Biology 107 Introduction to Metabolism I September 12, 2003

Introduction to Metabolism I Student Objectives:As a result of this lecture and the assigned reading, you should understand the following: 1.Despite the organized structure of cells, all living things tend toward disorder. To maintain order, living things and the cells they are made up of depend on a continual flow of energy from the environment. 2.Metabolism is the sum total of an organism's chemical processing; some chemical processes degrade complex molecules into simpler molecules (catabolic pathways), and some chemical processes synthesize complex molecules from simpler molecules (anabolic pathways).

Introduction to Metabolism I 3.Energy can only be described and measured by how it affects matter. Energy is the capacity to perform work - all organisms require energy to stay alive, and all organisms transform energy. 4.There are two (2) forms of energy: potential energy and kinetic energy. 5.The first law of thermodynamics (law of energy conservation) = the total amount of energy in the universe is constant and energy can be transferred and transformed, but it cannot be created or destroyed.

Introduction to Metabolism I 6.The second law of thermodynamics = energy conversions reduce the order of the universe. Heat, which is due to random molecular motion, is one form of disorder. The second law has direct applications to cellular activities - as explained in this law, energy cannot be transferred or transformed by the cell with 100% efficiency. 7.Chemical reactions in living organisms - the starting substances of chemical reactions are called reactants; reactants interact with one another to form new substances called products. 8.Chemical reactions, including those in cells, are of two types: endergonic (energy-requiring) and exergonic (energy-releasing).

Introduction to Metabolism I 9.In an endergonic biosynthetic reaction, the electrons forming the chemical bonds of the product are at a higher energy level than the electrons of the reactants (i.e., the reaction requires input of energy). 10.Cells supply the energy for endergonic reactions through coupled reactions in which endergonic reactions are linked to exergonic reactions. 11.ATP is the cell's main energy carrier. Most frequently, coupled reactions use ATP as the energy source, and ATP is renewable energy that cells regenerate from exergonic reactions.

Metabolic Pathways Reactions occur in a stepwise fashion Pathways are interconnected Chemical reactions are catalyzed by enzymes

Free Energy And Capacity To Do Work

Need For Continual Flow Of Energy Into Systems

Energy Profile For a Chemical Reaction

Energy Profiles For Energy-requiring and Energy- releasing Reactions

Enzymes Lower Activation Energy But They Do Not Change the Overall Energy Profile

Coupling Of Energy-releasing Reactions With Energy-requiring Reactions

Biology 107 Exam 1 Select the single choice which best answers the question or completes the idea in each question or statement. For fill in the blank questions, write clearly and only in the space provided on the answer sheet. Make sure you name is clearly written on each page of the exam and on your answer sheet. ALL ANSWERS MUST BE ON THE ANSWER SHEET TO BE GRADED. 1.Which of the following influence protein folding into functional molecules? A.The types of side chains ("R" groups) on the amino acids B.The temperature (kinetic energy) of the environment C.The polar nature of its solvent D.A and C E.All of the above

2.One of the ways that RNA differs from DNA is that: A.RNA does not contain phosphate groups but DNA does B.RNA contains a 5-carbon sugar while DNA contains a 6-carbon sugar C.RNA contains uracil while DNA contains thymine D.RNA is found only in bacteria and viruses, while DNA is found only in animal cells E.RNA directs the synthesis of DNA, which in turn synthesizes proteins 3.Which of the following statements correctly describes any chemical reaction that has reached equilibrium? A.The concentration of products equals the concentration of reactants. B.The rate of the forward reaction equals the rate of the reverse reaction. C.Both forward and reverse reactions have halted. D.The reaction is now irreversible. E.No reactants remain.

4. Which of these terms includes all of the others in the list? A.Nucleotide B.Nucleic acid C.Pyrimidine D.Purine E.Nitrogenous base 5.Which of the following IS NOT true regarding hydrogen bonds: A.They result from the unequal sharing of electrons in certain covalent bonds B.They contribute to some of the higher orders of configuration of proteins (i.e., secondary, tertiary, quaternary) C.They are stronger than covalent bonds D.They contribute to the property of surface tension in water E.They contribute to water's capacity as a solvent for polar molecules

6.Chemical bonds hold __________ together within __________. A.protons and neutrons; atomic nuclei B.atoms; elements C.molecules; elements D.protons and electrons; atoms E.atoms; molecules 7.Aldehydes and ketones contain the ______________ functional group.

8.By definition, for a protein to have a quaternary structure, it must: A.Consist of four polypeptide subunits B.Consist of two or more polypeptide subunits C.Have at least four disulfide bridges (bonds) D.Have four amino acids E.Exist in several alternative conformational states 9.For isomers: A.They have the same molecular formula but differ in molecular structure B.One form is created in nature and the other isomers are the result of synthetic processes in the laboratory C.They react the same way in chemical reactions D.The number of neutrons varies between the isomers E.All of the above

10.__________ is a cellular high energy compound that donates phosphate groups to other molecules to produce more chemically reactive intermediate forms of the original molecule. 11.Which is the correct ratio of C:H:O in a carbohydrate: A.2:2:1 B.2:1:2 C.1:1:1 D.1:2:1 E.None of the above 42.Pick an example of a hydrophobic molecule and describe the molecular characteristic(s) that makes it hydrophobic.

43.How does an exergonic chemical reaction differ from an endergonic reaction? 43.Describe what is meant by the general concept that hierarchies of biological organization produce emergent properties of life.