Enzymes

Cells will regulate their enzymes both directly and indirectly. Indirect regulation is due to: a. blocking the substrate from binding b. preventing transcription c. changing the active site so a substrate cannot bind d. a and c

Preventing transcription *Indirect regulation regulates the transcript of the gene, which codes for the enzyme.

How long is the average protein? a. 20 amino acids b. 100 amino acids c. 500 amino acids d. 1200 amino acids

100 amino acids *An average protein is about 100 amino acids in length and each location can have 20 different amino acids; therefore 20^100 different apoenzymes can be made responsible for specificity

How many different amino acids are used to make a protein? a. 4 b. 12 c. 20 d. 64

20 *An average protein is about 100 amino acids in length and each location can have 20 different amino acids; therefore 20^100 different apoenzymes can be made responsible for specificity

How many different combinations of amino acids can an average protein be? a. 120 b. 2000 c. 20^100 d. 100^20 e. 500

20^100 *An average protein is about 100 amino acids in length and each location can have 20 different amino acids; therefore 20^100 different apoenzymes can be made responsible for specificity

Some causes of denaturation include: a. changes in pH b. changes in temperature c. number of other proteins in the solution d. all of the above e. a and b

A and B *Denaturation is caused by extremes in pH and/or temperature.

Which of the following is a product from glycolysis? a. ATP b. pyruvate c. 3-phosphoglycerate d. all of the above e. a and b

A and B *Ending products from glycolysis is pyruvate, NADH and ATP

What happens to the coenzyme which is used in glycolysis? a. it becomes reduced b. it becomes oxidized c. it loses electrons d. a and c e. b and c

It becomes reduced *NADH is the reduced form of the coenzyme, NAD+

An example of indirect regulation is the: a. lactose operon b. competitive inhibitor c. noncompetitive inhibitor d. b and c

Lactose operon *Indirect regulation regulates the transcription of a gene. The lactose operon contains three genes which are transcribed as single mRNA, under the control of one promoter.

Which of the following is a coenzyme used in glycolysis? a. ribulose diphosphate carboxylase b. NAD+ c. 3-phosphoglycerate d. ADP

NAD+

NAD is made from a vitamin. Which vitamin? a. B12 c. C d. niacin e. E f. K

Niacin *NAD is made from vitamin niacin and is used to shuttle electrons and protons around the cell

Choose the one best answer: binds to the apoenzyme but not at the active site; prevents the substrate from binding to the active site. a. apoenzyme b. competitive inhibitor c. cofactor d. coenzyme e. non-competitive inhibitor

Non-competitive inhibitior *Non-competitive inhibitors bind to allosteric sites on the enzyme. Allosteric sites are a location other than the active site.

Choose the one best answer: binds to an allosteric site on an enzyme a. apoenzyme b. competitive inhibitor c. cofactor d. coenzyme e. non-competitive inhibitor

Non-competitive inhibitor *Non-competitive inhibitors bind to allosteric sites on the enzyme. Allosteric sites are a location other than the active site.

When a fermentation reaction occurs, NADH is: a. oxidized b. reduced c. acquires electrons d. a and c e. b and c

Oxidized *Fermentation oxidizes electron carriers so they can be reused; e.g., NADH --> NAD

True or False: A species with a large "bag of enzymes" has the following advantages: it can use a greater number of substances as nutrients and it requires fewer nutrients for making all of the biological molecules needed for survival

True

True or False: Although an organism's enzymes determine its habitat and niche, it's an organism's genes which determine its enzymes. Ultimately, it's an organism's genetic makeup which determines its habitat and niche.

True

True or False: The Calvin-Benson cycle is the "synthesis" part of photosynthesis.

True

True or False: The assortment of enzymes (bag of enzymes) an organism produces determines an organism's nutritional needs.

True

True or False: The combination of producers, consumers and decomposers within a habitat provide the enzymes necessary for the organisms within the habitat to survive.

True

Many of the different fermentation reactions are used to produce commercial products. One of the fermentation reactions which is used for making bread and an additive for gasoline, produces: a. CO2 b. ethanol c. oxidized NAD+ d. all of the above e. a and b

All of the above

Which of the following is a starting substrate for glycolysis: a. ATP b. ADP c. P d. glucose e. all of the above

All of the above

Which of the following is true about enzymes? a. they catalyze biological reactions b. they are not changed or consumed during the reaction c. a single enzyme can repeatedly catalyze reactions d. they are designed to work optimally under specific conditions (e.g., specific pH and temperature) e. all of the above

All of the above

Match the types of pathways with the appropriate description: e.g., glycolysis a. fermentation b. amphibolic c. anabolic d. a and b

Amphibolic *Glycolysis is an amphibolic pathway and is a source of ATP.

Match the types of pathways with the appropriate description: produces intermediates a. fermentation b. amphibolic c. anabolic d. a and b

Amphibolic *Intermediates are products from amphibolic pathways used in anabolic pathways for making amino and nucleic acids.

Match the types of pathways with the appropriate description: some catabolic pathways a. fermentation b. amphibolic c. anabolic d. a and b

Amphibolic *Special kind of catabolic pathway that releases energy for making ATP and produces products which are intermediates in anabolic pathways.

Match the types of pathways with the appropriate description: releases energy from chemical bonds for making ATP a. fermentation b. amphibolic c. anabolic d. a and b

Amphibolic Glycolysis is an amphibolic pathway. Glycolysis breaks down sugars to produce ATP by releasing energy from its chemical bonds.

Match the types of pathways with the appropriate description: synthesis pathways for making macromolecules a. fermentation b. amphibolic c. anabolic d. a and b

Anabolic *Anabolic pathways are any pathway which results in the synthesis of molecules and requires the input of energy (i.e., ATP)

Match the types of pathways with the appropriate description: requires energy in the form of ATP a. fermentation b. amphibolic c. anabolic d. a and b

Anabolic *Anabolic pathways result in the synthesis of molecules and requires the input of energy (i.e., ATP)

Match the types of pathways with the appropriate description: e.g., Calvin-Benson cycle a. fermentation b. amphibolic c. anabolic d. a and b

Anabolic *The Calvin-Benson Cycle is the synthesis of photosynthesis. This is an example of an anabolic pathway since anabolic pathways result in the synthesis of molecules.

Choose the one best answer: the way it folds on itself creates the active site a. apoenzyme b. competitive inhibitor c. cofactor d. coenzyme e. non-competitive inhibitor

Apoenzyme

Choose the one best answer: determines the specificity of the enzyme a. apoenzyme b. competitive inhibitor c. cofactor d. coenzyme e. non-competitive inhibitor

Apoenzyme *Apoenzymes are part of the enzyme which contain the active site and determines its specificity.

Choose the one best answer: protein a. apoenzyme b. competitive inhibitor c. cofactor d. coenzyme e. non-competitive inhibitor

Apoenzyme *Apoenzymes are proteins with great variety.

The pathway which fixes carbon dioxide out of the atmosphere is: a. called the glycolysis pathway b. also used to produce ATP c. called the Calvin-Benson cycle d. a and b e. b and c

Called the Calvin-Benson cycle *The Calvin-Benson Cycle is the synthesis of photosynthesis where the pathway fixes atmospheric CO2 into an organic form

Choose the one best answer: part of some but not all enzymes; often a vitamin a. apoenzyme b. competitive inhibitor c. cofactor d. coenzyme e. non-competitive inhibitor

Coenzyme *Coenzymes are vitamins or modified vitamins. Example, NAD, which is made from vitamin Niacin and is used to shuttle electrons and protons around the cell.

Choose the one best answer: e.g., NAD+ a. apoenzyme b. competitive inhibitor c. cofactor d. coenzyme e. non-competitive inhibitor

Coenzyme *NAD is made from vitamin niacin and is used to shuttle electrons and protons around the cell. Vitamin and modified vitamin molecules are often used as coenzymes.

Choose the one best answer: a metal ion which helps the enzyme bind to its substrate a. apoenzyme b. competitive inhibitor c. cofactor d. coenzyme e. non-competitive inhibitor

Cofactor *Metal ions, which improve binding between the enzyme and substrate, serve as cofactors.

Choose the one best answer: e.g., zinc a. apoenzyme b. competitive inhibitor c. cofactor d. coenzyme e. non-competitive inhibitor

Cofactor *The metal ion improves the binding between enzyme and substrate

Choose the one best answer: carries electrons, protons or functional groups released from a chemical reaction a. apoenzyme b. competitive inhibitor c. cofactor d. coenzyme e. non-competitive inhibitor

Competitive inhibitor

If an enzyme performs its catalysis inside of the cell, it is called an: a. endoenzyme b. exoenzyme c. extracellular enzyme d. a and c e. b and c

Endoenzyme *Endoenzymes catalyze reactions within the cell. Exoenzymes are secreted to catalyze reactions outside of the cell.

True or False: Based on what we know about ecology, the Earth can be imagined as a single organism. Its ability to survive is due to the pool of enzymes contributed by all of the species inhabiting its biosphere. And when some of these species become extinct, the Earth loses some of these enzymes. Potentially, if enough species go extinct, Earth as we know it might die.

False

True or False: The function of an enzyme is to increase the amount of energy necessary for a reaction to occur. This energy is called 'activation' energy. The effect is to speed up a chemical reaction.

False *Enzymes make reactions go faster by lowering activation energy. Enzymes speed up reactions by decreasing the activation energy.

True or False: The starting substrate for glycolysis is pyruvate. The starting substrate for the Calvin-Benson Cycle is reduced NADH.

False *Starting substrate for glycolysis is glucose and the starting substrate for the Calvin-Benson Cycle is CO2

Match the types of pathways with the appropriate description: e.g., beginning substrate is pyruvate and NADH a. fermentation b. amphibolic c. anabolic d. a and b

Fermentation *Pyruvate (from Glycolysis) + NADH --> Organic molecule + NAD

Which of the following pathways produces intermediates? a. glycolysis b. Calvin-Benson Cycle c. fermentation

Glycolysis *Intermediates are products from amphibolic pathways which are used in anabolic pathways. Glycolysis produces intermediates which can be used in anabolic pathways for making amino and nucleic acids.

Research has uncovered the way an organism responds to conditions which might cause denaturation of its enzymes. In response, an organism will produce a substance which binds to the enzyme and prevents it from unraveling. These molecules are called: a. competitive inhibitors b. inducers c. repressors d. heat shock proteins

Heat shock proteins *Heat shock proteins (HSP) are proteins that are produced by cells in response to exposure to stressful conditions. They help maintain the correct shape of proteins. Denaturation is caused by extremes in pH and/or temperature which cause stressful conditions.

Which of the following best describes the purpose of fermentation reactions? a. produce ATP b. synthesize macromolecules c. produce intermediates for anabolic reactions d. recycle electron carriers e. a and d

Recycle electron carriers *The fermentation pathway oxidizes electron carriers so they can be reused (recycled). An electron carrier is reduced when it receives an electron. It is oxidized when it gives away the electron.

The enzyme which is indispensable to all life, and which is the most plentiful enzyme on earth, is called: a. ribulose bisphosphate carboxylase b. catalase c. deoxyribose bisphosphate carboxylase d. carbon dioxide fixase

Ribulose bisphosphate carboxylase *Fixes carbon from CO2 to an organic molecule, is the most abundant protein on Earth and is perhaps the most important enzyme on Earth.

Carbon is cycled from the atmosphere to organic matter and then back into the atmosphere. The enzyme which carries out the first step of fixing carbon from carbon dioxide into an organic molecule is called: a. ribulose bisphosphate carboxylase b. ATP synthase c. catalase d. superoxide dismutase

Ribulose bisphosphate carboxylase *This is the key enzyme which fixes carbon from CO2 to an organic molecule

The genus of fungi which is used to make bread is: a. Candida b. Trichophyton c. Histoplasma d. Sacchromyces e. Mucor

Sacchromyces

Chemical reactions include reactants and products. If an enzyme catalyzes a chemical reaction, a reactant is also called a(n): a. activation energy b. product c. substrate d. competitive inhibitor

Substrate *Substance on which an enzyme reacts; will undergo a chemical reaction

Most enzymes are part of a pathway. A pathway has the following characteristics: a. the product of one enzyme in the pathway becomes the substrate for the next enzyme in the pathway b. the substrate of an enzyme becomes the product for the next enzyme in the pathway c. the product of the first enzyme in the pathway acts as a noncompetitive inhibitor of the last enzyme in the pathway d. a and c e. b and c

The product of one enzyme in the pathway becomes the substrate for the next enzyme in the pathway *The enzyme pathway is a series of enzymes where the product of one enzyme becomes the substrate for another.

Denaturation can be defined as: a. the mineralization of organic compounds b. the unraveling of protein structure and, if the protein is an enzyme, the loss of enzyme activity c. cycling of nitrogen back into its reservoir d. the reverse of evolution

The unraveling of protein structure and, if the protein is an enzyme, the loss of enzyme activity *Denaturation is a process of modifying the molecular structure of a protein. It involves the breaking of weak linkages, or bonds (e.g., hydrogen bonds), within a protein molecule that are responsible for the highly ordered structure of the protein in its natural state. A common consequence of denaturation is loss of biological activity (e.g., loss of the catalytic ability of an enzyme)

True or False: An organism's habitat, its niche, its relationship with other life forms, are determined by its 'bag of enzymes', ultimately by its genome.

True *Ecology is based on enzymes. An organism's habitat, its niche, its relationship with other life forms, are determined by its bag of enzymes, ultimately by its genome.

True or False: All chemical reactions require activation energy.

True *Enzymes speed up the reaction by lowering the activation energy. Without activation energy, enzymes cannot speed up.

True or False: Pathways can also be regulated directly and indirectly.

True *Feedback inhibition, where the end product of a pathway is a noncompetitive inhibitor of the first enzyme in the pathway is how the pathway interact directly. Regulating transcription of the genes which code for the pathways (ex: lactose operon) is how the pathway interacts indirectly.

True or False: Genetic engineering allow us to make metabolic hybrids. We can put a metabolic pathway from one organism into another. This has been done to clean up old, buried gasoline tanks so that the remaining residue is eliminated before it can contaminate soil and water.

True *Genetic engineering allows us to combine enzyme pathways from different organisms into a single organism. E.g., Pseudomonas aeruginosa and biomediation of gasoline-contaminated sites

True or False: Many biologically important chemical reactions require high activation energy and proceed too slowly for life to exist. Thus, in the absence of enzymes, life as we know it would not exist on planet Earth.

True *High activation energy = slow enzyme reaction

True or False: Enzymes are proteins which have an active site which fits perfectly with some molecule(s). Upon binding, the enzyme puts torque on the molecule(s) so that either the molecule breaks apart or combines with another molecule. Thus, the substrate and the reaction catalyzed by the enzyme is specific for that enzyme.

True *The site on an enzyme in which the substrate binds is called an active site. The active site and the substrate must fit perfectly, like a lock and key. The substrate can either be one, and after binding break apart, or be two and bind together to fit into the active site. Because of this, they are specific.

True or False: Anabolic pathways are integrated with catabolic pathways within a single cell. Moreover, within a habitat, metabolic pathways are integrated among the different species within the habitat.

True Catabolic pathways release energy for making ATP and produces products which are intermetiates in anabolic pathways.