Campbell et al. Chapter 6 is chemistry and physics oriented

Later, chapter 9 (before exam 1) we cover energy metabolism in more detail, then, (after exam 1) the reverse, namely photosynthesis, is covered in chapter 10

Metabolism is the general term for two kinds of reactions:
(1) catabolic reactions (breakdown)
(2) anabolic reactions (constructive)

Energy saved mostly through photosynthesis
released through respiration (breathing vs. cellular)

TRANSPARENCY (Fig. 6.10) ADP plus phosphate <-> ATP involved in storage and release of energy

TRANSPARENCY (Fig. 6.8) shows ATP made of Adenine, ribose and 3 phosphates, energy stored in 3rd phosphate bond

substrate -> product

TRANSPARENCY (Fig. 6.1) is a "cartoon" to show that the body's reactions can be quite complex.
There is a staggering array of enzymes, and a lot of energy is used to power the reactions.

Reminder: enzymes are named with suffix "-ase."

TRANSPARENCY (Fig. 6.19) For instance, the body can make some amino acids (example: isoleucine) from others (example: threonine). You must consume the some (essential ones).
This transparency also reminds us of homeostasis (regulation, Chapter 1) by negative feedback)

TRANSPARENCY (Fig. 6.13) overcome energy of activation - catalysts - enzymes

TRANSPARENCY (Fig. 6.15) is an intuitive figure to show that enzyme (sucrase) binds substrate (sucrose) and eventually is recycled as it releases the products of the reaction (glucose and fructose)

Energy - kinetic and potential (later, discussing bioelectricity, potential will also be Volts)
First law of thermodynamics - energy of universe is constant
Second law - things become more disordered
(It is highly recommended that you read a 10 page science fiction story by Isaac Asimov called "the final question" in which it is asked what happens after the universe is dissipated.)
Energy flows as entropy increases.
In general, heat is waste and not useful.
BTU's (British thermal units, which can be converted to calories) imply that energy and heat are related.
Heat stored in energies of covalent bonds in kcal / mol
Free energy can be used for work = what is stored in bonds minus what is wasted as heat
Exerogonic, e.g. cellular respiration C6H12O6 -> 6CO2 +6H2O + energy
the free energy is 686 kcal/mol

38 of them generated when respiration is complete
40.3% efficient, the rest is heat, usually considered as waste but useful in temperature regulation in warm blooded animals, homoiotherms, homeotherms.

TRANSPARENCY (Fig. 6.9) It is interesting to note that ATP delivers it's energy by transferring its phosphate to molecules, as shown in this example of the synthesis of glutamine from glutamic acid and ammonia.

TRANSPARENCY (Fig. 9.2) It is easy to mistakenly think that energy use is only by muscles, but this preview from Chapter 9 reminds you that a lot of the body's energy is used in transport and in reactions. This figure also reminds you that ATP transfers its 3rd phosphate to molecules and the phosphate is then released as inorganic phosphate to be eventually added to ADP to make ATP.

TRANSPARENCY (Fig. 6.16) is interesting because it will preview some stories that will come up later. Optimum tempreature for human enzyme may be near 37oC, body temperature. For a thermophilic bacterium, it may be very high, useful in PCR (polymerase chain reaction). Also, optimum pH for pepsin (proteolytic enzyme in stomach) is acidic while for trypsin (proteolytic enzyme in intestine) is slightly basic.

This page was last updated 6/17/02

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