Presentation on theme: "Prokaryotic and Eukaryotic Cell Structure"— Presentation transcript:
1Prokaryotic and Eukaryotic Cell Structure And a Little Taxonomy too!
2Taxonomy The science of classification of living organisms. So we can identify and understand relationships between organisms.
3Linnaean System First developed by Carolus Linnaeus (1707-1778). Method of classifying things in a hierarchical structure from most general to most similar.Binomial System (2 names)DomainKingdom (most general)Phylum or DivisionClassOrderFamilyGenusSpeciesEx. Eschericia colior E. coli
4ClassificationDomains constitute a level of classification above the kingdom.Domains are further subdivided into kingdoms etc.
65 KingdomsBased on similar morphology, geographic distribution, and if multicellular, the ability to interbreed.Bacteria
7Bergey System Another system for classifying Prokaryotes. Still use kingdom, division or phylum, class, order, family, genus, species.Classification based on similar morphological and biochemical characteristics.
8Eukaryotic and Prokaryotic Cells How are they different andhow are they the same?
9What Is a Cell? It is the fundamental unit of all living matter. Has all characteristics of life.Can live independently of other cells.
10All Cells Have the Following: EnzymesA protein that speeds up a chemical reaction.DNA – deoxyribonucleic acidA large molecule that stores genetic information.RNA – ribonucleic acidA large molecule involved in protein synthesis.ATP – adenosine triphosphateThe main energy currency of a cell.Amino AcidsProteins are composed of basically the same 20 amino acids.
11Eukaryotic Cell Structure Possess membrane-bound organelles.10-30µm in diameter.Eukaryote = “true nucleus”Their DNA is enclosed by a double membrane.
12Eukaryotic Cell Structure Cell MembranePhospholipid (fatty chain with a phosphate) bi-layer with different types of proteins interspersed.Separates inside of cell from external environment.It has selective permeability.Only certain things can get in and out.Other organelle membranes are similar in structure.
14Eukaryotic Cell Structure NucleusControls the functions of the cell (“the control center).Nuclear membrane – surrounds nucleus.Nucleoplasm – gelatinous matrix.Chromosomes – linear DNA molecules and proteins.Gene – specific DNA segment on the chromosome that contains the information for making a gene product, usually a protein.Nucleolus – where rRNA is made and is used to make a structure called ribosomes.
15Eukaryotic Cell Structure CytoplasmA semi-fluid, gelatinous, nutrient matrix.Contains storage granules and cell organelles.Most of cell’s metabolism occurs.Often called the cytosol.
16Eukaryotic Cell Structure Endoplasmic Reticulum (ER)An irregular maze of spaces enclosed by a membrane.“Assembly Line”Rough ERContains ribosomesInvolved in making proteinsSmooth ERDoes not contain ribosomesInvolved in lipid metabolism (fat storage)
17Eukaryotic Cell Structure RibosomesAre important in protein synthesis.Are found in the Rough ER.
19Eukaryotic Cell Structure Golgi Complex“packaging plant.”Stacks of flattened, membranous sacs.Completes and packages newly formed proteins and lipids.Packages them so that they are ready for storage within the cell or outside of the cell.
20Eukaryotic Cell Structure Lysosomes“garbage disposal system”1 µm diameterContain lysozyme and other enzymes that break down foreign material.Particles may enter cell by phagocytosis.Also involved in programmed cell death called autolysis or apoptosis.PeroxisomesMembrane-bound vesicles that generate and break down hydrogen peroxide (a dangerous and highly reactive chemical).Used to break down lipids (fats) and destroy toxic molecules.
21Eukaryotic Cell Structure Mitochondria“the power plant of the cell”0.5 – 1 µm in diameter, 7 µm in lengthWhere ATP (adenosine triphosphate) is formed.ATP is the energy currency of the cell.ATP is formed during a reaction called cellular respiration.ATP is formed from our food sources.
23Eukaryotic Cell Structure PlastidsSite of photosynthesis.Contain photosynthetic pigments.Photosynthesis – converting light energy into a source of chemical energy for organism.Chloroplasts – type of plastid that contains chlorophyll.Chlorophyll – a green photosynthetic pigment.
25Eukaryotic Cell Structure Cell WallExternal structure that provides rigidity, shape, and protection.May be composed of cellulose, pectin, lignin, chitin, and some mineral salts.Usually simpler than prokaryotic cells.
26Eukaryotic Cell Structure Plant CellsCells stained green (DNA) and red (keratin)Illustration by Robert Hooke (c.1665)askabiologist.asu.edu/.../rhooke.html
27Cell Walls Cell Walls Absent Present Animals Plants Protozoa Algae Mycoplasma species (type of bacteria)PresentPlantsAlgaeFungiMost Bacteria
28Eukaryotic Cell Structure FlagellaAn organelle of movement.Long, thin structure that moves like a whip to propel organism through liquid environment.Can be found in some species of protozoa, spermatozoa, and algae.CiliaOrganelle of locomotion.Usually short, hair-like structures that beat in coordinated, rhythmic movement.Can be found in some species of protozoa and types of cells that line respiratory tract.
29Eukaryotic Cell Structure Paramecium – sp. Protozoa. Notice the cilia.microbewiki.kenyon.edu/index.php/ParameciumEuglena – sp. Protozoa. Notice the flagella.
30Prokaryotic Cell Structure More simple than eukaryotic cells.Can perform all functions necessary for life.Prokaryotes comprise all bacteria and archaeans.Do NOT contain membrane-bound organelles.Typical E. coli cell is about 1 µm wide and 2-3 µm long.
31Prokaryotic Cell Structure Bacterial Cell WallProvides rigidity, strength, and protection.More complex than eukaryote cell walls.Composed of peptidoglycan (polymer of sugars and amino acids)Gram-positive bacteriaThick layer of peptidoglycan with some other molecules.Gram-negative bacteriaThinner layer of peptidoglycan with an outer membrane composed of lipid macromolecules.Genus Mycoplasma do not have cell walls.Archaens have cell walls but not composed of peptidoglycan.
32Prokaryotic Cell Structure Cell MembraneSimilar to eukaryotic cells.Contains proteins and phospholipids.Selectively permeable.It is very flexible and thin.
33Prokaryotic Cell Structure GlycocalyxThick, slimy, gelatinous material produced by the cell membrane and secreted outside the cell wall.Some bacteria have it.2 types of glycocalyx1. Slime LayerIs not highly organized or firmly attached to cell wall.Allows bacteria to glide or slide along surfaces.2. CapsuleHighly organized and firmly attached to cell wall.Chemical composition allows scientists to determine different types of bacteria.Prevent bacteria from being phagocytized by phagocytic white blood cells.Can attach bacteria to a wide array of surfaces.
35Prokaryotic Cell Structure Prokaryotic ChromosomeSingle, long, supercoiled, circular DNA molecule.Embedded in cytoplasm.Found in nuclear region of cell.Does not have a nuclear membrane.Contains all the information for carrying out life processes.Plasmids may also be found in prokaryotic cells.
36Prokaryotic Cell Structure PlasmidSmall, circular molecule of double-stranded DNA.Not part of the chromosome.Called extrachromosomal DNA.Found in the cytoplasm.May contain s genes.Number varies per cell.
37Prokaryotic Cell Structure CytoplasmSemiliquid interior of cells.Consists of water, enzymes, dissolved oxygen (in some bacteria), waste products, nutrients, proteins, carbohydrates, and lipids.Everything necessary for its metabolic functions.
38Prokaryotic Cell Structure Cytoplasmic ParticlesRibosomes are found in the cytoplasm.They are important in protein synthesis.Some substances are stored in cytoplasmic granules.Such as starch, lipids, sulfur, or iron.The type of substance stored depends on the species of organism.
40Prokaryotic Cell Structure FlagellaA mechanism for movement for some bacteria.Bacteria can be classified and identified by the arrangement of their flagella.Nonflagellated bacteria are usually considered to be nonmotile.Although there are exceptions.Pseudomonas fluorescens – aerobic soil bacteria.
41Prokaryotic Cell Structure Pili (Fimbriae)Not associated with motility.Thin, rigid, hair-like structure.Arise in cytoplasm and extend through the plasma membrane, cell wall, and capsule (if present).2 types of pili1. Adhesins - allows bacteria to adhere to surfaces.2. Sex pilusAllows for the transfer of genetic material through a process called conjugation.One bacteria attaches its sex pilus to another cell and transfers its genetic material to the other cell usually in the form of a plasmid.
42Prokaryotic Cell Structure Adhesin bacterial cell with pili (fimbriae) ultr23.vub.ac.be/.../fimbrialadhesion.htmlBacterial conjugation with sex pilus.
43Prokaryotic Cell Structure Spores (Endospores)Bacterial spores called endospores.Usually found in 2 genera: Bacillus and Clostridium.Form through the process sporulation.A copy of the chromosome and some cytoplasm is enclosed in a thick protein coat.This occurs when moisture and nutrients are low.Endospores are resistant to heat, cold, drying, and most chemicals.If adequate conditions are present, the endospore can become an active bacteria.
44Endospore Clostridium difficil forming an endospore. Associated with antibiotic related diarrhea caused by toxins producedRed structure is endospore forming.
45Prokaryotic Cell Reproduction Binary FissionOne parent cell splits to become 2 daughter cells.This process produces a clone of the parent cell.During this process, its chromosome is replicated in a process called DNA replication.Generation timeThe time it takes one parent cell to become 2 identical daughter cells.