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Micro term 3 quiz 1 > bacterial structure and function > Flashcards

bacterial structure and function Flashcards

levinson chapters 1 and 2

1
Q

what are the 5 major groups of organisms that cause human diseases?

A 
bacteria 
fungi
protozoa
helminths
viruses
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2
Q

what organisms are in the prokaryote kingdom?

A

bacteria

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3
Q

what organisms are in the protist kingdom?

A

fungi (yeasts and molds) and protozoa

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4
Q

what organisms are in the animal kingdom?

A

helminths (worms)

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5
Q

how can you distinguish protists from animals and plants?

A

protists are either unicellular or relatively simple microorganisms

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6
Q

which organisms are parasites?

A

helminths and protozoa

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7
Q

biological relationships of pathogenic microorganisms (table)

  • kingdom
  • pathogenic microorganisms
  • type of cells
A
  • animals
    • helminths
    • eukaryotic cells
  • protists
    • protozoa and fungi
    • eukaryotic cells
  • prokaryotes
    • bacteria
    • prokaryotic
    • viruses
    • noncellular
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8
Q

describe the structure of cells.

A

have a nucleus or nucleoid that contains DNA

nucleus surrounded by cytoplasm where proteins are synthesized and energy generated

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9
Q

describe the structure of viruses.

A

inner core of genetic material but no cytoplasm

depend on host cells to provide the machinery for protein synthesis and energy generation

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10
Q

how do eukaryotic cells replicate?

A

mitosis - one parent cell divides to make two progeny cells while retaining its cellular structure

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11
Q

how do prokaryotic cells replicate?

A

binary fission

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12
Q

how do viruses replicate?

A

disassemble
produce many copies of their nucleic acid adn protein
reassemble into multiple progeny

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13
Q

can bacteria replicate extracellularly?

A

most can, except rickettsiae and chlamydiae

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14
Q

what is the difference in nucleic acid between cells and viruses?

A

cells have both DNA and RNA

viruses have DNA or RNA but not both

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15
Q

what are the defining characteristics of eukaryotic cells?

A 
have a true nucleus with multiple chromosomes surrounded by a nuclear membrane
uses mitotic apparatus to ensure equal allocation of chromosomes to progeny
contain organelles (ie mitochondria and lysosomes) and ribosomes
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16
Q

what are the defining characteristics of prokaryotic cells?

A

nucleoid consists of a single cellular molecule of loosely organized DNA
lacks nuclear membrane and mitotic apparatus
no organelles and smaller ribosomes
rigid external cell wall that contains peptidoglycan

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17
Q

what is peptidoglycan and what is it made of?

A

polymer of AA and sugars that makes up the rigid cell wall of most prokaryotes

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18
Q

what is the cell wall of eukaryotes like?

A

either have a flexible cell membrane or rigid wall of chitin (fungi)

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19
Q

what is chitin and what is made of?

A

makes up rigid cell wall of fungi

made of a homopolymer of N-acetylglucosamine

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20
Q

what organisms have sterols?

A

eukaryotic cell membranes contain sterols

no prokaryotes except for mycoplasma do

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21
Q

which organisms are motile and which ones aren’t?

A

protozoa are motile, as are some bacteria

fungi and viruses aren’t

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22
Q

what do protozoa use to move?

A

three different organs of locomotion: flagella, cilia and psuedo-pods

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23
Q

what do bacteria use to move?

A

flagella

24
Q

how are microorganisms named?

A

bacteria, fungi, protozoa, and helminths are named according to binomial Linnean system (uses genus and species)
viruses aren’t

25
Q

what are the different shapes of bacteria?

A 
cocci = round
bacilli = rods
spirochetes = spiral-shaped
pleomorphic = variable in shape
26
Q

what determines the shape of bacterium?

A

its rigid cell wall

27
Q

how do cocci bacteria vary in terms of arrangement?

A

can occur in pairs = diplococci
in chains = streptococci
grapelike clusters = staphylococci

28
Q

what determines the arrangement of bacteria?

A

orientation and degree of attachment of the bacteria at the time of cell division

29
Q

how large are bacteria?

A

range in size from about 0.2 to 5 um

smalles are the same size as the largest viruses

30
Q

what is the outermost component of bacteria?

A

cell wall most commonly

some have capsule, flagella, and pili as well

31
Q

what is the function of peptidoglycan in the bacterial cell wall?

A

provides structural support and maintains characteristic shape of cell

32
Q

what factors are different between gram positive and gram negative bacteria? (general)

A

structure
chemical composition
thickness of cell wall

33
Q

what are the layers of bacterial cell walls?

A 
outer:
flagellum, techolic acid, pilus if present
capsule
outer membrane in gram-negative
peptidoglycan
cytoplasmic membrane
34
Q

how does the peptidoglycan layer vary between gram positive and gram negative bacteria?

A

much thicker in gram positive bacteria

many gram-positive

35
Q

how does the outer layer of gram positive and gram negative bacteria differ?

A

gram negative have a complex outer layer of lipopolysaccharide, lipoprotein, and phospholipid

36
Q

what is periplasmic space and which type of bacteria have it? what is found there?

A

in gram-negative bacteria
between outer-membrane layer and cytoplasmic membrane
where beta-lactamase enzymes are in some species

37
Q

what do beta-lactamase enzymes do? where would they be found?

A

enzymes that degrade penicillins and other beta-lactam drugs

in periplasmic space in gram-negative bacteria

38
Q

what is endotoxin and where is it found?

A

in gram-negative bacteria

lipopolysaccharide

39
Q

what are porin proteins and where are they found?

A

in the cell wall of both gram positive and gram negative bacteria
facilitate passage of small hydrophilic molecules into the cell
in gram-negative, allow entry of essential substances such as sugars, AA, vitamins, and metals and many antimicrobial drugs

40
Q

what are acid-fast bacteria?

A

ones that can’t be gramstained
mycobacteria
resist decoloratization with acid-alcohol after being stained with carbolfuchsin
due to high concentration of lipids (mycolic acids) in the cell walls

41
Q

what are mycolic acids? where are they found? how do they affect gram staining?

A

lipids found in high concentration in mycobacteria

prevent gramstaining

42
Q

what are the three components of the bacterial cell wall (that they consider important)?

A

peptidoglycan
lipopolysaccharide
teichoic acid

43
Q

what is peptidoglycan and where is it found?

A

complex, interwoven network that surrounds the entire cell and is composed of a single covalently linked macromolecule
found only in bacterial cell walls

44
Q

what is the structural importance of peptidoglycan?

A

provides rigid support for the cell
maintains cell shape
allows cell to withstand media of low osmotic pressure (such as water)

45
Q

what is peptidoglycan composed of (ie describe the carbohydrate backbone)?

A

alternating N-acetylmuramic acid and N-acetylglucosamine molecules
tetrapeptide consisting of D- and L-amino acids is attached to each of the muramic acid molecules

46
Q

what aspect of peptidoglycan varies between bacteria?

A

precise composition of tetrapeptide link attached to muramic acid

47
Q

what is diaminopimelic acid a component of and what organism is it unique to?

A

unique to bacterial cell walls

component of carbohydrate backbone

48
Q

what is D-alanine a component of and what does it do?

A

part of bacterial cell walls

involved in cross-links between the tetrapeptide and in the action of penicillin

49
Q

what is different about the AA in the tetrapeptide in bacterial cell walls?

A

contain the D-isomers of AA

most proteins contain the L-isomers

50
Q

what drugs target bacterial cell walls, and how?

A

penicillins, cephalosporins and vancomycin
inhibit the synthesis of peptidoglycan by inhibiting transpeptidase that makes the cross-links between two adjacent tetrapeptides

51
Q

how would gram-negative and gram-positive bacteria appear after being stained?

A

gram-positive will stain blue

gram-negative will stain red

52
Q

what are the steps in the gram stain procedure?

A

1: crystal violet dye stains all cells blue/purple
2: iodine solution is added - forms a crystal violet-iodine complex - all cells continue to appear blue
3: organic solvent (acetone or ethanol) extracts the blue dye complex from lipid-rich, thin-walled gram-negative bacteria to a greater degree than from thick-walled gram-positive bacteria
4: red dye safranin stains decolored gram-negative cells red/pink

53
Q

how is the gram stain used clinically?

A

used to identify bacteria and choose antibacterial treatment

54
Q

how do gram-negative bacteria versus gram-positive bacteria compare in terms of responsiveness to penicillin?

A

gram-positive are more susceptible

55
Q

what is the sensitivity of the gram stain procedure?

A

very low because it requires about 100,000 bacteria/mL to see 1 bacterium per microscope field
therefore need to incubate patient’s blood

56
Q

where is lysozyme found and what does it do to bacteria?

A

enzyme in human tears, mucus, saliva

cleaves peptidoglycan backbone by breaking glycosyl bonds

Micro term 3 quiz 1 (2 decks)

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