BIO CHAPTER SIX

feedback inhibition

A method of metabolic control in which the end product of a metabolic pathway acts as an inhibitor of an enzyme within that pathway.

induced fit model

Enzyme is induced to undergo a slight alteration to achieve optimum fit for the substrates

1st law of thermodynamics

The principle of conservation of energy. Energy can be transferred and transformed, but it cannot be created or destroyed.

Catabolism

breaking down of molecules

anabolic

building up (synthesis) of molecules

ATP function

chemical: supplies energy needed to synthesize macromolecules transport work: energy needed for muscles to contract, chromosomes to move, etc.

chemical energy

contains energy in chemical bonds of organic molecules (food)

second law of thermodynamics

energy cannot be changed from one form to another without a loss of usable energy (heat)

kinetic energy

energy of motion walking, ball moving

substrate concentration

enzyme activity increases as substrate concentration increases

Explain how enzymes affect energy of activation of a reaction

enzymes decrease energy of activation and speeds up reactions

how does the second law of thermodynamics relate to entropy

every energy transformation makes the universe less organized and more disordered (more entropy)

Law of Thermodynamics

explain why energy flows in ecosystems and cells

reduction

gain of electrons

higher entropy

higher disorder, more stable, less potential energy

Temperature and enzyme activity

higher temperature, higher enzyme activity too high of temperature can cause denaturation

Explain the purpose of metabolic pathways and how enzymes help to regulate them.

keeps reactions controlled, enzymes speed up these reactions

Oxidation

loss of electrons

enzyme

molecule that speeds up a chemical reaction without itself being affected by the reaction

lower entropy

more organized, less stable, more potential energy

Cofactors

necessary inorganic ions or non protein organic molecules at the active site in order to work properly metals, copper, zinc, iron

Coenzymes

nonprotein organic molecules

enzyme activation

not all enzymes are needed

Vitamins

relatively small organic molecules that are required in trace amounts in our diets for synthesis of coenzymes

endergonic reaction

require an input of energy to occur

metabolic pathways

series of linked reactions, beginning with a particular reactant and terminating with an end product

active site

the small portion of an enzyme where substrate molecules bind and undergo a chemical reaction

degradation

the substrate is broken down to smaller products

Synthesis

the substrates are combined to produce a larger product

mechanical energy

type of kinetic energy associated with the position or motion (walking) of an object

Which is NOT a correct attribute of a metabolic pathway? A. A constant supply of new enzymes must be produced to keep the metabolic pathway active. B. The product of one reaction can become the reactant for the next. C. Reactants act as substrates for specific enzymes. D. Reactants are the input molecules.

A. A constant supply of new enzymes must be produced to keep the metabolic pathway active.

Which statement most accurately describes the second law of thermodynamics? A. Energy cannot be changed from one form to another without a loss of usable energy. B. One usable form of energy can be completely converted into another usable form. C. Energy cannot be created nor destroyed but it can be changed from one form to another. D. Energy cannot be created or destroyed.

A. Energy cannot be changed from one form to another without a loss of usable energy.

If you give a child a surgary snack you might notice that they become hyperactive right afterward. Much of the sugar in the blood can be quickly absorbed by the neuronal cells of the brain where the glucose is quickly broken down to create ATP. This is an example of which factor affecting rates of enzymatic reactions? A. Substrate Concentration B. Temperature C. pH D. Enzyme Inhibition

A. Substrate Concentration

We often say that we need food for energy. In a biological sense, is this correct? A. Yes, because the food we eat has potential energy in its structure and this chemical energy can be converted into mechanical energy. B. Yes, because the smallest units inside the atoms that make up the food are simply pure energy. C. Yes, because the food must move through the digestive system, and motion is kinetic energy. D. No, because food consists of matter and cannot be transformed into energy. E. No, since all food matter stays matter, and energy remains energy.

A. Yes, because the food we eat has potential energy in its structure and this chemical energy can be converted into mechanical energy.

Some metabolic reactions require that one molecule undergoes a reaction that causes it to lose energy and that energy is then transfered to a new chemical bond on another molecule. This describes A. a coupled reaction. B. an anabolic reaction. C. the activation energy of a reaction. D. feedback inhibition.

A. a coupled reaction.

The location in which the enzyme and substrate complexes is called the A. active site. B. inhibitor site. C. receptor site. D. enzyme-substrate complex.

A. active site.

In which of the following ways is the enzyme inhibitor warfarin used? (multiple answer) A. rat poison B. anticoagulant medicine C. recreational drug D. cancer drug

A. rat poison B. anticoagulant medicine

pH and enzyme activity

All enzymes have an optimum pH value.

Which is true about energy of activation? A. Energy of activation is measured as the energy that is released after a reaction occurs. B. Adding the correct enzyme can lower the energy of activation. C. Energy of activation is the difference between the energy of the reactant and the energy of the product. D. The energy of activation is always lower than the energy of the reactant.

B. Adding the correct enzyme can lower the energy of activation.

While paddling your canoe down a river you notice many turtles laying on logs in the sun. This is an example of which factor affecting rates of enzymatic reactions? A. Substrate Concetration B. Temperature C. pH D. Enzyme Inhibition

B. Temperature

If A -> B -> C -> D -> E represents a metabolic pathway, then letter E would be A. a substrate. B. a product. C. energy. D. an enzyme. E. an enzyme-substrate complex.

B. a product.

The main reason that ATP is considered the energy currency in cells is because it A. carries a positive charge. B. contains accessible energy in phosphate bonds. C. contains an adenine base. D. contains a sugar ring.

B. contains accessible energy in phosphate bonds.

The function of an enzyme is to A. provide the energy for metabolic reactions. B. increase the rate of a metabolic reaction. C. change the direction of metabolic reactions. D. raise the energy of activation for a reaction.

B. increase the rate of a metabolic reaction.

Occasionally someone claims to have built a machine that can run forever, producing as much energy as it consumes. This has always been disproved because it violates A. the first law of thermodynamics. B. the second law of thermodynamics. C. laws preventing any conversion between types of energy. D. coupled reaction equations.

B. the second law of thermodynamics.

Which of the following statements is not true concerning enzymatic activity? A. Each enzyme has a preferred pH at which the enzyme reaction rate is highest. B. Above a certain temperature, an enzyme will become denatured. C. As the temperature increases, most enzymatic reactions will still proceed at the same rate. D. Enzyme activity increases as substrate concentration increases until the maximum rate is achieved.

C. As the temperature increases, most enzymatic reactions will still proceed at the same rate.

Which of the following statements is true about enzymes? A. Their 3D shape can vary and still be active. B. Boiling temperatures do not affect their activity. C. They catalyze only one specific type of reaction. D. They can associate with a wide variety of substrates. E. They are unaffected by changes in pH.

C. They catalyze only one specific type of reaction.

Enzymes are specific. This means that they A. have a preferred pH. B. have a preferred temperature. C. have a particular substrate. D. are only in certain cells.

C. have a particular substrate.

Each enzyme has a particular substrate because enzymes A. increase the energy of activation. B. decrease the productivity of the cell. C. have active sites complementary in shape to their substrates. D. are named for their substrate.

C. have active sites complementary in shape to their substrates.

In feedback inhibition of a metabolic pathway, where does the inhibitor bind? A. to the substrate of the first reaction B. to the product of the first reaction C. to the enzyme of the first reaction D. to a substrate or the product of the last reaction

C. to the enzyme of the first reaction

Which of the following can act as an enzyme cofactor? A. iron B. vitamines C. NAD+ D. All of the above.

D. All of the above.

Which of the following is NOT a correct statement about the second law of thermodynamics and entropy? A. The amount of disorder in the universe is always increasing. B. To maintain organization of a cell, a continual input of energy is required. C. Living cells without energy would become less organized. D. Carbon dioxide and water form glucose without the input of energy.

D. Carbon dioxide and water form glucose without the input of energy.

Which of the following statements most accurately describes the first law of thermodynamics? A. One usable form of energy cannot be completely converted into another usable form. B. One usable form of energy can be completely converted into another usable form. C. Energy cannot be created or destroyed. D. Energy can be neither created nor destroyed but it can be changed from one form to another.

D. Energy can be neither created nor destroyed but it can be changed from one form to another.

During an enzymatic reaction, what happens to the enzyme? A. It becomes the product. B. It becomes the substrate. C. It is used up. D. The enzyme and the substrate form a temporary complex.

D. The enzyme and the substrate form a temporary complex.

ATP contains A. an adenine base and two phosphate groups. B. an adenine base and three phosphate groups. C. an adenine base, a ribose sugar, and two phosphate groups. D. an adenine base, a ribose sugar, and three phosphate groups.

D. an adenine base, a ribose sugar, and three phosphate groups.

If an enzymatic reaction was controlled by feedback inhibition, we would expect it to stop A. only if the substrate was exhausted. B. when the cofactors are exhausted. C. when the product changed the pH. D. as soon as a critical level of end product builds up.

D. as soon as a critical level of end product builds up.

If you wished to increase enzyme activity, you would do all of the following except A. increase the temperature moderately. B. increase the concentration of substrate. C. change to optimum pH for the reaction. D. decrease the temperature.

D. decrease the temperature.

The high energy bond in ATP that is used by cells is found in or between A. the adenine base. B. the adenine and the ribose. C. the adenine and the phosphates. D. the phosphate groups.

D. the phosphate groups.

ATP cycle

This is the name applied to the cycle by which ATP are broken down to ADP with the release of energy, and the regeneration of ATP from ADP through the process of phosphorylation.

Entropy

a measure of the disorder of a system

oxidation-reduction reaction

a reaction that involves the transfer of electrons between reactants

ATP structure

adenine, ribose, 3 phosphate groups

exergonic reaction

spontaneous and release energy protein synthesis, muscle contractions

potential energy

stored energy food we eat- can be converted to kinetic energy

what are the environmental conditions that effect enzyme function

substrate concentration temperature pH enzyme activation enzyme cofactors

enzyme inhibition

substrate is unable to bind to the active site of an enzyme ex: poisons

energy of activation

the amount of energy required to start a reaction