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BIO 286 - Microbiology > Ch 2: Microbial Cell Structures (Bio 286 - Microbiology) > Flashcards

Ch 2: Microbial Cell Structures (Bio 286 - Microbiology) Flashcards

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Biology 101 flashcards
1
Q

optics and properties of light

A

visible light has wavelengths 400-750 nm; maximum resolution is 1 wavelength; magnification spreads light rays out to 150 micrometers (the resolution of our eyes = distance between photoreceptor cells)

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2
Q

refraction

A

passage through lens material bends light; parabolic lens brings ray to a focus point; lens with 2 differently shaped convex sides magnifies image

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3
Q

resolution

A

ability to distinguish two adjacent objects or points from one another; aka resolving power; improved by shorter wavelengths

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4
Q

resolving power (RP) (aka resolution)

A

calculated as : wavelength of light in nm / 2 x numerical aperture (where the numerical aperture describes the relative efficiency of a lens in bending light rays, numerical aperture is increased with oil immersion lenses)

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5
Q

spirochete

A

spiral shaped bacteria

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6
Q

spirillum

A

a more rigid/thicker spiral shaped bacteria

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7
Q

vibrio

A

curved rod, comma shaped bacteria

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8
Q

bacillus

A

Rod shaped bacteria

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9
Q

streptobacilli

A

rod-shaped bacteria occurring in chains

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10
Q

coccus

A

A spherical bacterium

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11
Q

diplococci

A

Spherical bacteria that occur in pairs

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12
Q

streptococci

A

spherical shaped bacteria occurring in chains

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13
Q

tetrad

A

spherical bacteria occurring in groups of 4

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14
Q

sarcina

A

spherical bacteria occurring in cubical amounts

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15
Q

staphylococci

A

Spherical shaped bacteria that form grape-like clusters

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16
Q

advantages to being small microbes

A

MORE SURFACE AREA RELATIVE TO CELL VOLUME (higher surface area/volume ratio); support greater nutrient and waste product exchange per unit cell volume; tend to GROW FASTER; mutations lead to faster evolutions

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17
Q

cell membrane

A

structure defining existence of cell

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18
Q

membrane constituents

A

approximately equal parts of phospholipids and proteins; have hydrophilic and hydrophobic regions that lock the protein in the membrane

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19
Q

phospholipid

A

consists of glycerol with ester links to two fatty acids and a phosphoryl head group

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20
Q

membrane proteins serve numerous functions

A

structural support; secretion of virulence factors; transmission of communication signals; ion transport and energy storage

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21
Q

transport across cell membrane

A

cell membrane acts as a SEMI PERMEABLE BARRIER because SELECTIVE TRANSPORT IS ESSENTIAL FOR SURVIVAL (diffusion and osmosis)

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22
Q

diffusion

A

easy permeation of the membrane by small uncharged molecules such as O2 and CO2

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23
Q

osmosis

A

diffusion of water across the membrane

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24
Q

diffusion of weak acids and weak bases

A

in their uncharged form they can diffuse across the membrane to change the pH of the cell (once diffused across the membrane into the cell, the acid/base will deprotonate/protonate to become charged, changing the pH)

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25
Q

transporters

A

a specific protein that facilitates transport of polar molecules and charged molecules

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26
Q

passive transport

A

molecules move along their concentration gradient

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27
Q

active transport

A

molecules move against their concentration gradient; requires energy

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28
Q

membrane lipids

A

phospholipids vary with respect to their phosphoryl head groups and their fatty acid side chains; variability is due to changes in temperature, where at high temperatures unsaturated fats (double bonds) dominate and at low temperatures saturated fats (no double bonds) dominate

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29
Q

membrane fluidity

A

membranes include planar molecules called reinforcing agents that fill gaps between hydrocarbon chains

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30
Q

sterols (cholesterol, egosterol)

A

reinforcing agents of the membrane in eukaryotes that regulate membrane fluidity

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31
Q

hopanoids / hopanes

A

reinforcing agents of the membrane in bacteria that regulate membrane fluidity

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32
Q

nucleoid

A

contains genetic material, NO NUCLEAR MEMBRANE, single circular chromosome, 500000-10000000 nt; HAPLOID; plasmids may be present; DNA is in close proximity to cytoplasm and ribosomes

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33
Q

prokaryote ribosome

A

two subunits (30S and 50S) that combine for a total size of 70S; dozens of proteins and three rRNA molecules; translates mRNA into proteins

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34
Q

thylakoids

A

extensively folded intracellular membranes

35
Q

carboxysomes

A

polyhedral bodies packed with enzyme Rubisco for CO2 fixation

36
Q

gas vesicles

A

to increase buoyancy

37
Q

phototroph structures

A

thylakoids, carboxysomes, gas vesicles

38
Q

other inclusion bodies

A

storage granules; glycogen, PHB and PHA for energy; sulfur for oxidation; volutin, phosphate; magnetosomes; membrane-embedded crystals of Fe3O4 fixation; orient the swimming of magnetotactic bacteria

39
Q

bacterial cytoskeleton

A

shape is determined by its shape-determining proteins: FtsZ, MreB, CreS

40
Q

FtsZ

A

forms a “Z-ring” for septum placement

41
Q

MreB

A

forms a coil inside rod-shaped cells

42
Q

Cres (“Crescentin”)

A

forms a polymer along inner side of crescent-shaped bacteria

43
Q

cell wall

A

confers shape and rigidity to cell and helps it withstand turgor pressure (influx of water)

44
Q

sacculus

A

bacterial cell wall that consists of a single interlinked molecule (peptidoglycan)

45
Q

peptidoglycan structure

A

long polymers N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM), bound to a peptide of 4-6 amino acids; where the peptides can form cross-bridges connecting the parallel glycan strands

46
Q

gram positive bacteria

A

thick cell wall; one membrane

47
Q

gram negative bacteria

A

thin cell wall; two membranes

48
Q

gram positive cell

A

polymers of sugars: ribitol-P and glycerol-P; other adducts: D-alanine and sugars; Lipoteichoic acid linked to lipids and act to anchor wall to membrane

49
Q

mycobacterial (Mycobacterium tuberculosis and M. leprae) cell envelopes

A

very complex, including unusual membrane lipids (mycolic acid) and unusual sugars (arabinogalactans)

50
Q

mycolic acids

A

lipid with a structure of RCH(OH)CH(R)COOH [where R is two long chains]

51
Q

R groups of different mycolic acids

A

corynebacterium (30-40 carbons — not too hydrophobic); nocardia (40-60 carbons — somewhat hydrophobic); mycobacterium (60-90 carbons — very hydrophobic)

52
Q

gram negative outer membrane

A

thin peptidoglycan layer consisting of one to two sheets; covered by an outer membrane that confers defensive abilities and toxigenic properties on many pathogens

53
Q

lipopolysaccharide

A

Lipid A (six fatty acids) for conserved structure; core (adaptor structures) for variable composition; O-Antigen (repeats) for important barrier functions

54
Q

flagellum structure

A

bacterial locomotion; electric motor; dozens of proteins; rotates rapidly; many are reversible; propels cell through environment

55
Q

monotrichous

A

single flagellum

56
Q

amphitrichous

A

flagella at both poles of the cell

57
Q

lophotrichous

A

cluster of flagella at one end

58
Q

peritrichous

A

flagella distributed over the entire cell

59
Q

flagella of spirochetes

A

AXIAL FILAMENTS; flagella located in the periplasm; bundles of many flagella; cause bacterium to corkscrew but can move through viscous media

60
Q

chemotaxis

A

movement of bacterium in response to chemical gradients (where attractants cause counterclockwise rotation and flagella to bundle together, and repellents cause clockwise rotation and flagellar bundles to fall apart)

61
Q

biased random walk

A

causes a net movement of bacteria toward attractants or away from repellents; movement toward attractant is favored so off-track movements will be redirected

62
Q

cell attachment methods

A

fimbriae, stalks, sex pilus

63
Q

fimbriae

A

attach cells to surfaces; constructed from thin filaments of protein “fimbrin”

64
Q

stalks

A

attach cells to surfaces; secretion systems attach cells to prey; six types

65
Q

sex pilus

A

similar to type 4 secretion system, but essential for bacterial pathogenicity

66
Q

capsule or glycocalyx

A

outermost layer of the cell; polymeric structures; most are CARBOHYDRATES but a few are peptides; variable in thickness; used to avoid phagocytosis; usually important for pathogenesis

67
Q

water

A

greatest volume of a cell (about 70%)

68
Q

protein

A

most abundant macromolecule of cells (about 16%) (followed by RNA, about 6%)

69
Q

fatty acid

A

hydrophobic

70
Q

phosphoryl head

A

hydrophilic

71
Q

lipoteichoic acid

A

linked to lipids in cytoplasmic membrane that anchors the cell wall to the membrane; only in gram positive cells

72
Q

lipopolysaccharide (LPS)

A

Molecule that makes up the outer layer of the outer membrane of Gram-negative bacteria; only in gram negative cells

73
Q

core (adaptor structures) of LPS

A

unique to genus

74
Q

mycoplasma

A

true bacteria; very small in size; no peptidoglycan wall [but has a single membrane so is considered a gram positive grouping]; variable in shape; important pathogens; contain cholesterol in membranes but don’t make it themselves; does NOT contain murein

75
Q

capsule

A

extracellular slime to make bacteria slippery to avoid phagocytes

76
Q

small microbes have a higher surface-to-volume ratio

A

which allows for higher nutrient exchange

77
Q

ESTER links

A

lipids in cytoplasmic membrane of bacteria and eukarya

78
Q

ETHER links

A

lipids in cytoplasmic membrane of Archaea

79
Q

hydrolytic enzymes

A

function in initial degradation of nutrients

80
Q

lysozyme

A

enzyme that cleaves bond between NAG and NAM to destroy peptidoglycan and cause bacterial cell lysis as a part of animals’ immune defense

81
Q

peptide cross bridges

A

only in Gram positive

82
Q

archaella of archaeans

A

rotate like bacterial flagella though they consist of multiple protein types

83
Q

endospores

A

contain small acid-soluble proteins (SASPs) which protect DNA from Ultraviolet light

BIO 286 - Microbiology (21 decks)

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