bacterial classification, structures, and replication Flashcards
(123 cards)
1
Q
range of sizes of bacteria
A
.1- 10 micrometers
2
Q
3 shapes of bacteria
A
- spheres (cocci)
- rods (bacilli; straight or bent)
- spirals (spirilla)
3
Q
what limits whats inside bacteria
A
its size (don’t have organelles)
4
Q
what do all bacteria have inside
A
- nucleoid (chromosomal DNA)
- cytosol (polyribosomes, proteins, carbohydrate inclusion)
- plasma membrane (phospholipid and protein)
- Cell wall
5
Q
what do SOME bacteria have inside (or outside)
A
- Flagella
- fimbriae (pili)
- Capsule
- outer membrane (gram - only)
- endospores (gram +)
- periplasm (gram - only)
6
Q
most bacteria have a _______ DNA chromosome
A
single circular supercoiled double-stranded (thats attached to cell membrane and central structures)
7
Q
the cytoplasm of bacteria is densely packed with?
A
ribosomes (more than eukaryotic cells) 70s
8
Q
what provides the shape of bacteria
A
cytoskeleton, homogenous to microfilaments or microbutubes of eukaryotic cells
9
Q
inclusion bodies
A
granules that contain reserve materials like glycogen, lipids, phosphates in bacterial cells
10
Q
permeability barrier
A
place of active transport in bacterial cells
11
Q
where are chromosomes attached in bacterial cells
A
attached to the membrane and aides in cell division (daughter chromosome segregation)
12
Q
how does a bacterial cell generate energy
A
electron transport chain
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)
14
Q
functions of cell wall
A
provides physical protection from mechanical direction or osmotic lysis, provides a barrier against toxins, determines cell shape
15
Q
whats unique about gram positive cell walls
A
- have may layers of peptidoglycan
- they have teichoic acid throughout (function is unknown but may help with attachment or secretion)
(variation is lipteichoic acid) - some have species specific cell wall components like polysaccharides and proteins
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
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
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)
19
Q
describe gram negative cell wall
A
two membranes and thin single layer of peptidoglycan in between
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
21
Q
periplasmic space
A
founding gram negative cell walls. contains a gel-like matrix. proteins important for transport, chemotactic, and hydrolytic roles
22
Q
lipopolysaccharides (LPS) are?
A
endotoxins
23
Q
what are the three structures that make up the lipopolysaccharide
A
- o antigen polysaccharide side chain (linked sugars-antigenec determinant)
- core polysaccharide(similar between species)
- lipid A (Toxin)-(phosopolipid with glucosamine instead of glycerol in outermsmbrane)
24
Q
mycoplasma are exceptions to the rules of bacteria because?
A
they have no cell wall
25
what are the smallest known bacterial species
mycoplasma (parasitic bacteria)
26
the membrane of mycoplasma contain a _____ molecule
sterol-like
27
what environments can you find mycoplasma
osmotically protected environments
28
what causes walking pneumoniae
mycoplasma pneumoniae
29
in negativing staining what takes up ink
everything except the bacteria
30
capsule
a slime layer of thick hydrophilic gel that surrounds the bacterial cell
31
usually polysaccharides are made up of single or multi sugars but some are made of what?
polypeptides
32
the discrete layer=
| and the amorphous=
capsule; slime layer
33
purposes of capsules
1. to protect bacteria from the immune system
| 2. provide nutrients- can be digested by enzymes
34
what is the presence of the capsule dependent on
the growth conditions. if nutrients aren't available for the bacteria it can be broken down into sugar
35
flagella are found in both
gram - and +
36
rotating helical protein
whip like structures of flagellin protein responsible for motility
37
monotrichous
one flagella
38
lophotrichous
lots of flagella coming out of one end of the bacteria
39
amphitrichous
one flagella coming out of each side of the bacteria
40
peritrichous
multiple flagellum coming out of all sides of bacteria
41
fimbriae
small hair like projections (200-400 per cell)
Function: attachment
found in gram + and - and composed of fimbrilin protein
42
pilli
longer and thicker than fimbriae (1-10 per cell)
| Function: attachment and DNA transfer; composed of piling protein
43
sex pili
a type of pili that transfers DNA between gram - bacteria
44
spores
resistant to heat and can germinate after centuries; purpose is survival under adverse conditions. quiescent
45
when are spores produced
in response to nutrient limitations or related sign that tough times are coming
46
how are spores made
by environmental slates (bacillus species)
47
spores are composed of DNA surrounded by ____
membrane/ cortex thats notmetbolically active
48
are spores found in gram + or gram- bacteria
gram + only
49
the cell membrane is a site for _____ like the eukaryotic cell _____
metabolic activity; mitochondria
50
cell wall rigidity is provided by
peptidoglycans
51
hair like pike mediate attachment to
human cells
52
plasmids separate??
pieces of circular DNA that can transfer itself
53
when a bacteria genome is larger it can?
survive in lots of difference places
54
what are the 4 important ways bacteria metabolism differs for eukaryotic cells
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
catabolism
breakdown of carbon source into ATP
56
anabolism
uses energy to synthesize macromolecules
57
3 types of energy generation in bacteria
1. embed-meyerhof glycolytic pathway
2. pentose phosphate pathway
3. krebs cycle
58
embden-meyerhof glycolytic pathway
atp, metabolic intermediates and pyruvate are fermented go into TCA cycle
59
pentose phosphate pathway
generates NADPH and Pentoses and ribose 5-phosphate
60
krebs cycle
generates ATP from oxidative phosphorylation (aerobic only)
61
carbon source varies by?
Bacterial species and environment
62
entry reactions require?
facilitated diffusion/transport
63
precursor are turned into?? metabolites
nucleotides, raw materials etc
64
fermentaton
starts with pyruvate and transfers electrons and protons via NAD + directly to an organic acceptor SUBSTRATE LEVEL PHOSPHORYLATION
65
repiration
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
reparation requires what?
a chain of carrier proteins found in the membrane
67
aerobes vs anaerobe classification is based on
the ability to cope with deleterious effects of oxygen
68
oxygen is only middle toxic but gets turned into
hydrogen peroxide (catalase or peroxidase) and superoxide anion (superoxide dismutase)
69
organisms that lack _____ and____ are strict anaerobes
catalase and superoxide dismutase
70
facultative aerobes
can grow with or without O2 (ecoli)
71
aerotolerant anaerobes
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
microaerophiles
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
halophile
require high concentration of salt for growht
74
osmophile
capable of growth in higher sugar concentrations
75
thermophile
can grow between 45-122 c
76
doubling time
time it takes a single bacteria to divide in two
77
doubling time is determined by
environmental conditions, and limited by expression of genes needed to metabolize nutrients and replicate DNA
78
lag phase
time when bacteria adapt to environemtn
79
exponential log phase slope of line =
growth rate -Td
80
stationary phase
where growth stops because nutrients are exhausted or toxic by product build up
81
Chromosomal DNA in bacteria are ____ in a _____
supercoiled; nucleic structure
82
DNA gyrase
introduces supercoils in bacterial chromosomal replication
83
Topoisomerase I
relaxes supercoils in bacterial chromosomal replication
84
steps to bacterial chromosomal replication
1. initiation (depends on growth rate)
2. Elongation
3. Termination
85
DNA replication is ____ and _____
Bidirectional and semi-conservative
86
bidirectional
proceeds away form origin and ends when polymerases meet at terminator
87
semi-conservative
each daughter DNA contains half new and half old DNA
88
Takes 40 mins replicate E. coli chromosome,
but cells divide every 20 mins. How is this
possible?
Rate of DNA replication is determined by rate of initiation
89
multi-fork replication
more than 2 origin points with one terminus
90
Mutations (spontaneous)
changes to DNA sequence occur once in every million cells for any one haploid gene
91
base substitution
when a nucleotide is changed
| Effect: no effect on sequence but could effect expression
92
insertion
when nucleotide is inserted
| Effect: If in coding sequence- frame shift
93
deletion
when nucleotide is deleted
| Effect: if in coding sequence- frame shift
94
nonsense
when a nucleotide change results in a STOP codon
| effect: truncated protein
95
missense
when nucleotide change results in an amino acid change
| Effect: dysfunctional protein or antibiotic resistance
96
duplication
when DNA sequence is abnormally copied
| Effect: may result in abnormal protein function or frameshift
97
homologous recombination
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
what does homologous recombination require
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
4 ways bacteria acquire DNA
1. natural transformation
2. conjugation
3. transduction
4. transposable elements
100
Natural transformation
ability to take up DNA from the environment (streptococcus and neisseria gonorrhoeae)
101
conjugation
transfer of plasmid DNA through sex pili
| enterococcus faecium
102
Transduction
bacteria phage (virus) accidentally inject bacterial DNA into host bacteria cell (s. pyogenies)
103
transposable elements
DNA that can insert or excise itself from the chromosome or plasmid (e.coli)
104
during bacterial transformation: once in the cell DNA either ____ or ____
gets degraded by nucleases used for raw materials or gets integrated into the chromosome via recombination pathway
105
Natural transformation
ability to take up DNA from environment
106
meditation by quorum sensing
in natural transformation when peptide pheromones produced by other bacteria are sensed by bacteria and turn on genes for competence
107
steps of conjugation
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
what are the two cycles of transduction
1. lytic cycle
| 2. lysogenic cycle
109
lytic cycle
the phage DNA attaches to bacteria and injects DNA into cytoplasm. creates new phages and the CELL LYSES to release new phages
110
lysogenic cycle
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
______ carry genes for antibiotic resistance or virulence genes
larger transposons
112
making mRNA and protein is ______
energetically expensive
113
why must bacteria tightly control gene expression
so only the proteins needed for a particular condition are expressed
114
quorum sensing
way that bacteria sense their environment (controls when certain proteins are made)
115
the strength of the integration between RNA polymerase and the promoter can determine
the amount of mRNA that gets made
116
RNA polymerase
binds to promoter located upstream of gene start codon
117
operon
multiple genes arranged together on same mRNA transcript expressed from same promoter (co-transcribed)
118
as soon as mRNA is made it can interact directly with ribosomes of bacteria cells because?
there are no organelles separating them
119
steps of genetic regulation
1. transcriptional
2. post- transcriptional
3. translational
4. post-translational
120
transcriptional genetic regulation
promoter activity is regulated by transcription factors, sigma actors dn other proteins
121
post transcriptional genetic regulation
mRNA stability
122
regulation of Lac operon is an example of what type of gene regulation
post translational regulation
123
virulence factors
genes directly related to the ability of bacteria to cause disease
