Carbohydrates, Proteins, Lipids, Nucleic Acids Section 3 Energy and Chemical Reactions Grade 10 Biology Fall 2010

Bell Ringer 1.What energy forms do each of these represent? 1.Tuning fork? 2.Flashlight? 3.Vinegar and baking soda? 4.Explosion?

Objectives Evaluate the importance of energy to living things Relate energy and chemical reactions Describe the role of enzymes in chemical reactions Identify the effect of enzymes on food molecules

Energy for Life Processes _______ : is the ability to move or change matter Energy exists in many ______ – Light, heat, chemical energy, mechanical energy, and electrical energy It can be _________ from one form to another If you kick a ball, the energy of your kick makes the ball move

Energy for Life Processes Energy can be ______ or _________ by chemical reactions A chemical reaction is a process during which ____________ between atoms are broken and new ones are formed, producing one or more different substances

Energy for Life Processes ___________ : starting materials for chemical reactants __________ : newly formed substances Chemical equations: summarize chemical reactions Reactants  Products The arrow reads changes to or forms

Energy in Chemical Reactions In chemical rxn.’s, ______ is absorbed or released when ______________ are broken and new ones are formed

Energy in Chemical Reactions This graph represents an _______________ reaction When water freezes, the process that leads to the formation of ice crystals causes _________ to be released When you fill an ice cube tray with water and place it in the freezer to make ice, heat is released from the water as the water freezes Products Reactants

Energy in Chemical Reactions This graph represents an ________________ graph When you remove ice cubes from the freezer, the ice cubes begin to melt When ice melts, it _______ heat from the environment Energy absorbed

Activation Energy Activation energy: the energy needed to start a __________ reaction – _____ Even in a chemical reaction that releases energy, activation energy must be _______ before the reaction can occur

Enzymes Chemical reactions in cells occur at relatively low temperatures because of the action of many enzymes _________ : substances that increase the speed of chemical reactions Most enzymes are _________ Enzymes are catalysts, which are substances that reduce the activation energy of a chemical reaction

Enzymes An enzyme increases the speed of a chemical reaction by _________ the ______________ of the reaction

Enzymes Help ______ maintain ___________ Without enzymes chemical reactions wouldn’t occur _________ to sustain life Ex. Pg 40, blood and carbon dioxide

Enzyme Specificity _________ : a substance on which an enzyme acts during a chemical reaction Enzymes act only on _______ substrates Ex. Enzyme amylase assists in the breakdown of starch to glucose in the following chemical rxn. starch  (amylase)  glucose Starch is amylase’s substrate

Enzyme Specificity An enzyme’s _____ determines its activity Typically, an enzyme is a large ______ with one or more folds on its surface ________ : site on an enzyme that attaches to a substrate Enzyme acts only on ____ substrate because only that substrate ____ into its active site (lock and key model)

Enzyme Specificity Step 1: when an enzyme first attaches to a _________ during a chemical reaction, the enzyme’s ______ changes slightly so that the substrate fits more ______ in the enzyme’s active site (page 41, figure 15)

Enzyme Specificity Step 2: at an active site, an _______ and a _______ interact in a way that reduces the __________ of the reaction, making the substrate more likely to react

Enzyme Specificity Step 3: the reaction is _______ when products have formed. The enzyme is now _____ to catalyze further reactions.

Factors in Enzyme Activity Any factor that ___________ of an enzyme can affect the enzyme’s activity Enzymes operate ____ within a specific temp. range, changing the temp. outside of this range will affect enzyme activity Enzymes operate best within a specific pH range, enzymes operating outside this range will loose effectiveness

Review 1._______________ energy is the energy required to start a chemical reaction. 2._______________ increase the speed of chemical reactions by reducing the activation energy. 3.List 3 ways that organisms use energy. 4.Carboxypeptidase is an enzyme that catalyzes reactions in the small intestines. The products of these reactions are amino acids. What are the substrates of carboxypeptidase? 1.Proteins 2.Carbohydrates 3.Lipids 4.Nucleic acids

Answers 1.Activation 2.Enzymes 3.Organisms store energy, use energy to power the chemical reactions of metabolism, and use energy to build cell structures. 4.Answers 1.Correct. Amino acids are the building blocks of proteins 2.Incorrect. Carbohydrates are made up of sugars 3.Incorrect. Lipids are not made up of amino acids 4.Incorrect. Nucleic acids are made up of nucleotides