Unit 3 AP Biology Key Concepts

What is the role of enzymes?

To speed up chemical reactions by lowering the amount of activation energy required.

How is enzyme structure related to enzyme function?

Enzyme substrate-active site binding is very specific in shape, size, and function. This distinguishes different enzymes for specific substrates. The tertiary shape must be maintained for functionality.

What determines whether a substrate can interact with an enzyme?

The substrate must be able to bind to the enzyme's active site and have compatible chemical properties.

What happens to an enzyme after the completion of a reaction?

It can be reused as they are not chemically changed by the reaction.

What is activation energy?

The energy needed to start a chemical reaction.

What are the different types of control groups?

Negative control and positive control.

What is the use of each type of control group?

They are used as a standard for comparison.

How are control groups different from controlled variables?

Controlled variables are aspects of an experiment that could be changed but are intentionally not changed. The control group is a group where all of the variables are controlled variables.

What is negative control?

Group with no response expected.

What is positive control?

A test using a substance known to produce a positive result. Testing the positive control allows you to see how to visualize a positive result and ensures that the reagents and protocols are working properly

What does it mean for an enzyme to be denatured?

The shape of its active site is changed so that it can no longer bind to its substrate. Typically irreversible and the catalytic ability is severely decreased/lost.

How do changes in pH affect enzyme activity?

Lower or greater pH than the optimum range will result in denaturation. This is because changes in pH can disrupt hydrogen bond interactions that help maintain the enzyme's tertiary structure.

How do changes in temperature affect enzyme activity?

Higher temperatures will denature the enzyme, while lower temperatures won't. Increases in temperature (in the optimum range) increase the reaction rate, speed of molecular movement, and frequency of enzyme-substrate collisions.

How do changes in enzyme concentrations affect the rate of reactions?

Decrease in enzyme concentrations lower the reaction rate. (Less opportunity for substrates to collide with active site). & Vice-versa.

How do changes in substrate concentrations affect the rate of reactions?

Initial increase in substrate concentration increases the reaction rate. (Greater chance for substrates to collide with active site). Substrate saturation eventually occurs and reaction rate remains constant.

How do changes in product concentrations affect the rate of reactions?

Increase in product lowers the reaction rate. Less chance of enzyme-substrate collisions.

How do competitive inhibitors affect enzyme activity?

They bind to the active site and compete with the normal substrate. If inhibitor concentrations exceed substrate concentrations, reactions are slowed.

How do noncompetitive inhibitors affect enzyme activity?

Bind to enzyme's allosteric site and cause conformational shape change for the active site. Substrate-active site binding is not possible. Increasing substrate concentration cannot prevent effects of noncompetitive inhibitor binding.

What do living things use chemical energy for?

To grow and reproduce, maintain their structures, and respond to their environments.

How is energy efficiently transferred in a biological pathway?

Through sequential reactions. (more controlled and efficient transfer of energy) The product of one reaction can serve as a reactant in a subsequent reaction.

How do organisms capture and store energy for use in biological processes?

Autotrophs capture energy directly from the sun.

How are the light-dependent reactions involved in the capturing and transforming of energy?

Pigments/chlorophyll capture light energy and transform it into high-energy electrons. The electrons become energized and use the energy to establish a proton gradient and reduce NADP+ to NADPH. PSI an PSII pass the electrons through the ETC and NADPH then carries them to the Calvin cycle.

What are the products of the light-dependent reactions?

ATP, NADPH, and oxygen.

How are the light-dependent reactions and the Calvin cycle related?

The energy captured in the light-dependent reactions power the production of carbohydrates in the Calvin cycle.

How do eukaryotes coordinate cellular respiration?

Cellular respiration in eukaryotes involves a series of coordinated enzyme-catalyzed reactions that capture energy from biological macromolecules.

How is an electrochemical/proton gradient formed during cell respiration?

Through the ETC. The ETC transfers energy from electrons in a series of coupled reactions and uses electron energy to establish electrochemical gradients across membranes. They gradients are maintained as a result of biological membrane impermeability to charged molecules/ions.

What processes do all forms of life use to produce ATP?

Cellular respiration and fermentation.

What is the function of the electron transport chain?

Allows for the efficient transfer of energy from electrons to a proton gradient.

What is the role of NADH and FADH2?

Electron carriers that donate high energy electrons to the ETC.

How does the electrochemical gradient power ATP synthase?

The electrochemical gradient provides stored energy that is transformed into the energy of chemiosmosis used by ATP synthase to synthesize ATP.

What is oxidative phosphorylation?

The process of making ATP using the stored energy of a proton gradient.

What is the importance of decoupling during respiration?

When decoupling occurs during cell respiration, heat is released and can be used for thermoregulation.

What is the purpose of glycolysis?

Glycolysis releases energy in glucose to form ATP and NADPH.

What is the fate of pyruvate?

It is transported to the mitochondria where it is oxidized.

What are the products of Krebs cycle?

During the Krebs cycle, carbon dioxide is released, ATP is synthesized, and NADH and FADH2 are produced.

What happens to the electrons extracted in glycolysis and Krebs cycle?

The electrons extracted in glycolysis and Krebs cycle are transferred by NADH and FADH2 to the ETC.

How does fermentation differ from aerobic cellular respiration?

Fermentation allows glycolysis to occur without oxygen and produces ethanol or lactic acid.

How is energy released from ATP?

Energy is released when the third phosphate is broken off of ATP resulting in ADP.

What does fitness refer to?

How does molecular variation within cells provide organisms with increased ability to respond to a variety of environmental stimuli?

Refers to the ability to survive and reproduce.

How does molecular variation within cells provide organisms with increased fitness?

Variation provides organisms with fitness advantages under changing environment conditions.