Microbio Exam 2
One mL of a bacterial cell culture contains 2 cells at the beginning of the experiment, 8 cells one hour later, 32 cells after 2 hours, and 128 cells after 4 hours. Which of the following describes the generation time of the culture?
g = 0.5 h g = t/n= 2 h/4 = 0.5 h t is the duration of exponential growth = 2 hours (growth after 2 hours is not longer exponential an thus would not be considered in the calculation) n is the number of generations during the period of exponential growth = 4
orthologs
genes that evolved from a common ancestral gene by speciation generally maintain a similar function to the gene they arise from
The genome sequence of a bacterium can provide information about the organism's __________.
genes, function, and evolutionary history
Turbidity
gets cell count by measuring the absorbance of the sample for most cells absorbance is proportional to cell number - doesn't destroy sample - limited to liquid culture - organisms must grow as individual cells
primosome
helicase and primase subcomplex of the replisome
The lac operon is ____ if glucose is present.
inactive
The lac repressor is _____ if there is lactose present
inactive
pan genome
includes extra genetic elements (plasmids, transposons, chromosomal islands) that are not shared between species
bacterial cell cycle
initiated by the binding of DNAa to the oriC blocking of oriC regions by SeqA; cell elongation Segregation of chromosomes Z-ring formation Cell division
What is codon bias?
multiple codons for the same amino acid are not used equally
What is the effect of methylating MCPs?
no longer respond to attractants
Genome assembly relies on_________________________.
overlap of a large numbers of short sequences
How does DNA Pol III recognize errors?
paused by the abnormal hydrogen bonding Proofreading exonuculease activity removes the mismatched nucleotide In Pol III, subunit DnaQ perfoms proofreading activity
what are the steps for regulation of cell development?
response trigger (stimulus) Development of the differentiated cell Reciprocal communication between the two differentiating and undifferentiated cells
What molecule translates the mRNA into the protein sequence?
ribosome
CCW rotation
run
regulons
several operons that are regulated by a single protein
core genome
shared by all strains of the species
Which of the following is a signal for the initiation of transcription?
sigma factor recognizes the promoter
What are the four sigma factors that control endospore formulation?
sigmaF, sigmaE, sigmaG, sigmaK
How are antibacterial agents classified?
Antimicrobial drugs are classified on the basis of •Molecular structure •Mechanism of action •Spectrum of antimicrobial activity
454 sequencing (2nd gen)
Apyrase cleaves unused deoxyribonucleotides. Sulfurylase convertsAMP + PPi into ATP. Luciferase consumes ATP and emits light. Light flash is detected by sensor.
Picrophilus oshimae Domain Shape Classification
Archaea Coccus Acidophile: Grow in pH of 0.3 Thermophile Aerobic Heterotrophic
What are some antibiotics that inhibit DNA gyrase?
Quinlones (nalidixic acid) Fluoroquinolone (ciprofloxacin) Novobiocin (also effective against some Archaea)
Elongation
RNA chain grows until the termination site
sigma factor
controls the binding of RNA polymerase to the promoter
Viable cell counts
counting the cells capable of multiplying via a plate count - can use specific media to count certain cells - can only count culturable cells - incubation and viability affect counts - small colonies may be missed
Direct (total) cell count
counting the total (alive and dead) number of cells in a sample microscopically - does not require growth - small cells might be missed
Genes that encoded for polymerases, gyrases, ribosomal proteins, and other proteins essential to cell replication, transcription, and translation are present on ________and _________. i.Viruses ii. Transposon iii. Plasmid iv. Chromosome a. i, ii b. ii c. iii d. iv e. iii, iv
d
exospores
formed differently, less robust
Bacteria replicate via
binary fission
single-strand binding proteins
bind to and stabilize single-stranded DNA
What is another group behavior that is only done when there is quorum?
biofilm formation
N-acylhomoserine lactone (AHL)
biomolecule used in the regulation of lux operon bioluminesence via quorum sensing
Chromosomal islands
blocks of genetic material that are part of the chromosome (rather than a plasmid or integrated virus) that contain clusters of genes for specialized functions not needed for simple survival
A culture of E. coli is treated with the antibiotic ciprofloxacin, a fluoroquinolone. You would expect which of the following: ____________. a) transcription would be inhibited b) cell wall synthesis would be impaired c) DNA replication would be inhibited d) protein synthesis would be inhibited
c
Describe how microorganisms divide
cell elongation septum formation formation of cell walls and cell separation
Pathogenicity islands
chromosomal islands containing genes for virulence
Arginine is considered a ___________ since it binds to a repressor protein. The conformational change results in the ____________ of the repressor to/from the operator resulting in negative control of transcription.
co-repressor (allosteric regulator is the thing that changes conformation) binding
external signals for sporulation
-desiccation -cell density -starvation
You are interested in removing viruses from liquid via filter sterilization; you would need to select a _________ pore-size membrane.
0.02 µm
You are interested in removing viruses from liquid via filter sterilization; you would need to select a _________ pore-size membrane. 0.2 um 10 um 0.45 um 0.02 um
0.02 µm membrane
1 Mbp
1 million base pairs
Rho-dependent termination
1. Protein Rho binds to GC-rich regions without secondary structure 2. RNA wraps around the Rho hexamer, pulling itself toward RNA polymerase. 3. Contact between Rho and RNA polymerase causes termination.
Initiation of Transcription
1. RNA polymerase holoenzyme (core enzyme and a sigma factor that recognizes promoter) scans DNA for promoter 2. Binding to the promoter sequence forms the closed complex. 3. RNA polymerase unwinds the DNA and begins transcription. Sigma factor leaves the complex.
What does class I topoisomerase mean?
Makes a single-strand break allows for rotation of one strand over the other
What is the optimal range for a thermophile? Hyper? Meso? Psychro?
45º and 80ºC >80º 20-40 <15-20
Polysome
A complex formed when multiple ribosomes are translating the same mRNA into proteins.
lagging strand
A discontinuously synthesized DNA strand that elongates by means of Okazaki fragments, each synthesized in a 5' to 3' direction away from the replication fork.
Endospore
A thick-walled protective spore that forms inside a bacterial cell and resists harsh conditions.
What are the key recognition sites for tRNA?
Acceptor stem D loop anti codon (3'-5')
bacteriostatic agent
Agent that has the ability to inhibit or retard bacterial growth. No destruction of viability of the microorganism is implied.
Translocation and termination of translation
Amino acid shifts from the A site to the P site Uncharged tRNA in the P site shifts to the E site and is ejected (cycle continues three times) Ribosome reaches a stop codon and no tRNA comes to bind release factors (RF) recognize the stop codon and cleave it
primase
An enzyme that joins RNA nucleotides to make the primer using the parental DNA strand as a template.
helicase
An enzyme that untwists the double helix of DNA at the replication forks.
Define Growth as it pertains to Microbiology.
An increase in the number of CELLS.
Rifamycin B
Antibiotic affecting transcription 1.Selectively targets bacterial RNA polymerase 2.Binds to the binds to the Mg2+ active site that blocks the exit channel 3.A synthetic derivative (rifampin) is used to treat tuberculosis, leprosy, and contacts of individuals with bacterial meningitis
What is one function of plasmids?
Antibiotic resistance
Thermus aquaticus Domain Shape Mobility Location Classification Use
Bacteria Gram-Negative Rod-shaped Immobile Heterotrophic found in hot springs Thermophile used in polymerase chain reaction (PCR)
Allovibrio fischeri Domain Shape Mobility Use
Bacteria- rod shaped Gram-Negative Motile Produces bioluminesence via the lux operon
How is the cell wall forming?
Bactoprenol phosphate transports NAM and NAG across the cell membrane during the synthesis of peptidoglycan, by flipping the repeating monomer units from the cytoplasm to the periplasm. Autolysin - break the glycosidic bonds between the peptidoglycan monomers at the point of growth along the existing peptidoglycan. They also break the peptide cross-bridges that link the rows of sugars together. In this way, new peptidoglycan monomers can be inserted and enable bacterial growth. Transglycosylase (transglycosidase) enzymes insert and link new peptidoglycan monomers into the breaks in the peptidoglycan Transpeptidase enzymes reform the peptide cross-links between the rows and layers of peptidoglycan to make the wall strong
What type of replication has equal products of division?
Binary fission
What is the natural direction of flagellar rotation?
CCW (run)
sensor kinases of chemotaxis
CheA and CheW get phosphorylated according to MCP binding
describe the controlling flagellar rotation step of chemotaxis
CheA and CheW pass P to CheY CheY interacts with the flagella motor to induce a tumble (CW rotation) CheZ dephosphorylates CheY
response regulator of chemotaxis
CheY CheA passes phosphorylation to CheY that interacts with the flagellar motor to induce CW rotation (TUMBLE)
Identify genetic elements of microorganisms
Chromosome- one circular chromosome with essential genes Viral genomes- DNA or RNA can be inserted into the chromosome Plasmids- small circular or linear chromosomes that contain non-essential information and are not always kept and replicates separately Organellar genomes Transposable elements- segment of inserted DNA that can move around within the genome
What are two ways to regulate gene expression and protein activity?
Control the activity of preexisting enzymes: - constitutive synthesis - constitutive synthesis and activity inhibited Control the amount of enzymes - translation controlled - transcription controlled
What are the three global regulatory proteins for Caulobacter differentiation?
CtrA DnaA GcrA
Not all bacteria divide via symmetric cell division. Caulobacter crescentus alternates between two cell forms: a cell with a flagellum and a stalked cell. Discuss the global regulators that control whether or not Caulobacter will have a flagella or a stalk.
CtrA: Levels high (prevents DNA replication) = swarmer cell CtrA: Levels decrease = increases in DnaA and GcrA and loss of flagella = stalked cell DnaA and GcrA: levels high stalked cell capable of replicating (DnaA activates genes needed for chromosomal replication and GcrA promotes cell elongation)
Describe the mechanism of Caulobacter cell differentiation
CtrA: activated by phosphorylation in response to external signals Cell division CtrA-P activates genes for flagella synthesis and functions of swarmer cells (inhibits initiation of DNA replication) Loss of flagella CtrA degraded and DnaA levels rise. Access to the origin of replication is allowed since CtrA-P is absent. Formation of stalk DNA replication and formation of Swarmer DnaA is degraded and GcrA increases allowing for cell elongation. As CtrA concentrations rise, GcrA declines.
E. coli is growing in culture medium containing glucose and lactose. Graph, glucose concentration, lactose concentration, cell density, cyclic AMP, and beta-galactosidase concentrations. Discuss the regulatory system(s) controlling expression of Beta- galactosidase in E. coli.
Cyclic AMP is required to induce a conformational change in CRP which can bind to CRP binding site upstream of the lac operon. Transcription of the lac operon will not proceed until cyclic AMP has bound to CRP. However, the synthesis of cyclic AMP is inhibited by glucose. When glucose is depleted cyclic AMP will be produced. Cyclic AMP will bind to CRP. CRP binds to the CRP binding site on the lac operon inducing transcription. Transcription will proceed as allolactose (inducer) binds to the repressor. The repressor is released from the operator and transcription proceeds resulting in the production of beta-galactosidase and lactose metabolism.
Which DNA polymerase is mainly responsible for chromosomal genome replication?
DNA Polymerase III
Describe the structure of DNA
DNA is comprised of a chain of one of four nucleotides linked by a phosphate backbone and phosphodiester bonds. It is made of two strands running antiparallel and the complementary base pairs are linked together by hydrogen bonds. The structure is a double helix.
Identify the different stages of gene information flow
DNA is transcribed into RNA which is translated into protein or used in regulatory mechanisms
binary fission
DNA replicates Min proteins will guide FtsZ to the cell midpoint Cell elongation continues and the septum forms and the two copies of the chromosome are pulled apart. Cell wall constricts and the FtsZ ring depolymerizes and the cell wall grows inward forming two daughter cells
Describe assembly
DNA strands are sequenced in smaller pieces and then overlapped by a computer to generate a consensus sequence
Sanger sequencing (1st gen)
Dideoxynucleotides halt DNA polymerization at each base, generating sequences of various lengths that encompass the entire original sequence. Terminated fragments are electrophoresed and the original sequence can be deduced. or they are tagged with fluorescence and read off that way
Autoinducer molecule (AHL)
Diffuses freely across the cell envelope Reaches high concentrations inside cell only if many cells are near Binds to specific activator protein and triggers transcription of specific genes
You experimentally change the DNA sequence directly upstream of a start codon of an operon in E. coli to investigate the function of this region of DNA. Analysis reveals that after the change the same amount of mRNA is made from the operon, but there are very few proteins made from the operon. What is the most likely function of the DNA sequence that you changed?
E. The DNA sequence likely functions as a ribosome-binding site.
What controls growth in a batch culture?
Finite resources
Overview of endospore formation
Five sensor kinases detect conditions which control endospore formation in a system that is similar to a two-component regulatory system but is much more complicated involving sigma factors.
What are the Fts proteins and what is their function?
Fts (filamentous temperature-sensitive) proteins: -Essential for cell division in all prokaryotes -Interact to form the divisome (cell division apparatus)
What proteins form the divisome and what is the function of each in this process?
Fts proteins- FtsA, FtsI, FtsK, and FtsZ FtsA - Anchor and recruits other divisome proteins. FtsZ - is essential for bacterial cell division and an ideal target for novel anti-bacterial drugs. Forms Z-ring and forms on the inside of the cytoplasmic membrane where it marks the future site of the septum of a dividing bacterial cell. FtsI - Transpeptidase - Penicilin Binding Protein, penicillin will target this gene and stops the formation of peptide bonds between precursors. Tsk - Chromosomal segregation proteins. ZipA - Anchors FtsZ
Formation of the divisome begins with the attachment of which protein in a ring around the center of the cell?
FtsZ
Identifying the sequence allows for
Functional predictions can be made based on the gene sequence identified and a putative cell physiology can be described Genomic information from many organisms can be collected to infer function/metabolism of one organism
Prosthecate bacteria
Gram-negative bacteria that have extensions projecting from the cells, thereby increasing their surface area stalked bacteria ex. caulobacter
Explain the second aspect of regulation of the lac operon (positive control)
If glucose is not present, cAMP levels rise and it binds to CRP which binds to the CRP-binding site and induces the binding of RNA Pol
ribosome binding site (Shine-Dalgarno sequence)
In a bacterial mRNA molecule, the sequence just upstream of the start codon to which a ribosome binds to initiate translation. ensures that the correct reading frame is achieved
describe the response to signal step of chemotaxis
MCP's bind attractant or repellent CheA and CheW get phosphorylated according to MCP binding
Identify properties and mechanisms which allow DNA to be packaged inside of the cell.
In prokaryotes, DNA is supercoiled by topoisomerase to allow it to be packed. (-) supercoiling is most common; DNA gyrase makes a double-stranded break and underwinds the DNA (+) supercoiling is useful for microorganisms in very hot environments
Predict how bacteria respond to changes in the environment
In response to a change in environmental conditions gene expression may also be under global control.
What are the three components of transcription?
Initiation of transcription Elongation Termination of transcription
Rho-independent transcription termination
Intrinsic termination: termination of transcription without addition of external factors Once termination sequence is transcribed --> transcribed mRNA forms a hairpin (stem) loop followed by multiple *uracils* --> Causes termination and complex dissociates
What is the function of a chemostat?
It introduces new resources as it drains out spent ones in order to keep the culture in the exponential growth phase.
Describe the bacterial growth curve
Lag phase, log phase, stationary phase, death phase The logarithmic graph is a straight line The arithmetic graph is a exp. curve
What sets the lower and upper limits of temperature?
Low: membrane gelling, transport and processes move too slowly High: protein denaturation, collapse of cytoplasmic membrane, thermal lysis
MCP proteins
Methyl-accepting chemotaxis proteins receptors on the ends of a cell that are used to sense concentration gradients by binding attractant or repellant
Why does oxygen affect growth?
Molecular oxygen is not toxic, but can be converted into toxic oxygen by-products that they are unable to deal with including superoxide anion, hydrogen peroxide, hydroxyl radical
Calculate Microbial Growth
N = (initial pop) *2^n where n is the number of generations g = t/n
Classification of Microbes by Osmotic Pressure
Nonhalophile Halotolerant Halophile Extreme halophile
Describe annotation
Once the consensus sequence is found, ORF need to be identified Computer finds possible start codons - finds stop codons - counts codons between start and stop - finds RBS (ribosome binding sites) - calculates codon bias - lists possible ORFs
What are the optimal ranges for acidophile alkaliphile neutrophile
Optimal growth below pH 5.5 above a pH 8 between pH 5.5 to 8
During translation the initiator tRNA starts out in the __ site. Elongation factors first enter into the tRNA in the __ site and the outgoing tRNA is released from the __ site.
P site A site E site
Identify controls that will control microbial growth
Physical: Heat, Radiation, Filters Chemical: Bacteriocidals, Bacteriostatic, Bacteriolytic
Why sequence a genome?
Population structure and evolutionary history Strain detection Outbreak investigation Insights into growth requirements Diagnostics Protein expression: immunology and drug design Insights into virulence
How do prokaryotes and eukaryotes differ in regards to transcription and translation?
Prokaryotes can do both transcription and translation at the same time. They also transcribe more than one gene per mRNA.
Why doesn't RNA polymerase bind without an inducer?
Promoter sequence weakly binds RNA polymerase because it is a poor sequence matching
Ion Torrent Sequencing (4th gen)
Proton (H+) release changes pH, generating an electrical signal. As DNA passes through the nanopore, base-specific electrical charges are emitted.
Describe the process of DNA replication
Replication begins at the origin of replication and proceeds via semiconservative replication Always proceeds via 5' to 3' and requires an RNA Primer because DNA Pol III can only add to 3' OH
What are the two categories of negative control?
Repression Induction
What are the two types of termination of transcription
Rho-Independent or Rho-Dependent
describe the mechanism of a two-component regulatory system
Sensor kinase receives an environmental signal and gets phosphorylated then it interacts with a response regulator that gets phosphorylated response regulator binds to an operator and blocks transcription
How to read a graph to determine optimal conditions?
Shortest generation time indicates optimal conditions.
What are the four types of replication that yield unequal products of division?
Simple budding Budding from hyphae Cell division of a stalked organism (caulobacter) Polar growth without differentiation in cell size
SMRT (3rd gen)
Single Molecule Real Time Nucleotides tagged with fluorescent light Emit light when integrated Computer picks up on this
What are the two types of Caulobacter cells?
Stalked and Swarmer (with flagella)
What is the function of negative control?
Stops transcription
Divisome
Synthesizes new cytoplasmic membrane and cell wall at the center of the rod-shaped cell and elongates until the septum is complete and cells seperate Molecules of FtsZ(related to tubulin) attach around the center of the cell. ZipA anchors the FtsZ ring to the cytoplasimc membrane FtsA(related to actin) connects the FtsZ ring to the cytoplasmic membrane and recruits other proteins
Describe the Environmental Factors that Control Growth
Temperature pH- alkaliphiles, acidophiles Osmotic pressure Oxygen
quorum sensing
The ability of bacteria to sense the presence of other bacteria via secreted chemical signals.
leading strand
The new continuous complementary DNA strand synthesized along the template strand in the mandatory 5' to 3' direction.
Horizontal gene transfer
The transfer of genes from one genome to another through mechanisms such as: plasmid exchange- conjugation viral activity- transduction uptake of foreign DNA- transformation
What are the different levels of regulation within the cell?
Transcription- Activation and Repression Translation Controlling Enzymes- feedback inhibition, degradation, covalent modification, protein-protein interactions
What type of topoisomerase is DNA gyrase?
Type II meaning that it makes a double stranded break and reseals it behind the unbroken helix
DNA synthesis is ____ in prokaryotes from the origin of replication (oriC)
bidirectional Two replication forks moving in opposite directions—speeds up replication
Describe the sporulation process
When SpoOA is phosphorylated, sporulation proceeds It develops into SpollE that dephosphorylates the inactive SpollAA to activate it Spoll AA binds to SpollAB causing it to release and activate sigmaF Early endospore genes are transcribed sigmaE signal from mother cell triggers the synthesis of σG in endospore and pro-σK in the mother cell. A signal from endospore activates σK Mother cell is lysed and endospore is released
Explain repression
When the corepressor binds to the regulatory protein (repressor), it binds to the operator region of the DNA to stop transcription
replisome
a complex of DNA polymerase and other enzymes that catalyzes the synthesis of DNA
One way that regulation is often studied is by examining the effects of mutations. For example, mutations within the parts of the lac operon have been well studied. Which of these mutants would be considered a constitutive mutant?
a mutation in the gene for the repressor if the repressor is ineffective then the lac operon would always be expressed.
DnaA protein
a protein that binds to the dnaA box sequence at the origin of replication in bacteria and initiates DNA replication
two-component regulatory system
a regulatory system consisting of two proteins: a sensor kinase and a response regulator
heterocysts
a specialized cell that engages in nitrogen fixation in some filamentous cyanobacteria
Termination of transcription in Bacteria occurs via _______________.
a stem-loop secondary structure in RNA immediately upstream from a run of uracils protein rho which binds to GC rich regions and pulls itself towards RNA polymerase to stop transcription
Picrophilus oshimae would be described as a
acidophile thermophile
positive control involves
activator protein to facilitate binding of the RNA polymerase to the promoter.
describe the adaptation step of chemotaxis
allows tumbling to occur so that the environment can be reassessed CheR methylates MCP's CheB demethylates MCP's
bacteriocidal agent
an agent that kills bacteria
Chemotaxis
an example of a two-component regulatory system if there is no attractant/repellant, random movement if there is an attractant/repellant, directed movement (more runs, less tumbles)
Streptomycin
antibiotic affecting translation binds to the region of 16S rRNA that forms part of the decoding A site and another protein responsible for the codon-anticodon binding at high concentrations binds the 30S-mRNA-tRNA initiation complex and prevents binding of the 50S subunit
Bacteriocins
antimicrobial peptides produced by bacteria that is typically transmitted via plasmids
What is an example of a repressive operon?
argenine operon
What do unmethylated MCP respond to?
attractants but insensitive to repellants
MotA
bacterial mobility protein
The transport of peptidoglycan precursors across the cytoplasmic membrane is facilitated by ___________________.
bactroprenol
If there is a mutation in the operator of a lac operon what would you expect to happen during transcription of the lac operon.
beta-galatosidase would be constitutively produced because the repressor cannot bind to the operator
Cells of E. coli are exposed to an attractant. The rate of autophosphorylation of CheA to form CheA-P is expected to __________. Because CheY will not be phosphorylated as frequently the flagella will rotate in the ___________ direction causing the cell to ________________.
decrease CCW run
Attractants _____ rate of autophosphorylation Repellants _____ rate of autophosphorylation
decrease increase
CheZ
dephosphorylates CheY
What influence does the major and minor groove have?
determine how protein interacts with DNA Most proteins bind to the major groove
paralogs
diverged within one species via gene duplication and mutation each gene holds a new function (though function is often related to parental)
DNA ligase
enzyme that chemically links DNA fragments together
What is an example of an inductive operon?
lac operon
During a growth curve of Aliivibriofischeri, when would you expect to see the strongest bioluminescence?
late log to early stationary phase
Bacteriolytic agents
lyse cells and is observed as a decrease in cell numbers or in turbidity
What is an example of an operon regulated via positive control?
maltose operon
The function of a kinase is _____.
phosphorylation
Regulation of enzyme activity occurs_____________________. at the start of transcription at any point on the enzymatic production pathway at the start of translation posttranslationally
post-translationally
MreB
protein that plays a role in determining the shape of the cell
Sequencing an organism's genome often leads to identification of hypothetical proteins, which are characterized as __________.
proteins that likely exist though their function is unknown
Classifications of Microbes by Temperature
psychrophile mesophile thermophile hyperthermophile
DNA binding proteins
regulate transcription form a homodimer (two identical polypeptides), fits into major grooves and along phosphate backbone
positive control
regulator protein binds to an inducer to activate the binding of RNA polymerase to DNA
Endospore formation in Bacillus subtilis is triggered by adverse external conditions that are monitored by a sensor kinase system which results in the ________.
release sigmaF
Activation of SpoOA also causes...
released of a toxic protein that lyses other cells not undergoing sporulation Sporulation cells produce an antitoxin
What is the function of DNA Pol I?
removes and replaces RNA primer with DNA
Explain induction
repressor is naturally bound to operator if corepressor is present, it releases from the operator region to allow transcription to occur
Negative control involves
repressor protein that prevents transcription
fruiting body
reproductive structure
Functions of sigma factors F, G, E, K
sigmaF= binds to RNA polymerase to promote transcription genes in sporulation (sigmaG) sigmaG = genes that cross into the mother cell and activates sigmaE sigmaE= required for transcription of genes inside mother cell including sigmaK sigmaK= causes mother cell lysis, release of endospore
What are the functions of stalked and swarmer cells?
swarmer cell that can freely disperse in the environment but cannot divide and a stalked cell for reproduction
constitutive synthesis
synthesis at a constant level in the presence or absence of inducer
global control
systems that regulate expression of many genes simultaneously
aminoacyl-tRNA synthatases
tRNA and amino acid are brought together
Elongation of translation
tRNA is guided into the A site (holds charged tRNA) peptide bond formation in the P site (holds the tRNA with the growing chain and forms peptide body via peptide transferase with the use of GTP (translocation))
What are the two criteria for antibiotics?
they must kill or retard the growth of the pathogen and must not harm the host
Identify some trends with increasing genome size
total ORFs increase relative percentage of ORFs for DNA replication and translation decreases relative percentage of ORFs for energy generation is level/ proportional relative percentage of ORFs for transcription and signal transduction increases (meaning there is more communication and regulation)
Initiation of translation
transcription factors initiate the initiation complex formation ribosome binds to the ribosome-binding site- before the transcription start site initiator tRNA enters at the P site
Although the mechanisms facilitating DNA uptake/exchange in Thermus aquaticus are unknown, genes to facilitate ____ have been identified within the genome
transformation conjugation
CW rotation
tumble
diauxic growth
two exponential growth phases
What regulation mechanism controls Allovibrio fischeri cells' bioluminescence?
two-component regulatory pathway: quorum sensing Ensures that enough members of the population are present to make a difference luxA and lux B actually give off light
describe evolution by gene duplication
when genes duplicate, they can either be conserved and maintain the same role or adopt a new function due to some eventual sequence change ex. RubisCo
