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MicroBio Exam #2
Ch. 4 starting Slide 13 through end of Ch. 6
160
Biology
Undergraduate 4
10/16/2011

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Term
Microbial Growth
Definition
an increase in cell numbers
Term
Generation
Definition
The formation of two cells from one
Term
Generation Time
Definition
Time required for the cell number to double (also called doubling time)
Term
Doubling Time
Definition
time required for the cell number to double This is a convenient growth parameter when you compare growths
among bacteria or in different conditions.(also called generation time)
Term
Binary Fission
Definition
Process by which most bacteria divide by
Term
Septum
Definition
In the proces of binary Fission, a septum is a partition or division formed by divisome
Term
Divisome
Definition
Cell division apparatus at septum
Term
FtsZ
Definition
After the DNA is duplicated in a cell undergoing Binary Fission, these Protiens form a ring and begin the dividing process.
Term
Min
Definition
The protien that determines the FtsZ ring assembly.
Term
MreB
Definition
Localizes synthesis of new peptidoglycan
Term
Autolysins
Definition
Creates small openings in peptidoglycan to which peptidoglycan can be added
Term
Autolysis
Definition
If there are Autolysins and new peptidoglycan is not added the cell with lyse because it has a hole in the wall. Also called Self Breaking.
Term
Peptidoglycan Synthesis Step 1 of 8
Definition
Sequential addition of L-Ala, D-Glu and L-Lys (or DAP in Gram[-]) to UDP-NAM
Term
Peptidoglycan Systhesis step 2 of 8
Definition
Attachment of a dipeptode D-Ala-D-Ala
Term
Peptidoglycan Synthesis Step 3 of 8
Definition
Transfer of NAM-pentapeptide to a membrane-bound lipid bactoprenol. UMP is released.
Term
Peptidoglycan Synthesis Step 4 of 8
Definition
NAG from UDP-NAG is linked to NAM
Term
Peptidoglycan Synthesis Step 5 of 8
Definition
Bactoprenol carrying NAM-NAG moves to the outer side of the membrane where transpeptodases and transglycosylases (two so-called penicillin-binding proteins) bind to D-Ala-D-Ala part.
Term
Peptidoglycan Synthesis Step 6 of 8
Definition
Transglycosylase attaches the new disaccharide unit to an existing peptidoglycan chain.
Term
Peptidoglycan Synthesis Step 7 of 8
Definition
Transpeptidase then links two peptide side chains with the pentiglycine cross link (Staphlococcus aureus). The terminal D-Ala is removed in the process. Other bacteria (eg.E.coli) directly form a peptide bond without pentaglycine.
Term
Peptidolycan Synthesis Step 8 of 8
Definition
One phosphate is removed from bactoprenol, which then moves back to the cytoplasmic side for recycle.
Term
Trasglycosylases
Definition
Enzymes that interact with bactoprenol to insert cell wall precursors into growing points of cell wall and to catalyze glycosidic bond formation
Term
Transpeptidases
Definition
Enzymes that catalyze the final step in cell wall synthesis to form the peptide cross links between muramic acid residues in adjacent glycan chains (inhibited by the antibiotic penicillin and others)
Term
How many D-Ala are removed during Transpeptidation and why
Definition
One is removed, which drives the reaction forward (no ATP needed)
Term
β-lactam antibiotics (eg. Penicillin)
Definition
block transpeptidation by directly binding and preventing the activity of transpeptidase
Term
Cycloserine
Definition
inhibits two enzymes
that make D-Ala-D-Ala dipeptide.
Term
Bacitracin
Definition
binds to and inhibits
dephosphorylation of bactoprenol,
blocking its recycle.
Term
Vancomycin
Definition
blocks transpeptidation
but by binding to D-Ala-D-Ala and
preventing cross-linking.
Term
Exponential Growth
Definition
growth of a microbial population in which cell
numbers double within a specific time interval
Term
Batch culture
Definition
a closed-system microbial culture of fixed volume (no extra
nutrients except the ones to start with and no waste removal)
Term
Lag phase
Definition
required to adapt to a new growth condition
Term
Exponential phase
Definition
log phase (number of cells doubles regularly)
Term
Stationary phase
Definition
run out of food or produce waste products. Equilibrium
between new cell division & cell death (cryptic growth)
Term
Death phase
Definition
metabolic balance is affected and cells begin to die. Sometimes
they lyse and other times they don't
Term
Total Cell Count
Definition
Includes both viable and dead cells
Term
Viable Cell Count
Definition
Measures number of living cells (Colony Forming Units, CFU) Complex and slow, but provide info about viable cells
Term
Turbidity measurement
Definition
an indirect
but very rapid and useful method of
measuring microbial growth
Term
Optical Density (OD)
Definition
The higher OD
value, the more turbid the cell
suspension
Term
What must be done to keep a culture in a constant enviroment?
Definition
You must continually feed it and remove wastes.
Term
Continuous culture
Definition
keeping a culture in a constant enviroment. Done in a Chemostat
Term
Chemostat
Definition
Where a Continuous Culture is kept.
Term
Limiting nutrient
Definition
Used to control the culture in a chemostat by limiting the amount of a nutrient such as glucose or phosphate. Can be used to adjust the population density
Term
Growth Rate
Definition
change in cell number per unit time
Term
Growth Yield
Definition
amount of biomass produced during bacterial
growth on a given substrate. YATP= Grams of dry cell material
produced per mole of ATP.
Term
growth medium
Definition
When a cell has to
make everything from scratch this requires more energy and more time
Term
Factors affecting Growth Rate
Definition
growth medium, temperature, water availability, osmolarity, and pH
Term
temperature
Definition
a major environmental factor controlling microbial growth
Term
Cardinal temperatures
Definition
Minimum,
Optimum, and Maximum temperatures
characteristic of each microorganism
Term
psychrophiles
Definition
cold loving. Cellular macromolecules function at low temps, Membranes contain unsaturated fatty acids that keep it fluid at low temperature. Enzymes have more α-helices and fewer β-sheets, Proteins contain more polar amino acids and fewer hydrophobic amino acids.
Term
mesophiles
Definition
Organisms that live at the temperature range of warm blooded
mammals.
Term
thermophiles
Definition
Optimum temperature is above between 45 and 80 °C. Bacteria have lipids rich in saturated fatty acids. Archaea have lipid monolayer rather than bilayer.
Term
hyperthermophiles
Definition
Temp optimum above 80 °C There are several habitats on earth where things live at temperatures near or above the
boiling point of water. Hot springs, deep sea vents.
Term
4 groups of microbes based on temp optima
Definition
psychrophilies, mesophiles, thermophiles, hyperthermophiles
Term
psychrotolerant
Definition
Organisms that grow at 0 °C (not well but do grow) but have optima of 20 - 40 °C. These are a problem for the food industry and in your refrigerator. Just
because cells aren't able to grow doesn't mean that they are dead.
Term
Acidophiles
Definition
-Organisms that prefer low pH.
- Many fungi prefer this. Also many bacteria are acidophiles.
- In these organisms, the plasma membrane is stabilized by high H+ concentration and when shifted to more neutral pH the membrane dissolves and the bacteria lyse.
Term
Alkaliphiles
Definition
- Prefer high pH.
- Usually found in regions with high carbonate deposits (soda lakes).
Term
Neutrophiles
Definition
pH between 6-8
Term
Halotolerant
Definition
Grow optimally at
normal salt concentrations
(0.85%) but are able to grow well
at high salt concentrations
(reduced water activity) (7.5%)
Term
Halophiles
Definition
Organisms which
grow optimally in salt
concentrations equal to sea
water. (3% NaCl + many other
minerals)
Term
Extreme halophiles
Definition
Organisms that live in extremely salty environments
(15 - 30% NaCl). Some actually grow on salt crystals
Term
Osmophiles
Definition
Organisms that live in high sugar concentrations
Term
Xerophiles
Definition
Organisms that live in very dry environments
Term
The higher the water activity
Definition
the more
water is available for
microbes to use
Term
Synthesis of compatible solutes
Definition
increase the concentration of a solute inside
the cell which is compatible with the cell (non-inhibitory to biochemical processes)
so the water does not move out of the cell
Term
Examples of compatible solutes used by microbes
Definition
Glycine betaine, proline, glutamate, trehalose, glycerol
Term
Staphylococcus epidermidis
Definition
Halotolerant, grows on your skin
Term
Aerobes
Definition
need oxygen, includes Obligate, Facultative, Microaerophilic.
Term
Anaerobes
Definition
don't need oxygen, includes Aerotolerant and Obligate
Term
Catalase Test
Definition
Add 30% hydrogen peroxide to bacterial cells and look for bubbles. Cells of the immune system (Phagocytes) produce hydrogen peroxide to
kill bacteria. Bacteria that produce catalase are able to survive this
chemical attack from the immune system. Catalase is therefore a virulence
factor.
Term
Virulence factor
Definition
How well a bacteria will stand up to an immune system.
Term
Clostridium
Definition
One of the best known genera of anaerobic bacteria,
Term
Clostridium botulinum
Definition
Causes Botulism
Term
Clostridium tetani
Definition
causes tetanus after a deep puncture wound
Term
green fluorescent protein
Definition
Found in Jellyfish. This protien absorbs ultraviolet light from the sunlight, and then emits it as lower energy green light.
-This protien can be used to look directly at the inner workings of cells, by attaching the protien to any object you are interested in watching, i.e. a virus and see how it spreads through a host by shining ultraviolet light on it.
Term
Steady-State (4)
Definition
All living things must have an energy source to maintain this. NOT Equilibruim because there is no reverse reaction, the system is not closed, and there is a constant input of reactants and outflow of products
Term
Biological catalysts
Definition
lower the energy of activation (a.k.a. enzymes) Typically protiens. Increase the rate of reaction by 10 to the 8th - 10 to the 20th times.
Term
ΔG°' (4)
Definition
Will tell you what the concentration of reactants and products are at the end of a reaction (equilibrium) but won't tell you hohw long the reaction will take.
Term
Activation energy (4)
Definition
Required to bring all molecules ina chemical reaction into the reactive state
Term
Catalyst (4)
Definition
usually required to breach activiation energy barrier.
Term
Active Site (4)
Definition
an Enzyme must bind it's subtrate here
Term
Ribozymes (4)
Definition
RNA Enzymes
Term
Enzyme-substrate specificity (4)
Definition
The shape of the enzyme is very important because it ust be just the right shape to bind it's substrates and carry out its reaction.
Term
Physical conditions that affect Enzyme shape (4)
Definition
pH and Temperature.
Term
Cofactors and the two types (4)
Definition
Small non-protien molecules that participate in catalysis but are not substrates. Prosthetic groups and Coenzymes
Term
Prosthetic Groups (4)
Definition
Tightly (covalently) bound cofactors
Term
Coenzymes (4)
Definition
Loosely bound cofactors that are used to carry small molecules (functional groups) or electrons from one enzyme to another.
Term
Reduction potential (4)
Definition
The tendency to be reduced of a compound
Term
Electron Carriers (4)
Definition
Prothetic groups or Coenzymes
Term
fermentation (4)
Definition
Oxidation of organic compounds in the
absence of an external electron acceptor. Organisms that
ferment actually use an internal electron acceptor, substrate-level phosphorylation.
Term
respiration (4)
Definition
Oxidation of organic compounds in the
presence of an external electron acceptor, oxidative phosphorylation.
Term
Glycolysis (4)
Definition
Conversion of glucose to pyruvate
Term
Production of fermentation products (4)
Definition
conversion of pyruvate to
various fermentation products
Term
Glycolysis (4)
Definition
See Slides 30-34 in chapter 4
Term
Aerobic respiration (4)
Definition
External electron acceptor is
oxygen
Term
Anaerobic respiration (4)
Definition
External electron acceptor is
something other than oxygen
Term
Electron Transport System (4)
Definition
Part of Aerobic Respiration. Electron carriers are oriented in the membrane in such a way that, as
electrons are transported, protons are separated from electrons.During this process, several protons are released outside of the membrane,
resulting in the generation of proton motive force.
Term
electrochemical gradient of
protons (4)
Definition
proton motive force, drives conversion of ADP to ATP through ATP
synthase
Term
Inhibitors of ETS (4)
Definition
cyanide (CN-) & CO binds to the Fe of the porphyrin ring (in a-type
chytochromes) and prevents it from accepting electrons.
Term
Uncouplers (4)
Definition
- prevent ATP synthesis without affecting electron transport (uncoupling
PMF and ATP synthesis)
Term
Anabolism (4)
Definition
Some of energy conserved as
ATP during catabolism is used for
biosynthesis of cell material
Term
Gluconeogenesis (4)
Definition
essentially running
glycolysis backwards.
Term
Primary Structure of nucleic acids (6)
Definition
Sequence
of nucleotides in a DNA or RNA molecule
Term
Secondary Structure (6)
Definition
folding structure in a
DNA or RNA molecule.
Term
DNA polymerases (6)
Definition
Enzymes that do the replication or copying of DNA in a cell.
Term
RNA polymerase (6)
Definition
Enzyme that makes an RNA copy of the gene. mRNA.
Term
Ribosomes (6)
Definition
Converts the mRNA into protien by reading the three letter at a time and hooking the correct amino acids together to make a protien.
Term
Genetic Code
Definition
The way that information is stored in DNA or RNA is the sequence of the nucleotides taken 3 at a time.
Term
codon
Definition
Three letter sequence that codes for an amino acid in mRNA
Term
Regulation
Definition
Not all genes are active at the same time. If they were it would
constitute a tremendous waste of energy. Instead they are turned on
(transcribed) only when they are needed.
Term
inducible
Definition
Genes that are not on all of the time, turned on by inducers
Term
constitutive
Definition
Genes that are always turned on
Term
Operon
Definition
unit of transcription
Term
introns
Definition
spaces in gene coding
Term
exon
Definition
the actual coding part or a gene
Term
Minor Groove
Definition
Smaller groove in DNA
Term
Major groove
Definition
Bigger grove in DNA
Term
DNA binding proteins
Definition
bind DNA by interacting with regions of DNA
containing repeated sequences that are arranged in inverse orientation (inverted
repeats)
Term
denaturation (6)
Definition
melting of doublestranded
DNA into single-stranded DNA
Term
Hyperchromicity (6)
Definition
Single-stranded DNA
(ssDNA) absorbs more UV light than doublestranded
DNA (dsDNA) so when dsDNA melts
(denatures) you get an increase in absorbance
Term
DNA hybridization
Definition
Since the ability of two strands of DNA to base pair depends on them having
complementary antiparallel sequences, denatured DNA strands in solution can
find each other and reform the double helix if they are cooled slowly in the same
solution.
Term
Negative supercoiling
Definition
is when the DNA is
twisted in the opposite direction of the
helix and positive supercoiling is when
the DNA is twisted in the same direction
as the helical turns.
2. Positive supercoiling have been discovered in extreme thermophiles. This may
stabilize their DNA in hot environments. Reverse gyrase is an enzyme that catalyzes
positive supercoiling in some extreme thermophiles.
DNA Supercoiling
- Negative supercoiling is
most common in nature.
Gyrase (topoisomerase II is the enzyme that introduces it.
Term
Positive supercoiling
Definition
discovered in extreme thermophiles. This may
stabilize their DNA in hot environments. Reverse gyrase is an enzyme that catalyzes
it in some extreme thermophiles
Term
Topoisomerase I
Definition
an enzyme that cleaves the
phosphodiester bond in a single strand in the DNA and
causes the tension to relax. This removes the supercoiling
Term
Genetic elements
Definition
nucleic acids that:
1. Have genes.
2. Replicate themselves
Term
Prokaryotic Chromosomes
Definition
No nucleus so transcription and translation
are coupled - as soon as the mRNA has begun
being made translation begins
Term
Eukaryotic Chromosomes
Definition
Transcription and translation are not coupled
since mRNA must be transported out of
nucleus.
Term
DNA Replication is..
Definition
Semiconsevative & Bi-directional
Term
Okazaki fragments
Definition
small pieces of a DNA strand are about 1000 nucleotides long
Term
Requrements for DNA Replication
Definition
Template, Primer, Primase, DNA Polyerase III, neucleotide Triphosphates, DNA polymerase, DNA helicase, Single-stranded binding protien, DNA Ligase
Term
Template
Definition
must have something to copy. The strand that is copied is called the template
Term
Primer
Definition
Must have a starting place. You must have something to hook the nucleotides to (-
OH group) as they are brought in place. This is a short strand of RNA. Remember that
the nucleotides are added in a 5' to 3' direction
Term
Primase
Definition
A specific type of RNA polymerase that copies the first 11 nucleotides by making
an RNA chain 11 ribonucleotides long
Term
DNA polymerase III
Definition
Enzyme that catalyzes the addition of the nucleotides to the primer
and then to the growing DNA strand
Term
Nucleotide triphosphates
Definition
dATP, dTTP, dCTP,
dGTP. Precursors for the growing chain
Term
DNA polymerase I
Definition
When replication is well
under way this enzyme chews up the RNA
primer (RNase H) and replaces it with DNA.
Term
DNA helicase
Definition
This is a DNA unwinding protein.
Term
Single-stranded binding protein
Definition
Proteins that
bind to the unwound (ss)DNA and prevent it
from re-base pairing
Term
DNA Ligase
Definition
Attaches the ends of two DNA
strands
Term
Base pairing
Definition
DNA polymerase III reads the template nucleotides accurately
and usually inserts the correct complementary nucleotide, way of DNA replicaton fidelity
Term
Proofreading
Definition
DNA polymerase III is able to detect incorrect nucleotides that
are not complementary and remove them by chewing back the new strand
from the 3' end (3
Term
Transcription
Definition
Making an RNA copy of a
gene. Messenger RNA (mRNA). This
carries the information in the DNA for
protein synthesis. The enzyme that does
this is called an RNA polymerase
Term
RNA Polymerase
Definition
Catalyzes Trasncription
Term
Three steps of Transcription
Definition
Initiation, Elongation, termination
Term
Rho dependent
Definition
RNA Polymerase reaches a
Term
Rho independent
Definition
Inverted repeats (GC-rich
region of RNA roughly 20 bp upstream
from the 3
Term
Operons
Definition
prokaryotic transcriptional units whose expression is controlled by a
single regulator sequence
Term
Translation
Definition
Converting the mRNA into
protein by reading the three letters at a time
and hooking together the correct amino
acids to make a protein. Ribosomes do
this.
Term
Components of Translation
Definition
1. Aminoacyl-tRNA - tRNAs carrying the amino acids
2. mRNA - carries the genetic instructions from the DNA
3. Ribosomes - catalyze assembly of the amino acids into
peptides
4. Translation Factors - proteins that are not part of the
ribosome but are required for proper protein synthesis.
Term
Codon-anticodon interaction
Definition
Note that codon-anticodon recognition by
base-pairing is also anti-parallel. The first two positions in codon should form
standard base pairing but the third one can form irregular base pairing (Wobble
base pairing)
Term
degeneracy
Definition
no one-to-one correspondence between the
amino acid and the codon
Term
Open Reading Frame
Definition
a
start codon (mostly AUG, sometimes GUG) followed by some number of
codons and then a stop codon in the same reading frame.
Term
polysomes
Definition
A single mRNA with several rbosomes translating at the same time.
Term
coupled transcription and
translation
Definition
Done when there is no nucleus, ribosomes can bind to the mRNA before
it is finished being transcribed
Term
Primary structure
Definition
the sequence of amino acids in a peptide or protein
Term
Secondary structure
Definition
the repeating conformational patterns
formed by twist and fold in a polypeptide
Term
Tertiary structure
Definition
a unique 3-dimensional shape formed
by combinations of secondary structures of a polypeptide
Term
Quaternary structure
Definition
a unique 3-dimensional shape formed by
more than two polypeptides
Term
Disulfide bonds
Definition
occur intramolecularly (i.e within a single polypeptide chain) and
intermolecularly (i.e. between two polypeptide chains)
Term
Quintary structure
Definition
an assembly or complex formed by
more than two proteins
Term
Denaturation
Definition
unfolding of polypeptide chain
Term
Renaturation
Definition
restoring proper folding upon removal of denaturing agents
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