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Microbiology > bacterial classification, structures, and replication > Flashcards

bacterial classification, structures, and replication Flashcards

1
Q

range of sizes of bacteria

A

.1- 10 micrometers

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2
Q

3 shapes of bacteria

A
  1. spheres (cocci)
  2. rods (bacilli; straight or bent)
  3. spirals (spirilla)
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3
Q

what limits whats inside bacteria

A

its size (don’t have organelles)

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4
Q

what do all bacteria have inside

A
  1. nucleoid (chromosomal DNA)
  2. cytosol (polyribosomes, proteins, carbohydrate inclusion)
  3. plasma membrane (phospholipid and protein)
  4. Cell wall
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5
Q

what do SOME bacteria have inside (or outside)

A
  1. Flagella
  2. fimbriae (pili)
  3. Capsule
  4. outer membrane (gram - only)
  5. endospores (gram +)
  6. periplasm (gram - only)
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6
Q

most bacteria have a _______ DNA chromosome

A

single circular supercoiled double-stranded (thats attached to cell membrane and central structures)

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7
Q

the cytoplasm of bacteria is densely packed with?

A

ribosomes (more than eukaryotic cells) 70s

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8
Q

what provides the shape of bacteria

A

cytoskeleton, homogenous to microfilaments or microbutubes of eukaryotic cells

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9
Q

inclusion bodies

A

granules that contain reserve materials like glycogen, lipids, phosphates in bacterial cells

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10
Q

permeability barrier

A

place of active transport in bacterial cells

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11
Q

where are chromosomes attached in bacterial cells

A

attached to the membrane and aides in cell division (daughter chromosome segregation)

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12
Q

how does a bacterial cell generate energy

A

electron transport chain

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13
Q

how do bacterial cells receive and secrete things

A

they contain receptor proteins (chemotaxis) and they have secretion of exoproteins (exotoxins hydrolytic enzymes)

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14
Q

functions of cell wall

A

provides physical protection from mechanical direction or osmotic lysis, provides a barrier against toxins, determines cell shape

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15
Q

whats unique about gram positive cell walls

A
  1. have may layers of peptidoglycan
  2. they have teichoic acid throughout (function is unknown but may help with attachment or secretion)
    (variation is lipteichoic acid)
  3. some have species specific cell wall components like polysaccharides and proteins
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16
Q

describe the structure of peptidoglycan (murrain)

A

peptidoglycan condition of linear GLYCAN CHAINS (backbones) of two alternating sugars (NAG and NAM). a PEPTIDE SIDE CHAIN and a PENTAGLYCINE INTERBRIDGE form crosslinks between glycan chains

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17
Q

where are lysozyme present and what do they cleave

A

present in tears, saliva and mucus (innate immune system).

Cleaves beta 1-4 glycosidic bonds between NAG and NAM polysaccharides of petioglycan

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18
Q

Penicillin

A

antibiotic affective agains gram positive bacteria (blocks cell wall synthesis by inhibiting transpeptidase and carboxypeptdase enzymes the form crosslinks between glycan chains)

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19
Q

describe gram negative cell wall

A

two membranes and thin single layer of peptidoglycan in between

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20
Q

gram negative bacterial cell walls have _____ outer membranes

A

impermeable. has porins that allow diffusion of hydrophilic solute molecules and excludes harmful molecules from the environment

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21
Q

periplasmic space

A

founding gram negative cell walls. contains a gel-like matrix. proteins important for transport, chemotactic, and hydrolytic roles

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22
Q

lipopolysaccharides (LPS) are?

A

endotoxins

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23
Q

what are the three structures that make up the lipopolysaccharide

A
  1. o antigen polysaccharide side chain (linked sugars-antigenec determinant)
  2. core polysaccharide(similar between species)
  3. lipid A (Toxin)-(phosopolipid with glucosamine instead of glycerol in outermsmbrane)
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24
Q

mycoplasma are exceptions to the rules of bacteria because?

A

they have no cell wall

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25
Q

what are the smallest known bacterial species

A

mycoplasma (parasitic bacteria)

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26
Q

the membrane of mycoplasma contain a _____ molecule

A

sterol-like

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27
Q

what environments can you find mycoplasma

A

osmotically protected environments

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28
Q

what causes walking pneumoniae

A

mycoplasma pneumoniae

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29
Q

in negativing staining what takes up ink

A

everything except the bacteria

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30
Q

capsule

A

a slime layer of thick hydrophilic gel that surrounds the bacterial cell

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31
Q

usually polysaccharides are made up of single or multi sugars but some are made of what?

A

polypeptides

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32
Q

the discrete layer=

and the amorphous=

A

capsule; slime layer

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33
Q

purposes of capsules

A
  1. to protect bacteria from the immune system

2. provide nutrients- can be digested by enzymes

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34
Q

what is the presence of the capsule dependent on

A

the growth conditions. if nutrients aren’t available for the bacteria it can be broken down into sugar

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35
Q

flagella are found in both

A

gram - and +

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36
Q

rotating helical protein

A

whip like structures of flagellin protein responsible for motility

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37
Q

monotrichous

A

one flagella

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38
Q

lophotrichous

A

lots of flagella coming out of one end of the bacteria

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39
Q

amphitrichous

A

one flagella coming out of each side of the bacteria

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40
Q

peritrichous

A

multiple flagellum coming out of all sides of bacteria

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41
Q

fimbriae

A

small hair like projections (200-400 per cell)
Function: attachment
found in gram + and - and composed of fimbrilin protein

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42
Q

pilli

A

longer and thicker than fimbriae (1-10 per cell)

Function: attachment and DNA transfer; composed of piling protein

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43
Q

sex pili

A

a type of pili that transfers DNA between gram - bacteria

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44
Q

spores

A

resistant to heat and can germinate after centuries; purpose is survival under adverse conditions. quiescent

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45
Q

when are spores produced

A

in response to nutrient limitations or related sign that tough times are coming

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46
Q

how are spores made

A

by environmental slates (bacillus species)

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47
Q

spores are composed of DNA surrounded by ____

A

membrane/ cortex thats notmetbolically active

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48
Q

are spores found in gram + or gram- bacteria

A

gram + only

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49
Q

the cell membrane is a site for _____ like the eukaryotic cell _____

A

metabolic activity; mitochondria

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50
Q

cell wall rigidity is provided by

A

peptidoglycans

51
Q

hair like pike mediate attachment to

A

human cells

52
Q

plasmids separate??

A

pieces of circular DNA that can transfer itself

53
Q

when a bacteria genome is larger it can?

A

survive in lots of difference places

54
Q

what are the 4 important ways bacteria metabolism differs for eukaryotic cells

A
  1. speed- bacteria metabolize at a rate 10 to 100 times faster
  2. versatility- bacteria use a greater variety of compounds as energy sources
  3. simplicity- no organelles so macromolecules synthesis
  4. uniqueness- some biosynthetic processes (peptidoglycan synthesis and LPS toxins) are unique to bacteria
55
Q

catabolism

A

breakdown of carbon source into ATP

56
Q

anabolism

A

uses energy to synthesize macromolecules

57
Q

3 types of energy generation in bacteria

A
  1. embed-meyerhof glycolytic pathway
  2. pentose phosphate pathway
  3. krebs cycle
58
Q

embden-meyerhof glycolytic pathway

A

atp, metabolic intermediates and pyruvate are fermented go into TCA cycle

59
Q

pentose phosphate pathway

A

generates NADPH and Pentoses and ribose 5-phosphate

60
Q

krebs cycle

A

generates ATP from oxidative phosphorylation (aerobic only)

61
Q

carbon source varies by?

A

Bacterial species and environment

62
Q

entry reactions require?

A

facilitated diffusion/transport

63
Q

precursor are turned into?? metabolites

A

nucleotides, raw materials etc

64
Q

fermentaton

A

starts with pyruvate and transfers electrons and protons via NAD + directly to an organic acceptor SUBSTRATE LEVEL PHOSPHORYLATION

65
Q

repiration

A

substrate oxidation coupled to transport of electrons through a chain of carriers in the membrane to an acceptor molecule (usually oxygen) more effieincent than fermentation and provides more energy

66
Q

reparation requires what?

A

a chain of carrier proteins found in the membrane

67
Q

aerobes vs anaerobe classification is based on

A

the ability to cope with deleterious effects of oxygen

68
Q

oxygen is only middle toxic but gets turned into

A

hydrogen peroxide (catalase or peroxidase) and superoxide anion (superoxide dismutase)

69
Q

organisms that lack _____ and____ are strict anaerobes

A

catalase and superoxide dismutase

70
Q

facultative aerobes

A

can grow with or without O2 (ecoli)

71
Q

aerotolerant anaerobes

A

anaerobic fermentation but can tolerate oxygen (streptococci). they aren’t killed by o2 but not able to use respiration. evenly spread throughout test tube

72
Q

microaerophiles

A

need oxygen for fermentation or respiration but are poisoned by high concentrations of oxygens. will gather in upper part of test tube but not at very top

73
Q

halophile

A

require high concentration of salt for growht

74
Q

osmophile

A

capable of growth in higher sugar concentrations

75
Q

thermophile

A

can grow between 45-122 c

76
Q

doubling time

A

time it takes a single bacteria to divide in two

77
Q

doubling time is determined by

A

environmental conditions, and limited by expression of genes needed to metabolize nutrients and replicate DNA

78
Q

lag phase

A

time when bacteria adapt to environemtn

79
Q

exponential log phase slope of line =

A

growth rate -Td

80
Q

stationary phase

A

where growth stops because nutrients are exhausted or toxic by product build up

81
Q

Chromosomal DNA in bacteria are ____ in a _____

A

supercoiled; nucleic structure

82
Q

DNA gyrase

A

introduces supercoils in bacterial chromosomal replication

83
Q

Topoisomerase I

A

relaxes supercoils in bacterial chromosomal replication

84
Q

steps to bacterial chromosomal replication

A
  1. initiation (depends on growth rate)
  2. Elongation
  3. Termination
85
Q

DNA replication is ____ and _____

A

Bidirectional and semi-conservative

86
Q

bidirectional

A

proceeds away form origin and ends when polymerases meet at terminator

87
Q

semi-conservative

A

each daughter DNA contains half new and half old DNA

88
Q

Takes 40 mins replicate E. coli chromosome,
but cells divide every 20 mins. How is this
possible?

A

Rate of DNA replication is determined by rate of initiation

89
Q

multi-fork replication

A

more than 2 origin points with one terminus

90
Q

Mutations (spontaneous)

A

changes to DNA sequence occur once in every million cells for any one haploid gene

91
Q

base substitution

A

when a nucleotide is changed

Effect: no effect on sequence but could effect expression

92
Q

insertion

A

when nucleotide is inserted

Effect: If in coding sequence- frame shift

93
Q

deletion

A

when nucleotide is deleted

Effect: if in coding sequence- frame shift

94
Q

nonsense

A

when a nucleotide change results in a STOP codon

effect: truncated protein

95
Q

missense

A

when nucleotide change results in an amino acid change

Effect: dysfunctional protein or antibiotic resistance

96
Q

duplication

A

when DNA sequence is abnormally copied

Effect: may result in abnormal protein function or frameshift

97
Q

homologous recombination

A

occurs anytime there is a source of recombinant DNA and strand breaks in bacterial chromosome. A type of genetic recombination in which nucleotide sequences are exchanged between two similar or identical molecules of DNA.

98
Q

what does homologous recombination require

A
  1. donor DNA must have large region of identical nucleotide sequence to host chromosome
  2. Recipient cells must have recA gene which controls entire process
99
Q

4 ways bacteria acquire DNA

A
  1. natural transformation
  2. conjugation
  3. transduction
  4. transposable elements
100
Q

Natural transformation

A

ability to take up DNA from the environment (streptococcus and neisseria gonorrhoeae)

101
Q

conjugation

A

transfer of plasmid DNA through sex pili

enterococcus faecium

102
Q

Transduction

A

bacteria phage (virus) accidentally inject bacterial DNA into host bacteria cell (s. pyogenies)

103
Q

transposable elements

A

DNA that can insert or excise itself from the chromosome or plasmid (e.coli)

104
Q

during bacterial transformation: once in the cell DNA either ____ or ____

A

gets degraded by nucleases used for raw materials or gets integrated into the chromosome via recombination pathway

105
Q

Natural transformation

A

ability to take up DNA from environment

106
Q

meditation by quorum sensing

A

in natural transformation when peptide pheromones produced by other bacteria are sensed by bacteria and turn on genes for competence

107
Q

steps of conjugation

A
  1. sex pilus attaches to another cell and a type IV secretion bridge is formed
  2. it transmits copies of plasmid to other cells
  3. plasmid DNA gets degraded and recombines with chromosomes or can be turned into new plasmid
108
Q

what are the two cycles of transduction

A
  1. lytic cycle

2. lysogenic cycle

109
Q

lytic cycle

A

the phage DNA attaches to bacteria and injects DNA into cytoplasm. creates new phages and the CELL LYSES to release new phages

110
Q

lysogenic cycle

A

phage injects DNA into cytoplasm. the phage DNA INTEGRATES into the host chromosome. portage DNA is copied as cell divides. Exposure to stress (like UV light) triggers excision from host chromosome.

111
Q

______ carry genes for antibiotic resistance or virulence genes

A

larger transposons

112
Q

making mRNA and protein is ______

A

energetically expensive

113
Q

why must bacteria tightly control gene expression

A

so only the proteins needed for a particular condition are expressed

114
Q

quorum sensing

A

way that bacteria sense their environment (controls when certain proteins are made)

115
Q

the strength of the integration between RNA polymerase and the promoter can determine

A

the amount of mRNA that gets made

116
Q

RNA polymerase

A

binds to promoter located upstream of gene start codon

117
Q

operon

A

multiple genes arranged together on same mRNA transcript expressed from same promoter (co-transcribed)

118
Q

as soon as mRNA is made it can interact directly with ribosomes of bacteria cells because?

A

there are no organelles separating them

119
Q

steps of genetic regulation

A
  1. transcriptional
  2. post- transcriptional
  3. translational
  4. post-translational
120
Q

transcriptional genetic regulation

A

promoter activity is regulated by transcription factors, sigma actors dn other proteins

121
Q

post transcriptional genetic regulation

A

mRNA stability

122
Q

regulation of Lac operon is an example of what type of gene regulation

A

post translational regulation

123
Q

virulence factors

A

genes directly related to the ability of bacteria to cause disease

Microbiology (7 decks)

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