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 2.a.1 – All living systems require constant input of free energy (8.1-8.3).  4.b.1 – Interactions between molecules affect their structure and function.

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Presentation on theme: " 2.a.1 – All living systems require constant input of free energy (8.1-8.3).  4.b.1 – Interactions between molecules affect their structure and function."— Presentation transcript:


2  2.a.1 – All living systems require constant input of free energy (8.1-8.3).  4.b.1 – Interactions between molecules affect their structure and function (8.4 & 8.5).

3  The totality of an organism’s chemical processes  Concerned with managing the material and energy resources of the cell

4  Pathways that break down complex molecules into smaller ones, releasing energy  Example: Cellular respiration  DOWNHILL!

5  Pathways that consume energy, building complex molecules from smaller ones  Example: Photosynthesis, condensation synthesis  UPHILL!

6  Energy cannot be created or destroyed  It can be converted from one form to another  The sum of the energy before the conversion is equal to the sum of the energy after the conversion

7  Some usable energy dissipates during transformations and is lost  During changes from one form of energy to another, some usable energy dissipates, usually as heat  The amount of usable energy therefore decreases

8  Ability to do work  The ability to rearrange a collection of matter  Forms of energy: › Kinetic › Potential › Activation

9  Kinetic: › Energy of action or motion › Ex: heat/thermal energy  Potential: › Stored energy or the capacity to do work › Ex: chemical energy

10  Energy needed to convert potential energy into kinetic energy Potential Energy Activation Energy

11  The portion of a system's energy that can perform work  Known as ΔG

12 ΔG = Δ H - T Δ S Δ = change (final-initial) ΔG = free energy of a system ΔH = total energy of a system (enthalpy) T = temperature in o K ΔS = entropy of a system

13  If the system has: › more free energy=less stable (greater work capacity) › less free energy=more stable (less work capacity) › As rxn moves towards equilibrium, ΔG will decrease

14  These are the source of energy for living systems  They are based on free energy changes  Two types  Two types: exergonic and endergonic

15  Exergonic: › chemical reactions with a net release of free energy › Ex: cellular respiration › - ΔG, energy out, spontaneous  Endergonic: › chemical reactions that absorb free energy from the surroundings › Ex: Photosynthesis › + ΔG, energy in, non-spontaneous

16 - ΔG+ΔG+ΔG

17  Couples an exergonic process to drive an endergonic one  ATP is used to couple the reactions together  Types:  Types: mechanical, transport, chemical

18  ATp  Adenosine Triphosphate  Made of: 1. Adenine (nitrogenous base) 2. Ribose (pentose sugar) 3. 3 phosphate groups* *bonds can be broken to make ADP


20  Three phosphate groups and the energy they contain  Negative charges repel each other and makes the phosphates unstable › Tail is unstable = more free energy = more instability  Works by energizing other molecules by transferring phosphate groups  Hydrolysis of ATP = free energy is released as heat (can be adv or not adv)

21  Energy released from ATP drives anabolic reactions  Energy from catabolic reactions “recharges” ATP  Very fast cycle › 10 million made per second Coupled RXN


23  Takes place in cytoplasm and mitochondria  Using special process called substrate-level phosphorylation › Energy from a high- energy substrate is used to transfer a phosphate group to ADP to form ATP

24  Biological catalysts made of protein  Speeds up rxn without being consumed  Cause the speed/rate of a chemical rxn to increase › By lowering activation energy

25 AB + CD AC + BD *AB and CD are “reactants” *AC and BD are “products” *Involves bond forming/breaking *Transition state: can be unstable

26 Unstable state Energy is released as heat

27  Lower the activation energy for a chemical reaction to take place  Why do we need enzymes? › Cells can’t rely on heat to kick start rxns › Why? Denaturation, heat can’t decipher between rxns › Enzymes are selective! Can only operate on a given chemical rxn Intro to Enzymes movie


29  Substrate – › the material the enzyme works on  Enzyme names: › Ex. Sucrase › “- ase” name of an enzyme › 1st part tells what the substrate is (i.e. Sucrose)

30  Some older known enzymes don't fit this naming pattern  Examples: pepsin, trypsin

31  The area of an enzyme that binds to the substrate  Structure is designed to fit the molecular shape of the substrate  Therefore, each enzyme is substrate specific


33 Enzyme + Enzyme-Enzyme + Subtrate Sub complexProduct Notice: Complex becomes product, but enzyme stays the same! Enzyme is NOT CONSUMED!

34 1. Lock and Key model 2. Induced Fit model Reminder: Reminder: Enzymes and substrates are usually held together by weak chemical interactions (H/ionic bonds)


36  Substrate (key) fits to the active site (lock) which provides a microenvironment for the specific reaction

37  Substrate “almost” fits into the active site, causing a strain on the chemical bonds, allowing the reaction

38  Usually specific to one substrate  Each chemical reaction in a cell requires its own enzyme  Don’t change during rxn  Always catalyze in direction towards equilibrium

39 1) Active site is template for enzyme 2) Enzymes may break/stretch bonds needed to be broken/stretched 3) Active site is microenvironment 4) Active site directly participates in chemical rxn

40  Environment  Cofactors  Coenzymes  Inhibitors  Allosteric Sites

41  Factors that change protein structure will affect an enzyme.  Examples: › pH shifts (6-8 optimal) › Temperature (up, inc activity) › Salt concentrations

42  Cofactors: › Non-protein › Non-protein helpers for catalytic activity › Examples: Iron, Zinc, Copper  Coenzymes: › Organic molecules that affect catalytic activity › Examples: Vitamins, Minerals, usually proteins

43  Competitive › mimic the substrate and bind to the active site (compete for active site) › Toxins/poisons – Ex: DDT › Can be used in medicine – painkillers, antibiotics Noncompetitive Noncompetitive  Noncompetitive Noncompetitive › bind to some other part of the enzyme › Causes active site to change shape Inhibitor video Inhibitor video


45  Identify forms of energy and energy transformations.  Recognize the Laws of Thermodynamics.  Recognize that organisms live at the expense of free energy.  Relate free-energy to metabolism.  Identify exergonic and endergonic reactions.  Identify the structure and hydrolysis of ATP.  Recognize how ATP works and is coupled to metabolism.  Recognize the ATP cycle  Relate enzymes and activation energy.  Recognize factors that affect enzymes specificity and enzyme activity..  Recognize factors that control metabolism.

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