Cell Unit Lecture V

1. Cell Unit Lecture V Enzymes and Macromolecules

2. Biology Standards Covered • 1b ~ students know enzymes are proteins that catalyze biochemical reactions without altering the reaction equilibrium and the activities of enzymesdepend ontemperature, ionic conditions, and the pH of the surroundings • 1h ~ students know most macromolecules (polysaccharides, nucleic acids, proteins, and lipids) in cells and organisms are synthesized from a small collection of simple precursors (monomers & polymers)

3. Standards translated • 1b ~ an enzyme is a specialized protein that makes a reaction happen or increases the rate of a reaction. Enzymes are affected by pH (acidity), temperature, and salty conditions. • 1h ~ Most macromolecules (polymers) are made in cells from a small collection of simple molecules (monomers) • This is like a Lego house (polymer) made up of individual Legos (monomers)

4. Carbon Based Molecules • All living things are made up of a collection of atoms and molecules that work together to support life • Nearly all living things on planet Earth are supported by one atom, an atom of Carbon • There are Four primary Carbon Based Molecules supporting all life on our planet: • Carbohydrates ~ sugars • Lipids ~ fats • Proteins ~ amino acid chain (polypeptide) • Nucleic acids ~ DNA, RNA, & ATP

5. Carbon Based Molecules • Carbon is the most important element in living systems • It has: • 6 Protons • 6 electrons • 6 Neutrons • Mass of 12.011 amu • It bonds in four directions and can form double bonds

6. Carbon Based Molecules • Carbon based molecules can be small and they can be very large. • The smallest are called monomers and usually consist of one carbon ring or molecule • Larger carbon based molecules are made up of many monomers to form a polymer • Mono = one • Poly = many

7. Carbon Based Molecules • Carbohydratesas carbon based molecules • Also known as “sugars” • Made up of three elements • Carbon • Hydrogen • Oxygen • A couple of the simplest carbohydrates are fructose and glucose • These are single carbon ring molecules that provide energy for cellular respiration

8. Carbon Based Molecules • Carbohydrates can be a simple sugar like Glucose or many Glucose monomers linked together • A Disaccharide is a sugar that has twoGlucose monomers • The most common disaccharide is sucrose

9. Carbon Based Molecules • Polysaccharides are many Glucose monomers linked together • Starch~ a polysaccharide sugar made by plants to store energy • Cellulose ~ a polysaccharide made by plants to form cell walls • Glycogen ~ a polysaccharide made by animals to store sugar for energy (usually in the liver)

10. Good Carbs & Bad Carbs

11. Carbon Based Molecules • Lipids are an important carbon based molecule that can be broken down into energy for the cell and function as part of the cell’s structure • They include fats, oils, and cholesterol • They are non-polar and repel polar substances like water

12. Carbon Based Molecules • A phospholipidhaving a phosphate head and two fatty-acid tails is a monomer of the polymer known as the cell membrane • The phosphate head of the phospholipid attracts water because it is polar while the fatty-acid tails repel it as it passes through the membrane

13. Carbon Based Molecules • Lipids store a huge amount of energy in their fatty-acid tails • A lipid is saturated if the Carbon chain is loaded with Hydrogen atoms • A lipid is unsaturated if there are a few or more double bonds between Carbons making it “kink”

14. Carbon Based Molecules • Proteinsare another important carbon-based molecule made up of several dozen to thousands of amino acids • An amino acid chain is also known as a polypeptide chain because of its many peptide bonds holding the amino acids together

15. Carbon Based Molecules • Each amino acid is made up of the same functional groups except for one R – Group • Amino group • Carboxyl group • Hydrogen & base Carbon • UniqueR Group • Amino acids are monomers while a protein is the polymer

16. Carbon Based Molecules • Nucleic acids are the fourth Carbon based molecule • They are all made up of monomers called nucleotides • DNA, RNA, and ATP are nucleic acids that are found in all living organisms • ATP pictured here has 3 phosphates bonded to a 5-Carbon sugar and a Nitrogen base

17. Carbon Based Molecules

18. Enzymes the special protein • An enzyme is a protein polymer that is made up of many amino acid monomers • Cells use enzymes to catalyze biochemical reactions • To “make them happen” • To “speed up reactions” • An enzyme has a unique 3-dimensional shape that defines the role/job that it performs • An enzymes shape is maintained by being in the right temperature, pH (acidity), and ionic conditions

19. Enzymes the special protein • Chemical Reactions • Reactants  Products • Water + Carbon Dioxide  Glucose + Oxygen + Water • Activation energy is the “energy required to start a chemical reaction” • Think of pushing a ball to the top of a small hill so that it can roll down a very steep slope on the other side • The energy it took to push the ball to the top of the hill is the activation energy • Enzymes often lower activation energies

20. Enzymes the special protein • When enzymes are present, the breakdown of Glucose happens easier 

21. Enzymes the special protein • pH is the “percent Hydrogen” of a solution • Also known as “acidity” • The scale is based on Powers of 10 and goes from 0  14 with Zero being the MOST Acidic and 14 being the MOST Basic

22. Enzymes the special protein • An enzyme protein has an active site where a substratemolecule attaches • This makes it possible for a chemical reaction to occur and the enzyme acts as a catalyst

23. Enzymes the special protein • Enzymes are often referred to as having a “lock and key” model • Enzymes are affected by temperature and as temp. increases, enzyme activity increases