Exam 4 Flashcards
(138 cards)
1
Q
Two types of growth in prokaryotes
A
Intercalary and Polar
2
Q
Most common form of intercalary growth
A
binary fission
3
Q
4 types of polar growth
A
- Simple Budding
- Budding by hyphae
- Cell Division in Stalked Bacteria
- Polar growth without differentiation of cell size
4
Q
The growth of most microbes occurs by the process of
A
binary fission
5
Q
What are the progeny like after the cell goes through binary fission?
A
The two progeny are exactly the same as the original cell
6
Q
Steps in Binary Fission
A
- Cell Elongation
- Septum Formation (pinch b/w cells)
- Completion of Septum
- Formation of Walls
- Cell Separation
7
Q
What happens to the DNA during binary fission
A
The DNA is copied (1 origin of replication to 2). The origins more to opposite sides of the cell and pull it apart.
8
Q
Enzyme that moves the origins of replication to the opposite sides during binary fission
A
translocase
9
Q
Steps in cell division
A
- DNA replication
- Formation of Divisome
- Cell elongation
10
Q
proteins that ensure divisive forms at cell center
A
Min
11
Q
proteins form ring where cell begins division
A
FtsZ
12
Q
proteins that help hold FtsZ ring to cytoplasmic membrane
A
FtsA
13
Q
in all 3 domains, this relaxes supercoils ahead of the replication fork
A
type II topoisomerase (DNA Gyrase)
14
Q
in all 3 domains, this unwinds double helix at the replication form
A
DNA helicase
15
Q
in all 3 domains, this adds RNA primer
A
primase
16
Q
in all 3 domains, this adds deoxyribonucleotides in a 5’ to 3’ direction, complementary to the 3’ to 5’ strand
A
DNA polymerase (mainly DNA polymerase III)
17
Q
What is the direction of synthesis in DNA replication
A
5’ to 3’
18
Q
How is replication terminated in circular chromosomes?
A
Tus proteins recognize Ter sites and block the progress of the replication fork
19
Q
How is replication terminated in eukaryotic chromosomes?
A
eukaryotes have telomerase to complete the ends of linear chromosomes to form the telomeres at each end
20
Q
what happens to telomeres as you age
A
Telomeres get shorter as you age, but the only thing you lose is repeats
21
Q
proteins that ensure divisome forms at cell center
A
Min
22
Q
protein that forms ring were cell begins division
A
FtsZ
23
Q
protein that helps hold ftsZ ring to cytoplasmic membrane
A
FtsA
24
Q
proteins that form filamentous spiraled bands around inside of cell under the cytoplasmic membrane to direct new cell wall to be made at certain locations
A
MreB
25
penicillin binding proteins that are transpeptidases that insert new peptidoglycan into expanding cell wall
FtsI
26
proteins that are DNA translocates that move DNA during cell division
FtsK
27
Direction of synthesis in the replication bubble
5' to 3'
28
How do bacteria and archaea terminate replication?
Circular chromosomes have Ter sites across from the origin of replication are recognized by Tus proteins that block the progress of the replication fork
29
sequences in the DNA where the Tus proteins bind
Ter sites
30
How do eukaryotes terminate replication?
Eukaryotes have telomerase to complete the ends of linear chromosomes to form the telomeres at each end
31
How does the MinE protein change as it moves through the cell
MinE proteins increase in concentration as it goes to the center of the cell
32
where does cell division take place
where the MinE protein concentration is at it's highest
33
where does the FtsZ ring form
at high concentration of MinE protein
34
create small openings in existing cell wall
Autolysins
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When may autolysis (spontaneous cell lysis) occur
if there is an error in inserting new cell wall material
36
steps of cell wall synthesis
1. Formation of peptidoglycan precursors
2. Transport of Pep. Precursors to expanding cell wall
3. Insertion of peptidoglycan precursors into existing cell wall
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hydrophobic lipid alcohol that binds the peptidoglycan precursor and facilitates transport through the cytoplasmic membrane
Bactoprenol
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peptide bonds formation between pentapeptide of peptidoglycan precursor and tetra peptide of an existing peptidoglycan unit
Transpeptidation
39
what is growth?
increase in the number of cells
40
An example of an organism that grows through simple budding
sacharomyces
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an example of a microbe that grows by budding from hyphae
hyphomicrobium
42
the end of the cell that begins to elongate in budding by hyphae
hypha
43
What are the steps in budding by hyphae?
1. End of cell begins to elongate and hypha lengthens DNA replication.
2. Copy of chromosomes enters bud.
3. Formation of cross-septum
4. Progeny that gets release has flagella
44
What happens when the progeny produced in budding by hyphae are ready to divide?
They will drop their flagella and follow the steps for budding by hyphae
45
example of a microbe that divides using the steps for cell division in stalked bacteria
caulobacter
46
Steps of cell division in stalked bacteria
1. Loss of flagellum
2. Initiation of DNA synthesis and stalk begins to grow
3. Elongated stalked cell (synthesis of flagellum) and stalk attaches to a surface
4. Previsional cell - cross band formation
47
How do eukaryotes grow?
Sexual and/or asexual reproduction
48
2 parents (meiosis from haploid cells (egg & sperm); fusion of haploid cells yields diploid zygote)
sexual reproduction
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1 parents (mitosis keeps policy the same, so haploid yields haploid and diploid yields diploid)
asexual reproduction
50
What is the life cycle of Saccharomyces cerevisiae
1. Budding - replication of genome
2. Haploid (1n) form
3. Diploid (2n) form
51
haploid form of saccaromyces that are germinated
ascospores
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How do alpha and A strains (mating types) affect the haploid form of saccharomyces
A gives rise to more A cells
alpha gives rise to more alpha
via mitosis
53
When can cells of opposite mating types fuse?
Only under stress-like conditions
54
What is the life cycle of Chlamydomonas?
During sexual reproduction (stressful state), + and - type fuse at their flagella. Once they fully fuse together, they form a crusty outer layer (zygote, protects meiosis happening).
55
Why does meiosis occur in Chlamydomonas?
It occurs so that when conditions are favorable, the zygote breaks open to release the mature haploid cells
56
transition period to allow synthesis of enzymes for biosynthesis
lag phase
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period of regularly dividing cells, the culture is becoming more turbid
exponential phase
58
period where the essential nutrients have been depleted, toxic products build up, and growth stops while cells wait for the environment to be conducive for growth
stationary phase
59
What happens if conditions never look good in stationary phase?
Endospore forming microbes begin to form endospores
60
period where cells die and viable count can be taken
death phase
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time required for one cell to form two cells
generation (doubling) time
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growth pattern where number of cells doubles over a regular time interval
exponential growth
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N=number of cells=
No2^n
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Generation time=G=
t/n
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counts the total number of cells by direct microscopic count (hemocytometer)
total cell count
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How does a hemocytometer work?
Has grid to count cells. In five of the 25 squares, you count n cells in each. The grid of 25 squares has 0.1 microliters.
67
How do you count viable cells?
plate or colony count
68
continuous culture devices that maintain cell populations in exponential growth for long periods
chemostats
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What must be controlled in a chemostat to keep the culture alive, and how is it controlled?
Dilution rate & concentration of limiting nutrients.
| OverFlow (containing microbial cells) & Flow-Rate Regulator (introduces fresh medium)
70
What do the colors indicate in viability staining?
```
Green = Living
Red = Dead
```
71
What does FISH stand for
fluorescent in situ hybridization
72
How is fluorescence microscopy used to distinguish between organisms? What does it distinguish between?
Fluorescing ogligonucéeotides complementary in base sequence to sequences in rRNA. It can distinguish between prokaryotes and eukaryotes. It can go further to distinguish between bacteria and archaea. It can go even further to distinguish certain groups in bacteria or archaea
73
What does FISH-MAR stand for?
FISH-microautoradiography
74
How can FISH-Mar determine an organism's ability to use CO2?
Feed radioactive substance (CO2) and the ones that can metabolize it become radioactive and fluoresce
75
What property of a culture is being measured by turbidity measurements?
It measures how many cells are present, but not necessarily living cells
76
What measurement is used for a turbidity measurement?
spectrophotometer
77
What units is turbidity measured in?
optical density (OD)
78
What is the spectrophotometer measuring?
absorbency: an increase in cell numbers decreases the unscattered light measured and increases the OD
79
What does a standard curve represent?
Correlated turbidity measurements with actual cell number or mass to estimate cell number of future cultures
80
What is the difference between pasteurization and sterilization?
Pasteurization - reduces microbial load by killing most pathogens and inhibiting the growth of spoilage microbes
Sterilization - killing of all organisms
81
What is flash pasteurization?
Heat above which most microbes can survive for a brief period of time. 71 degrees celsius for 15 seconds
82
Four methods of physical sterilization
Heat (most common), Radiation, Filtration, and Cold/Gas
83
decimal reduction time
time it takes to kill 90% of the population. achieved better at higher temperatures
84
The temperature needed for heat sterilization depends on the ___ temp of growth for an organism
maximum
85
What equipment is used to heat sterilize?
Autoclave at 121 degrees celsius, using steam heat under pressure
86
What factors determine the amount of autoclave time needed for sterilization?
number, size, density
87
List 4 factors that increase heat resistance
high pH, high solute concentration, thermophiles, endospores (low water content)
88
What are the different types of radiation used for sterilization?
UV and Ionizing Radiation (more lethal)
89
What does UV Radiation do?
Sterilizes surfaces because it cannot penetrate solids. Causes thymine dimers in DNA.
90
What does Ionizing radiation (x rays, electrons, and gamma rays) do?
Causes breaks in the DNA strands. Breads hydrogen bonds and disulfide bridges in proteins. Can penetrate solids.
91
a device that has pores too small for microbes to git through but large enough for the liquid or gas to pass
filter
92
How do depth filters work?
Fibrous sheets or mats that trap filter particles from liquids and the air
93
What is commonly sterilized by depth filters?
liquids and gases
94
How do membrane filters work?
Thin sheets with 0.2 micrometer pores needed to filter our major pathogens. Act like sieves
95
What is commonly sterilized by membrane filters
antibiotics & other pharmaceuticals
96
freeze drying
lyophilization
97
chemicals that kill organisms
cidal agents
98
chemicals that inhibit (limit) the growth of microbes
static agents
99
antimicrobial growth agents that bind tightly to their cellular targets, lysis does not occur
Ex: triclosan blocks fatty acid synthesis in may bacteria
bactericidal agents
100
antimicrobial growth agents that kill cells by lysis
| Ex: penicillin inhibits cell wall synthesis
bacteriolytic agents
101
antibiotic inhibitors of protein synthesis by binding to ribosomes
bacteriostatic agents
102
azoles prevent formation of normal fungal cell membrane
fungistatic agents
103
digests paper
cytophaga
104
Antimicrobial chemicals used in the petroleum industry
mercurics, phenols, cationic detergents, methylisothiazolinone prevent growth
105
antimicrobial chemicals used in the air conditioning industry
chlorine, phenols, methylisothiazolione to prevent growth of bacteria in cooling towers
106
British surgeon found that survival rate of surgical patients increased if he sterilized instruments and used disinfectants during surgery
Lister
107
4 Categories of chemical antimicrobial agents used to control microbes considered to be harmful to humans
1. Sterilants
2. Disinfectants
3. Sanitizers
4. Antiseptics and Germicides
108
destroy all forms of life (ex. ethylene oxide gas, formaldehyde 3% or 37%, glutaraldehyde 2%, hydrogen peroxide, and peroxyacetic acid)
sterilant
109
kill microbes, but endospores are typically resistant (ex. ethylene oxide gas, formaldehyde 3%, glutaraldehyde, hydrogen peroxide, and peroxyacetic acid)
disinfectant
110
reduce the microbial load but may not eliminate all microbes
sanitizers
111
kill or inhibit growth of microbes on living tissue (Ex. triclosan)
antiseptics & germicides
112
Who was the first to coin the term chemotherapy
Ehrlich
113
the ability to kill or inhibit a pathogen without harming the host
selective toxicity
114
The first chemotherapeutic antimicrobial drug (created by Ehrlich and used to cure syphilis)
Salvarsan - it did not meet the criteria of selective toxicity
115
How do synthetic agents differ from antibiotics?
Synthetic agents are manmade and antibiotics are organic
116
highest concentration the drugs that will eliminate microbe
toxic dose
117
lowest concentration of the drug that will eliminate microbe
therapeutic dose
118
How does the sulfa drug, sulfanilamide, disrupt folic acid synthesis in bacteria?
Folic acid comes from p-Aminobenzoic acid. The bacteria will try to use sulfanilamide to make folic acid but it won't work. It confuses the cell.
119
How does ionizing disrupt mycelia acid synthesis in Mycobacterium?
inhibits mycelia acid synthesis and helps treat TB by making mycobacterial cells to look like any other gram positive cell
120
compounds that interact with bacterial DNA gyrate preventing the gyrase from supercoiling DNA
quinolones
121
What is the origin of all antibiotics?
Bacteria and Fungi
122
What term is used to describe the range of effectiveness for an antibiotic?
Antimicrobial Spectrum of Activity
123
effective against a wide variety of bacteria
broad spectrum antibiotics
124
effective on a subject of bacteria
narrow spectrum antibiotics
125
discovered by Alexander fleming because it was formed on Staphylococcus by chance
Penicillin made by Penicillium
126
What class of antimicrobial is penicillin?
Beta Lactan
127
bacteriolytic antimicrobial chemicals that are the most important and have low host toxicity
Beta Lactan
128
mode of action of beta lactan antibiotics
inhibit cell wall synthesis in bacteria by binding to transpeptidases
129
Made by fungus Cephalosporium. Same mode of action as penicillin but broader spectrum of activity and highly resistant to beta lactamases
cephalosporins
130
What do Carbapenems and Monobactams have in common?
They are derived from fungi
131
Derived from from Streptomycin cattle. Resistant to beta lactamase but degraded by kidneys. Must be given with a drug to prevent degradation. Broad spectrum
Carbapenems
132
Produced by Chromobacter violaceum. Beta-lactamase resistant. Helpful against Pseudomonas infections in CF patients.
Monobactams
133
Mutation rate of E. coli
1/100k - 1/1 billion progeny
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genome replication and cell division that produces 2 identical cells
vertical gene transfer
135
steps of transformation
binding DNA from donor cell
update of ssDNA
Rica mediated homologous recombination
previously susceptible cell is now resistant to antibiotics
136
transfer of any gene from one bacterium to another via a virus
generalized transduction
137
transfer of a specific region of bacterial chromosome to another bacterium via a virus; requires a lysogen to be removed incorrectly, a rare event
specialized transduction
138
Describe how resistance plasmids can make a bacterium resistant to an antibiotic.
The contain genes encoding enzymes that actively pump antibiotic out of cell and inactivate antibiotic. Plasmid and chromosomes can be transferred by conjugation
