Biological Energy

Question 1

What does it mean when we say biological systems are open energy systems?

Answer 1

Energy is exchanged between biological systems and their surroundings.

Question 2

What is a cell’s metabolism?

Answer 2

All of the chemical reactions that take place inside cells.

Question 3

What do most life forms ultimately get their energy from?

Answer 3

The sun

Question 4

What is the first law of thermodynamics?

Answer 4

Energy cannot be created nor destroyed, just transferred and/or transformed.

Question 5

List some examples of work that cells need to do.

Answer 5

• Build complex molecules
• Transport materials
• Power motion of cilia or flagella
• Contract muscle fibers

Question 6

Are energy transfers and transformations completely efficient? Why?

Answer 6

No, some is lost in an unusable form, such as heat.

Question 7

Define heat.

Answer 7

Energy transferred from one system to another that is not work.

Question 8

Why do living things consume sugar as a major energy source?

Answer 8

Sugar molecules contain a lot of energy in their bonds.

Question 9

What molecule provides the light reactions of photosynthesis with energy?

Answer 9

ATP

Question 10

What is a metabolic pathway?

Answer 10

a series of chemical reactions that takes a starting molecule and modifies it, step-by-step, through a series of metabolic intermediates, eventually yielding a final product.

Question 11

What is an anabolic pathway?

Answer 11

Builds polymers; requires energy

Question 12

What is a catabolic pathway?

Answer 12

breaks polymers down into monomers; releases energy

Question 13

Do the chemical reactions of metabolic pathways occur on their own?

Answer 13

No, they require enzymes.

Question 14

How is energy stored at the molecular level?

Answer 14

Atoms arranged in molecules in ways that have potential energy.

Question 15

What do enzymes do?

Answer 15

Lower activation energies of chemical reactions inside the cell.

Question 16

Why do cells use enzymes?

Answer 16

The reactions critical to a cell occur too slowly under normal temperatures.

Question 17

How do enzymes work?

Answer 17

binding to the reactant molecules and holding them in such a way as to make the chemical bond-breaking and -forming processes take place more easily

Question 18

Do enzymes change the free energy of a reaction?

Answer 18

No.

Question 19

How can temperature affect an enzyme?

Answer 19

Increase in temperature generally speeds up a reaction, with or without an enzyme. Too high of a temperature can denature an enzyme, destroying the enzyme and its function.

Question 20

What can pH and salinity changes do to an enzyme?

Answer 20

Extreme pH or salt levels can denature an enzyme.

Question 21

Differentiate the lock and key model and induced fit model for enzyme-substrate complex formation.

Answer 21

Lock and key: Enzyme and substrate fit together perfectly in one instantaneous step
Induced fit: As enzyme and substrate come together, their interaction results in a mild shift in enzyme formation, forming an ideal bonding arrangement.

Question 22

List the ways enzymes can lower activation energies.

Answer 22

1. Bring substrates together at optimal orientation
2. Create optimal environment for reaction within active site
3. Compromising bond structure, making it easier to break
4. Taking part in the reaction itself

Question 23

BiDifferentiate cofactors and coenzymes. What do they do?

Answer 23

Cofactors: Inorganic ions
Coenzymes: Organic helper molecules.
Both bond to enzymes to promote optimal shape and function.