Bio 1 General Biology – Exam 2 Outline

Bio 1 General Biology ? Exam 2 Outline

Powering Life: Energy (Ch. 4) How is a cell able to perform all of its functions to survive? I. Energy

A. Two forms of energy 1. Potential energy

Examples? 2. Kinetic energy

Examples? Energy can be changed from one form to another! Ex. Food = potential energy which changes into kinetic energy when organism moves around or grows

B. Thermodynamics ? the study of energy and its transformations 1. First Law of Thermodynamics (Conservation of Energy)

a. Organisms cannot create energy that it needs to live. It must capture it from the environment and change it into a usable form. Ex. Photosynthesis ?uses sunlight energy and converts it to chemical energy contained in the bonds in sugars that plant produces. Ex. Animals eat food, which is transformed to chemical energy, which is transformed into mechanical energy, muscle movement etc.

2. Second Law of Thermodynamics

a. Whenever energy is converted, some useable energy is degraded into a less useable and ordered form (heat). We are not losing energy just changing it to a less useable form. Ex. Food is used for movement which releases heat energy (less usable form)

b. No process involving energy conversion is 100% efficient. Why? As a result, what happens to the amount of useable energy over time?

3. The Laws of Thermodynamics and Us a. What do Arctic peoples tend to produce more of? b. What is the upside of this extra production? c. What is the downside of this extra production?

View course website animations on energy and thermodynamics

D. Measuring Energy 1. Calorie

Ex. Can measure caloric content of a peanut (or any food) by burning it under a container of water to convert all of the stored chemical energy to heat and then measure the temperature increase of the water

2. Kilocalories (kcal) ? units of 1,000 calories; calories on food packages are actually kilocalories Ex. One peanut has 5 food calories (5 kcal) which is enough energy to increase temp. of 1 kg (a little more than a quart) of water by 5? C. A handful would boil 1 kg of water.

II. How Energy Is Used By Living Things (The Energy Molecule: ATP) Carbs, fats and other fuel molecules we get from food do not drive work in our cells. They must be broken down so that their energy is released. Chemical energy (ATP) is released by the breakdown of organic molecules during cellular respiration. In what organelle does ATP production occur? ATP then powers cellular work.

A. ATP (Adenosine triphosphate) ? the energy molecule 1. 3 phosphate groups each with a negative charge.

2. When energy is needed, ATP is broken down, a phosphate is removed, & energy is released.

3. When cell needs a place to store energy, a phosphate is added back on.

B. Renewable ATP 1. A working cell recycles all of its ATP about once each minute. That is about 10 million ATP molecules spent and regenerated per second per cell. 2. ATP can be restored by adding a phosphate group back to ADP. 3. This takes energy; like recompressing a spring 4. This is where food enters the story. Chemical energy that cellular respiration harvests from food is put to work regenerating the cell's supply of ATP.

III. Using Energy Efficiently with Enzymes Watch the Amoeba Sisters Enzymes: The Proteins that Remind Us of PacMan

Go to: and read about metabolism and enzymes and answer the following: A. What is metabolism? B. What is an enzyme and what do they do for us? C. How Enzymes Work

1. Enzymes enable reactions to occur faster by reducing the amount of energy required to get reactions going. 2. Enzymes bind to their substrate which makes the substrate more vulnerable to chemical alteration. 3. Each enzyme is specific to the reaction it speeds up (> 5000 enzymes exist)

Ex. Lactase = enzyme that breaks down lactose (milk sugar) 4. Vitamins help enzymes bind to their substrates.

D. What will stop enzymes from working?

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