Exam 2

What are the 5 mechanisms of antibiotic action?

5 Mechanisms of Action: -inhibition of cell wall synthesis -inhibition of protein synthesis -inhibition of nucleic acid replication and transcription -injury to plasma membrane -inhibition of essential metabolite synthesis

Explain the importance of osmotic pressure to microbial growth

A hypertonic environment, or an increase in salt or sugar cause plasmolysis. Microbes need a certain osmotic pressure to maintain integrity and get nutrients. Extreme or obligate halophiles require high osmotic pressure Facultative halophiles tolerate high osmotic pressure

Explain the overall function of metabolic pathways.

A series of enzymatically catalyzed chemical reactions occurring in a cell is called a metabolic pathway; occurs in prokaryotes and eukaryotes Metabolic pathways exist because cells need to perform chemical reactions to maintain bodily functions to stay alive.

During aerobic respiration, how many ATP are generated by oxidative phosphorylation? A. 34 B. 38 C. 4 D. 2

A. 34 Oxidative phosphorylation occurs in the ETC. 10 NADH x 3 ATP/NADH = 30 ATP 2 FADH2 x 2 ATP/FADH2 = 4 ATP

Which of the following compounds is NOT an enzyme? A. coenzyme A B. dehydrogenase C. cellulase D. sucrase

A. Coenzyme A

Which of the following statements about anaerobic respiration is FALSE? A. It involves the reduction of an organic final electron acceptor. B. It generates ATP. C. It yields lower amounts of ATP when compared to aerobic respiration. D. It requires cytochromes.

A. It involves the reduction of an organic final electron acceptor.

Both respiration and photosynthesis require the use of an electron transport chain. A. True B. False

A. True

Both respiration and photosynthesis require the use of an electron transport chain. A. true B. false

A. True

Carbon fixation occurs during the light-independent phase of photosynthesis. A. True B. False

A. True

Glycolysis is utilized by cells in both respiration and fermentation. A. True B. False

A. True

In general, ATP is generated in catabolic pathways and expended in anabolic pathways. A. true B. false

A. True

Microorganisms in deep-sea vents and caves serve as autotrophic primary producers in the absence of sunlight. A. True B. False

A. True

List and provide examples of three types of phosphorylation reactions that generate ATP.

ATP is generated in 3 ways in cells: 1. Substrate level phosphorylation where the phosphate from an organic molecule (like glucose-‐6-‐phosphate) is given to ADP to produce ATP 2. Oxidative phosphorylation where reduced coenzymes like NADH2 and FADH donate electrons to the electron transport chain and ATP is produced by chemiosmosis. 3. Photophosphorylation: Energy released from the transfer of electrons (oxidation) of chlorophyll through a system of carrier molecules is used to generate ATP (requires light!!!)

Compare and contrast aerobic and anaerobic respiration

Aerobic -uses oxygen -no alcohol or lactic acid is made -large amount of energy is released(38ATP) -CO2 and water are always made -takes place in mitochondria. Anaerobic -does not use oxygen -alcohol or lactic acid are made -small amount of energy is released -CO2 is sometimes made, water is never made -Takes place in cytoplasm.

Oxidation-reduction

Also known as redox; a chemical reaction in which the oxidizing agent is reduced (by losing oxygen) and the reducing agent is oxidized (by gaining oxygen).

Explain the overall purpose of metabolic pathways.

It is the buildup and breakdown of nutrients in the cell to create energy.

Compare the phases of microbial growth and describe their relation to generation time.

LAG PHASE- period of little or no cell division, can last for 1 hour or several days; however, cells are not dormant. undergoing intense metabolic activity involving synthesis of enzymes and various molecules LOG PHASE- cells begin to divide and enter a period of growth. reproduction is active during this period and generation time reaches a constant minimum. since constant, it is a straight line. cells are most active metabolically and is preferred for industrial purposes where a produce needs to be produced STATIONARY PHASE- period of equilibrium. growth rate slows, microbial deaths balance the number of new cells, and the population stabilizes DEATH PHASE- the number of deaths eventually exceeds to number of new cells formed. phase continues until population is diminished to a tiny fraction of cells or until it dies out completely

Compare and contrast the light-dependent and light-independent reactions of photosynthesis.

Light-dependent (photo stage): -uses light energy -input is H20, ADP + P, & NADP+ -output is O2, ATP, NADPH -Catabolic Rx -takes place in the thylakoid membrane Light-independent (synthesis stage or Calvin Benson Cycle): -makes glucose -uses ATP and NADPH to reduce CO2 -input: CO2, ATP, NADPH -output: glucose, ADP + P, NADP+ -In prokaryotes: occurs in the cytoplasm -In eukaryotes: occurs in the stroma

Compare and contrast obligate aerobes and microaerophiles

Microaerophiles need oxygen because they cannot ferment or respire anaerobically. However, they are poisoned by high concentrations of oxygen. Obligate aerobes need oxygen because they cannot ferment or respire anaerobically. They gather at the top of the tube where the oxygen concentration is highest.

What is the difference between narrow spectrum of microbial activity and broad-spectrum antibiotics?

Narrow spectrum: Only active against a small group of bacteria -- Know you are treating those specific bacteria when using these drugs Broad-spectrum: Work against a wide variety of bacteria -- Can be used in cases where you may not be exactly sure what bacteria is causing the infection

Metabolism of Cyanobacteria: What is its reducing power (what is oxidized?) and its carbon source? Is O2 produced? Heterotrophic or autotrophic?

Reducing power: H2O Carbon source: CO2 Is O2 produced: Yes Metabolism: Photoautotrophic

Metabolism of Photosynthetic Eukaryotes: What is its reducing power (what is oxidized?) and its carbon source? Is O2 produced? Heterotrophic or autotrophic?

Reducing power: H2O Carbon source: CO2 Is O2 produced: yes Metabolism: Photoautotrophic

Metabolism of Green & Purple Sulfur Bacteria: What is its reducing power (what is oxidized?) and its carbon source? Is O2 produced? Heterotrophic or autotrophic?

Reducing power: H2S (Hydrogen Sulfide) Carbon source: CO2 Is O2 produced: No Metabolism: Photoautotrophic

Metabolism of Green & Purple non-Sulfur Bacteria: What is its reducing power (what is oxidized?) and its carbon source? Is O2 produced? Heterotrophic or autotrophic?

Reducing power: Organic compounds Carbon source: Organic compounds Is O2 produced: No Metabolism: Photoheterotrophic

Identify the methods of action and preferred uses of chemical disinfectants.

Sterilization by pasteurization, autoclave, or dry heat & Chemical disinfection with phenol, halogens, alcohol, or antibiotics 1. Careful attention should be paid to the properties and concentration of the disinfectant to be used. 2. The presence of organic matter, degree of contact with microorganisms, and temperature should also be considered.

Streptococcus lacks an electron transport chain. How does this bacterium re-oxidize NADH? Where is the NADH formed?

The bacterium relies on fermentation for ATP production. Two ATP and NADH are produced when a glucose molecule is converted to two molecules of pyruvate. The NADH is then re-oxidized by reduction of pyruvate to lactate by the enzyme lactate dehydrogenase. The NADH is formed in the cytoplasm.

Summarize energy production in cells in a single sentence.

To produce energy, an organism requires 1. the donation of an electron 2. an electron carrier 3. a final electron acceptor

Compare and contrast aerotolerant anaerobes and anaerobes

Unlike strict anaerobes, aerotolerant anaerobes have protection against the oxidizing power of molecular oxygen so can exist in the presence of O2. O2 is toxic for anaerobes.

An organism that uses glucose for both its energy and carbon source is a

chemoheterotroph

NADP+ is an example of a

coenzyme

A metal ion is an example of a

cofactor

Of what metabolic niche is cyanobacteria

photoautotroph

Of what metabolic niche is green non-sulfur bacteria

photoheterotroph

How is ATP generated in the reaction shown?

substrate-level phosphorylation

An enzyme is an example of a:

catalyst

Describe the patterns of microbial death caused by treatments with microbial control agents.

1. Bacterial populations subjected to heat or antimicrobial chemicals usually die at a constant rate. 2. Such a death curve, when plotted logarithmically, shows this constant death rate as a straight line. 3. Time to kill a microbial population is proportional to the number of microbes. 4. Microbial species and life cycle phases (i.e. endospores) have different susceptibilities to physical and chemical controls. 5. Organic matter may interfere with heat treatments and chemical control agents. 6. Longer exposure to lower heat can produce the same effect as shorter time at higher heat.

Describe the chemiosmotic model for ATP generation.

1. The chemiosmotic theory explains how ATP is generated in the mitochondria. 2. The synthesis of ATP is driven by the proton motive force. 3. The development of the proton gradient and then the subsequent movement of protons back across the membrane provides the energy required for ATP synthesis.

Explain the products of the Krebs cycle.

1.Decarboxylation of pyruvic acid produces ONE CO2 molecule and ONE acetyl group. 2.Two-carbon acetyl groups are oxidized in the Krebs cycle. Electrons are picked up by NAD+ and FAD for the electron transport chain. 3.From one molecule of glucose, oxidation produces six molecules of NADH, two molecules of FADH2, and two molecules of ATP. 4. Decarboxylation produces six molecules of CO2.

How many ATP are produced when an aerobic bacterium metabolizes a single glucose molecule (i.e., aerobic respiration)? Diagram or explain the stages where each ATP is produced or e- shuttles are reduced.

38 ATP During glycolysis, 2 ATP and 2 NADH are gained During acetyl CoA formation, 2 NADH are gained In the Krebs Cycle, 2 ATP, 6 NADH, and 2 FADH2 are gained. In the ETC, the 10 NADH and 2 FADH2 are oxidized to form 34 ATP.

Describe the effects of microbial control agents on cellular structures.

Alteration of membrane permeability 1. The susceptibility of the plasma membrane is due to its lipid and protein components. 2. Certain chemical control agents damage the plasma membrane by altering its permeability. Damage to proteins and nucleic acids 1. Some microbial control agents damage cellular proteins by breaking hydrogen and covalent bonds. 2. Other agents interfere with DNA and RNA replication and protein synthesis.

Describe how an ecological community can exist without light

An ecological community can exist without light by exploiting the energy in H2S. These communities can be seen in deep-sea vents, and deep caves. The primary producers are chemoautotrophic bacteria instead of photoautotrophic plants/microbes.

Compare and contrast facultative anaerobes and anaerobes

Anaerobes are microorganisms that can survive in the lack of free oxygen; obligatory, also known as stringent microbes are anaerobes that can only survive in the anaerobic environment. Some species, known as facultative anaerobes, can support the growth both in the presence or absence of free oxygen.

Which of the following is the best definition of oxidative phosphorylation? A. ATP is directly transferred from a substrate to ADP. B. A proton gradient allows hydrogen ions to flow back into the cells through transmembrane protein channels, releasing energy that is used to generate ATP. C. Electrons are passed through a series of carriers to O2. D. Electrons are passed through a series of carriers to an organic compound.

B. A proton gradient allows hydrogen ions to flow back into the cells through transmembrane protein channels, releasing energy that is used to generate ATP.

FADH2 is the oxidized form of this coenzyme. A. True B. False

B. False Oxidized form of FADH2 is FAD

A bacterium that only possesses the ability to ferment obtains energy A. by aerobic respiration only. B. by glycolysis only. C. only in the absence of oxygen. D. by fermentation or aerobic respiration. E. only in the presence of oxygen.

B. by glycolysis only

Which of the following is the best definition of fermentation? A. the partial reduction of glucose to pyruvic acid B. the partial oxidation of glucose with organic molecules serving as electron acceptors C. the complete catabolism of glucose to CO2 and H2O

B. the partial oxidation of glucose with organic molecules serving as electron acceptors

Define bacterial growth, including binary fission.

Bacterial growth refers to an increase in bacterial numbers, not an increase in the size of individual cells. They usually reproduce by binary fission (the division of a cell into two replicate cells.)

What is the difference between an agent that acts like a biocide versus a bacteriostatic agent?

Bactericidal decrease the number of bacteria, while bacteriostatic antibiotics do not decrease. Instead, they stagnate multiplication

Which of the following statements are TRUE? 1-Electron carriers are located at ribosomes. 2-ATP is a common intermediate between catabolic and anabolic pathways. 3-ATP is used for the long-term storage of energy and so is often found in storage granules. 4-Anaerobic organisms are capable of generating ATP via respiration. 5-ATP can be generated by the flow of protons across protein channels. A. 1, 2, 3 B. 2, 3, 5 C. 2, 4, 5 D. 1, 3, 4 E. All of the statements are true.

C. 2, 4, 5

What is the fate of pyruvic acid in an organism that uses aerobic respiration? A. It is catabolized in glycolysis. B. It is oxidized in the electron transport chain. C. It is converted into acetyl CoA. D. It is reduced to lactic acid.

C. It is converted into acetyl CoA

Which of the following statements about photophosphorylation is FALSE? A. Light liberates an electron from chlorophyll. B. It occurs in photosynthesizing cells. C. It requires CO2. D. Energy from oxidation reactions is used to generate ATP from ADP.

C. It requires CO2

Identify the role of ATP as an intermediate between catabolism and anabolism.

Catabolic reactions provide the energy needed for anabolic reactions. Catabolism means breaking down i.e., complex molecules are broken down into simple substances. It is energy giving. Anabolism is building up of substance, i.e., simpler substances are combines together to form a more complex molecule. It is energy taking.

Catabolism vs Anabolism

Catabolism is the use of the cell's energy in order to break down complex substances into simpler ones. An example is using energy to break down complex carbohydrates into simple sugars (leads to ATP synthesis) Anabolism is the use of the cell's energy to build up (biosynthesis) complex substances from smaller units. An example is using energy to synthesize proteins from amino acids. (involves ATP breakdown)

Summarize energy production in cells in a single sentence.

Cells use oxidation and reduction reactions in catabolism to extract energy from nutrient molecules.

An organism that uses CO2 for carbon and H2S for energy is a

Chemoautotroph

Which of the following statements about the steps in photosynthesis is incorrect? A. The light-independent reactions are anabolic B. The light-independent reactions take place in the cytoplasm of prokaryotes C. Photophosphorylation occurs during the light-dependent reactions D. Carbon dioxide is reduced during the light-dependent reactions

D. Carbon dioxide is reduced during the light-dependent reactions

In green and purple bacteria, electrons to reduce CO2 can come from A. H2O. B. CO2. C. C6H12O6. D. H2S.

D. H2S

What is the difference between sterilization and disinfection?

Disinfection is to destroy pathogenic microorganisms, sterilization is to destroy all viable microorganisms

Describe the chemical reactions of, and list some products of, fermentation.

During fermentation, an organic electron acceptor (such as pyruvate or acetaldehyde) reacts with NADH to form NAD+, generating products such as carbon dioxide and ethanol (ethanol fermentation) or lactate (lactic acid fermentation) in the process. Methane and Citric Acid may also be products of fermentation

Where do chemoautotrophs get their energy and carbon?

E: Reduced inorganic compounds C: CO2 Examples:

Where do chemoheterotrophs get their energy and carbon from?

E: organic compounds C: organic compounds Examples: humans, pathogens, fermenters, parasites, animals *ANY TYPE OF CONSUMER

Where do photoautotrophs get their energy and carbon? Give examples

E: sun C: CO2 Examples: Oxygenic plants, cyanobacteria, and algae Anoxygenic green and purple sulfur bacteria

Where do photoheterotrophs get their energy and carbon?

E: sun C: organic compounds Examples: anoxygenic green and purple non-sulfur bacteria

Explain how microbes are classified on the basis of oxygen requirements.

OBLIGATE AEROBES: oxygen required FACULTATIVE ANAEROBES: both aerobic and anaerobic growth, greater growth in presence of oxygen OBLIGATE ANAEROBES: only anaerobic growth, ceases in presence of oxygen AEROTOLERANT ANAEROBES: only anaerobic growth, but continues in presence of oxygen MICROAEROPHILES: only aerobic growth, oxygen required in low concentration

Compare and contrast oxidative phosphorylation and photophosphorylation.

Oxidative Phosphorylation: -occurs in the inner membrane during aerobic respiration -electrons are transferred from one electron carrier to another along the ETC to generate ATP Photophosphorylation: -occurs in the thylakoid membrane of chloroplasts during the light-dependent state of photosynthesis -requires light energy -electrons are transferred from one electron carrier to another along the ETC to generate ATP

List a few of the types of physical and chemical control of microorganisms. Which ones are sterilants and which ones are disinfectants?

Physical Control: Autoclave- Sterilant Pasteurization- Sterilant Dry Heat- Sterilant Chemical Control: Phenol- disinfectant Halogens- disinfectant Alcohol- disinfectant

Classify microbes into three groups on the basis of preferred temperature range.

Psychrophiles: -10C - 20C Mesophiles: 10C - 50C Thermophiles: 40C - 70C

List the phases of bacteria growth and describe what occurs in each phase

While in the lag phase, the cells adjust to their environment and population size remains stable while cells only grow in size. Once the population enters the log phase, the growth continues, but at a faster rate. This eventually leads to an exponential or logarithmic growth phase wherein the cells reach the highest rate of reproduction. In the stationary phase, the nutrients are starting to deplete rapidly, and the toxins or waste products are starting to accumulate. Physical and chemical stresses such as change in temperature and pH (acidity) also push the cells to enter this phase. The cells still divide. However, other cells also start to die resulting in an equilibrium. (Divisons = deaths) At the death stage, the number of living cells decreases at an exponential rate. (Death > divisions)

Identify why the pH of culture media is controlled

because most bacteria grow between a pH of 6.5 and 7.5

Name a use for each of the four elements (carbon, nitrogen, sulfur, and phosphorus) needed in large amounts for microbial growth.

carbon- structural organic molecule, energy source, organic compounds that make up living cells chemoheterotrophs use organic carbon source, autotrophs use CO2. Nitrogen- In amino acids and proteins, some bacteria use NH4 or NO3, few bacteria use N2 in nitrogen fixation, synthesis of DNA and RNA, synthesis of ATP sulfur- used to synthesize sulfur-containing amino acids and vitamins phosphorus- essential for the synthesis of nucleic acids and phospholipids of cell membranes, found in bonds of ATP

The breakdown of molecules is known as

catabolism