Energy!

Big Idea #2: Energy is needed to do stuff.

Big Idea #2

• Biological Systems utilize free energy and molecular building blocks to grow, to reproduce

and to maintain dynamic homeostasis

Essential Knowledge

• 2A1: All living systems require constant input of free energy.

Energy

• Ability to do something (i.e. move)• 2 general types:

–Potential energy- stored energy–Kinetic energy – moving energy

Potential vs. Kinetic Energy

• Resting objects• Nuclear• Hydroelectic (water

behind a dam)• Food • Moving objects

• Radiation (light particles/waves)

• Thermal (heat)• Electrical (movement of

electrons)

1st Law of Thermodynamics

• Energy cannot be created

nor destroyed•May change

from one form to another

Ex: Solar Energy Chemical Energy

2nd Law of Thermodynamics

• No rxn is 100% efficient lose energy • Systems spontaneously increase entropy

(disorder)

Entropy

• Amount of energy in an unusable form – usually heat

• Is always increasing b/c systems are always losing usable forms of energy

Biologically Speaking…

• Living orgs require an energy input. • Ex: orgs must get energy from sun, deep

thermal vents, or eating

Remember 10% Rule!

Order and Organization Require Energy

Things naturally break down – to keep them from breaking down or to put them together requires an input of energy

Energy Coupling

• Processes that release energy are coupled to ones that require an input of energy

• More energy must be released than is required

Example

• Flexing a muscle requires an energy input and breaking down food releases energy (ATP).

Do You Have Any

Band Aids?

Exergonic Reactions

• Release free energy• Used in living things to provide energy

for other processes

The Most Significant Exergonic Reaction

ATP + H2O ADP + Pi + Energy

Making ATP is an Endergonic Reaction

• Requires an input of energy• Made in cellular respiration (input of chemical

energy in food)

Uses of Free Energy

• Maintain body temp (some organisms)/Internal temp regulation

• Reproduction• Growth• Movement

Body Temp Regulation

• Endothermy: Use heat released by metabolic reactions to keep a stable temp

• Ex: Humans 98.6⁰

Body Temp Regulation

• Ectothermy: Use external sources to try to maintain body temp.• Ex: snakes/reptiles

Reproduction

• Requires a huge amount of energy • Many species only reproduce when energy is available

– I.e. most plants flower in spring when sunlight energy is abundant

Growth

• Extra free energy not needed for cellular processes (movement and reproduction) can be

put to growth• Ex: extra calories become stored fat

Energy Deprivatio

n

• Mass is broken down

to provide energy

• No energy input = death

RIP Tako

Smaller Organisms Require More Food Per Body Mass

• Smaller orgs have more surface area to volume lose more heat… must replenish

that energy loss by eating more

The Trophic Levels

• Energy goes up food chain• At every level energy is being lost due to

entropy.

• So…less energy available for high levels of food

chain• Rarely enough energy to

support more than 3-4 levels on a food chain

Energy on an Ecological Level

• The more energy available for a population, the more it will grow

• Ex: rain forests have most abundant plant life – constant energy source

Energy Doesn’t Cycle!!!!!!