Microbiology Chapter 6 HW

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 -Reducing power -Precursor metabolites

1. ______ refers to energy-requiring metabolic processes that result in the biosynthesis of macromolecules and cellular structures. 2. Which of the following is not a catabolic process? 3. The Tricarboxylic Acid Cycle (TCA cycle) occurs after ______.

-Anabolism -Protein synthesis -glycolysis

Which of the following compounds can be generated from precursor metabolites produced during glycolysis?

-Glycerol, a component of lipids -Some small amino acids like alanine, leucine, and valine. -Peptidoglycan, a component of bacterial cell walls.

The breakdown products of proteins can enter which of the following metabolic pathways?

-Glycolysis -TCA cycle -Pentose phosphate pathway

1. Hydrogen is transported from other reactions to the electron transport chain by ______. 2. Hydrogen consists of 3. During the electron transport chain, ATP will be made from 4. Which of the following contain a metal ion that can accept and donate electrons?

-NADH and FADH2 -one proton and one electron. -ADP + Pi -Cytochromes

Which of the following compounds can be generated from precursor metabolites in the TCA cycle?

-Some amino acids like aspartate, glutamate, and proline. -Certain protein components.

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?

B only

What is the most important point in the first paragraph?

Biologists thought that yeast cells multiplying in grape juice convert sugar into CO2 and alcohol.

Some enzymes require a cofactor or a coeznyme in order to be active. What is the difference between cofactors and coenzymes?

Cofactors are non-protein components that assist enzymes and are typically trace elements; coenzymes are organic cofactors that loosely carry molecules or electrons.

Consider the image you labeled showing a metabolic pathway under allosteric regulation. Which enzyme in this pathway is most likely under allosteric control?

Enzyme a

How do chemolithotrophs acquire energy?

From inorganic compounds

A population of bacteria is breaking down some lipids to support microbial growth. Where do the products of lipid breakdown enter the central metabolic pathway?

Glycolysis TCA cycle

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

Identify which of the following are coenzymes.

NAD+ FAD NADP+

Eventually Eduard Buchner showed that crushed (destroyed) yeast cells could convert sugar to ethanol and CO2. What did this experiment show?

Something was released from the crushed cells that could still convert sugar to alcohol.

One of the methods used to identify S. enterica in the lab is growth in tetrathionate broth, a selective enrichment medium for this organism. What does this mean?

Tetrathionate broth inhibits the growth of non-Salmonella bacteria and encourages the growth of Salmonella.

In prokaryotic cells, the electron transport chain (ETC) is located in the ______, whereas in eukaryotic cells, the ETC is located in the ______.

cytoplasmic membrane; inner membrane of mitochondria

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: Most people who get Salmonella contract it from turtles.

false

T/F: The cytoplasmic membrane is permeable to protons

false

T/F: The location of the photosynthetic pigments that form photosystems is the stroma of the chloroplast.

false

Streptococcus pneumoniae lacks an electron transport chain. Therefore, S. pneumoniae generates ATP via ______.

fermentation

The rate of growth in flask 1 is slower than that in flasks 2 and 3, and you detect the production of lactic acid. The E. coli in this tube can be most accurately described as undergoing ______.

fermentation

The high-energy electrons of photosystem I are directly passed on to ______.

ferredoxin

In prokaryotic cells undergoing respiration, protons are pumped

from inside the cell to outside the cytoplasmic membrane

In eukaryotic cells undergoing respiration, protons are pumped

from the mitochondrial matrix to the intermembrane space

When polysaccharides are broken down, their breakdown products can be oxidized for energy by entering which of the following metabolic pathways?

glycolysis

In bacteria, proton pumps are protein complexes that

move protons from the interior of the cell to the exterior

Consider the biochemical pathway: A → B → C Enzyme 1 catalyzes A → B Enzyme 2 catalyzes B → C Enzyme 1 can use

only A as a substrate

Cells obtain energy by ______ food molecules such as glucose.

oxidizing

Anabaena is a genus of filamentous cyanobacteria commonly found in aquatic environments, where it harvests energy from sunlight and fixes both carbon dioxide and nitrogen. Knowing this, how would you classify Anabaena?

photoautotroph

Removing the electron transport chain of E. coli would

prevent oxidative phosphorylation

Enzymes are usually ______.

proteins

The Calvin Cycle takes place in the ______ of chloroplasts.

stroma

Which of the following binds to the active site of an enzyme?

substrate

The electrons excited by photons of light are replaced by electrons from ______ in photosystem II, and by electrons from ______ in photosystem I.

water; photosystem II

The Calvin Cycle uses ______ and ______, produced in the light reactions of photosynthesis, to drive the fixation of carbon dioxide.

ATP and NADPH

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?

ATP, reduced electron carriers, and precursor metabolites.

Consider a metabolic pathway under allosteric regulation. Label the pathway components and the diagram showing a "before and after" of an enzyme under allosteric regulation.

*picture

Identify the final electron acceptor at the end of the tandem photosystems of cyanobacteria when non-cyclic photophosphorylation is used.

*picture

Label the components involved in the chemical reaction.

*picture

Label the diagram that shows the impact of enzymes on the energy level of chemical reactions

*picture

Label the diagram that shows the impact of enzymes on the energy level of chemical reactions.

*picture

Label the graphs demonstrating the effect of environmental factors on enzyme activity.

*picture

Label the intermediates and products of glycolysis. Not all labels are used.

*picture

Label the overview of the central metabolic pathways and their associated components. Not all labels are used.

*picture

Place the labels to show the relationships between catabolic reactions and anabolic reactions.

*picture

Label the reactants and intermediates of the transition step and the TCA cycle. Not all labels are used.

+picture

1. What is oxidation? 2. Early in glycolysis, two phosphates are added to the glucose molecule. These phosphates come from 3. During glycolysis, a single 6-carbon molecule of glucose is converted to two 3-carbon pyruvate molecules. During the later steps in this process, how many molecules of ATP are generated? 4. The two 3-carbon molecules glucose is split into are converted through a series of steps into pyruvate. During these steps 5. After glycolysis, pyruvate can be converted into ______ under anaerobic conditions.

-The loss of electrons from a molecule. -breaking down ATP -4 -NAD+ is converted to NADH. -lactic acid

Why would an organism use fermentation to generate ATP?

-The organism lacks an electron transport chain. -A suitable inorganic terminal electron acceptor is not available.

Consider the image you labeled showing a metabolic pathway under allosteric regulation. Imagine if the final enzyme in the pathway was under allosteric regulation instead of the first. What impacts would this have?

-There would be a buildup of intermediate b. -The reaction would be less efficient.

Which of the following statements accurately describe biochemical pathways? Choose all that apply.

-They convert an initial substrate through a series of steps into an end product -They are well-organized and structured -They can be linear, branched, or cyclical. -They are carefully regulated

1. The coenzyme NADH is generated by 2. The electron carrier proteins in the electron transport chain shuttle electrons to 3. During the electron transport chain in bacteria, protons are 4. In anaerobic respiration, the terminal electron acceptor would also be oxygen. 5. The enzyme ATP synthase uses energy from ______ to make ATP.

-by oxidation reactions in glycolysis and the Krebs cycle -a terminal electron acceptor. -shuttled to the outside of the cell membrane. -false -protons re-entering the cell.

1. Glycolysis takes place in the ______. 2. The TCA (Krebs) cycle takes place in the mitochondria of eukaryote cells. Where does it take place in prokaryote cells? 3. What happens to carbon dioxide after it is released during reactions of the TCA cycle? 4. How many molecules of NADH are generated for each turn of the TCA cycle? 5. How many ATP molecules are produced in the TCA cycle for each glucose molecule that enters glycolysis? 6. For each glucose molecule that enters glycolysis, how many times does the TCA cycle "turn"?

-cytoplasm -The cytoplasm -It diffuses out of the cell. -3 -2 -2

1. Glycolysis makes products that feed into 2. 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? 3. For each glucose molecule broken down by glycolysis, how many net ATP molecules are produced?

-electron transport chain, TCA cycle AND fermentation -Pyruvate -2

1. The terminal electron acceptor in aerobic respiration is ______. 2. Glycolysis is the central metabolic pathway that involves the breakdown of ______. 3. The energy released during the reactions of glycolysis is used to form ______. 4. Cells prefer to use carbohydrates as energy sources because

-oxygen -glucose -adenosine triphosphate -they are such good donors of hydrogen and electrons

1. The main purpose of cellular respiration is to 2. Where do NADH and FADH2 go after being produced in the TCA cycle? 3. True or false: In prokaryotes and eukaryotes, the TCA cycle takes place in the mitochondria. 4. Where does the TCA cycle take place in bacteria?

-produce energy -Electron transport chain. -false -Cytoplasm

1. In bacteria, the electron transport chain is located in 2. In aerobic respiration, the last carrier protein in the electron transport chain transfers 3. The electron transport chain is part of ______.

-the cytoplasmic membrane -two electrons to oxygen. -respiration

You are studying the metabolism of the phototrophic green sulfur bacterium Chlorobaculum tepidum and realize that it is running a reversed TCA cycle! How do you explain this observation?

C. tepidum is using the reversed TCA cycle to fix carbon dioxide.

Consider the growth of Sulfurospirillum halorespirans using lactate as a source of carbon and electrons, and perchloroethylene (PCE) as an electron acceptor. How would scientists classify this species based on its metabolism?

Chemoorganoheterotroph

Scientists isolated a new species of bacteria growing in sediments collected from a 63 meter deep site at the bottom of Lake Washington in Seattle This species, named Labrys methylaminiphilus, is capable of obtaining its carbon and energy needs from methylamine (CH3NH2), a derivative of ammonia (NH3) in which one H atom is replaced by a methyl (CH3) group. L. methylaminiphilus grows at a temperature range of 10-35°C, with optimal growth at 28-30°C, and a pH range of 4.0-9.5, with optimal growth at 5.0-7.0. Because methylamine is a single carbon compound resulting from the breakdown of decaying organic matter, methylotrophic ("methyl-feeding") bacteria like L. methylaminiphilus play an important role in carbon cycling in lake sediments and other environments. Consider the growth of L. methylaminiphilus on methylamine. How would you classify this species based on its metabolism?

Chemoorganoheterotroph

The researchers were also able to grow Sulfurospirillum halorespirans using hydrogen gas as an electron donor and acetate as a source of carbon, using perchloroethylene (PCE) as an electron acceptor. When demonstrating growth in this manner, how would scientists classify this species?

Chemoorganoheterotroph

S. enterica can switch to anaerobic respiration in tetrathionate broth. What does this tell us about the organism?

It is a facultative anaerobe.

You set up a third test tube containing 8 mL water, 1 mL PTU, 1 mL potato juice, and 3 mL catechol. If this third test tube turned brown, this would suggest which of the following?

PTU is a competitive inhibitor of catechol oxidase

You set up a third test tube containing 8 mL water, 1 mL PTU, 1 mL potato juice, and 3 mL catechol. If this third test tube showed no change, this would suggest which of the following?

PTU is a non-competitive inhibitor of catechol oxidase.

The results of your test tubes suggest which of the following?

PTU is an inhibitor of catechol oxidase.

What do you think the researchers included as part of their enrichment culture in order to isolate Sulfurospirillum halorespirans?

Perchloroethylene Lactate Soil sample from a PCE-contaminated site

Greenlake is a small lake in Seattle, WA that sometimes experiences blooms of cyanobacteria, photosynthetic nitrogen-fixing bacteria that typically grow as filaments. These blooms are especially likely to occur during warm summer weather and result in the production of large quantities of biomass that then dies off and decomposes, leading to unpleasant odors. In addition to the aesthetic problems, some strains make toxins that can be dangerous to ingest, leading to the closing of the lake. Treatment of the water with alum (aluminum sulfate) to remove phosphorus from the water has helped to limit growth of cyanobacteria. How would you classify the cyanobacteria from Greenlake in terms of their carbon and energy sources?

Photoautotroph

You inoculate fern spores onto the surface of a growth medium in Petri dishes and wait for them to develop into gametophytes, a stage in the life cycle of a fern. The medium contains sources of nitrogen, phosphate, and a number of other macro- and micro-nutrients, but no carbon. After a few weeks, you see a contaminant growing on your plates. Assuming the organism is not digesting the agar itself, which of the following is most likely your contaminant?

Photoautotrophic species of bacteria, archaea, or protists

Which of the following represents the correct sequence of events during photosynthesis?

Photosystem II (ATP production) --> Photosystem I (NADPH production)

Pasteur set up the following experiment: he prepared a solution of sugar, ammonia, mineral salts, and trace elements, and added some yeast cells to it. He then measured the number of yeast cells as well as the sugar and alcohol levels over time. He noted that as the yeast cells multiplied, sugar levels decreased and alcohol levels increased, suggesting that the yeast cells were converting the sugar to alcohol. What do think would be an appropriate control for this experiment?

Preparing a solution of sugar, ammonia, mineral salts, and trace elements, but not adding any yeast cells to the solution.

At the beginning of the Calvin cycle, carbon dioxide is attached to ______.

RuBP

When bacteria such as S. enterica infect the intestinal tract, inflammation results. This is one of the body's immune defenses. Researchers have recently discovered that tetrathionate is produced in the intestinal tract as a result of inflammation. Why is this important?

The presence of tetrathionate gives the Salmonella a competitive advantage over the normal microbiota such as E. coli.

When setting up the reaction in tube 1, you measure the rate of product (brown pigment) formation upon adding the catechol substrate. If you set up another tube but instead add twice the amount of substrate, what do you think would be the effect on the rate of product (brown pigment) formation compared to the first test tube? Assume that the enzyme is not saturated with substrate.

The rate of the second tube would be faster than that of the first tube

What happens to the protons received from NADH in bacteria?

They are transported across the cytoplasmic membrane, setting up a proton motive force.

A hydrogen atom consists of

a proton and an electron

The rate of growth in flask 3 is substantially faster than that in flask 1 and somewhat faster than that in flask 2. The E. coli in this tube can be most accurately described as undergoing ______.

aerobic respiration

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 ______.

anabolism

The rate of growth in flask 2 is substantially faster than that in flask 1, but somewhat slower than that in flask 3. You detect the production of nitrite. The E. coli in this tube can be most accurately described as undergoing ______.

anaerobic respiration

As bacteria grow in broth, oxygen becomes depleted. At that point, most bacteria switch to fermentation to continue growing. In tetrathionate broth however, S. enterica can switch to anaerobic respiration. This gives the organism a growth advantage because

anaerobic respiration yields more ATP per glucose molecule than fermentation.

A culture of bacteria is breaking down sugars to yield energy. This is best described as ______.

catabolism

The synthesis of ATP via ATP synthase, driven by a proton motive force, is called ______.

chemiosmosis

In the electron transport chain, protons are pumped across the cell membrane. This results in

the formation of a proton motive force

In aerobic respiration, oxygen acts as

the terminal electron acceptor

In this case, a person who contracted Salmonella from a turtle was classified as having a primary infection. A person who acquired Salmonella by person-to-person transmission from a person with a primary infection would be classified as having a secondary infection.

true

T/F: Glyceraldehyde-3-phosphate and 3-phosphoglycerate are three-carbon molecules produced during the Calvin Cycle.

true

T/F: In a biochemical pathway, the product of the first reaction becomes the substrate in the second reaction.

true

T/F: Plastoquinone is the primary electron acceptor for electrons leaving photosystem II.

true

T/F: Protons used to set up the proton motive force are generated as macromolecules like glucose are oxidized in the cell.

true

T/F: The Calvin Cycle fixes carbon dioxide into organic molecules.

true

T/F: The energy captured in the phosphorylation of ADP to ATP comes from the proton motive force created in respiration.

true

T/F: Whenever a molecule is oxidized, another molecule must be reduced.

true

What is a synonym for the word "employed" which we see in this sentence: Pasteur studied the relationship between yeast and alcohol production using a strategy commonly employed by scientists today?

used