Microbiology (1113) Exam 2/2.0
Affinity
An attraction to
_________ refers only to energy-requiring metabolic processes that result in the biosynthesis of macromolecules and cellular structures.
Anabolism
A culture of bacteria is breaking down sugars to yield energy. This is best described as ________. A. biosynthesis B. catabolism C. anabolism D. metabolism
B. Catabolism
Where do NADH and FADH2 go after being produced in the TCA cycle? A. Substrate-level phosphorylation B. Electron transport chain C. Calvin cycle
B. Electron transport chain
Glycolysis is the central metabolic pathway that involves the breakdown of A. Fatty acids B. Glucose C. Starch
B. Glucose
The TCA cycle occurs after A. The Calvin cycle B. Glycolysis C. Electron transport chain D. Fermentation
B. Glycolysis
The main purpose of cellular respiration is to A. Produce CO2 B. Produce energy C. Produce glucose
B. Produce energy
In the electron transport chain, protons are pumped across the cell membrane. This results in A. the loss of electrons. B. the formation of a proton motive force. C. the reduction of NADH. D. the creation of water.
B. The formation of a proton motive force
Bacteria and Archaea generally multiply by the process of?
Binary fission
A hydrogen atom consists of A. a variable number of protons and electrons. B. a proton and several electrons. C. a proton and an electron. D. protons only. E. electrons only.
C. A proton and an electron
Consider how an aerobically respiring bacterial cell uses glycolysis, the TCA cycle, and oxidative phosphorylation to break apart and oxidize glucose. What are the three main benefits these central metabolic pathways yield to the cell? A. ADP, carbon dioxide, and water B. ATP, glucose, and carbon dioxide C. ATP, reduced electron carriers, and precursor metabolites D. Oxygen, fermentation, and precursor metabolites E. ATP, oxidized electron carriers, large carbon polymers
C. ATP, reduced electron carriers and precursor metabolites
Consider the biochemical pathway: A → B → C Enzyme 1 catalyzes A → B Enzyme 2 catalyzes B → C If enzyme 2 is inactive, which of the following compounds will accumulate? A. B and C B. A and B C. B only D. C only E. A only
C. B only
Which of the following contain a metal ion which can accept and donate electrons? A. Quinolone B. Chelators C. Cytochromes
C. Cytochromes
Streptococcus pneumoniae lacks an electron transport chain. Therefore, S. pneumoniae generates ATP via _________. A. oxidative phosphorylation B. aerobic respiration C. fermentation
C. Fermentation
In eukaryotic cells undergoing respiration, protons are pumped A. across the cytoplasmic membrane. B. from inside the mitochondria to the cytoplasm. C. from the mitochondrial matrix to the region between the inner and outer mitochondrial membranes (intermembrane space). D. from inside the cell to outside the cell.
C. From the mitochrondiral matrix to the region between the inner and outer mitochondrial membranes
Energy source
Compound that a cell oxidizes to harvest energy; also called an electron donor
Tricarboxylic acid (TCA) cycle
Cyclic metabolic pathway that incorporates acetyl-CoA, ultimately generating ATP (or GTP), CO2, and reducing power; also called the Krebs cycle and the citric acid cycle.
Proteins that contain heme, a molecule that holds an iron atom in its center
Cytochromes
A culture of E. coli is 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 _________. A. glycolysis B. catabolism C. metabolism D. anabolism
D. Anabolism
In prokaryotic cells undergoing respiration, protons are pumped A. from outside the cell to inside the cell. B. from the mitochondrial matrix to the intermembrane space. C. from the periplasmic space to inside the cell. D. from inside the cell to outside the cell membrane.
D. From inside the cell to outside the cell membrane
The terminal electron acceptor in anaerobic respiration is A. Nitrate B. Water C. Pyruvic acid D. Oxygen
D. Oxygen
Exergonic
Describes a chemical reaction that releases energy because the starting compounds have more free energy than the products.
Endergonic
Describes a chemical reaction that requires a net input of energy because the products have more free energy than the starting compounds.
Who showed that crushed yeast cells could convert sugar to ethanol and CO2?
Edward Buchner
Examples of Coenzymes
FAD, NAD+, NADP+
coenzymes include ______, _______, _____
FAD, NAD+, NADP+
T/F: All biochemical pathways have the same number of enzymatic reactions.
False
T/F: An enzyme can only bind one substrate at a time.
False
T/F: an enzyme speeds up a chemical reaction in the cell, but can only be used once.
False
T/F: in prokaryotes and eukaryotes, the TCA cycle takes place in the mitochondria
False
T/F: the cytoplasmic membrane is permeable to protons
False
Proteins that are synthesized from the vitamin riboflavin
Flavoproteins
Proton Motive Force
Form of energy generated as an electron transport chain moves protons across a membrane to create a chemiosmotic gradient.
Proton motive force
Form of energy generated as an electron transport chain moves protons across a membrane to create a chemiosmotic gradient.
The three central metabolic pathways that gradually oxidize glucose to CO2 are __________, the __________ __________ pathway, and the __________ cycle.
Glycolysis, the pentose phosphate pathway, and the TCA cycle.
Electron Transport Chain (ETC)
Group of membrane-embedded electron carriers that pass electrons from one to another, and, in the process, create a proton motive force.
Photosynthetic organisms
Harvest the energy of sunlight
Pentose phosphate pathway
Metabolic pathway that starts the degradation of glucose, generating reducing power in the form of NADPH, and two precursor metabolites.
Anaerobic respiration
Metabolic process in which electrons are transferred from the electron transport chain to a terminal electron acceptor other than O2.
Aerobic respiration
Metabolic process in which electrons are transferred from the electron transport chain to molecular oxygen (O2).
Fermentation
Metabolic process that stops short of oxidizing glucose or other organic compounds completely, using an organic intermediate as a terminal electron acceptor.
Cellular Respiration
Metabolic process that transfers electrons stripped from a chemical energy source to an electron transport chain, generating a proton motive force that is then used to synthesize ATP.
Cellular respiration
Metabolic process that transfers electrons stripped from a chemical energy source to an electron transport chain, generating a proton motive force that is then used to synthesize ATP; also called cellular respiration.
Respiration
Metabolic process that transfers electrons stripped from a chemical energy source to an electron transport chain, generating a proton motive force that is then used to synthesize ATP; also called cellular respiration.
Catabolism
Metabolic processes that harvest energy released during the breakdown of compounds such as glucose, using it to synthesize ATP.
Anabolism
Metabolic processes that synthesize and assemble the subunits of macromolecules, using energy of ATP; biosynthesis.
The sum of all chemical reactions in a cell is called __________.
Metabolism
metabolic pathways of organisms such as E. Coli
Model for eukaryotic cells
Adenosine Diphosphate (ADP)
Molecule that accepts an inorganic phosphate (P), generating ATP.
Energy released from electrons passing down the electron transport chain is coupled to?
Movement of protons across the membrane
NAD+/NADH
Nicotinamide adenine dinucleotide
products characteristics of specific microbes
identifying markers
Exponential (Log) Phase
Stage in the growth curve during which cells divide at a constant rate; generation time is measured during this period of active multiplication
Oxidative Phosphorylation
Synthesis of ATP using the energy of a proton motive force created by harvesting chemical energy.
Oxidative phosphorylation
Synthesis of ATP using the energy of a proton motive force created by harvesting chemical energy.
Photophosphorylation
Synthesis of ATP using the energy of a proton motive force created by harvesting radiant energy.
Substrate-Level Phosphorylation
Synthesis of ATP using the energy released in an exergonic (energy-releasing) chemical reaction during the breakdown of the energy source.
Substrate-level phosphorylation
Synthesis of ATP using the energy released in an exergonic (energy-releasing) chemical reaction during the breakdown of the energy source.
oxidizes an acetyl group to release two molecules of CO2; generates some ATP and precursor metabolites and the most reducing power of all the central metabolic pathways
TCA cycle
Energy
The capacity to do work
Some enzymes act with the assistance of a non-protein component. This component is called a __________; if that component is an organic molecule it can be called a __________.
cofactor, coenzyme
In prokaryotic cells, all the central metabolic pathways occur in the _________.
cytoplasm
In prokaryotes, the electron transport chain is located in the ___________ membrane, whereas in eukaryotic cells it is in the ___________ membrane of mitochondria.
cytoplasmic, inner
In electron transport chains, quinones, cytochromes, and flavoproteins are all __________ carriers.
electron
The energy released is then used to drive anabolic reactions in the cell that are ______.
endergonic
Consider how cells obtain energy to make ATP. The chemical that serves as the electron donor is the __________ source, and the one that ultimately accepts those electrons is the __________ electron acceptor.
energy, terminal
The binding of a substrate to the active sites of an enzyme causes the shape of the flexible enzyme to change slightly. This induced fit results in a temporary intermediate called ________-__________ ___________.
enzyme-substrate complex
In terms of energy, the series of catabolic reactions by which a cell breaks down glucose are _______.
exergonic
T/F: cells growing in glucose-salts medium use glucose exclusively as an energy source
false
The energy available to do work is ______ _______.
free energy
What does the term planktonic mean?
free-floating bacteria
The primary pathway used by many organisms to convert glucose to pyruvate is ________.
glycolysis
splits glucose and gradually oxidizes it to two molecules of pyruvate; generates some ATP and reducing power plus 6 precursor metabolites
glycolysis
cofactors include ______, ______, ______
magnesium, zinc, copper
The series of sequential chemical reactions that converts a starting compound to an end product is called a _______ _________.
metabolic pathway
the sum total of chemical reactions in a cell
metabolism
The TCA cycle completes the ______ of glucose
oxidation
Although a modest amount of ATP is generated via substrate-level phosphorylation by the central metabolic pathways, these pathways produce a large amount of reducing power that can be used to generate a much larger quantity of ATP via __________ phosphorylation.
oxidative
energy from exergonic reactions is used to create a proton motive force that drives the addition of P to ADP
oxidative phosphorylation
Each type of the major electron carriers is referred to by two different abbreviations (NAD+/NADH,NADP+/NADPH, and FAD/FADH2. The first of each pair refers to the ___________ form and the second of each pair refers to the __________ form.
oxidized, reduced
breaks down glucose, although primary role is production of NADPH and two precursor metabolites for use in biosynthesis
pentose phoshphate pathway
What is the exponential or log phase?
period of exponential growth
The sun's radiation energy and an electron transport chain create a proton motive force that drives the addition of P to ADP
photophosphorylation
Unlike chemoorganotrophs, photosynthetic organisms generate ATP by __________.
photophosphorylation
Cellular respiration uses the __________ power of NADH and FADH2 generated in glycolysis, the transition step, and the TCA cycle to synthesize ATP.
reducing
Cellular __________ is the process that transfers electrons extracted from glucose via the central metabolic pathways to the electron transport chain, where they are used to generate a proton motive force that can be harvested to make ATP via oxidative phosphorylation.
respiration
What are primary metabolites?
small molecules made by cells as they multiply
Energy released in an exergonic reaction that is used to power the addition of P to ADP.
substrate-level phosphorylation
T/F: In a biochemical pathway, the product of the first reaction becomes the substrate in the second reaction.
True
T/F: protons used to test up the proton motive force as generated as macromolecules like glucose are oxidized in the cell
True
T/F: the energy captured in the phosphorylation of ADP to ATP comes from the proton votive force created in respiration
True
T/F: whenever a molecule is oxidized, another molecule must be reduced
True
An organic cofactor that functions as a loosely bound carrier of molecules or electrons to assist an enzyme is called a ______.
coenzyme
Most coenzymes are derived from __________.
vitamins
TCA cycle has how many ATP?
22
Glycolysis has how many ATP?
6
Some enzymes require a cofactor or a coeznyme in order to be active. What is the difference between cofactors and coenzymes? A. Cofactors are non-protein components that assist enzymes and are typically trace elements; coenzymes are organic cofactors that loosely carry molecules or electrons. B. Cofactors transfer molecules or electrons from one compound to another while coenzymes are trace elements that assist in enzyme function. C. Cofactors are non-protein molecules while coenzymes are composed of amino acids. D. Coenzymes are non-protein molecules while cofactors are composed of amino acids.
A
Chemically defined medium
A culture medium in which the exact chemical composition is known
Complex medium
A culture medium that contains protein digests, extracts, or other ingredients that vary in their chemical composition
Differential medium
A culture medium with an ingredient that certain microorganisms change in a recognizable way; used to differentiate microbes based on their metabolic traits
Selective medium
A culture medium with an ingredient that inhibits the growth of microbes other than the one being sought
What is a colony?
A distinct mass of cells (about 1 million cells are required for a colony to be easily visible to the naked eye).
Enzyme
A molecule, usually a protein, that functions as a catalyst, speeding up a biological reaction.
What is agar?
A polysaccharide extracted from seaweed, used to solidify culture media.
Pure culture
A population descended from a single cell
What is aseptic technique?
A procedure to minimize the chance that other organisms will be accidentally introduced.
What is binary fission?
A process in which a cell grows and divides to produce two new daughter cells
What is a petri dish?
A small circular dish used to culture bacteria or cells
What is a closed system?
A system where neither matter nor energy can enter or leave Also referred to as a batch culture, because nutrients aren't renewed nor are wastes removed.
During the electron transport chain, ATP will be made from A. ADP + Pi B. ADP + H2O C. ADP + 2Pi
A. ADP + Pi
The energy released during the reactions of glycolysis is used to form A. Adenine triphosphate B. Glycerol C. Guanine triphosphate
A. Adenine triphosphate
In bacteria, protons received from NADH A. are transported (or pumped) through the membrane to the outside of the cell. B. act as coenzymes. C. are passed along the electron transport chain along with the electrons. D. are the terminal electron acceptors.
A. Are transported through the membrane to the outside of the cell
The synthesis of ATP via ATP synthase, driven by a proton motive force, is called A. chemiosmosis. B. cyclophosphorylation. C. substrate-level phosphorylation. D. glycolysis. E. the TCA cycle.
A. Chemiosmosis
Where does the TCA cycle take place in bacteria? A. Cytoplasm B. Mitochondria C. Cell membrane
A. Cytoplasm
In prokaryotic cells, the electron transport chain (ETC) is located in the ___________, whereas in eukaryotic cells, the ETC is located in the ____________. A. cytoplasmic membrane; inner membrane of mitochondria B. cytoplasm; mitochondrial matrix C. periplasmic space; cytoplasmic membrane D. cytoplasmic membrane; outer membrane of mitochondria
A. Cytoplasmic membrane; inner membrane of mitochondria
Consider the biochemical pathway: A → B → C Enzyme 1 catalyzes A → B Enzyme 2 catalyzes B → C Enzyme 1 can utilize A. only A as a substrate. B. either A or B as substrate, but c. not both. D. neither A nor B as substrate. E. both A and B as substrates. F. only B as a substrate.
A. Only A as a substrate
Removing the electron transport chain of E. coli would A. prevent oxidative phosphorylation. B. interfere with the function of its mitochondria. C. prevent glycolysis.
A. Prevent oxidative phosphorylation
Which of the following is NOT a catabolic process? A. Protein synthesis B. Fermentation C. TCA cycle D. Glycolysis
A. Protein synthesis
What are two fundamental tasks that all cells must accomplish to grow? a. synthesize new parts and harvest energy to power reactions b. mate and produce offspring c. consume food and digest food
A. synthesize new parts and harvest energy to power reactions
What is not essential for an electron transport chain to function?
ATP
Substrate
(1) Substance on which an enzyme acts to form products; (2) surface on which an organism will grow.
FAD/FADH2
(flavin adenine dinucleotide)
NADP+/NADPH
(nicotinamide adenine dinucleotide phosphate)
Steps of the Central Metabolic Pathway
1. Glycolysis 2. Pentose Phosphate pathway 3. TCA Cycle 4. Cellular respiration 5. Fermentation Gary Put Toes on Carries Face
For each glucose molecule broken down by glycolysis, how many NET ATP molecules are produced?
2
In bacteria, proton pumps are protein complexes that A. move protons from the exterior of the cell to the interior. B. pump protons and electrons through the cell membrane. C. move protons from the interior of the cell to the exterior. D. synthesize water from hydrogen and oxygen. E. break down water into hydrogen and oxygen.
C. Move protons from the interior of the cell to the exterior
Cells obtain energy by ________ food molecules such as glucose. A. redoxing B. phosphorylating C. oxidizing D. reducing E. anabolizing
C. Oxidizing
Enzymes are usually ________. A. nucleic acids B. lipids C. proteins D. carbohydrates E. steroids
C. Protiens
The two 3-carbon molecules that glucose is split into during glycolysis are converted through a series of steps ending in what 3-carbon molecules? A. Citric acid B. Acetyl-CoA C. Pyruvate
C. Pyruvate
In aerobic respiration, oxygen acts as A. a coenzyme. B. one of the electron carriers, passing electrons down the ETC. C. the terminal electron acceptor. D. a reducing agent.
C. The terminal electron acceptor
The process by which chemolithosutotrophs and photoautotrophs incorporate CO2 into organic compounds is called __________ __________.
Carbon fixation
Biosynthesis
Cellular processes that synthesize and assemble the subunits of macromolecules, using the energy of ATP.
metabolic wastes of Lactococcus and Lactobacillus species contributing to flavor and texture
Cheese
Oxidation-reduction reactions
Chemical reactions in which one or more electrons is (are) transferred from one molecule to another.
Terminal Electron Acceptor
Chemical that is ultimately reduced as a consequence of fermentation or respiration.
Terminal electron acceptor
Chemical that is ultimately reduced as a consequence of fermentation or respiration.
Glycolysis
Metabolic pathway that oxidizes glucose to pyruvate, generating ATP and reducing power.
Cells prefer to use carbs as energy sources b/c they are such good donors of ________ and _______.
Hydrogen and electrons
When discussing electron carriers in the context of biological reactions, why do we often ignore the location of protons?
In aqueous solutions, protons do not require carriers.
Activation energy
Initial energy required to break a chemical bond.
What is the streak plate method?
Inoculating loop is used to draw the inoculum back and forth across the agar plate to separate individual cells of microbial population
What is the lag phase?
Intense activity preparing for population growth, but no increase in population
What is an agar plate?
It is a petri dish with the solid medium required for growth of the colony: it comes from red algae
Central metabolic pathways
Known as the three key metabolic pathways: Glycolysis, the TCA cycle, and the pentose phosphate pathway; the transition step is often considered a part of the TCA cycle.
The 5 distinct phases in populations Growth Curve when microorganisms growing in a closed vessel of liquid medium are what?
Lag phase, exponential or log phase, stationary phase, death phase, phase of prolonged decline
Precursor Metabolites
Metabolic intermediates that can be either used to make the subunits of macromolecules or oxidized to generate ATP.
Precursor metabolites
Metabolic intermediates that can be either used to make the subunits of macromolecules or oxidized to generate ATP.
What are secondary metabolites?
Not produced as part of normal growth usually have antibiotic properties - (protect remaining nutrients from competitors) usually collected in batch culture
In aerobic respiration, ______ serves as the terminal electron acceptor
O2
Chemoorganotrophs
Obtain energy by degrading organic compounds
Facultative Anaerobe
Organism that can survive with or without oxygen
Obligate Anaerobe
Organism that cannot multiply, and is often killed, in the presence of oxygen
Obligate Aerobe
Organism that requires oxygen
Which forms of phospohorylation require an electron transport chain for ATP production?
Photophosphorylation and oxidative phosphorylation
Biofilm
Polymer-encased community of microorganisms
Lipid-soluble organize molecules that move freely in the membrane; includes one that serves as a source of vitamin K for humans and other mammals
Quinones
Oxidized
Refers to loss of electrons.
Reduced
Refers to the gain of electrons.
The electron transport chain is apart of ______
Respiration
Metabolic pathway
Series of sequential chemical reactions that are a part of metabolism
T/F The location of the photosynthetic pigments that form photosystems is the stroma of the chloroplast.
True
Adenosine Triphosphate (ATP)
The energy currency of cells. Hydrolysis of the bonds between its phosphate groups can be used to power endergonic (energy-consuming) reactions.
Who was Robert Koch?
The greatest contributor to methods of cultivating bacteria (1843-1910) German
What is the generation time?
The time it takes for a population to double in number
What is a growth curve?
This is a graph of the number of organisms in a growing population over time
Redox reactions
Transfer of electrons from one compound to another; one compound becomes reduced and the other becomes oxidized.
TCA cycle stands for?
Tricarboxylic acid cycle
The critical site of an enzyme to which a substrate binds by weak forces is called the __________ __________.
active site
the set of chemical reactions that synthesize and assemble the subunits of macromolecules
anabolism
Consider a cell extracting energy from the chemical bonds of glucose. This is an example of catabolism, and the reactions that release energy are exergonic. The cell can then use the captured energy to drive __________ (biosynthesis), synthesizing and assembling subunits of macromolecules in a series of __________ reactions, which require energy.
anabolism, endergonic
When a molecule other than O2 serves as the terminal electron acceptor for the electron transport chain, the organism is utilizing __________ respiration.
anaerobic
microbial breakdown of corn stalks, sugar cane, and wood into ethanol
biofuels
Consider the 3 key central metabolic pathways (glycolysis, pentose phosphate pathway, and TCA cycle). If you had to summarize what these pathways accomplish as they oxidize glucose, what three important items would you say they produce? a. co2 b. water c. precursor metabolites d. reducing power e. ATP
c,d,e
the set of chemicals that degrade compounds, releasing their energy
catabolism
The process that links the electron transport chain to ATP synthesis is called the _________ theory
chemiosmotic
metabolic processes unique to prokaryotes
target of antimicrobial drugs
Generation time
the time it takes for a population to double in number
