Cell Structure and Taxonomy - Biology PDF

MODULE 3: CELL STRUCTURE AND TAXONOMY  UNIT EXPECTED OUTCOMES Explain the “cell theory” Explain the taxonomical classifications of microorganisms State the contributions of different scientists to the study of the cells Describe and differentiate the prokaryotic and eukaryotic...

MODULE 3: CELL STRUCTURE AND TAXONOMY  UNIT EXPECTED OUTCOMES Explain the “cell theory” Explain the taxonomical classifications of microorganisms State the contributions of different scientists to the study of the cells Describe and differentiate the prokaryotic and eukaryotic cell structures  English physicist who wrote Micrographia to describe observations with the microscope First to use the word “cell” in identifying microscopic structure He was describing box-like cells of cork which resembled monastery cells ROBERT HOOKE  CELL THEORY One of the basic principles of biology that states: All living organisms are composed of cells The cell is the basic unit of life Cells arise from pre-existing cells  CELL THEORY SCIENTISTS WHO CONTRIBUTED: Theodore Schwann: “All animals are made of cells.” Developed the cell doctrine that all living things are composed of cells Established that cell as the basic unit of all living things  CELL THEORY SCIENTISTS WHO CONTRIBUTED: Matthias Schleiden Studied cells as the common element among all plants and animals  CELL THEORY SCIENTISTS WHO CONTRIBUTED: Rudolph Virchow Father of Pathology Introduced the third dictum that all cells come from cells: “Omnis cellula e cellula” Cell Theory of Biogenesis  CELL THEORY VIRCHOW’S CELLULAR PATHOLOGY The cell, the smallest living unit of the normal human body, is the basis of all of disease Cells encounter many stresses as a result of changes in their environment  CELL THEORY ABIOGENESIS vs. BIOGENESIS SPONTANEOUS GENERATION (ABIOGENESIS) Living organisms arise from non-living matter A vital force forms life BIOGENESIS Living organisms arise from pre-existing life  CELL Fundamental living unit of any living organism Exhibits the basic characteristics of life: Metabolism: chemical reactions occurring within a cell Growth Reproduction Responds to stimuli in its environment Mutation MAJOR CATEGORIES OF MICROBES ACELLULAR (INFECTIOUS PARTICLES) CELLULAR (MICROORGANISMS)  TAXONOMY Science of classification of living organisms Functions Nomenclature Classification Taxa: kingdom or domains, divisions or phyla, classes, orders, families, genera, species Identification  TAXONOMY CAROLUS LINNAEUS Father of Taxonomy Devised the binomial nomenclature Genus: first name Specific Epithet: second name Species: 1st and 2nd name Example: Escherichia coli or Escherichia coli Devised the hierarchical classification system Published Systema Naturae  TAXONOMY EARNST HAECKEL Proposed the 3 kingdom classification of organisms  TAXONOMY EARNST HAECKEL Proposed the 3 kingdom classification of organisms  TAXONOMY HERBERT COPELAND Four kingdom classification of organisms Added the kingdom Monera  TAXONOMY ROBERT WHITTAKER Proposed the five kingdom classification which is the most common system used today Classification is based on structural similarities and differences and the way organisms obtain nutrition  TAXONOMY CARL WOESE Classified organisms into three domains and six kingdoms Domains: Archaea, Bacteria, Eukarya  TAXONOMY CARL WOESE Classified organisms into three domains and six kingdoms Kingdoms: Archaebacteria, Eubacteria, Protista, Fungi, Plantae, Animalia  ORIGIN OF CELLS Cells are divided into 2 main classes based on whether or not they contain a nucleus Prokaryotic cells Bacteria, Archaea Eukaryotic cells Algae, Protozoa, Fungi, Plants, Animals, Humans  CHARLES DARWIN ORIGIN OF CELLS Evolution: changes in populations over time First to propose a feasible mechanism for evolution called Natural Selection Proposed the theory of universal descent through an evolutionary process in his book “On The Origin of Species” All species descended from a common ancestor  ORIGIN OF CELLS LAST UNIVERSAL COMMON ANCESTOR Most recent population of organisms from which all organisms now living on earth have a common descent Existed 3.5 to 3.9 billion years ago  ORIGIN OF CELLS Life first emerged at least 3.8 billion years ago, 750 million years after Earth was formed The very first cells to appear on Earth were a type of Archaea The first eukaryotic cells appeared on Earth 1.6 to 2.7 billion years ago Eukaryotic cells evolved from prokaryotic organisms by a process of intracellular symbiosis First primitive eukaryotic cells: single-celled and independent Complex multicellular organisms: through evolution  ORIGIN OF CELLS ENDOSYMBIOSIS Suggests that eukaryotic cells arose when a much larger prokaryotic cell engulfed smaller bacterial cells that began to live and reproduce inside the prokaryotic cell  Result of regressive or reverse VIRUSES evolution Composed of only a few genes protected by a protein coat Depend on the metabolic machinery of a host cell to reproduce Acellular  EU: true EUKARYOTES KARYO: nut or nucleus Eukaryotes are microorganisms with a true nucleus enclosed by a nuclear membrane EUKARYOTIC CELLS Large complex cells divided into separate compartments by membrane-bound organelles Each organelle serves an essential function Fungi, protozoa, algae, plants, animals 10-30um in diameter  EUKARYOTES CELL MEMBRANE Plasma, cytoplasmic, or cellular membrane Skin around the cell Composed of a phospholipid bilayer with embedded proteins that separates the internal contents from the surrounding environment of the cell Selectively permeable  EUKARYOTES NUCLEUS Command center of the cell Enclosed by membranes Contains the cell’s DNA and directs the synthesis of proteins and ribosomes  EUKARYOTES NUCLEUS Nucleoplasm: gelatinous matrix Chromosomes DNA: linear, beads on a string Histones Nuclear membrane Nucleolus Site of rRNA synthesis  GENES EUKARYOTES Located along DNA molecules Each gene contains the genetic information that enables the cell to produce gene products Proteins, rRNA, tRNA Genotype Organism’s complete collection of genes  EUKARYOTES CYTOPLASM Semifluid, gelatinous, nutrient matrix Majority of the volume of the cell Contains cytosol, organelles, and granules or particles called cytoplasmic inclusions Site of metabolic reactions CYTOSOL: semifluid portion  EUKARYOTES ENDOPLASMIC RETICULUM Responsible for the synthesis, folding, modification, and transport of proteins  EUKARYOTES RIBOSOMES Protein factories Consist mainly of rRNA and proteins Polyribosomes Two sub-units Large: 60s Small: 40s 40s + 60s = 80s Produced in the nucleolus Transported to the cytoplasm and produce proteins when joined with mRNA  EUKARYOTES GOLGI COMPLEX Packaging plants Completes transformation of newly synthesized proteins into mature, functional ones Packages proteins into small membrane-enclosed vesicles to be transported within or outside the cell  EUKARYOTES LYSOSOMES Garbage disposal or digestive system of the cell Digest macromolecules, old cell parts, and microorganisms Contain acid hydrolases that break down macromolecules  EUKARYOTES PEROXISOMES Carry out oxidation reaction to produce hydrogen peroxide Catalyze conversion of hydrogen peroxide to oxygen and water Contain oxidases and catalases Synthesized in the free ribosomes Numerous in hepatocytes  MITOCHONDRIA EUKARYOTES Generates chemical energy for biochemical reactions Abundant in cells with high energy requirement (stomach parietal cells, kidney tubule cells, adrenal cortex, and hepatocytes) Other functions: Accumulation of calcium Synthesis of sodium and proteins Oxidation of fatty acids HTTP://MICRO.MAGNET.FSU.EDU/CELLS/MITOCHONDRIA/IMAGES/MITOCHONDRIAFIGURE1.JPG  EUKARYOTES CYTOSKELETON Made up of filamentous proteins to strengthen, support, stiffen, and give shape to the cell  PLASTIDS EUKARYOTES Membrane-bound structures containing photosynthetic pigments CHLOROPLASTS Contain chlorophyll Found in plant cells and algae PHOTOSYNTHESIS Use of light energy to convert carbon dioxide and water into carbohydrates and oxygen Conversion of light energy into chemical energy  EUKARYOTES CELL WALL External structure that provides rigidity, shape, and protection to the cell Cellulose Algae and plants Chitin Fungi and exoskeleton of beetles & crabs Lignin Pectin Mineral salts EUKARYOTES CELL WALL Present in: Plants Algae Fungi Bacteria Absent in: Animals Protozoa Mycoplasma sp.  EUKARYOTES ORGANELLES OF LOCOMOTION: FLAGELLA Enable cells to swim through liquid environment Present in spermatozoa, protozoa, algae Whipping motion  EUKARYOTES ORGANELLES OF LOCOMOTION: CILIA Beat with a coordinated rhythmic movement Thinner, shorter, and more numerous Present in protozoa and human body  PROKARYOTES CELL MEMBRANE Similar to eukaryotic cell membrane which consists of phospholipids and proteins Contains enzymes to catalyze metabolic reactions Selectively permeable  PROKARYOTES CELL MEMBRANE MESOSOMES Invaginated structures formed by the localized infoldings of the plasma membrane Site of cellular respiration CHLOROPHYLL AND OTHER PIGMENTS Found within the infoldings of the cell membrane in cyanobacteria  PROKARYOTES CHROMOSOMES Consist of a single long, supercoiled, circular DNA molecule Control center of the cell Suspended in the cytoplasm BACTERIAL NUCLEOID DNA-occupied space within a bacterial cell PLASMIDS Extrachromosomal DNA  PROKARYOTES CYTOPLASM Semiliquid Contains enzymes, oxygen, waste products, nutrients, proteins, carbohydrates, lipids Cytoplasmic granules Starch, lipids, sulfur, iron PROKARYOTES CYTOPLASM Cytoplasmic particles Ribosomes Site of protein synthesis 30S + 50S = 70S  PROKARYOTES BACTERIAL CELL WALL Peptidoglycan (Murein) Most important structure Polysaccharide chains linked together by small peptide chains Its thickness and exact composition varies with the species of bacteria Basis for classifying bacteria as Gram Positive or Gram Negative  GLYCOCALYX PROKARYOTES Slimy, gelatinous material produced by the cell membrane and secreted outside the cell wall SLIMY LAYER Not highly organized Not firmly attached to the cell wall Easily detaches from the cell wall and drifts away Pseudomonas aeruginosa Produce R COLONIES when cultured HTTPS://WWW.QUORA.COM/WHAT-IS-THE-POSITION-OF-SLIME-LAYER-AND-CAPSULE-IN-RESPECT-TO-A-BACTERIAL-CELL  GLYCOCALYX PROKARYOTES CAPSULE Highly organized Firmly attached Anti-phagocytic Produce S COLONIES H. influenzae, Neisseria meningitides, Streptococcus pneumoniae HTTPS://WWW.QUORA.COM/WHAT-IS-THE-POSITION-OF-SLIME-LAYER-AND-CAPSULE-IN-RESPECT-TO-A-BACTERIAL-CELL PROKARYOTES GLYCOCALYX CAPSULE INDIA INK: negative staining PROKARYOTES FLAGELLA Thread-like protein appendages for movement Flagellin: protein threads Do not contain microtubules Not membrane-bound  PROKARYOTES AXIAL FILAMENTS Flagella-like fibrils of spirochetes Allow spirochetes to move in a spiral or helical manner  PROKARYOTES PILI / FIMBRIAE Hair-like structures arising from the cytoplasm of Gram negative bacteria Pilin: protein components which are arranged helically to form a cylinder TYPES For attachment to surfaces Causes urethritis Sex Pilus For transference of genetic material  PROKARYOTES ENDOSPORES Dormant stage of some bacteria that allow them to survive extreme conditions that could kill them (e.g. drought or extreme heat) Commonly found in soil and water Resistance to UV and gamma radiation, desiccation, lysozyme, temperature, starvation, and chemical disinfectants SPORULATION Process of spore formation REFERENCES A brief history of the kingdoms of life. (2019, February 14). Earthling Nature. https://earthlingnature.wordpress.com/2011/12/05/a-brief-history-of-the-kingdoms-of-life/ BD Editors. (2017, April 27). Cytosol. Biology Dictionary. https://biologydictionary.net/cytosol/ Carroll, K. C., Butel, J. S., & Morse, S. A. (2019). Jawetz Melnick & Adelbergs medical microbiology 28 E. McGraw Hill Professional. Engelkirk, P. G. (2018). Burton's microbiology for the health sciences 11th ed.(ch 1). Philadelphia: Lippincott Williams & Wilkins. Parker, N., OpenStax, Schneegurt, M., Tu, A. T., Forster, B. M., & Lister, P. (2016). Microbiology. Robert Hooke. (2019, 28). Biography. https://www.biography.com/scholar/robert-hooke VanPutte, C. (2016). Seeley’s essentials of anatomy and physiology ( 11th ed.). NewYork:McGraw-Hill Higher Education THANK YOU!