CHAPTER 5 ENERGY AND LIFE 1.Chemical Reaction: A chemical reaction Involves the making of bonds between atoms. Energy can be absorbed or released in chemical Reactions. Chemical reactions In the body is called METABOLISM. 2.Enzymes are organic Catalysts that provide Energy to start a chemical reaction. Enzymes Speed up chemical reactions. Carbonic Anhydrase is an enzyme that helps remove Carbon Dioxide from blood. Carbon Dioxide is converted to Carbonic Acid. Without this enzyme: 200 molecules  per hour per liter of water With this enzyme: 600,000 molecules  per second per liter of water

Carbonic Anhydrase enzyme Carbonic Anhydrase from the Marine Diatom Thalassiosira weissflogii Carbonic Anhydrase from the Marine Diatom Thalassiosira weissflogii

The enzyme carbonic anhydrase catalyzes the hydration/dehydration reaction: CO 2 + H 2 O  H 2 CO 3 The reaction for dissociation of H 2 CO 3 into its constituent ions: H 2 CO 3  H + + HCO 3 -

Substrate: Enzymes rely on shapes. Substrates are specific Sites on a molecule where enzymes bind. Shape is important When it comes to Enzyme action. Think Of the enzymes as being Like “KEYS” that can Fit into specific sites. The Site where the enzyme Binds is called an active Site and the molecule to Which the enzyme binds Is called the SUBSTRATE.

A model of an enzyme attaching to a substrate.

Cells have THOUSANDS of DIFFERENT Enzymes. Enzymes can be Different in different cells. Cells can have SPECIFIC purposes. For Example, Heart Cells, Nerve Cells and even the cells of the EYES have Different enzymes which affect different chemical reactions. Heat, Acidity and Enzyme concentration affect Enzyme function. If the human body temperature reaches 112 degrees F many enzymes Are destroyed. Even a temperature of 105 degrees F affects enzymes. Eating an all protein diet can affect the acidity of the blood causing Enzyme problems. Pepsin Enzyme is an enzyme that helps digest food and can exist in a High acid environment. Pepsin is found in the human stomach.

Cells Transfer Glucose energy by converting the energy into an cell energy Transfer molecule called ATP – Adensine Triphosphate. STARCH -> Enzyme action to get Glucose -> Enzyme action to get ATP There is also Carbon Dioxide and Water too. When ATP is broken down by cell enzymes: ATP -> ADP + P + Energy for the cell. ADP - Adensine Diphosphate P - Phosphorus The ATP molecule is composed of : One Sugar; One Adenine group and 3 Phosphate groups.

PHOTOSYNTHESIS Some plants can absorb energy from the sun to produce ATP and Carbohydrates. There are Three Stages to photosynthesis: 1. Energy Capture (the light reactions) 2. Using this energy to make ATP. 3. ATP is used to make Carbohydrates. (The Calvin Cycle-called the Dark Cycle). In this cycle Carbon Dioxide is important. 6 CO H 2 O + light → C 6 H 12 O O H 2 O This is the equation for the Calvin Cycle. carbon dioxide + water + light energy → glucose + oxygen + water

In Photosynthesis PIGMENT molecules absorb energy from the sun. In your Own eyes the pigment cells, Retinal absorb light energy so you can see. In plants the MAJOR pigments are: 1.CHLOROPHYLL. These pigments absorb RED and BLUE light. Plants look green because Chlorophyll REFLECTS GREEN LIGHT. 2.Carotenoids. These pigments absorb yellow and orange light. COLD Temperatures break down CHLOROPHYLL. This is why is the fall you can see the Carotenoid pigments. Think of all the yellow, orange and even red colors you can see in the leaves during the fall.

In animal cells no photosynthesis can take place. Euglena protists are an exception. Animals rely on FERMENTATION and on OXIDATIVE RESPIRATION to power their cells. 1.FERMENTATION: IS ANAEROBIC…it DOES NOT need oxygen. This is thought to be an ANCIENT way for a cell to operate and suggests that CELLS were at one point able to survive on an Earth with little of NO oxygen on it. This takes place in the CYTOPLASM of the cell. 2.OXIDATIVE RESPIRATION: IS AEROBIC…IT DOES need oxygen. This is also called the KREBS CYCLE. This takes place in the MITOCHONDRIA of the cells.

In both Fermentation and In Oxidative Respiration(Krebs Cycle) Glucose Is broken down into the compound PYRUVATE. This initial process is Called GLYCOLYSIS….the breakdown of GLYCOGEN(GLUCOSE). Lysis Means to BREAK DOWN. Glucose  undergoes Glycolysis(ENZYMES)  Pyruvate Pyruvate can undergo Fermentation or Oxidative Respiration. Pyruvate  Fermentation  Lactic acid(causes leg cramps) + ethyl alcohol + Carbon Dioxide Pyruvate  Oxidative Respiration  36 ATP molecules.

Fermentation in cells. When You need a Quick boost of Energy. Think about how You get out of breath. You Build an OXYGEN DEBT.