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Ch 3

Micro

QuestionAnswer
Characteristics of Life Grwth Reproduction Responsiveness Metabolism
Prokaryotes * Lack nucleus * Can read DNA and make protein simultaneously * Lack various internal structures bound w phospholipid membranes * Typically 1.0 µm in diameter or smaller * Composed of bacteria and archaea * Smaller than Eukaryotes
Eukaryotes * Nucleus * Have internal membrane-bound organelles * Larger: 10–100 µm in diameter * Have more complex structure * Composed of algae, protozoa, fungi, animals, and plants
Glycocalyces * Gelatinous, sticky substance surrounding the outside of the cell * Composed of polysaccharides, polypeptides, or both
Two Types of Glycocalyces Capsules Slime layer
Capsule Composed of organized repeating units of organic chemicals Firmly attached to cell surface May prevent bacteria from being recognized by host Certain bacteria w/ capsules cause pneumonia
Slime layer Loosely attached to cell surface Water-soluble Sticky layer allows prokaryotes to attach to surfaces Dental biofilm that can cause cavities
Flagella Are responsible for movement Have long structures that extend beyond cell surface Are not present on all bacteria Structure Composed of filament, hook, and basal body Basal body anchors the filament and hook to cell wall.
Flagella Function Rotation propels bacterium through environment. Rotation varies; can be counterclockwise (straight) or clockwise (freaks out) Bacteria move in response to stimuli (taxis). Runs & tumbles Chemotaxis Phototaxis Positive & negative taxis
Fimbriae Sticky, bristlelike projections/rodlike protinaceous extensions Used by bacteria to adhere to one another and to substances in environment Shorter than flagella Serve an important function in biofilms
Pili Special type of fimbriae Also known as conjugation pili Longer than fimbriae but shorter than flagella Bacteria typically have only one or two per cell. Transfer DNA from one cell to another (conjugation)
Bacterial Cell Walls Provide structure/shape/protect cell frm osmotic forces Assist cells in attaching to other cells/resistin antimicrobial drugs Target cell wall of bacteria with antibiotics (animal cells do not have cell walls) Give bacterial cells characteristic shapes
Bacterial Cell Walls peptidoglycan polysaccharide Peptidoglycan is composed of 2 types of regularly alternating sugar/glucose molecules NAG NAM Tetrapeptides (4 aa) Form connections/crossbridges between NAMs
Gram-Positive Bacterial Cell Walls Relatively thick layer of peptidoglycan Contain unique chemicals called teichoic acids/lipoteichoic acids Appear purple following Gram staining procedure Mycobacterium = Up to 60% mycolic acid in acid-fast bacteria helps cells survive desiccation
Gram-Negative Bacterial Cell Walls Thin bilayer of peptidoglycan contains phospholipids/proteins/(LPS) Lipid A portion of LPS can cause fever/vasodilation/inflammation/shock/blood clottin May impede the treatment of disease Appear red followin Gram staining procedure
Bacteria Without Cell Walls A few bacteria lack cell walls Often mistaken for viruses due to small size and lack of cell wall Have other features of prokaryotic cells such as ribosomes
Bacterial Cytoplasmic Membranes - Structure aka phospholipid bilayer Composed of lipids/associated proteins: Integral proteins Peripheral proteins (function as receptors) Cytoplasmic membranes aka cell membrane and the plasma membrane
Bacterial Cytoplasmic Membranes - Function Controls the passage of substances into/out of the cell Energy storage Harvest light energy in photosynthetic bacteria Naturally impermeable to most substances Proteins allow substances to cross membrane Maintain concentration and electrical gradient
Diffusion the net movement of a chemical down its concentration gradient (from higher conc to lower conc)
Facilitated diffusion certain cytoplasmic membrane proteins act as channel or carriers to allow certain molecules to enter or exit the cell.
Osmosi diffusion of water across a semipermeable membrane
Active Transport requires energy, transport proteins, & moves substances against their electrochemical gradients
Group translocation a substance is chemically modified during transport
Cytosol Liquid portion of cytoplasm Mostly water Contains cell’s DNA in region called the nucleoid
Inclusions May include reserve deposits of chemicals Presence of specific inclusions is diagnostic for several pathogenic bacteria Cyanobacteria have gas vesicles which provide buoyancy
Endospores Unique structures produced by some bacteria Defensive strategy against unfavorable conditions Vegetative cells transform into endospores when multiple nutrients are limited or environmental conditions change Resistant to extreme conditions
Ribosomes Sites of protein synthesis/production Composed of polypeptides and ribosomal RNA (rRNA) 70S
Cytoskeleton Internal structure (scaffolding) Composed of three or four types of protein fibers Can play different roles in the cell: Cell division Cell shape Segregate DNA molecules Move through the environment
Glycocalyces Function in the formation of biofilms Adhere cells to one another and inanimate objects
Flagella Consist of basal body, hook, and filament # differences w bacterial flagella Archaeal/bacterial flagella evolve separately Structure/arrangement Diff structurally/functionally frm prokaryotic flagella Filaments anchored to cell by basal body; no hook
Archaeal cytoplasm similar to bacterial cytoplasm 70S ribosomes Fibrous cytoskeleton Circular DNA
Archaeal cytoplasm also differs from bacterial cytoplasm Different ribosomal proteins Different metabolic enzymes to make RNA Genetic code more similar to eukaryotes
Glycocalyces Not as organized as prokaryotic capsules Help anchor animal cells to each other Strengthen cell surface Provide protection against dehydration Function in cell-to-cell recognition and communication
Eukaryotic Cell Walls and Cytoplasmic Membranes Animal and most protozoa do not have cell walls Fungi, algae, plants, and some protozoa have cell walls.
Cilia Shorter and more numerous than flagella Coordinated beating propels cells through their environment. Also used to move substances past the surface of the cell
Nucleus ‘Control center of cell’ Often largest organelle in cell Contains most of the cell's DNA RNA synthesized in nucleoli present in nucleoplasm. Surrounded by nuclear envelope Contains nuclear pores (import and export)
Endoplasmic reticulum (ER) Netlike arrangement of flattened, hollow tubules continuous with nuclear envelope Functions as transport system
Smooth endoplasmic reticulum (SER) Lipid synthesis
Rough endoplasmic reticulum (RER) Ribosomes adhere to outside layer – protein synthesis
Golgi body ‘shipping department’ Receives, processes/ packages large molecules for export from cell Packages molecules in secretory vesicles Composed of flattened hollow sacs surrounded by phospholipid bilayer Not in all eukaryotic cells
Mitochondria ‘Powerhouse’ Have two membranes composed of phospholipid bilayer Produce most of cell’s ATP Interior matrix contains 70S ribosomes and a circular molecule of DNA (just like bacteria).
Chloroplasts Light-harvesting structures found in photosynthetic eukaryotes Use light energy to produce ATP Have two phospholipid bilayer membranes and DNA Have 70S ribosomes (just like bacteria)
Endosymbiotic Theory Differences in DNA, 70S ribosomes/ 2 bilipid membranes lead to an evolutionary discovery Eukaryotes formed from a union of small aerobic prokaryotes w larger anaerobic prokaryotes. Smaller prokaryotes became internal symbionts. Lost their ability to ex
Endosymbiotic Theory Lost their ability to exist independently. Larger cell became dependent on symbiont for aerobic ATP production. Aerobic prokaryotes evolved into mitochondria. Similar scenario for origin of chloroplasts
A cell may allow a large or charged chemical to move across the cytoplasmic membrane, down the chemical's electrical and chemical gradients, in a process called? a. active transport b. facilitated diffusion c. endocytosis d. pinocytosis facilitated diffusion
Which of the following statements concerning growth and reproduction is false? a living organism must reproduce to be considered alive
A "9+2" arrangement of microtubules is seen in? a. archaeal flagella b. bacterial flagella c. eukaryotic flagella d. all prokaryotic flagella eukaryotic flagella
Which of the following is most associated with diffusion? a. symports b. antiports c. carrier proteins d. emdocytosis carrier proteins
Which of the following is NOT associated with prokaryotic organisms? a. nucleotid b. glycocalyx c. cilia d. circular dna cilia
Which of the following is true of Svedbergs? a. Theyre not exact but compare b. theyre abbr sv c. theyre prokaryotic in nature but exhibit some eukaryotic characteristics d. They are an expression of sedimentation rate during high speed centrifugation they are an expression of sedimentation rate during high-speed centrifugation
Which of the following statements is true? a. the cell wall of bacteria are composed of peptidoglycan b. peptidoglycan-fatty acid c. Gram+ bact walls thin layer of peptidoglycan anchored d. peptidoglycan is found cellwalls of fungi, algae, and plants the cell wall of bacteria are composed of peptidoglycan
Which of the following is NOT a function of the glycocalyx? a. it forms pseudopods for faster mobility of an organism b.protect bact cell from dryin out c. hides bact cell from other cells d. allows bact to stick to a host it forms pseudopods for faster mobility of an organism
Bacterial flagella are _____________ ? a. anchored to the cell by a basal body b. composed of hami c. surrounded by an extension of cytoplasmic membrane d. composed of tubulin in hollow microtubules in a 9+2 arrangement are anchored to the cell by a basal body
Which cellular structure is important in classifying a bacterial species as Gram-negative or positive? a. flagella b. cell wall c. cilia d. glycocalyx cell wall
A Gram-negative cell is moving uric acid across the cytoplasmic membrane against its chemical gradient. Which of the following statements is TRUE? the acid moves by an active proces such as active transport
Gram-positive bacteria? a. have a thick cell wall, which retains crystal violet dye b. contain teichois acids in their cell walls c. appear purple after Gram staining d. all of the above all of the above
Endospores _______________. a. reproductive structures of some bacteria b. occur in some archaea c. cause shock, fever, and inflammation d. dormant, resistant cells are dormant, resistant cells
Inclusions have been found to contain? a. DNA b. sulfur globules c. dipicolinic acid d. tubulin sulfur globules
Dipicolinic acid is an important component of? a. gram + archaeal wallss b. cytoplasmic membranes in eukaryotes c. endospores d. Glogi bodies endospores
Glycocalyx "sugar cup" composed of polysaccharides and or polypeptides
Flagella 1. long whip 2. made of tubulin in eukaryotes 3. made of flagellin in bacteria
Axial Filaments responsible for motility of spirochetes
Cilia made of tubulin in eukaryotes
Fimbriae 1. bristlelike projections found in quantities of 100 or more 2. numerous "grappling hook" projections
Pili 1. responsible for conjugation 2. extensions not used for cell motility
Hami numerous "grappling hook" projections
Ribosomes site of protein synthesis
Cytoskeleton allows contraction of the cell
Centriole contains microtubules in "9+0" arrangement
Nucleus site of most DNA in eukaryotes
Mitochondria its internal membranes are sites for ATP production
Chloroplast light harvesting organelles
ER functions as the transport system within a eukaryotic cell
Golgi body packages large molecules for export from a cell
Peroxisome contains enzymes to neutralize hydrogen peroxide
Created by: Cpvander