Unit 3: Energy Flow: Concept 1 & 2

Metabolism

All of the chemical reactions within each cell of an organism

- provide energy for life's processes

- creates key molecules

Chemical reactions

The breaking and forming of bonds between different substances during chemical changes

- BREAKING a bond requires energy to be ABSORBED

- FORMING a bond allows enrgy to be RELEASED in the form of heat, light, etc

- law of conservation of mass: no enrgy in the system is lost, it just changes form

Catabolic

A biochemical reaction where LARGER molecules are broken down into SIMPLER compounds (a release in energy = exergonic)

Anabolic

A biochemical reaction where SMALLER molecules build LARGER molecules (requires consuming energy to do it: endergonic)

Activation energy

The amound of energy needed to make a chemical reaction start

Reactant (substrate)

Substances that are CHANGED during a chemical reaction

Product

Substances that are MADE by a chemical reaction

Endothermic

ABSORBS energy (in the form of heat or light)

- ex. Photosynthesis

Exothermic

RELEASES energy (in the form of heat or light)

- ex. Cellular respiration

Enzyme

Mostly proteins that SPEED UP biochemical reactions by LOWERING the activation energy (they are also catalysts)

- bind to reactants (substrate) and help to break/form bonds —> releasing a newly created product

- NOT changed in a reaction and CAN be used repeatedly

- CRTICIAL for the regulation of life's processes in ALL organisms!

Catalyst

Substances that SPEED UP reactions withOUT being permanently altered

Active site

location on an enzyme where the substrate binds

- fits only one substrate. After substrate connection, bind tightens —> induced fit

Denaturation

enzymes active site gets deformed and loses its specific shape → loss of biological activity

- caused by ENVIRONMENTAL changes like extreme changes in pH, temp, ion strength, and solubility

ATP

(Adenosine triphosphate) the source of energy for use and storage at the cellular level

Chemiosmosis

The movement of ions down a concentration gradient

Summarize how energy changes during a chemical reaction as bonds are broken and formed

A. Energy is RELEASED when bonds are FORMED

B. Energy is ABSORBED when bonds are BROKEN

C. ALL reactions require energy to be absorbed and released

D. NO energy in the stem gets lost but can seem lost due to a change in form

Explain the overall function of enzymes in biochemical reactions like photosynthesis and cellular respiration

Enzymes, mostly proteins, SPEED UP biochemical reactoins by LOWERING the activation energy. They are also labeled CATALYSTS, substances that SPEED UP reactins withOUT being permanently altered.

Describe 5 factors that affect the rate of chemical reactions

1. TEMPERATURE (heat): as temp increases, the rate of the reaction increases (to a degree) due to molecules moving faster and colliding more

2. pH: how acidic a solution is; enzymes work in specific pH ranges—they can lose function outside of that range and not be able to speed up the reaction

3. SUBSTRATE CONCENTRATION: the higher the amount of substrate, the faster the reactions

4. CATALYSTS: speed up reactions by lowering the activation energy needed

5. COMPETITVE INHIBITOR: slows down reactions by competing with substrate for the enzyme's active site

Explain the purpose of ATP

The molecule ___ carries and stores energy for cell function

Describe the ATP-ADP cycle. Include what is and is not recycled, and the role of ATP synthase

A. ATP is really unstable, so it doesn't take a lot of energy to break the body between the 2nd and 3rd phosphates

B. When this happens and the P goes off to bond elsewhere, energy is released for the cell to use

C. When consumed food gets broken down during cellular respiration, the energy gets stored in ATP by adding a 3rd phosphate back on to ADP

D. ADP is recycled, nothing else necessarily is

E. ATP syntahse is the enzyme that catalyzes the addition of the 3rd phosphate to made ADP —> ATP

Note: the last 2 phosphate groups hold a lot of bonding energy, energy is released when a phosphate group is removed, ADP + phosphate group = ATP (ADP is recycled)

Explain that the energy is used for when a phosphate is removed, and where the energy initially comes from

This energy initially comes from 3 types of macromolecules: carbs, lipids, proteins (in that order):

- carbs are broken down first (4 cal/g of energy)

- lipids are broken down seconds (9 cal/g of energy)

- proteins are broken down last (4 cal/g of energy)

- nucleic acids ARE N E V E R BROKEN DOWN

Summarize why the overall process of breaking down ATP is considered an exothermic process, while the overall process of forming ATP is considered an endothermic process

A. It doesn't take much energy to break the 3rd phosphate off (since ATP is so unstable). Therefore, more energy is released than absored by the process —> EXOTHERMIC

- ATP = ADP + P —> EXOTHERMIC

B. It takes a LOT of energy to attach the 3rd phosphate, so very little is released when ATP is formed. B/c more energy is absored than released —> ENDOTHERMIC

- ATP + ADP + P + energy —> ENDOTHERMIC