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Metabolism. I. The nature of energy A. 2 kinds of E B. First law of thermodynamics C. Second law of thermodynamics II. The nature of metabolism A. Energy changes in metabolic reactions: endergonic and exergonic B. Metabolic pathways: 2 types III. ATP: the main Energy carrier

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I. The nature of energy

A. 2 kinds of E

B. First law of thermodynamics

C. Second law of thermodynamics

II. The nature of metabolism

A. Energy changes in metabolic reactions: endergonic and exergonic

B. Metabolic pathways: 2 types

III. ATP: the main Energy carrier

A. Structure and function of ATP

B. The ATP/ADP cycle

IV. Enzymes

A. Enzyme structure and function

B. Effects of temperature and pH on enzymes

V. Cell Membranes

i the nature of energy
I. The nature of energy

A. 2 kinds of E B. First law of thermodynamics

A. 2 kinds of energy

B. First law

Energy cannot be created or




Implications of First Law:

1. The energy of the Universe is a constant.

2. The energy of the Universe has existed forever.

c second law of thermodynamics
C. Second law of thermodynamics

In every energy exchange, there is a loss as heat energy.

Heat energy is a loss because it cannot do the work of the cell.

Closed system: no energy input from outside source

Open system: receives energy input from outside source

Entropy: a measure of disorganization in a system

Energy flow through an


Primary producers get the

energy first and convert it

into chemical energy on which

the rest of the ecosystem


One way flow: in as light

energy– out as heat energy


90% loss – 10% capture

*Kinetic energy = Heat energy + Free Energy

ii the nature of metabolism

A-B A + B

A + B A-B

II. The nature of metabolism

A. Energy changes in metabolic reactions: endergonic and exergonicB. Metabolic pathways: 2 types

Exergonic graph?


E out

E in


Energy from exergonic rx used to drive

endergonic rx.

B. Metabolic pathways

Catabolism: break down

Anabolism: synthesis

coupled rx


A cow must eat at least 100 pounds of grain to gain less

  • than 10 pounds of muscle tissue. This illustrates
  • the first law of thermodynamics.
  • the second law of thermodynamics.
  • that some energy is destroyed in every energy conversion.
  • that energy transformations are typically 100% efficient.

Glucose molecules provide energy to power the swimming

  • motion of sperm. In this example, the sperm are changing
    • a. chemical energy into potential energy.
          • b. kinetic energy into chemical energy.
          • c. chemical energy into kinetic energy.
          • d. kinetic energy into potential energy.

The energy available to do work is

a. free energy

b. kinetic energy

c. heat energy

d. potential energy


Which of the following is correct?

a. kinetic energy = potential energy + heat energy

b. kinetic energy = free energy + potential energy

c. kinetic energy = free energy + heat energy

d. kinetic energy = kinetic energy + free energy


Which one of the following processes is endergonic?

  • the synthesis of glucose from carbon dioxide and water
  • the release of heat from the breakdown of glucose
  • the breakdown of glucose to power ATP formation
  • the burning of wood
iii atp the main energy carrier
III. ATP: the main energy carrier

Reasons why ATP is such a good energy carrier

1. Small

  • easily stored
  • mobile

2. Easily regenerated

3. Energy transferred

  • phosphorylation

4. Energy transferred is

roughly the amount needed

iii atp the main energy carrier1
III. ATP: the main energy carrier

(e.g. digestion)

Loss of heat energy!!!!

photosynthesis and respiration

In RS, the potential energy of glucose is converted into the potential energy

of ATP which can then be hydrolyzed to provide free energy for cellular work.

Photosynthesis and respiration

Glucose = potential energy

PS: anabolic

RS: catabolic

They are coupled reactions!

The products of ps are the

reactants of rs.


Which of the following is NOT a reason why ATP is such

  • a good energy carrier?
  • ATP is small and thus easily stored
  • ATP is easily regenerated
  • The energy from ATP can be transferred
  • ATP converts potential energy into free energy
  • The energy released by ATP is roughly equivalent to
  • that which is needed.

Which of the following is NOT a correct statement?

  • Photosynthesis and respiration are coupled reactions
  • Photosynthesis is anabolic and respiration is catabolic
  • The products of respiration are the reactants of
  • photosynthesis
  • d. Plants do both photosynthesis and respiration
iv enzymes
IV. Enzymes

Facilitate metabolic reactions

Neutralize toxins

Enzymes work by lowering the

energy barrier required for

reactions to take place.


Many reactions would go without enzymes,

but would use too much energy and take

too much time.

iv enzymes1
IV. Enzymes

A. Enzyme structure and function

Catabolic or anabolic?

Hydrolysis or

dehydration synthesis?

(- ase ending)

enzyme control and inhibition
Enzyme control and inhibition

Feedback inhibition site

Feedback inhibition

effect of temp and ph on enzyme activity
Effect of temp and pH on enzyme activity

Enzymes are denatured at high temperature and high and low pH.


What do enzymes NOT do?

  • Use potential energy to break chemical bonds
  • Convert products into reactants
  • Convert reactants into products
  • Lower the activation energy required for chemical
  • reactions to go.
  • e. Detoxify toxins

Which of the following conditions does NOT result in

enzyme denaturation?

a. very high temperature away from optimum

b. very low temperature away from optimum

c. very high pH away from optimum

d. very low pH away from optimum


An enzyme that is exposed to high heat far from its

  • optimum activation temperature experiences the breakage
  • of what type of bonds?
      • a. Covalent
      • b. Hydrogen
      • c. Ionic
      • d. Peptide
v cell membranes anatomy and physiology
V. Cell membranes: anatomy and physiology

A. Membrane structure and function

1. main components: phospholipids and proteins

Phospholipid bilayer

Hydrophobic barrier


(extracellular fluid/ intracellular fluid)

roles of proteins
Roles of proteins

Self- antigens

b movement across the membrane
B. Movement across the membrane

1. passive transport: diffusion and osmosis2. active transport

Solutes, solvents, solutions

Movement of like species from area of high concentration to low [ ]

Passive transport requires no energy

Only requirement is for a [ ] gradient

Facilitated diffusion uses

transport proteins to effect

passive transport of ions and

polar molecules.

1 passive transport
1. passive transport

Osmosis = movement of a solvent from area of low [solute] to high

[solute] across a differentially (selectively) permeable membrane

Hypotonic, hypertonic, and isotonic solutions

2 active transport
2. active transport


Requires energy and protein pumps

Movement is with disregard to the [ ] gradient


What does the phospholipids bilayer create?

    • a passage for polar substances into the cell
    • a hydrophilic environment to separate the ECF and ICF
    • a barrier to the movement of cholesterol
    • a hydrophobic barrier to the movement of charged
    • compounds

What is always necessary for passive transport to take


a. energy from ATP

b. transport proteins

c. ions or polar molecules

d. a concentration gradient


Under which of these conditions will water move into a cell?

a. cell is in isotonic solution

b. cell is in hypertonic solution

c. cell is in hypotonic solution

d. none of these

3 cellular communication
3. Cellular communication

Signal transduction

4 electron transport systems
4. Electron transport systems

Electron donor

Final electron acceptor