Microbiology Ch.5-7
Quorum sensing can best be described as the ability of microorganisms to _____.
"sense" the density of cells within their own population
Translation of mRNA into protein begins before transcription is complete in
both eukaroytes and prokaryotes
The pigments of photosynthetic organisms capture ____ energy.
radiant
The electron transport chain is part of
respiration
In prokaryotes, translation begins when the ribosome binds to the ___ of the mRNA.
ribosome binding site
Protein synthesis occurs on the
ribosomes
During the electron transport chain in bacteria, protons are
shuttled to the outside of the cell membrane
In competitive inhibition such as occurs with sulfa drugs, as the concentration of the _____ increases relative to the ______, the more likely the active site of the enzyme will be occupied, thereby blocking the regular function of the enzyme.
inhibitor; substrate
Eukaryotic mRNA contains non-coding regions called
introns
When a repressor binds to the operator site on DNA,
it blocks RNA polymerase binding and mRNA synthesis
When a bacterium is grown on glucose only
it must synthesize all the amino acids it needs
In an inducible operon, when a substrate of inducer is present,
it reacts with the repressor and inactivates it
As part of cellular respiration. a membrane-bound enzyme called ATP _____ uses energy from a proton- motive force to add a phosphate group to ADP.
synthase
Repressible
synthesis is turned off when not needed
In some degradative pathways, in the absence of an inducer (e.g.: arabinose):
the activator protein can't bind to the DNA, and RNA polymerase can't bind to the promoter site
Proton motive force is
the form of energy that results from the electrochemical gradient established by the electron transport chain
When an amino acid such as arginine binds to a repressor,
the repressor binds to the operator site
Two different mechanisms for copying DNA strands are used because
the strands are oriented into two different directions
The process of transcription is similar to
the synthesis of the leading strand during DNA replication
Cells prefer to use carbohydrates as energy sources because:
they are such good donors of hydrogen and electrons
Which of the following describe enzyme specificity?
-With few exceptions, a unique enzyme is required to catalyze each reaction in a cell. -Hydrogen and ionic bonding occur to induce correct fit between substrate and active site. -Substrate must align spatially with the active site
Aqueous solutions of ethyl or isopropyl alcohol are commonly used as an antiseptics and disinfectants because they _____.
-do not leave residue -are relatively non toxic -are relatively inexpensive -quickly kill vegetative bacteria and fungi
Choosing the correct antimicrobial procedure depends on how many factors including _____.
-environmental conditions -type and number of microbes -composition of item
Phenolic compounds are effective _______
-in the presence or organic contaminants, even in detergent solutions, against most vegetative bacterial cells
Sulfa drugs interfere with the bacterial pathway for the synthesis of folate because they
-inhibit enzyme in the pathway -have a structure similar to an intermediate (para-aminobenzoic acid, or PABA) in the pathway.
Chlorhexidine solutions are commonly used for _____.
-mouthwashes -antiseptics of skin and skin wound care
All of the following are disadvantages of using alcohol solutions for disinfection EXCEPT: _____
-they do not leave a residue
oxidative phosphorylation and photophosphorylation are similar in that both processes _____.
-use an electron transport chain to set up a proton motive force used to generate ATP.
If an organism lost the ability to make primase, what would it be unable to do?
Add a short sequence of complementary RNA to the existing strand of DNA
Polyadenylation
Adenine derivatives at the 3' end
Irradiation and high pressure
Can destroy microbes without altering the product
Chemical additives
Can prevent microbial growth, but carry risk of toxicity
The photosystems of cyanobacteria, plants, and algae are located in thylakoid membranes. In plants and algae, these are found in the stroma of cholorplasts that are very similar in structure to cyanobacteria. Why is this similarity not surprising?
Chloroplasts appear to have descended from an ancestor of a cyanobacterium
In anerobic respiration, the terminal electron acceptor would also be oxygen.
False
T/F RNA is synthesized on both strands of the DNA called the transcript
False
T/F: In Prokaryotes and eukaryotes, the TCA cycle takes place in the mitochondria
False
The purpose of RNA synthesis is to provide a new copy of DNA as the original strand deteriorates over time.
False
non-cyclic photophosphorylation
Generates ATP and NADPH
cyclic photophosphorylation
Generates ATP only
During transcription, RNA polymerase synthesizes ____ from a(n) _____ template.
RNA; DNA
In transcription, ____ is synthesized, while in translation, _____ is synthesized.
RNA; protein
On one of the strands of bacterial DNA, the new complementary strand is synthesized discontinuously into small pieces of DNA called:
Okazaki fragments
What components of RNA is different from one person (or bacterium) to the next?
Order of nitrogenous bases
The initial transfer RNA occupies the _____ site on the ribosome.
P site
A _______ is the physical expression of the genes present and can change depending upon what genes are turned "on"?
Phenotype
Three basic parts of DNA nucleotides
Phosphate, deoxyribose, nitrogenous base
What usually terminates the process of translation?
Presence of a stop codon on mRNA
During DNA replication, why are primers necessary?
Primers provide DNA polymerase with the 3' end needed for synthesis
Some members of which of the following groups can use inorganic chemicals such as hydrogen sulfide and ammonia for energy?
Prokaryotes only
The processes of transcription and translation differ between prokaryotes and eukaryotes in the following way:
Prokaryotes transcribe and translate simultaneously
An open reading frames (ORF) potentially encodes which of the following?
Protein
Flavoproteins
Proteins that are synthesized from the vitamin riboflavin
Cytochromes
Proteins that contain heme, a molecule that holds an iron atom in its center
The two 3-carbon molecules that glucose is split into during glycolysis are converted through a series of steps ending in what 3-carbon molecule?
Pyruvate
Environments with _____ temps are likely to show more bacterial growth on an exposed agar plate
warmer
Refers to energy-requiring metabolism processes that result in the biosynthesis of macromolecules and cellular structures.
Anabolism
_______ refers to energy-requiring metabolic processes that results in the biosynthesis of marcomolecules and cellular structures.
Anabolism
Nitrates and nitrites are added to processed meats to prevent the germination of ____ endospores.
Clostridium botullinum
RNA _____ produced by primase provide DNA polymerase with the 3' end needed for synthesis during DNA replication
primers
The main purpose of cellular respiration is to
produce energy
All of the following are examples of means by which microorganisms can respond to changing environmental conditions EXCEPT
production of different ribosomes
DNA polyremase
can only add nucleotides into a certain direction
______ are groups of three bases in mRNA that specify one amino acid in the amino acid chain.
codons
TCA cycle completes the _______ of glucose
oxidation
Transcription begins when RNA polymerase binds to the
promoter on the DNA
The enzyme ATP synthase uses energy from
protons re-entering the cell
Example of activation energy
The energy of a small flame used to light the natural gas of a Bunsen Burner.
Alcohol-based solutions of certain antimicrobial chemicals like iodine are called
tincture
The mechanism that cells use to detect and react to changes in the external environment is ____
two component regulatory system
In aerobic respiration, the last carrier protein in the electron transport chain transfers
two electrons to oxygen
Anoygenic photosynthesis bacteria like the purple bacteria and green bacteria may use any of the following electron donors for reducing power EXCEPT
water
A mechanism that blocks transcription
will block the production of mRNA
All of the following statements about liquid household bleach (sodium hypochlorite) are true EXCEPT it ___?
works well in the presence of excess organic material
Unlike oxygenic photosynthetic organisms, purple bacteria and green bacteria have only a single photosystem and cannot use water as an electron donor, with production of O2 as a byproduct. This makes them _____ photosynthetic bacteria.
anoxygens
Two strands of the DNA molecule are
antiparallel
Germicidal chemicals
are often poorly understood with regards to mechanisms of action; usually react irreversibly with proteins, DNA, cytoplasmic membranes, or viral envelopes
Repressible operons such as the arg operons
are usually in the "on" mode
Introns are removed and exons are spliced together
before translation
Early in glycolysis, two phosphates are added to the glucose molecule. These phosphates come from:
breaking down ATP
The coenzyme NADH is generated by
by oxidation reactions in glycolysis and the Krebs cycle
What happens to carbon dioxide after it releases during reactions of the TCA cycle?
it diffuses out of the cell
Consider the lac operon; When ____ is not available, a repressor prevents transcription. When lactose is available, some of it is converted into ___, which is an inducer.
lactose; allolactose
The lac operon only functions when _____ is present in the medium but ____ is absent from the medium.
lactose; glucose
A(n) ____ is a cluster of genes that perform related functions, found in _____.
operon, prokaryotes
Coordinated sets of genes that are regulated as a single unit are referred to as ______.
operons
Specific point on the DNA molecule where replication begins is the
origin of replication
In oxidation-reduction reactions, or redox reactions, the substances that loses electrons is ___, and the substance that gains electrons is _____.
oxidized; reduced
The terminal electron acceptor in aerobic respiration is
oxygen
The central metabolic pathway that generates reducing power in the form of NADPH is the ____ pathway.
pentose phosphate
The bond connecting amino acids is a ____ bond.
peptide
mRNA is produced when a region of DNA is known as the template is copied. The newly synthesized strand of mRNA is called the
transcript
A cell has only a limited number of electrons carrier molecules. During glycolysis, if electrons are not removed from NADH, the cell soon runs out of available NAD+, and the breakdown of glucose ends. This presents a problem for cells that lack a suitable terminal electron acceptor for the electron transport chain or thay cannot respire. The solution to this problem is called
fermentation
RNA is chain of
nucleotides
Hydrogen consists of
one proton and one electron
A set of regulated genes transcribed as a single mRNA molecule, along with the sequence that control its expression, is called an
operon
Pyruvate and pyruvic acid
-terms that refer to the ionized and the undissociated forms of the molecule -are term soften used interchangeably
In prokaryotes, the mRNA transcript encounters ribosomal subunits immediately as it leaves the DNA
True
When a single molecule of glucose is processed by glycolysis in an E. coli cell, which of the following make up the net gain of this process?
-6 precursor metabloites -2 molecules of ATP -2 molecules of NADH
Calvin cycle can be viewed as having three essential stages. Place them in the correct order.
1. CO2 is added to ribulose 1,5-bisphosphate (RuBP). 2.ATP and NADPH are used to reduce 3-phosphoglycerate (3PG) to glyceraldehyde 3-phosphate (G3P). 3. Ribulose 1,5-bisphosphate (RuBP) is generated.
Place the following events in transcription in the correct order
1.RNA ploymerase binds to the promoter region just upstream of the gene 2.RNA polymerase unwinds the DNA at the promoter site and begins to transcribe the template strand of DNA 3.RNA polymerase moves along the template strand of DNA adding complementary RNA nucleotides, extending the mRNA 4.Transcription continues until a terminator site in the DNA is reached. 5.the mRNA transcript is released.
For each glucose broken down by glycolysis, how many net ATP molecules are produced?
2
Detecting different fermentation products can be an important tool in identifying bacteria. What two fermentation pathways are particularly useful in differentiating members of the family Enterobacteriaceae?
2,3-Butanediol fermentation, mixed acids fermentation
How many molecules of NADH are generated for each turn of the TCA cycle?
3
Boiling water for at least ___ minutes can be an effective means of killing vegetative cells and viruses.
5
DNA strands are synthesized in the _____ direction
5' to 3'
RNA polymerase synthesizes a strand of RNA in the ____ direction.
5' to 3'
Repressor is synthesized in a form that binds to the operator, blocking transcription
A molecule called an inducer attaches to the repressor, changing its shape so it can no longer attach to the operator
Repressor is synthesized in a form that cannot bind to the operator, so transcription can proceed
A molecule termed a corepressor attaches to the repressor; the corepressor-repressor complex can bind to the operator.
The synthesis of aromatic amino acids such as tyrosine, phenylanine, and tryptophan requires what type of metabolic pathway?
A multi step, branching pathway
Describes termination of translation?
A stop codon is reached and the polypeptide is released from the ribosome
Replication, transcription, and translation take place in the bacterial cytoplasm.
True
NOT a catabolic process?
A. Glycolysis B. TCA Cycle C. Protein Synthesis D. Fermentation E. These are all catabolic processes C
Preventing contamination in the microbiology lab requires the stringent practice of ______.
Aseptic technique
Based on what you know about biological safety levels (BSLs), the bacteria normally found in yogurt would be _____.
BSL-1
High-efficiency particulate air (HEPA) filtration may be used in a number of settings, including _____.
Biological safety, vacuum cleaners, passenger aircraft, hospital rooms
With respect to their synthesis, how are amino acids typically grouped?
By structurally related families that share common biosynthesis pathways
Constitutive
Constantly synthesized
Contains a metal ion that can accept and donate electrons?
Cytochromes
The TCA (Krebs) cycle takes place in the mitochondria of eukaryote cells. Where does it take place in prokaryote cells?
Cytoplasm
Where does the TCA cycle take place in bacteria?
Cytoplasm
Which cellular component is damaged by UV radiation?
DNA
Which of the following shows the direction genetic info flows?
DNA --> RNA --> protein
Best describes the difference between disinfectant and antiseptic.
Disinfectants are antimicrobial chemicals used on inanimate objects or surfaces to remove most of the pathogenic microorganisms. Antiseptics are antimicrobial chemicals that can be used on skin or tissue to achieve the same result.
Where do NADH and FADH2 go after being produced in the TCA cycle?
Electron transport chain
Testing for the ability of organisms to produce mixed acids via fermentation can be clinically important because it can differentiate members of the _____ family.
Enterobacteriaceae
Eukaroytic mRNA usually specifies multiple proteins
False
The TCA cycle occurs after
Glycolysis
Compounds such as ATP and ADP reflect a cell's relative energy supply and often serve as allosteric regulators of catabolic pathways. Which of the following best explains the relationship between levels of ATP and ADP and allosteric regulation of such catabolic pathways?
High levels of ADP inhibit, and high levels of ADP stimulate, the catabolic pathways
Salting and drying decrease the availability of water in food, resulting in an environment that is _____ relative to microbes, thereby preventing their growth.
Hypertonic
Metal compounds typically kill microbes by _____.
Inactivating enzymes and other proteins
______ is the destruction of microbes by subjecting them to extremes of dry heat, reducing them to ashes.
Incineration
What is contamination?
Intro of an unwanted organisms into a culture
The two primary iodine preps are tinctures of iodine and ______.
Iodophores
______ provides an alternative to heat for sterilization and disinfection, but the process damages some types of plastics.
Irradiation
What are limitations to the use of peroxygen peracetic acid?
It has a sharp, strong odor, and it irritates the skin and eyes.
What role does the sigma factor of RNA polymerase have in transcription?
It recognizes and binds to the promoter region of the template DNA
Select the enzymes that function in DNA replication.
Ligase, Primase, DNA polymerases, Helicase
Cap
Methylated guanine derivative at the 5' end
Heat-sensitive fluids such as sugar solutions, beer, and wine can be passed through paper thin membranes called ______ to remove unwanted microbes.
Microfilters
Chlorine and iodine are thought to kill microbes by reacting with ____ in a cell.
Proteins
Post translational modification event?
Proteins are folded into functional shapes by chaperones
Germicides from most to least potent
Sterilants, High level disinfectants, Intermediate level disinfectants, and low level disinfectants
Inducible
Synthesized only when needed
When selecting an appropriate chemical disinfectant, it is important to realize that the death rate is significantly influenced by _____.
Temperature and pH
What happens when a hairpin loop forms in the mRNA?
The RNA polymerase and the mRNA dissociate from the DNA.
Consider two different processes for converting glucose to CO2, and water. In the first, the glucose is burned (literally, as in a fire); in the second, the glucose is converted in a series of multiple stages in a cell. Which of the following statements correctly describes the free energy in these two approaches?
The change in free energy in the same regardless if the number of steps involved.
What is the active site of an enzyme?
The critical site to which a substrate binds to weak forces.
Hydrogen is transported from other reactions to the electron transport chain by _____.
NADH and FADH2
In competitive inhibition, why is the inhibitor able to bind to the active site, thereby blocking access of the substrate?
The inhibitor has a chemical structure similar to the normal substrate.
After mRNA is made, what generally occurs?
The mRNA is translated to protein.
In photosynthesis by cyanobacteria and chloroplasts, why is O2 generated?
The process strips electrons from H2O, generating O2.
Instead of fulfilling both their energy and carbon needs from organic compounds the way chemoheterotrophs do, why do chemolithotrophs incorporate CO2 into an organic form to fulfill their carbon needs?
They fulfill energy needs from inorganic compounds such as H2S and NH3 that lack carbon, so they need to obtain their carbon elsewhere.
What is the purpose of the slanted surface in an agar plate?
To increase the surface area for observable growth
What does the word "transcribe" mean?
To make a copy
____ is the process of decoding the info carried by mRNA to synthesize a protein
Translation
If you know the sequence of nucleotides in mRNA, you can deduce the DNA sequence it was transcribed from. (True or False)
True
Nucleotide subunits of DNA and RNA are composed of three units: a 5-carbon sugar, a phosphate group, and a nucleobase. They are initially synthesized ____
as ribonucleotides that can be converted to deoxyribosenucleotides by replacing the 2+ hydroxyl group with a hydrogen atom
Facts that most effect how much time is needed to kill all organisms in the canning proces?
-Temp -Concentration of organisms
In the absence of lactose,
a repressor binds to the operator
The electron carrier proteins in the electron transport chain shuttle electrons to
a terminal electron acceptor
Pigments that increase the efficiency of the light capture by absorbing wavelengths not absorbed by other pigments are called ___ pigments.
accessory
In carbon catabolite repression, CAP functions as a(n) _____ , while cAMP functions as a(n)
activator; indicator
The three central metabolic pathways that gradually oxidize glucose to CO2 are catabolic. However, they also generate precursor metabolites and reducing power that can be diverted for use in anabolic pathways. To reflect this dual role, these pathways are sometimes called _______ pathwhays.
amphibolic
A culture of E. coli cells growing on glucose salts agar (GSA), a chemically defined medium that contains glucose as its sole carbon source. E. Coli utilizes the glucose for both its energy and carbon needs. During metabolism, it uses precursor metabolites of its central metabolic pathways and ATP to build up the biological macromolecules needed to make cell components. These biosynthetic reactions are best described as _____
anabolism
You are studying bacteria you isolated from sediments at the bottom of the pond. Your research reveals they are using sulfate (SO42) as a terminal electron acceptor. This tells you they are capable of ____ respiration
anaerobic
Glycolysis takes place in the
cytoplasm
In bacteria the electron transport chain is located
cytoplasmic membrane (plasma membrane)
Ionizing radiation harms cells destroying DNA and damaging ____.
cytoplasmic membranes
In prokaryotes, the electron transport chain is located in the _____ membrane, whereas in eukaryotic cells it is in the _____ membrane of mitochondria.
cytoplasmic; inner
According to the rules of complementary base pairing, the nucelobase ____ forms hydrogen bonds with guanine
cytosine
Exposing proteins to high heat may cause them to _____.
dentaure
Potentially harmful chemicals referred to as ______ by products (DBPs) form when chlorine and other disinfectants react with chemicals in the water.
disinfection
To achieve equivalent microbial killing, ____ heat requires longer exposure times and higher temp than ____ heat.
dry; moist
One bacterial chromosome replicates to become two chromosomes with:
each made of one strand of DNA from the original chromosome and one RNA strand
All of the following are true regarding pigments involved in photosynthesis EXCEPT
each photosynthetic organism has a single type
Glycolysis makes products that feed into
electron transport chain, TCA cycle, and fermentation
Binding of an activator to an activator binding site on DNA
enhances the ability of RNA ploymerase to bind to the promoter site
One advantage of having genetic control mechanisms is
enzymes are inly produced when they are needed
Bacteria use two-component regulatory systems to detect and react to changes in the ___.
external environment
A segment of DNA encoding a protein or an RNA molecule is a ________.
gene
Glycolysis is the central metabolic pathway that involves the breakdown of
glucose
Most lipids are synthesized from _____ and _____ acids.
glycerol; fatty
The TCA cycle occurs after
glycolysis
Early in the process of DNA replication, the enzyme ______ separates the two strands.
helicase
The chemiosmotic theory, proposed by Peter Mitchell in 1961, explains _____.
how the electron transport chain is linked to ATP synthesis.
purines and pyrimidines are synthesized
in distinctively different manners
Synthesis of mRNA is
in the 5' to 3' direction with new nucleotides being added to the 3' end of the mRNA molecule.
hydrogen peroxide is a more effective germicide on ____
inanimate objects
In a biosynthetic pathway, the end product generally acts as the allosteric inhibitor, allowing the cell to shut down the pathway when the product begins accumulating. This mechanism of control is called feedback ______.
inhibition
Microorganisms that are free living are _____ to chemical disinfectants than microorganisms in a biofilm.
less resistant
When incubating a plate, it should be placed in the incubator with
lid side down
Oxidation is
loss of electrons
Compared to the ATP gain per glucose molecule in prokaryotes, that of eukaryote is _____.
lower
Soap generally does not destroy most microbes, but it aids in their _____.
mechanical removal
The Voges-Proskauer test detects acetoin, the terminal electron acceptor of 2,3-butanediol fermentation. Similar to how the methyl-red test can test for mixed acids fermentation, the Voges-Proskauer test is important in helping differentiate between _____.
members of the Enterobacteriaceae family
During elongation. RNA polymerase synthesizes a single-stranded RNA molecule using the ____ strand of the DNA template
minus (-)
The ______ DNA strand is used as the template from RNA synthesis
minus (-)
A prokaryote transcript that carries one gene is called _____ RNA while a transcript that carries multiple is called _____ RNA
monocistronic; polycistronic
A concentrated culture of cells will take _____ time to kill than a dilute culture of the same organism.
more
Consider the max theoretical ATP yield from oxidative phosphorylation of a single molecules of glucose in prokaryotes. Match the relative contributions of the central metabolic pathways and final yield with their approximate contribution in terms of ATP, include the following pair, already given: 6 ATP from the transition step.
- 6 ATP: Glycolysis - 22 ATP: TCA cycle - 34 ATP: Total max yield
Consider the ATP-generating processess of proakryotic chemoorganoheterotrophs. Match the metabolic process with the information that correctly applies.
- Aerobic respiration: Uses an electron transport chain; yields more ATP than the other 2 processes. - Anaerobic respiration: Uses an electron transport chain; does not yield either the most of the least amount of ATP relative to the other two processes. - Fermentation: Does not use an electron transport chain; yields the lease ATP of three processes.
After glycolysis, pyruvate can be converted into _____ under anaerobic conditions.
lactic acid
Match each of the three central metabolic pathways with the correct description
- Glycolysis: Splits glucose and gradually oxidizes it to two molecules of pyruvate; generates some ATP and reducing power plus six precursor metabolites. -Pentose phosphate pathway: Breaks down glucose, although primary role is production of NADPH and two precursor metabolites for use in biosynthesis. -Tricarboxylic acid cycle (TCA cycle): Oxidizes an acetyl group to release two molecules of CO2; generates some ATP and precursor molecules and the most reducing power o all the central metabolic pathways.
Match the pigment type with the function.
- Reaction-center pigments: Electron donorsl emit high energy electrons that are passed to an electron transport chain. -Antennae pigments: Function as a funnel; capture energy of light and transfer it to other pigments.
A general group of electron carriers found in electron transport chain is quinones, that ______.
- are lipid soluble freely organic molecules that move freely in the membrane, transferring electrons between different protein complexes.
Advantages of using ionizing radiation for sterilization?
-Can be used on heat-sensitive material -Effectiveness at killing pathogens -Can be used after packaging
Which of the following are post-transcriptional modifications found only in euakryotes?
-Polyadenylation -Capping
Heat treatment
Most common and reliable, but can alter flavor and appearance of product.
Only euakryotic mRNA is processed before translation
True
Prokaryotes lack membrane bound organelles
True
Consider the three central metabolic pathways that gradually oxidize glucose to CO2. Why are these amphibolic pathways?
-"Amphi" means "both kinds", which reflects the dual role of these central metabolic pathways. -Although they are catabolic, the precursor metabolites and reducing power they generate can be diverted for biosynthesis (anabolism).
The three central metabolic pathways-- glycolysis, the pentose phosphate pathway, and the tricarboxylic acid cycle (TCA cycle)-- modify organic molecules to generate what three useful components for the cell?
-ATP, Precursor metabolites, Reducing power (NADH, FADH2, NADPH)
Which of the following statements about RNA interference are true?
-Binding of RNA in the RISC to complementary mRNA leads to enzymatic destruction of that mRNA stretch -A short strand of RNA within a RISC unit hybridizes to a complementary sequence of mRNA
In order to form lipids, how are fatty acids and glycerol synthesized?
-Fatty acid chains are assembles from 2-carbon acetyl groups from the transition step; the precursor to glycerol comes from glycolysis
Which of the following compounds can be generated from precursor metabolites produced during glycolysis?
-Glycerol, component of lipids -Some small amino acids like alanine, lecuine, and vaine -Peptidoglycan, component of bacterial cell walls
Why are plates labeled on the bottom of the agar plate?
-Labeling the bottom allows labeling of different sections of the plate. The lid might rotate and labels would not match the sections. -The info about the plate is still available even if the lid becomes separated from the bottom -Plates are stored on their lids so this makes it easy to see labels even when on the shelf of the incubator
What are the roles of ribosomes in translation?
-Ribosomes detect sequences that indicate where translation should start and finish -Aligning amino acids and catalyzing formation of peptide bonds between them
Correctly describes cythochromes found in an electron transport chain?
-Several different cytochromes exist. -Cytochromes are proteins that contain heme, a molecule that holds an iron atom in center
Which types of sterile media are solid in nature?
-Slants -Agar plates
Two 3-carbon molecules enter the pay-off phase of glycolysis for each initial glucose molecule, meaning the steps of this phase occur twice for each glucose. During this pay-off phase of glycolysis, what is the total number of NADH and ATP molecules produced from a single glucose molecule?
2 NADH and 4 ATP
If the codon GGU is positioned in the A site of the ribosome, which of the following will occur?
A tRNA with the anticodon CCA will deliver its amino acid to the site
Which of the following is not a catabolic process?
A. Glycolysis B. TCA cycle C. Protein synthesis D. Fermentation E. These are all catabolic processes. C
Which of the following occurs in both prokaryotes and eukaryotes?
A. Transcription B. DNA replication C. Translation D. All of these D
During the electron transport chain, ATP will be made from
ADP + Pi
The energy released during the reaction of glycolysis is used to form
ATP
When a molecule other than O2 serves as the terminal electron acceptor for the electron transport chain, the organism is utilizing ______ respiration.
Anaerobic
You are growing E. coli in a medium that includes nitrate. If the bacteria run out of O2, you might expect them to continue growing using ____ respiration, using ____ as a terminal electron acceptor.
Anaerobic; nitrate.
In both glucose and lactose are present in a medium, why is the lac operon not transcribed?
Cells preferentially use glucose and only use lactose if the glucose is depleted
Translation occurs on ribosomes only in prokaryotes
False
Translation of eukaryotic mRNA can occur in the nucleus after exons are spliced together
False
In order to form lipids, how are fatty acids and glycerol synthesized?
Fatty acid chains are assembled form 2-carbon acetyl groups from the transition step; the precursor to glycerol comes from glycolysis
The Calvin cycle
Incorporates carbon dioxide into organic compounds
Quinones
Lipid soluble organic molecules that move freely in the membrane; includes one that serves as a source of vitamin K for humans and other mammals
Consider common human pathogens. Most of their enzymes likely function best under which of the following environmental conditions?
Moderate pH around 7, Temperature around 37 degrees C, Low salt
The two 3-carbon molecules glucose is split into are converted through a series of steps into pyruvate. During these steps
NAD+ is converted to NADH
Catabolism
The set of chemical reactions that degrade compounds, releasing their energy.
Anabolism
The set of chemical reactions that synthesize and assemble the subunits of macromolecules.
Why is translation needed?
The subunits of nucleic acids are nucleotides, while those of proteins are amino acids.
Metabolism
The sum total of chemical reactions in a cell
Why does anaerobic respiration yield less energy than aerobic respiration?
The terminal electron acceptors used in anaerobic respiration have lower electron affinities than O2.
T/F: Polycistronic RNA carries more than one gene
True
T/F: Quorum sensing allows bacteria to detect population density, facilitating coordinated activities such as biofilm formation
True
T/F: Several codons code for the dame amino acid, which is called the redundancy of the code. Because of redundancy, the genetic code is said to be degenerate
True
T/F: When a repressor is bound to the operator of an operon, transcription is blocked.
True
The sequence of DNA bases ultimately determines the sequence of amino acids in a polypeptide
True
Unlike DNA, RNA is usually single stranded
True
For each glucose molecule that enters glycolysis, how many times does the TCA cycle "turn"?
Two
How many ATP molecules are produced in the TCA cycle for each glucose molecule that enters glycolysis?
Two
If one strand of DNA contains the bases ACAGT, what would be the complementary bases on the mRNA strand?
UGUCA
non-cyclic photophosphorylation
Uses photosystem I and II.
cyclic phosphorylation
Uses photosystem I only
The part of the bacterial RNA polymerase that recognizes a promoter us a subunit called ____
sigma factor
In prokaryotes, the first AUG after a ribosome-binding site typically functions as a ______codon.
start
What types of organisms are, or include groups that are, capable of photosynthesis?
-Algae, plants, bacteria
Correct statements about autoclaving
-Autoclaving is consistently effective in sterilizing most objects. -Biological indicators such as heat-resistant endospores are used ensure that an autoclave is working properly. -Adding pressure to the autoclave increases the temp of the steam in it. -Autoclaving involves use of both temp and pressure.
Microbial metabolism plays many roles of importance to humans. Match up the following examples with their microbial prcocesses.
-Biofuels: Microbial breakdown of corn stalks, sugar canes, or wood into ethanol. -Cheese: Metabolic wastes of Lactococcus and Lactobacillus species contributing to flavor and texture. -Identifying markers: Products characteristics of specific microbes -Model for eukaryotic cells: Metabolic pathways of organisms such as E. Coli -Targets of antimicrobial drugs: Metabolic processes unique to prokaryotes.
Match up each type of enzyme inhibition with its characteristic.
-Competitive inhibition: Inhibitor binds to active site of enzyme., blocking access of the substrate. -Non competitive inhibition by regulatory molecules: Inhibitor reversibly changes the shape of the enzyme so that the substrate can no longer bind to the active site -Non competitive inhibition by enzyme poisons: Inhibitor permanently changes the shape of the enzyme, making the enzyme non functional.
Match organisms with the correct location of the photostems.
-Cyanobacteria: Embedded in the membranes of thylakoids located within the cells. -Plants and algae: In thylakoids located in the stroma of the chloroplast -Purple bacteria: In extensive invaginations of the cytoplasmic membrane. -Green purple: In chromosomes attached to the inner surface of the cytoplasmic membrane
Match each US agency to the type of germicidal chemicals it is responsible for regulating.
-FDA: Chemicals used to process medical devices -EPA: Chemicals used as pesticides
Match the aldehyde on the left with the characteristics on the right.
-Glutaraldehyde: Because of the toxicity of this sterilant, treated items must be thoroughly rinsed with sterile water before use. -Formaldehyde: Used to kill bacteria and inactivate viruses in vaccines; also used to preserve biological specimens.
Match the type of pasteurization with its description.
-High temp short time (HTST) method: Most commonly used; products will still require refrigeration or freezing. -Ultra high temp (UHT) method: Involves higher temp for a short time; products can be stored at room temp
Best summarizes prokaryotes as a group in terms of their metabolism?
-Highly diversive with respect to compounds they use for energy but remarkably similar in their biosynthetic processes.
Peroxygens are powerful oxidizing agents that ____
-Include hydrogen peroxide and peracetic acid -can be used as sterilants under controlled conditions
What are characteristics of chlorine when used to disinfect drinking water?
-It kills many pathogens -It is effective even at very low levels
Accurately describes the pentose phosphate pathway?
-Its primary role is the production of compounds used in biosynthesis -It breaks down glucose -It yields reducing power in the form of NADPH.
Match the fermentation pathway with the correct end products
-Lactic acid fermentation: Lactic acid -Ethanol fermentation: Ethanol, CO2 -Butyric acid fermentation: Butyric acid, butanol. acetone, isopropanol, CO2H2 -Propionic acid fermentation: Propionic acid, acetic acid, CO2 -Mixed acids fermentation: Acetic acid, lactic acid, succinic acid, ethanol, CO2H2 -2,3-Butanediol fermentation: Formic acid, ethanol, lactic acid, 2-3 butanediol, CO2H2
Advantages to the use of peracetic acid as a germicide?
-Leaves behind no residue -Even more potent than hydrogen peroxide -It can be combined with hydrogen peroxide to sterilize items in less than an hour
Which of the following microbes are highly resistant to chemical control methods?
-Myobacterium species -Protozoan cysts and oocysts -Non enveloped viruses -Bacterial endospores
Correctly describes the transition step and the tricarboxylic acid (TCA) cycle?
-The transition step converts the pyruvate from glycolysis into acetyl-CoA. -Together they generate the most reducing power of all the central metabolic pathways. -The TCA cycle oxidizes 2-carbon acetyl group to release two molecules of CO2.
Place the following steps in the correct order to show how the spatial arrangement of electron carriers in a bacterial electron transport chain helps explain how protons are shuttled from one side of the membrane to the other.
1. An electron carrier donates electrons to a hydrogen carrier, which also picks up protons. 2. They hydrogen carrier passes electrons to a carrier that only accepts electrons. 3.Because the electron carrier only accepts electrons. the protons are released to the outside of the cell. 4. A proton motive force is set up as protons are moved from the inside of the cell to the outside.
Match each of the following items that may have influence the selection of an antimicrobial procedure with its correct description/ rationale.
1: Environmental conditions: Dirt, grease, and bodily fluids in/on an area can interfere with control methods, as can temp, pH, and humidity levels. 2: Composition of the item: Different materials respond differently to control measures. Some may even be destroyed by certain methods, preventing their use. 3: Type of microbe: Certain microbes are highly resistant to killing methods 4: Risk for infection: Items that may come into direct contact with body tissues are more likely to cause serious infections if contaminated. 5: Number or microorganisms: It takes longer to kill a large number of microbes than a small number.
Produced by the transition step for each molecule of glucose that enters glycolysis?
2 NADH, 1 precursor metabolite (2 molecules of acetyl-CoA)
Consider the theoretical maximum ATP yield from the complete oxidation of glucose via aerobic respiration in prokaryotic..... contribution in terms of ATP (substrate level phosphorylation plus oxidative phosphorylation) with the correct metabolic process.
8 ATP: Glycolysis 6 ATP: Transition step 24 ATP: TCA cycle 38 ATP: Total yield of aerobic respiration
Only a fraction or organisms die during a given time interval. Therefore, if 90% of a bacterial population dies during the first 3 minutes, then approximately ____ of the remaining population will be killed during the next 3 minutes.
90%
NOT sterilization method?
A. Pasteurization B. Autoclave C. Hot air oven D. Filtration Answer: A
T/F: The temp and time used in the commercial canning process is enough to reduce 1012 C. botullinum endospores to only one spore.
True
Boiling is not a reliable method for sterilization because
it does not destroy heat-resistant endospores
Each enzyme functions best within a narrow range of environmental conditions. Three important environmental conditions that influence enzyme activity are ____, ____, and salt concentration.
pH, temperature
Ethanol can be produced during fermentation by removing CO2 from pyruvate to generate acetaldehyde, which then serves as the terminal electron acceptor, yielding ethanol. Humans have taken advantage of microorganisms capable of this process in a number of ways. Which of the following are examples of this?
-Making spirits -Wine and beer making -Making biofuels -Bread making
Consider the use of low temp storage for preservation of food. Which of the following are accurate statements?
-Psychotrophic and some psychrophillic microorganisms can grow at refrigeration temp. -Refrigeration inhibits the growth of many pathogens and spoilage microorganisms by slowing or stopping critical enzyme reactions.
Unlike plants, algae and cyanobacteria that uses chlorophylls as photosynthetic pigments, anoxygenic photosynthetic bacteria use _______________ to absorb light.
bacteriochlorophylls.