3.1 Metabolism and Energy

Question 1

All living things require energy
EX:

Answer 1

Ex. to skate, to sing, to dance, to mvmt of your
eye muscles as you read this slide

Question 2

Energy is required not just for mvmt, but for also:

Answer 2

✓Growth
✓Maintenance
✓Repair

Question 3

Brain is 2% of your body mass and does not have large moving parts, BUT

Answer 3

uses 20% of energy!

Question 4

Many ______ and ______consume large amounts of energy

Answer 4

Plants and Animals

Question 5

Living organisms must ________, _______ and ___ ______

Answer 5

capture, store and use
energy

Question 6

ATP is made by

Answer 6

mitochondria in Eukaryotes

Question 7

Metabolism

Answer 7

the sum of the chemical
reactions (anabolic, to
build and catabolic, to
breakdown) taking place
within an organism

Question 8

Most living organisms
obtain energy via:

Answer 8

1. Directly from the sun
   through photosynthesis
2. Consuming energy-rich
   molecules within food

Question 9

All energy exists in one of two states:

Answer 9

1. Kinetic energy
2. Potential energy

Question 10

Kinetic Energy

Answer 10

▪ Occurs as a result of motion

▪ (e.g., waves in the ocean or heart muscles contracting)

▪ Useful b/c it can perform work by making other objects move

Question 11

Potential Energy

Answer 11

▪ Stored within an object; depends on location and/or chemical structure

▪ Ex. Chemical potential energy stored in food molecules

▪ Ex. Gravitational potential energy of Earth at high elevations gives the diver potential energy

Question 12

The First Law of Thermodynamics

a.k.a. “The Law of Energy Conservation”

Answer 12

• Energy cannot be created nor destroyed; it can only be changed from one form to another

1. Light energy comes from the sun
2. Converted to chemical energy by plants
3. Stored in plant cells as carbs
4. Pass on to other organisms when they eat the plants
5. Converted to other forms of energy (e.g., mechanical)

Question 13

Converting energy from one form into another depends on

Answer 13

the breaking and
forming of chemical bonds

Question 14

During a chemical reaction the
amount of __________ ______ that is available changes

Answer 14

potential energy

Ex. Electrons have more potential energy the farther they are from the nucleus

Question 15

For bonds to break (in
reactants), energy is
absorbed, b/c

Answer 15

energy is required to pull an electron away

Question 16

When bonds are formed (in
products),

Answer 16

energy is released

Question 17

Bond Energy

Answer 17

Is a measure of strength/stability of a covalent bond measured in kJ/mol

Question 18

All chemical reactions require ______ to start, even if it ultimately produces energy

Answer 18

energy

Question 19

Activation Energy (Ea)

Answer 19

Minimum amount of energy needed to break bonds in reactants to start a chemical rxn

Question 20

Transition State

Answer 20

Temporary condition in which bonds have reached their breaking point (in reactants)
and new bonds are ready to be formed (in products)

Question 21

Exothermic Reactions

Answer 21

Net release of E

Question 22

Endothermic Reactions

Answer 22

Net absorption of E

Question 23

The Second Law of Thermodynamics

Answer 23

Every time energy is converted to another form, some of the useful energy becomes unusable (usually in the form of thermal E) and increases the
Entropy of the universe

Question 24

Even cells only convert about __ __ __________ _______ in glucose into a form usable for
metabolism, the rest is lost as thermal E to the env.

Answer 24

40% of potential energy

Question 25

Entropy

Answer 25

The degree of disorder in a system

Question 26

Total Entropy of a system and its surroundings ________ during
a chemical reaction

Answer 26

Increase

Therefore, all systems in the universe tend towards entropy

Question 27

In chemical reactions, Entropy Increases when:

Answer 27

Solids react to form liquids/gases

Liquids react to form gaseous products

Total # of product molecules > # of reactant molecules

Question 28

Living things are highly ordered
structures and may seem to
therefore not follow The Second
Law of Thermodynamics
* This is NOT TRUE!

Answer 28

Living cells can, by expending
energy, establish and maintain
complex and orderly structures and processes

Entropy of the organism ↓, but the overall entropy of the universe ↑

Question 29

Spontaneous Changes

Answer 29

A change that will continue to occur on its own once is has started; DOES NOT require
a continuous supply of energy

E.g., a match will continue to burn once it’s lit

Question 30

A non-spontaneous reaction requires…

Answer 30

continual energy input

E.g., keeping a pot of water boiling on the stove

Question 31

To determine whether a change will occur spontaneously you must look at:

Answer 31

1. Energy changes
2. Entropy
3. Temperature

Question 32

Gibbs Free Energy

Answer 32

Since rxns aren’t 100% efficient, whatever energy that remains to do work is known as FREE ENERGY

required to build molecules, repro. and mvmt

ΔG = Gfinal – Ginitial

Question 33

If ΔG is “-” negative

Answer 33

products have less free energy than reactants

energy is released (exergonic)
→ spontaneous

(e.g., oxidation of glucose)

Question 34

If ΔG is “+” positive

Answer 34

products have more free energy than reactants

energy is absorbed (endergonic)→ non spontaneous

(e.g., photosynthesis)

Question 35

Coupled Reactions

Answer 35

Cells continuously carry out thousands of rxns

Free energy released by exergonic rxns can be used to make endergonic reactions happen (called energy coupling)

Combined, the rxns have – ΔG, so they occur spontaneously

Question 36

Endergonic rxns must be coupled with exergonic rxns that release more free energy than the endergonic rxn requires

Answer 36

Rxns are part of a metabolic pathway, which products of one
reaction are used immediately as reactants for the next reaction in the pathway

Question 37

Catabolic Pathway

Answer 37

complex molecules broken down, releasing energy

(e.g. cellular respiration) ΔG -ve

Question 38

Anabolic Pathway

Answer 38

simple molecules combined, consuming energy

(e.g. photosynthesis) ΔG +ve

Question 39

All living things perform activities that increase the free energy available

Answer 39

Movement, growth, repair, reproduction

Therefore, a continual supply of energy is required

This energy comes from ATP!