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Transcript
Cell Structure Schleiden, Schwann and Virchow - 1800s The cell is the basic and smallest unit of life All cells arise from pre-existing cells The cell is the working unit of organisms All cells perform the following functions • • • • • Obtain and metabolize nutrients Grow and develop Respond to environment Adapt and genetically evolve Use DNA for information storage All cells are made of… Lipids: membranes, energy Carbohydrates: walls, energy Nucleic Acids: genetic information, protein synthesis Proteins: many things - enzymes, antibodies… Cell Types Prokaryotic Cells Simpler, smaller, and the most primitive Lack a nucleus and organelles Include Eubacteria and Archaea Eukaryotic Cells More complex, larger, and more modern Have a nucleus and organelles Include Fungi, Algae, Protozoa, Animals, Plants Prokaryotic cell Prokaryotic Cells In Detail Cell Membrane Same as eukaryotic BUT ALSO contain metabolic enzymes Prokaryotes resemble naked organelles External Structure of Prokaryotic Cells • • • • • Glycocalyces “sugar cup” Attach to surfaces Prevent phagocytosis Streptococcus pneumoniae & Klebsiella pneumoniae Flagella • Movement • Arrangements: • • • • Peritrichous Polar Amphitrichous Show taxis: Chemo/photo Fimbriae & Pili • Fimbriae: sticky, proteinaceous bristle like projections for adherance • Pili: protein pilin, for movement Cell walls • Peptidogylcan: polysaccharide of alternating sugars • Two types: • Gram + • Gram – Gram (+) = THICK, naked peptidoglycan Gram (-) = THIN peptidoglycan, outer membrane Cell Membrane Selectively permeable barrier Built of phospholipid bilayer and proteins Proteins act as receptors and pores Animal cells contain cholesterol in membranes Fungi have ergosterol Non-Gram Staining Bacteria Mycobacteria - wax coat, e.g. TB and leprosy Mycoplasma - no walls, e.g. walking pneumonia Cytoplasm Contain genetic material Site of replication, transcription, and translation • Ribosomes • Inclusions • Gas vesicles Endospores • Highly resistant • Vegetative cell sporulates • Bacillus • Clostridium Prokaryotic Chromosomes Circular DNA - half to one million base pairs One copy of each chromosome (haploid) Many Also Have Plasmids Sometimes called “mini-chromosomes” Small circles of DNA - 10,000 base pairs Carry emergency genes - e.g. drug resistance Can be passed around during bacterial mating In Lab, You Will Be Responsible For… Gram Staining Capsules Flagella Spores Pili/Fimbrae Fat/PHB Granules Eukaryotic Cells Eukaryotic Walls Vary… Location - just outside membrane Plants = cellulose (chain of glucose) Algae = cellulose or minerals (silica, calcium…) Insect and Fungi = chitin (chain of NAG) Animals and protozoa lack walls Eukaryotic Chromosomes Linear DNA = at least 1 million base pairs Two copies of each chromosome (diploid) Viruses and Non-Living Agents Not made of cells or classified as life Cannot carry out life functions without a host Contain a few genes that make few proteins