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Microbiology > Chapter 3 > Flashcards

Chapter 3 Flashcards

(61 cards)

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1
Q

Capsule

A

A distinct, thick gelatinous material that surrounds some micro organisms

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2
Q

Chemotaxis

A

Movement of a cell toward or away from a certain chemicals in the environment

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3
Q

Cytoplasmic membrane

A

A phospholipid by layer in bedded with proteins that surrounds the cytoplasm and defines the boundary of the cell

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4
Q

Endospore

A

A extraordinarily resistant dormant cell produced by some types of bacteria

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5
Q

Flagellum

A

A type of structure used for cell movement

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6
Q

Gram negative bacteria

A

Bacteria that have a cell wall characterized by a thin layer of peptidoglycan surrounded by an outer membrane; when gram stained, these cells are pink

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7
Q

Gram positive bacteria

A

Bacteria that have a cell wall characterized by a thick layer of peptidoglycan; when gram stained these cells are purple

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8
Q

Lipopolysaccharide

A

Molecule that takes up the outer layer of the membrane of Gram negative bacteria

Endotoxins

Lipid A (immune systems recognizes)
O antigen (can be used to identify species or strains)
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9
Q

Peptidoglycan

A

A macromolecule that provides strength to the cell wall; it is only found in bacteria

Alternating series of N-acetylmuramic acid (NAM), N-acetylglucosamine (NAG)

Tetrapeptide links glycan chains

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10
Q

Lipopolysaccharide

A

The gel like material that fills the region between the cytoplasmic membrane and the outer membrane of gram-negative bacteria

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11
Q

Protein pili

A

Cell surface structures that allows cells to adhere to certain surfaces; some types are involved in the mechanism of DNA transfer

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12
Q

Plasmid

A

An extrachromosomal DNA molecule that replicates independently of the Chromosome

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13
Q

Ribosome

A

Structure that facilitates the joining of amino acids during translation; composed of ribosomal RNA and proteins

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14
Q

Transport systems

A

Mechanisms used to transport nutrients and other small molecules across the cytoplasmic membrane

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15
Q

Hans Christian Joachim Gram

A

Danish physician, studied cause of pneumonia

Developed methods to stain bacteria

Identified two major groups of bacteria using “Gram stain”: gram positive and negative

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16
Q

Light Microscope

A

Magnifies up to 1,000x

Commonly used in labs to observe cell size, shape, and motility

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17
Q

Electron microscope

A

can magnify more than 100,000x

Reveals many fine details of cell structure

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18
Q

Atomic force microscope

A

Can produce images of individual atoms on a surface

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19
Q

Bright-field microscope

A

Evenly illuminates the field of view and generates a bright background

Three Key Concepts:
Magnification
Resolution
Contrast

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20
Q

Magnification

A

Apparent increase in size

Two lens types: objective and ocular
Objective (4x, 10x, 40x, and 100x) Ocular (10x)

Condenser lens: focuses light on specimen

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21
Q

Resolution

A

Resolving power (0.2um), or ability to distinguish 2 objects that are very close together.

Determines how much detail of specimen

Factors: quality and type of lens, wavelength light, magnification, and specimen preparation

Immersion oil: displaced air as medium, prevents refraction of light

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22
Q

Contrast

A

Determines how easily cells can be seen

Stains increase contrast but kill microbes

Wet mount: microscope that increases contrast

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23
Q

Dark field microscope

A

Directs light toward specimen at angle, increasing constrast

Cells appear as bright objects against dark background

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24
Q

Phase contrast Microscope

A

Special optics amplify difference between refractive index of dense material and surrounding medium

Increases contrast

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25
Differential interference contrast microscope
Makes image 3 dimensional Separates light into two beams that pass through specimen and recombine (3D)
26
Fluorescence Microscopes
Cells or materials either naturally fluorescent or tagged with fluorescent dyes Molecules typically absorb at UV wavelength Epifluorescent: UV light projected onto, not through, specimen
27
Scanning laser microscope
Obtain detailed views of interior of intact cells that have been stained with a fluorescent dye
28
Confocal microscopy
Images find slices of a specimen using a laser beam and mirrors to illuminate and scan across specimen
29
Multiphoton microscopy
Similar to confocal, but lower energy used. Less damaging, allows Time lapse Light penetrates deeper
30
Transmission electron microscope (TEM)
Beams of electrons pass through or scatter Thin sectioning can detail fine cell structures, but process may distort cells Freeze fracturing or etching- reveals shape of internal structures
31
Scanning Electron Microscope (SEM)
Used to observe surface details Beams scatter on surface of thin metal 3D
32
Wet mount
Drop of a liquid specimen, observes living organisms Smear: drying and fixing specimen before staining to visualize Basic dyes: carry positive charge Acidic dyes: carry negative charge
33
Simple stains
A basic dyes used to stain cells. Easy way to increase contrast Methylene blue, crystal violet, safranin, and malachite green
34
Differential stains
A multi step procedure is used to stain cells and distinguish one group of micro organisms from another Gram stain Acid fast stain: for organisms that hardly stain ``` Steps to staining: Primary stain: crystal violet Mordant: iodine Decolorizer: alcohol Counterstain: safranin ```
35
Special stains
Special procedure used in stain specific cell structures Capsule stain. Stains poorly Endospore stain: uses heat to dye Flagella stain
36
Fluorescent dyes and tags
Fluorescent dies in tags absorb ultraviolet light and then in the light of a longer wavelength Fluorescent dyes Fluorescent tags
37
Shape of prokaryotic cells
Most common Coccus: spherical Rod (bacillus): cylindrical ``` Other Vibrio: short curved rod Spirillum Spirochete Pleomorphic: many shapes ```
38
Cytoplasmic membrane
Selectively permeable: O2, Co2, N2, small hydrophobic molecules, and water pass Aquaporins facilitate water passage Other molecules use transport systems
39
Simple diffusion
Movement from high to low concentration across membrane
40
Osmosis
Diffusion of water across selectively permeable membrane due to unequal salute concentration Hypertonic Isotonic Hypotonic
41
Electron transport chain
Converts energy into ATP Uses energy from electrons to move protons out of cell
42
Passive transport
Facilitated diffusion Movement down gradient; no energy required
43
Active transport
Movement against gradient
44
Group Translocation
Chemically alter compound
45
Penicillin
Interferes with peptidoglycan synthesis Prevent cross linking of adjacent glycan chains More effective against gram-positive bacteria
46
Capsules and Slime layers
Capsule: distinct, gelatinous Slime layer: diffuse, irregular Most are glycocalyx Once attached cells can grow as biofilm Some evade host immune system
47
Flagellum
Bacterial Basal body: anchors to cell wall and cytoplasmic membrane Hook Filament: made up of flagellin subunits Archael Chemically distinct Use energy from ATP Eukaryotic Covered by cytoplasmic reticulum Microtubules in 9 + 2 arrangement
48
Chemotaxis
Bacteria sense a chemical and move toward it (nutrient) or away from it (toxin)
49
Pili
Shorter than flagella Fimbriae: allows surface attachment Sex pilus: join bacteria for a type of DNA transfer
50
Ribosomes
Involved in protein synthesis, joins amino acids Prokaryotic: 70S (30S and 50S subunits) Eukaryotic: 80S
51
Cell wall
Protozoa: self contained, no cell wall Animal cells lack cell wall Fungal cell wall contain chitin Plant cell wall contain cellulose
52
Endocytosis
Cells take up material from surrounding environment by forming invaginations in cytoplasmic membrane
53
Exocytosis
Internal vesicles fuse with the cytoplasmic membrane and release their contents
54
Secretion
Secreted proteins carry a signal sequence that act as a tag, proteins going to other organelles have specific tags. Ribosomes that synthesize proteins attached to endoplasmic reticulum
55
Actin filaments
Allow movement Polymerize or depolymerize
56
Microtubules
Framework for organelle and vesicles movement, made of tubulin Found in mitotic spindles, cilia, and flagella
57
Intermediate filaments
Provide mechanical support
58
Nucleus
Contains genetic info Surrounded by 2 phospholipid bilayers Large molecules can pass Nucleolus synthesize ribosomal RNAs
59
Endosymbiotic theory
Ancestors of mitochondria and chloroplasts were bacteria residing with other cells
60
Endoplasmic reticulum
Rough: Dotted with ribosomes, synthesize proteins Smooth: lipid synthesis and degradation, calcium storage
61
Golgi apparatus
Macromolecules from ER are modified and sorted for delivery in vesicles

Microbiology (10 decks)

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