University:
LaGuardia Community College
Course:
SCB 115 | Principles Of Biology
Academic year:

2023
Views:

180

Pages:

14
Author:

Evelin Ball

2.13 Opening Questions: Can chemical reactions be speeded up? Starches might eventually break down into sugars, but it goes much faster when the protein amylase is present. • How might amylase speed up the change from starch to sugar? • What do you think is happening at the molecular level? If you still have your cracker, try another taste! Chemical Reactions • Reaction – Process of chemical change • Reactant – Molecule that enters a reaction • Product – A molecule remaining at the end of a reaction • Some reactions require a net input of energy – others end with a net release of energy – Endergonic reaction: require a net input of energy – Exergonic reaction: net release of energy Chemical Reactions Endergonic reaction! Exergonic reaction! 2.13 Enzymes speed chemical reactions. • The sum total of all the chemical reactions in an organism is called its metabolism. • An enzyme is a protein that speeds up a chemical reaction without being changed itself. Almost every metabolic reaction occurs with the help of an enzyme. 2.13 Enzymes speed chemical reactions by lowering activation energy. Energy requirements without enzyme Activation Energy Enzyme lowers = Lower the energy required Activation for reaction to Energy proceed Substrates Energy requirements with enzyme Products Progress of the reaction 2.13 Each enzyme recognizes one specific target molecule called its substrate. 2.13 Inhibitors are molecules that prevent enzymes from working. Competitive inhibitors bind to the active site. 2.13 Inhibitors are molecules that prevent enzymes from working. Noncompetitive inhibitors bind to a distant site. 2.13 Like all proteins, enzyme function depends on shape. • Changes in shape can prevent function. • Lactase is an enzyme that breaks down lactose (milk sugar). • Gene mutations can change the shape of lactase and make it ineffective, leading to lactose intolerance. 6.1 Opening Questions: What molecule holds the instructions for living things? Do these organisms all share the same genetic code? Explain. Aquatic Algae Caterpillar Mushroom Elephant Protist Flower Human 6.1 DNA is the molecule that holds the instructions for all living things. • DNA is shorthand for Deoxyribose Nucleic Acid • A DNA molecule is a double helix with two strands made up of a long string of nucleotides. 6.1 Each nucleotide consists of a sugar, a phosphate, and a base. Nucleic Acids • Structure of nucleotide