An Introduction to MetaBOlism Chap 8 pg 142-159

Many reactions in our bodies are “coupled” together!

Metabolism & Metabolic Pathways

All of the chemical reactions that occur in a cell MetabolIsm: “Change” All of the chemical reactions that occur in a cell Metabolism is driven by cellular respiration Converts energy from sugars to do work!

METABOLIC PATHWAYS E1 E2 E3 E4 A B C D E A series of steps, catalyzed by enzymes that create a new product Most reactions in a cell are “coupled” ( linked) NOT random Every rxn in a cell requires its specific enzyme! Can you think of 3 enzymes you know? E1 E2 E3 E4 A B C D E

Catabolic Pathways “Downhill” Reactions…release energy Breakdown complex molecules into simpler molecules Ex: Hydrolysis Reactions Ex: Cellular Respiration

Anabolic Pathways “Uphill” Reactions…consume energy Build complex molecules from simpler molecules Ex: Dehydration Synthesis Reactions Ex: Protein Synthesis from Amino Acids

You try… Catabolic or Anabolic `1) 2) 3)

Energy released from the catabolic reaction can be used to drive the anabolic reaction. this transfer is called energy coupling

Energy Energy: the capacity to do work Kinetic Energy: energy of motion Potential Energy: stored energy Bond Energy or Chemical energy: the potential energy available for release in a chemical reaction (stored/found in ATP)

Organic compounds store energy in their arrangements of atoms. Cells harvest chemical energy stored in molecules and use this to generate ATP. Organic compounds store energy in their arrangements of atoms. The goal is to break these bonds and release energy our cells can use.

Laws of energy Transformation (Thermodynamics) 1) Energy cannot be created or destroyed Only transferred and transformed! 2) Changes in energy increases entropy Entropy: the measure of disorder or randomness

Free Energy: energy available to do work Represented by G therefore the change in free energy = G Final energy-Initial energy If G is NEGATIVE the reaction is Exergonic (energy has been released in products...ex=out) If G is POSITIVE the reaction is Endergonic (energy has been consumed in reactants...end=in)

What type of reactions cause these squid to glow What type of reactions cause these squid to glow?!? Describe the change in free energy!

How would the following scenario be similar or different?

Atp, cellular work & coupling RxnS Sec 8.3 pg 149

A cell does 3 main kinds of work: I) Chemical work carrying out endergonic rxns (like building polymers) II) Transport work pumping substances across membranes (against concentration gradients) III) Mechanical work Beating of cilia, contraction of muscle cells etc

Energy Coupling: The use of an exergonic process to drive an endergonic one!

The structure of (ATP) Nitrogenous base: adenine Sugar: ribose 3 phosphate groups

The 3 Phosphate groups are each neg. charged Creates a mutual repulsion & instability  chemical equivalent of a compressed spring

The hydrolysis of ATP ATP + H20  ADP + Pi + energy

The hydrolysis of ATP Exergonic rxn  releases energy Energy is used to drive many cellular processes ! Example of chemical work: Making the amino acid glutamine from glutamic acid and ammonia (see fig 8.9)

The hydrolysis of ATP Example of Transport work: Ex) ATP hydrolysis drives protein pumps in the cell membrane  changes the shape & binding affinity Example of Mechanical work: ATP attaches to motor proteins, hydrolysis helps create movement along cytoskeletal track can move vesicles & organelles!

Regeneration of ATP

Big Idea: Free energy becomes available for metabolism by the conversion of ATP  ADP, which is coupled to many steps in metabolic pathways!

Assignment: Concept Check 8.2 Qs 1-3 pg 149

Relevant Links KHAN Academy- https://www.khanacademy.org/science/biology/energy-and- enzymes/atp-reaction-coupling/v/reaction-coupling-to-create-glucose-6-phosphate Bozeman- https://www.youtube.com/watch?v=7IqgrcBkGRU https://www.youtube.com/watch?v=YHMxMGEjUwE