CHAPTER 5 ENERGY AND LIFE

1. Chemical Reaction: A chemical reactionInvolves 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 provideEnergy to start a chemical reaction. EnzymesSpeed 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 Anhydraseenzyme

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: CO2 + H2O H2CO3 The reaction for dissociation of H2CO3 into its constituent ions: H2CO3 H+ + HCO3

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Substrate: Enzymes rely on shapes. Substrates are specificSites on a molecule where enzymes bind.

Shape is importantWhen it comes toEnzyme action. ThinkOf the enzymes as beingLike “KEYS” that canFit into specific sites. TheSite where the enzyme Binds is called an activeSite and the molecule toWhich the enzyme bindsIs called the SUBSTRATE.

A model of an enzyme attaching to a substrate.

Cells have THOUSANDS of DIFFERENT Enzymes. Enzymes can beDifferent in different cells. Cells can have SPECIFIC purposes. For Example, Heart Cells, Nerve Cells and even the cells of the EYES haveDifferent 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 causingEnzyme 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 energyTransfer 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 CO2 + 12 H2O + light → C6H12O6 + 6 O2 + 6 H2O

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 anexception. Animals rely on FERMENTATION and on OXIDATIVERESPIRATION 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) GlucoseIs broken down into the compound PYRUVATE. This initial process isCalled GLYCOLYSIS….the breakdown of GLYCOGEN(GLUCOSE). LysisMeans 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. WhenYou need a Quick boost ofEnergy. Think about howYou get out of breath. YouBuild an OXYGEN DEBT.