AP Bio Ch 8The analogy is made that a cell is a chemical factory. Explain why this might be an appropriate analogy. Bioluminesence and all other metabolic activities carried out by the cell are precisely anabklic and controlled. The totality of an organisms chemical reactions. Describe what is meant by a metabolic pathway.
AP Bio Ch 8 Flashcards | Quizlet
The analogy is made that a cell is a chemical factory. Explain why this might be an appropriate analogy. Bioluminesence and all other metabolic activities carried out by the cell are precisely coordinated and controlled. The totality of an organisms chemical reactions. Describe what is meant by a metabolic pathway. Contrast catabolic pathways with anabolic pathways. Give examples of each type.
Explain whether each type releases energy or stores energy. A metabolic pathway begins with a specific molecule, which is then altered in a series of defined steps, resulting in a certain product. Catabolic pathways release energy by breaking down complete molecules to simpler compounds. Anabolic pathways, in contrast, consume energy to build complicated molecules from simpler ones. How can catabolic and anabolic pathways work together?
Energy released from the downhill reactions of catabolism can be stored and used to drive the uphill reactions of the anabolic pathways. Energy is the ability to cause change. Give an example that helps explain what this might mean to life. In everyday life, energy is important because some forms of energy can be used to do work -- that is, to move matter against opposing forces such as friction and gravity.
For example, you expend energy to turn the pages of a book, and your cells expend energy in transporting certain substances across membranes. Contrast kinetic with potential energy. What is a biological example of kinetic? What is a biological example of potential? Kinetic energy can be associated with the relative motion of objects. An object not presently moving may still posses energy, called potential energy; it is energy that matter has because of its location or structure. The contraction of leg muscles pushes bicycle pedals b.
Molecules store energy because of the arrangement of their atoms. There are laws that govern energy and its transformations in matter. The study of these laws is known as thermodynamics. State the first law of thermodynamics and give a biological example. State the second law of thermodynamics. Why does this explain that energy can't be recycled? The energy of the universe is constant -- energy can be transferred and transformed but not created or destroyed. Every energy transfer or transformation increases the disorder entropy of the universe.
In the process of carrying out chemical reactions that perform various types of work, living cells unavoidably convert organized forms of energy to heat, thus losing energy. Of what is entropy a measure? Use some examples to help explain. How is spontaneity of a reaction related to entropy?
Entropy is a measure of disorder, or randomness. You can observe increasing entropy in the gradual decay of an old building. As a cheetah converts chemical energy to kinetic energy, it is also increasing the disorder of its surroundings by producing heat and small molecules that are the breakdown products of food.
For a process to occur spontaneously, it must increase the entropy of the universe. Living organisms are an example of both low entropy meaning high order and high entropy meaning low order. Explain how both can be occurring in a living organism simultaneously. Cells create ordered structures from less organized starting materials, like how amino acids are ordered into specific sequences of polypeptide chains.
However, an organism also takes in organized forms of matter and energy from their surroundings and replaces them with less ordered forms. For example, an animal obtains starch, proteins, etc.
Since the world in getting more and more random, how can organisms be getting more and more ordered? Complex organisms evolve from simpler ancestors. The entropy of an organism may decrease, so long as the entropy of the universe increases. Thus, organisms are islands of low entropy of the universe. How does the second law of thermodynamics explain the diffusion of a substance across a membrane? When a substance diffuses across a membrane, it goes from a high concentration to a low concentration, or high entropy to low entropy.
Since this action requires energy, this helps to increase the entropy of the universe. It also adds to the entropy of the destination. Describe the forms of energy found in an apple as it grows on a tree; then falls and is digested by someone who eats it.
As an apple forms, it has chemical energy, which, after an apple is eaten by a person, becomes potential energy that may become kinetic energy. What is free energy? How is it calculated? Free energy measures the portion of a system's energy that can perform work when temperature and pressure are uniform through the system.
It is calculated by using this formula: It gives them the power to predict which kind of changes can happen without help. How are free energy related to equilibrium? As a reaction proceeds toward equilibrium, free energy of the mixture of the reactants and products decreases. What type of reaction is shown in the diagram at right - exergonic or endergonic? Explain how you know. Would this be a spontaneous or not?
In the body what type of reaction might this represent? This is an exergonic reaction because it has a net release of energy, but then it proceeds to lose free energy. Endergenic - it absorbs free energy over time. What types of work does a cell do? Give an example of each. How does energy coupling help explain how a cell does its work? It helps cells manage their energy resources to do work by using an exergonic process to drive an endergonic one.
ATP is the immediate source of the energy used to do work. Diagram a molecule of ATP and explain where the energy is located in the molecule. How does ATP perform work? Give an example of the types of reactions that are powered by the hydrolysis of ATP. With the help of specific enzymes, the cell is able to couple the energy of ATP hydrolysis directly to energenic processes by transferring a phosphate group from ATP to some other molecule, such as a reactant.
The three types of cellular work - mechanical, transport and chemical -- are nearly always powered by the hydrolysis of ATP. ATP is like a rechargeable battery. How does ATP get regenerated? It can be regenerated by the addition of phosphate to ADP. Just because a reaction is spontaneous doesn't mean that it will happen any time soon! How is this related to activation energy?
It needs an initial investment of energy to start the reaction, called activation energy. The diagram at right shows a chemical reaction as it takes place without an enzyme and the same reaction with an enzyme. The Ea activation energy provides a barrier that determines the rate of reaction, and it is higher without the enzyme.
What type of macromolecule is an enzyme? How do enzymes recognize their substrate? How does this relate to "specificity"? How are substrates held in active sites? Enzymes are proteins which have unique 3-D shapes. The specificity of an enzyme results from its shape, which is a consequence of its amino acid sequence. This is how enzymes recognize their substrates. The active site is typically a pocket or groove on the surface of a protein. There should be a comfortable fit between the shape of an enzyme's active site and the shape of its substrate.
Explain how an enzyme catalyzes a reaction. Enzymes enter active site; enzyme changes sides so its active side embraces the substrates induced fit. Substrates held in active site by weak interactions such as hydrogen bonds and ionic bonds. Active site and R groups of its amino acids can lower Ea and speed up reaction by a acting as a template for a substrate orientation, b stressing the substances and stabilizing the transition state, c providing favorable microenvironment, d participating directly in the catalytic reaction.
Substrates are converted into products 5.