inner membrane Plastids synthesize and store food reserves Found in Chloroplasts photosynthetic protists and plants Chromoplasts Chloroplasts contain chlorophyll and is the site of photosynthesis Chloroplasts Use light energy to convert CO2 and water to carbohydrates and O2. Chloroplasts contain chlorophyll and is the site of photosynthesis Chloroplasts Use light energy to convert CO2 and water to carbohydrates and O2. Like mitochondria, chloroplasts are encompassed by two membranes. Chloroplasts contain chlorophyll and is the site of photosynthesis Chloroplasts Use light energy to convert CO2 and water to carbohydrates and O2. Like mitochondria, chloroplasts are encompassed by two membranes. Stroma contains DNA, ribosomes, lipid droplets, and starch granules. Chloroplasts contain chlorophyll and is the site of photosynthesis Chloroplasts Use light energy to convert CO2 and water to carbohydrates and O2. Like mitochondria, chloroplasts are encompassed by two membranes. Stroma contains DNA, ribosomes, lipid droplets, and starch granules. Thylakoids contain chlorophyll Endosymbiotic Theory: Mitochondrion and chloroplast were once bacteria  Endosymbiotic Theory: Mitochondrion and chloroplast were once bacteria Evidence of the Endosymbiotic Theory Cyanobacteria 1. Mitochondria and chloroplasts contain DNA and ribosomes. Chloroplast 2. DNA and ribosomes are Photosynthe tic eukaryote similar to DNA and Proto- ribosomes in bacteria. eukaryot e Protomitochondrio n 3. Between the two membranes Mitochondri a that encloses chloroplasts, Heterotrophi c eukaryote peptidoglycan has been found in some algae. 4. Mitochondria are closely related to bacteria called  Recent endosymbiotic discovery: Nitroplast First discovered in 1998 as a bacterium, UCYN-A Reported in March 2024 as an organelle in algae Nitrogen fixation: converts nitrogen into usable forms Tyler H. Coale et al. Nitrogen-fixing organelle in a marine alga.Science384,217.222(2024).DOI:10.1126/science.adk1075