AP Biology - UNIT 2B: CELL MEMBRANE STRUCTURE & MEMBRANE TRANSPORT ASSESSMENT

(ENERGY / ATP / ENZYMES) An Introduction to Metabolism

• What is ENERGY?

• the capacity to do work or cause change (in chemical terms, it’s the capacity to rearrange matter)

(ENERGY / ATP / ENZYMES) An Introduction to Metabolism

• ENERGY CAN’T BE _______ OR _________, BUT IT CAN ______ ____!

1. CREATED

2. DESTROYED

3. CHANGE FORM

(ENERGY / ATP / ENZYMES) An Introduction to Metabolism

• ____ ______ is released to the environment with every energy transformation.

1. Heat energy

(ENERGY / ATP / ENZYMES) An Introduction to Metabolism

• What is KINETIC ENERGY?

• energy of motion (heat, light)

(ENERGY / ATP / ENZYMES) An Introduction to Metabolism

• What is POTENTIAL ENERGY?

• stored (in the bonds)/positional energy (chemical)

(ENERGY / ATP / ENZYMES) An Introduction to Metabolism

• Fill in this chart about TYPES OF ENERGY.

(ENERGY / ATP / ENZYMES) An Introduction to Metabolism

• *Many biological processes involve the transfer of energy from one molecule to another. In order to maintain high levels of organization, organisms need a constant supply of energy! Cells need a constant supply of energy for…

• Normal cell/tissue maintenance & repair

• Performing the life functions (metabolism)

  • Growth

  • Excretion

  • Nutrition

  • Transport

  • Synthesis

  • Respiration

  • Reproduction

  • Regulation

(ENERGY / ATP / ENZYMES) CELLULAR METABOLISM

• What is CELLULAR METABOLISM?

• all chemical rxns

(ENERGY / ATP / ENZYMES) CELLULAR METABOLISM

• What are EXERGONIC REACTIONS?

• releases energy; energy is a product

• BONDS ARE BROKEN

• Example: Cellular Respiration! (occurs in Mitochondria)

  • C₆H₁₂O₆ + O₂ → CO₂ + H₂O + ENERGY (ATP + heat)

    • ENERGY → Chemical energy is stored in molecules of ADENOSINE TRIPHOSPHATE (ATP) (the energy molecule of the cell)

(ENERGY / ATP / ENZYMES) CELLULAR METABOLISM

• What are ENDERGONIC REACTIONS?

• All synthesis rxns

• requires energy; energy is a reactant

• BONDS ARE FORMED

• Example: Photosynthesis! (occurs in Chloroplast)

  • ENERGY + CO₂ + H₂O → C₆H₁₂O₆ + O₂

  • ENERGY → Sunlight energy (a form of kinetic energy)

(ENERGY / ATP / ENZYMES) A CLOSER LOOK AT ATP!

• ATP consists of…

• ADENINE (also found in DNA/RNA) + RIBOSE SUGAR (also found in RNA) → Adenosine

• 3 PHOSPHATE GROUPS → Triphosphate

• 2 HIGH ENERY BONDS (covalent) between phosphate groups.

  • (High energy bonds are often indicated by ~, instead of “straight” covalent bonds)

(ENERGY / ATP / ENZYMES) A CLOSER LOOK AT ATP!

• Label the ATP molecule.

(ENERGY / ATP / ENZYMES) A CLOSER LOOK AT ATP!

• Why is ATP an UNSTABLE molecule?

• The negative atoms in the phosphate groups repel each other, giving the molecule a high amount of potential energy (the bonds “want” to break)!

  • high energy “pops” that get used in cells when the bond breaks

(ENERGY / ATP / ENZYMES) PHOSPHORYLATION REACTIONS

• What are PHOSPHORYLATION REACTIONS?

• *reactions that transfer phosphate groups, causing the transfer of energy from one molecule to the other*

• “ENERGY COUPLING"

• Involves the breaking of high energy bonds from ATP → EXERGONIC (That “pop” of energy can be used to do “work” in the cell.)

(ENERGY / ATP / ENZYMES) PHOSPHORYLATION REACTIONS

• Label this DEPHOSPHORYLATION reaction.

(ENERGY / ATP / ENZYMES) PHOSPHORYLATION REACTIONS

• When a phosphate group that breaks off from ATP can be transferred to another molecule, making a new bond…

• ENDERGONIC

(ENERGY / ATP / ENZYMES) PHOSPHORYLATION REACTIONS

• The molecule that receives a phosphate group is…

• PHOSPHORYLATED

(ENERGY / ATP / ENZYMES) PHOSPHORYLATION REACTIONS

• The molecule that loses a phosphate group is…

• DEPHOSPHORYLATED

(ENERGY / ATP / ENZYMES) PHOSPHORYLATION REACTIONS

• ATP provides the energy for 3 types of cellular work…

• Chemical (like synthesis reactions: DNA synthesis, protein synthesis)

• mechanical (like the movement of cilia or flagella, muscles)

• transport (like movement of ions against the gradient)

  • Endocytosis/Exocytosis

(ENERGY / ATP / ENZYMES) ATP/ADP CYCLE

• Label the diagram.

(ENERGY / ATP / ENZYMES) Why can’t the cell just use the chemical energy stored in glucose? (Why did an intricate multi-step pathway evolve to create ATP?)

• It would release too much energy at once! Metabolic pathways evolved to slowly release and transfer the energy without damaging the cell.

• ATP holds & releases smaller, more manageable amounts of energy so none is wasted. (Energy efficiency)

(ENERGY / ATP / ENZYMES) Why can’t the cell just use the chemical energy stored in glucose? (Why did an intricate multi-step pathway evolve to create ATP?)

• Compare GLUCOSE and ATP.

• GLUCOSE:

  • lots of energy

  • STABLE for travel in bloodstream

• ATP:

  • smaller amounts of energy

  • only utilized INSIDE CELLS

  • unstable (easy to break bonds)

(ENERGY / ATP / ENZYMES) Why can’t the cell just use the chemical energy stored in glucose? (Why did an intricate multi-step pathway evolve to create ATP?)

• 1 glucose is equivalent to __ ATP!

• 32

(ENERGY / ATP / ENZYMES) ENZYMES: Nature’s Catalysis for Life!

• What are ENZYMES?

• Enzymes are specialized proteins that act as biological catalysts, starting and speeding up chemical reactions necessary for life.

• They are required for reactions to occur, allowing processes like digestion, energy production, and DNA replication to happen efficiently.

• Each enzyme is highly specific with a specific shape/active site, binding to a particular substrate and facilitating a unique reaction making them essential for maintaining the body’s metabolism and homeostasis.

• Often (but not always) have “-ASE” endings

• Enzymes are needed in very small amounts because they are recycled/reused (unchanged) after the reaction occurs

• they are not interchangeable!

(ENERGY / ATP / ENZYMES) ENZYMES: Nature’s Catalysis for Life!

• Where do enzymes work?

• Enzymes can’t be consumed in our diet…they are synthesized in cells. Most enzymes work inside the cell (anywhere from 1000 - 4000 in animal cells), but some get secreted (sent out) and work outside the cell…like digestive enzymes inside the stomach or mouth.

(ENERGY / ATP / ENZYMES) ENZYMES: Nature’s Catalysis for Life!

• What is the ACTIVE SITE?

• ACTIVE SITE the site where the chemical reaction occurs

• The substrate enters the active site - the shape is very important!

(ENERGY / ATP / ENZYMES) ENZYMES: Nature’s Catalysis for Life!

• What is the SUBSTRATE?

• the substances that interact with the enzyme (reactants)

(ENERGY / ATP / ENZYMES) Enzyme Specificity

• Explain enzyme specificity.

• Every reaction has its own specific enzyme. They are not interchangeable.

• Enzymes are not included in the chemical reaction, but can be written over the yield sign because:

  • they do not get changed in any way

  • they are recycled (used over and over again)

(ENERGY / ATP / ENZYMES) Enzyme Specificity

• Label the process of an enzyme.

(ENERGY / ATP / ENZYMES) Enzyme Specificity

• What is the TRANSITION STATE?

• highest energy position of the rxn

(ENERGY / ATP / ENZYMES) Enzyme Specificity

• Draw the graph of an enzyme reaction.