Some Basics on Matter and Energy in General Biology | BIOL 1001, Study notes of Biology

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MATTER AND ENERGY

Some basics you should know:

---matter is anything that takes up space and

has mass

-the physical material of the universe

---Energy is the capacity to do work.

There are two major

categories of energy

1. potential energy

2. kinetic energy

---Potential energy is energy stored in matter

because of its position or location.

---Kinetic energy is the energy of motion.

Potential energy in biological systems

can be stored in chemical bonds

The Laws of Thermodynamics Describe the

Properties of Energy

Energy transfer by organisms is subject to

two laws of thermodynamics

---First Law of Thermodynamics which states

that energy can be transferred and

transformed, but it cannot be created or

destroyed (i.e., the energy of the universe

is constant).

---Second Law of Thermodynamics which

states that every energy transfer or

transformation makes the universe more

disordered (i.e., every process increases

entropy at the cost of useful energy)

---Entropy is the measure of disorder,

randomness.

100 units

chemical

energy

(concentrated)

gas

25 units kinetic energy

(motion)

75 units heat

energy

Fig. 6.

Why do you get hot when you

work out?

• (^) Muscles are broken down and heat up when you

workout.

• (^) All the chemical energy in food is directly converted

to the energy of heat.

• (^) As the energy in food is converted to the energy of

movement, all the energy is converted to heat.

• (^) As the energy in food is converted to the energy of

movement, some of the original energy is converted

to heat.----

If every energy transfer loses usable energy,

why doesn’t life on the planet simply run out

of energy?

The planet isn’t a closed system.

Energy is constantly flowing in from the

sun.

A closed system is a system which

is completely isolated from its

surroundings.

In an open system energy can be

transferred between the system

and the surroundings.

ENERGY FLOW IN CHEMICAL REACTIONS

In all chemical reactions you begin with one

set of substances, reactants, and

end with a different set of substances,

products.

A + B C + D

Reactants Products

Thermodynamics determines whether or not

a chemical reaction will occur in the

cell, and how much energy it will consume

or release

Chemical reactions are either exergonic or

endergonic

---Exergonic reactions are reactions that

release energy.

---Endergonic reactions are energy-requiring

reactions.

energy

released

products

reactants

Exergonic reaction

Fig. 6.

Burning glucose-exergonic reaction

glucose oxygen

6 O O

energy

released

O

H H

water

6 O C O

carbon

dioxide

Fig. 6.

products

energy

used

Endergonic reaction

reactants

Fig. 6.

glucose

6 O O

oxygen O

H H

water

Photosynthesis-endergonic reaction

energy

6 O C O

carbon

dioxide

Fig. 6.

EXERGONIC

REACTIONS

ENDERGONIC

REACTIONS

Releases energy Requires energy

Reaction is

energetically downhill

Reaction is

energetically uphill

Spontaneous reaction Non-spontaneous

reaction

(requires an energy

source)

If energy is given off in a

reaction, you can assume that:

• (^) It is an endergonic reaction.
• (^) It is an exergonic reaction.--
• (^) Entropy is decreasing.
• (^) The laws of thermodynamics have been

defied.

Although exergonic reactions release energy

overall, they may require some energy to get

them started.

This “starter energy” is called activation energy.

--- Activation energy is the amount of energy

that reactant molecules must absorb

to start a reaction

Burning glucose (sugar): an exergonic reaction

Fig. 6.6

Photosynthesis: an endergonic reaction

high

low

energy

content

of

molecules

progress of reaction

glucose

activation

energy from

light captured

by photosynthesis

CO 2

• H 2

O

net energy

captured by

synthesizing

glucose

Coupled reactions

Chemical reactions which release

energy can be coupled to chemical

reactions which require energy.

relaxed

muscle

relaxed

muscle

Exergonic reaction:

Endergonic reaction:

Coupled reaction:

20 units

energy

ATP

ATP

contracted

muscle

contracted

muscle

100 units

energy released

80 units energy

released as heat

ADP

ADP

P

P

Fig. 6.9

Coupled reaction: glucose breakdown and protein synthesis