Biology

Unit 1 Notes: Metabolism, Energy

& Homeostasis

(1) Homeostasis

• Homeostasis:Maintaining internal stability / balance.

• When/Why does this happen?• Anytime there are changes inside your body, or directly around your body, away from

how it normally is.

• Helps keep you living and healthy, and keeps energy cycling through cells.

• Examples:• Shivering when cold

• Bicarbonate in blood to neutralize acid

• Increasing respiratory rate when blood oxygen is low

(2) Energy Cycling & Transfer

• All living things need energy so that their cells can “do work” / stay alive.

• Organisms need to be able to:• Release potential energy from the bonds of molecules.

• Store extra energy in newly formed bonds of molecules (for later).

• Metabolism = The breaking down, and building of molecules inside cells in order to transfer energy and matter.

(3) Important Metabolic Reactions

• There are 2 very common and important metabolic reactions cells use:• Hydrolysis

• Dehydration Synthesis

• These reactions are used to release or store energy as cells need to.

• Both reactions involve water.

(4) Hydrolysis

• What does it mean?• Hydro = Water

• Lysis = Explode / Break Apart

• Hydrolysis = “To use water to break apart”.

• What is the purpose?• Release energy from molecules so that cells can use it.

• What happens?• Water is added to a larger polymer.

• The bonds holding the polymer together are broken.

• Energy is released.

(5) Dehydration Synthesis

• What does it mean?• Dehydrate = Remove Water

• Synthesis = Put Together / Make

• Dehydration Synthesis = “To remove water to put together”.

• What is the purpose?• Store energy for later, in newly formed bonds/molecules.

• What happens?• Water is removed from individual monomers.

• New bonds are formed connecting the monomers together (to form a polymer).

• Energy is stored.

(6) ATP & ADP

• ATP = Adenosine Triphosphate = “Energy Storing Molecule”

• ADP = Adenosine Diphosphate

• Your cells use ATP to store energy for later, and break apart ATP when they need energy to do work.

ATP(“TRI-

phosphate)

ADP(“DI-

phosphate)

(7) ATP & Metabolic Reactions

• Cells use Hydrolysis & Dehydration Synthesis with ATP.

• ATP ADP• Water is added to ATP.

• A phosphate is removed from ATP + the bond is broken.

• Energy is released + ADP is formed.

• ADP ATP• Water is removed from ADP.

• A phosphate is added to ADP + a new bond is formed.

• Energy is stored + ATP is formed.