Chapter 8.1Cell Energy

Chapter 8.1

An organism’s metabolism transforms matter and energy, subject to the laws of thermodynamics.

MetabolismAll of the chemical reactions that occur within an organismMetabolic pathways begin with a specific molecule, which is altered in a series of specific steps.

Each is catalyzed by a specific enzyme

Metabolic Pathways--Catabolism

Metabolism as a whole manages the material and energy resources of the cell

Catabolic PathwaysBREAKDOWN PATHWAYSRelease energy when breaking down complex molecules to simpler molecules“downhill” pathway

Examples???Cellular respiration

Metabolic Pathways--Anabolic

Consumes energy to build complicated molecules from simpler ones

Biosynthetic pathways “Uphill” pathway

Examples???Protein synthesis

Bioenergetics

The study of how energy flows through living organisms

EnergyThe capacity to cause change

Forms of energy are used to do work

What are the forms of energy?Kinetic Energy—relative motion of an object

Thermal Energy (Heat)—kinetic energy associated with random movement of atoms. Also includes light.

Potential Energy—energy possessed due to location or structure

Chemical Energy—potential energy available for release in a chemical reaction

Chemical Energy

What is the chemical energy?

What process breaks down food to release this energy?

The laws of energy transformation

ThermodynamicsThe study of energy transformations that occur in a collection of matter

SystemMatter under study

Isolated system—unable to exchange either energy or matter with surroundings

Open system—energy and matter can be transferred between the system/surroundings

First Law of Thermodynamics

First Law of Thermodynamics Energy can be transferred and transformed, but it cannot be created or destroyed.PRINCIPLE OF CONSERVATION OF ENERGY

Second Law of ThermodynamicsDuring every energy transfer or transformation some energy becomes unusable and unable to do work.Energy is lost as HEATEvery energy transfer or transformation increases the entropy

(disorder/randomness) of the universe

Checkpoint:

1) Which term most precisely describes the cellular process of breaking down large molecules into smaller ones?

A) catalysis

B) metabolism

C) anabolism

D) dehydration

E) catabolism

Checkpoint

2) Which of the following is (are) true for anabolic pathways?

A) They do not depend on enzymes.

B) They are usually highly spontaneous chemical reactions.

C) They consume energy to build up polymers from monomers.

D) They release energy as they degrade polymers to monomers.

Checkpoint

3) Which of the following is a statement of the first law of thermodynamics?

A) Energy cannot be created or destroyed.

B) The entropy of the universe is decreasing.

C) The entropy of the universe is constant.

D) Kinetic energy is stored energy that results from the specific arrangement of matter.

E) Energy cannot be transferred or transformed.

Checkpoint4) For living organisms, which of the following is an important consequence of the first law of thermodynamics?

A) The energy content of an organism is constant.

B) The organism ultimately must obtain all of the necessary energy for life from its environment.

C) The entropy of an organism decreases with time as the organism grows in complexity.

D) Organisms are unable to transform energy.

E) Life does not obey the first law of thermodynamics.

CheckPoint5) Living organisms increase in complexity as they grow, resulting in a decrease in the entropy of an organism. How does this relate to the second law of thermodynamics?

A) Living organisms do not obey the second law of thermodynamics, which states that entropy must increase with time. B) Life obeys the second law of thermodynamics because the decrease in entropy as the organism grows is balanced by an increase in the entropy of the universe. C) Living organisms do not follow the laws of thermodynamics. D) As a consequence of growing, organisms create more disorder in their environment than the decrease in entropy associated with their growth. E) Living organisms are able to transform energy into entropy.

Checkpoint:

6) Which of the following types of reactions would decrease the entropy within a cell?

A) dehydration reactions

B) hydrolysis

C) respiration

D) digestion

E) catabolism

Checkpoint Answers

1. E—catabolism

2. C –They consume energy to build up polymers from monomers.

3. A -- Energy cannot be created or destroyed.

4. B -- The organism ultimately must obtain all of the necessary energy for life from its environment.

5. D -- As a consequence of growing, organisms create more disorder in their environment than the decrease in entropy associated with their growth.

6. A -- dehydration reactions