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Chapter 2: Energy, Life and the

Biosphere

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1. Take in materials, convert into energy, and release waste

2. Chemical organization – made of cells3. Complex structural organization4. Contain DNA-instructions for maintaining

everything5. Sense and react to changes in

environment6. Grow and Develop7. Reproduce (sexually or asexually)8. Communicate9. Move under THEIR own power

Characteristics of Organisms

What is Bioenergetics?The study of

energy and energy flow in living systems (environments) and the organisms (plants and animals) that utilize them

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EnergyCapacity to do work or cause change.

Required by all organisms

May be Chemical or Free energy

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Chemical Energy is the energy stored in organic molecules

Free energy is the energy available to do work

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Autotrophs: obtain energy and nutrients from the sun or chemicals.

1. Photoautotroph: Capture energy from the sun to make organic compounds through photosynthesis

2. Chemoautotroph: Capture free energy from chemicals to make organic compounds through chemosynthesis.

Obtaining Energy

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Heterotrophs: obtain energy and nutrients from other organisms.

1. Carnivore: Meat eater2. Herbivore: Plant eater3. Omnivore: Meat and Plant eater

Obtaining Energy

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Autotrophs and Heterotrophs carry out chemical reactions that release the free energy in organic compounds in a process called…

Releasing Energy

Cellular Respiration

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Exists in many forms◦ Heat, light, chemical energy, electrical energy

ENERGY

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A flashlight converts the chemical energy stored in batteries into light and heat. Most of the energy is converted to heat. Only a small percentage of the original energy in the battery is converted into light energy.  

Most Energy becomes HEAT

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Energy flows from the environment through producers to consumers and finally to decomposers.

Energy Flow

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Producers: Produce food other organisms use

Consumers: Consume plants and other organisms for food

Decomposers: Break down and use dead plants and animals for food

Energy Flow cont…

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Decomposers cont.

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Food chains describe the eating relationships or transfer of energy in one direction between organisms in an ecosystem

Energy Flow in Food Chains

In this simple food chain, the grass generates energy it gathers fromthe sun through photosynthesis, which is then passed along to thegrasshopper, the frog, the snake, and finally the hawk.

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Food chains also show available energy

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Food webs show how energy and nutrients flow throughout overlapping food chains of an ecosystem.

The arrow points to whomis getting the energy/nutrients

Energy Flow in Food Webs

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Life is found in air, on land, and in fresh and salt water.

The BIOSPHERE is the portion of Earth that supports living things.

The Biosphere includes all ecosystems (living and nonliving components of an area) which include many habitats (where particular organisms live).

Biosphere

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Ecosystems of the World

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Abiotic factors- the nonliving parts of an organism’s environment.◦ Examples include air currents, temperature,

moisture, light, and soil.◦ Abiotic factors affect an organism’s life.

Ecosystems

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Biotic factors- all the living organisms that inhabit an environment.◦ Examples include Bear, fish, insects, bacteria◦ All organisms depend on others directly or

indirectly for food, shelter, reproduction, or protection.

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The First Law of Thermodynamics is the Law of Conservation of Energy. This law states that energy cannot be created, nor can it be destroyed. The energy of the universe is constant. However, that energy can change forms: electricity, light, heat, and sound are all different forms of energy.

First Law of Thermodynamics

This useful energy doesn’t just disappear; rather, it becomes energy that cannot be utilized by the process.

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The direction of energy flow is from high to low quality forms. Each conversion results in the production of energy (as HEAT – which is unavailable for work).

The Second Law of Thermodynamics is the Law of Increasing Entropy. This law states that the universe is always moving toward a greater state of disorder, or entropy.

Second Law of Thermodynamics

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Anything that happens spontaneously, that is, without an input of energy, will result in molecules being more disorganized, more random, more mixed together, and more spread out.

The law of increasing entropy also explains why houses don’t spontaneously assemble from a pile of wood on the lawn, spills don’t mop themselves up, and dust doesn’t gather itself into a neat pile, ready to be swept up. Such processes that result in an increase of organization (that is, a decrease in entropy) require energy input and are not spontaneous.

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Total energy of the universe remains the same (1st law). It is, however randomly dispersed as heat energy-an unusable form of energy for organisms – which increases the entropy of the universe (2nd law)

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-Order is important. Our bodies represent a high degree of order: atoms and molecules are meticulously organized into a complex system ranging in scale from the microscopic to the macroscopic.- Atoms are organized into molecules, which are organized into cells, which are in turn organized into the organs, bones, muscles, and skin that make up the human body.

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Exergonic Reactions- E+ released, spontaneous

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Endergonic – Uses E+ , not spontaneous

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Free energy = available energy Enthalpy (H) = total energy of a system

◦ ball rolling down hill, glucose molecule Entropy (S) = disorder of a system

◦ Diffusion, messy room Temperature (T) = in Kelvin C+273

◦ Cherry bomb will not explode unless temp is increased…more spontaneous with increase in temp

◦ All these factors can affect the spontenaity of a chemical reaction

Gibbs Free Energy Equation

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Gibbs Free Energy (G) - The energy associated with a chemical reaction that can be used to do work.  The free energy of a system is the sum of its enthalpy (H) plus the product of the temperature (Kelvin) and the entropy (S) of the system:

G < 0 = spontanteous, exergonic reaction, ex: cell respirationG > 0 = not spontaneous, endergonic, ex: photosynthesisG = 0 = equilibrium

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To release chemical energy to perform work…cells must break and make chemical bonds = chemical reaction

2.6 Metabolism & Energy Transfer

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All cells have them They lower the activation energy of

chemical reactions..they are catalysts They are reusable They work properly in certain conditions

◦ At certain temperatures, certain pH range, certain salinity, etc.

The name of the enzyme usually ends in ase◦ Catalase, sucrase, lactase, etc.

Enzymes

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Enzymes

FreeEnergy

Progress of the reaction

Reactants

Products

Free energy of activation

Without EnzymeWith Enzyme

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Specific enzymes catalyze specific reactions

How Enzymes Work

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The structure of an enzyme has a small area called an Active Site

The active site brings the substrate and enzyme closer together

Active Site

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Reactant molecule of a reaction. What fits into the active site.

This is how it goes…◦ The substrate fits into the active site of an

enzyme, activation energy is lowered, chemical reaction from substrate to product occurs, the product breaks away from the enzyme.

Substrate

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Induced Fit ModelEnzyme changes shape when it binds its substrate

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Once the newly formed molecules (or products) break away from the enzyme, the enzyme is unchanged.

Many reactions are reversible (two molecules combine to form one, one molecule broken to form two)

The Enzyme-catalyzed Reaction

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Enzyme reactions can be faster at higher temps but above certain temps, out of a certain pH range, or without certain ions…enzymes can unfold or Denature.

Denaturation renders the enzyme useless.

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Inhibitors Allosteric factors pH Temperature Salinity (salt concentration) Enzyme concentration Substrate concentration

Factors that affect efficiency of an enzyme…

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Competitive Inhibitors- have similar structure to the enzymes substrate, so they compete with the substrate for the active site of an enzyme.

Noncompetitive Inhibitors- do not attach to the active site and block the enzyme-substrate complex from forming. They react with portions of the active site, which results in the changing of its shape so that it can no longer bind with the substrate.

Inhibitors

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Some enzymes have special areas other than active site…regulatory site. Any molecule that attaches to the regulatory site is called an allosteric factor.

Join with regulatory site and change the shape of the entire enzyme preventing it from binding with the substrate.

Not all allosteric factors are bad, some actually bring the enzyme and substrate together.

Allosteric regulators

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Enzymes function best in a particular pH. If too many ions (H+ or OH-) are present,

the enzyme may denature (unfold). To a certain extent, high temps increases

the rate of an enzymes activity. Too high temperatures..the enzyme can denature.

pH & Temperature

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Enzyme/substrate concentration

For a given enzyme concentration, the rate of reaction increases with increasing substrate concentration up to a point, above which any further increase in substrate concentration produces no significant change in reaction rate. This is because the active sites of the enzyme molecules at any given moment are virtually saturated with substrate.

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To avoid wasting energy, ATP binds an enzyme in catabolism that shuts the enzyme off, effectively shifting the cell to an anabolic state.

This process is called feedback inhibition.