Cellular Energy: ATP & Enzymes. What is it? Where do organism s get it? How do they use it?

Transcription

1 Cellular Energy: ATP & Enzymes What is it? Where do organism s get it? How do they use it?

2 Where does Energy come from? Ultimately, from the sun. It is transferred between organisms in the earth s lithosphere, but is slowly lost with every transfer

3 Energy The capacity to perform work; to rearrange matter 2 forms: Potential Energy (PE): stored energy, due to position or structure Kinetic Energy (KE): Energy of motion Heat is KE associated with the movement of molecules/atoms

4 Energy is transferred not created Total amount of Energy in Universe is constant (1 st Law) Nothing created or destroyed, only transformed One result of ALL energy transfers is the production of heat (2 nd Law) Heat = disordered, unharnessed KE. This KE is LOST; cannot be used to perform work

5 Heat loss during rxns

6 Chemical Reactions Reactants (Substrates): The starting materials that are consumed during a chemical reaction. Products: The ending materials of a chemical reaction. Endergonic (energy input): Store Energy products have higher energy than reactants. Exergonic (energy output): Release Energy products have lower energy.

7 Endergonic Products have more energy than reactants Photosynthesis: Reactants = CO 2 & H 2 O + light energy Products = sugar molecules

8 Reactants have more energy than products Bonfire Reactants: Cellulose (glucose), O 2 Products: light, heat, CO 2, H 2 O Cellular respiration burns glucose to harness energy for work Exergonic

9 ANABOLIC REACTIONS Anabolic and Catabolic Reactions Glycogen Triglycerides Protein Uses energy Uses energy Uses energy Glucose + Glucose Glycerol + Fatty acids Amino acids + Amino acids CATABOLIC REACTIONS Glycogen Triglycerides Protein Glucose Glycerol Fatty acids Amino acids Yields energy Yields energy Yields energy Yields energy

10 Cellular metabolism The sum of all cellular endergonic and exergonic reactions. The ATP molecule delivers and transfers energy to parts of a cell that are conducting these reactions.

11 ATP Sugar, base, and 3 phosphates groups Covalent bonds + negatively charged phosphates groups = high PE!

12 Energy Transfer Some freed energy is lost as heat The rest is transferred via the phosphate group when it binds to another molecule (phosphorylation)

13 ATP fuels ALL cellular work

14 ATP is continually regenerated

15 Enzymes are also required to drive reactions

16 Exergonic Reaction without Enzyme

17 Enzymes lower Activation Energy Some energy (E A ) must be applied to begin a rxn Sometimes the energy barrier is prohibitively large Enzymes reduce that barrier, allowing rxn to proceed with LESS energy input

18 Enzyme are not consumed, they are recycled 1. Available enzyme w/ active site 2. Substrate binds 3. Conversion to products 4. Products released

19 Enzymes possess: Ideal temperature regimes Ideal ph ranges Cofactors (inorganic molecules & ions) and coenzymes (organic molecules)

20 Competition & Inhibition Some molecules may mimic enzymes (competitive inhibition) Either shutdown OR accelerate reaction Others change enzyme conformation (noncompetitive inhibition) Always shuts down reaction

21 Concept Check Enzymes catalyze reactions in a cell. There are hundreds of different enzymes in a cell each with a unique three-dimensional shape. Why do cells have so many different enzymes? a) Each enzyme molecule can only be used once. b) The shape of enzyme s active site generally fits a specific substrate. c) The substrate molecules react with enzymes to create new enzymes. d) Enzymes are randomly produced. With thousands of different shapes one is likely to work.

22 What molecules provide energy to bodies? 1. Adenosine triphosphate (ATP) 2. Creatine Phosphate (CP) 3. Carbohydrates (Glucose) 4. Fats

23 What molecules provide energy to organisms? Adenosine triphosphate (ATP) THE energy carrying molecule in the body Muscles store only enough ATP for 1 3 seconds of activity ATP is generated continuously Usually via carbohydrate catabolism with or without O 2

24 ATP structure

25 Substrates for producing ATP After depleting stored ATP, cells turn to other sources of stored energy to regenerate ATP: Creatine phosphate (CP) Carbohydrates (Glucose) Triglycerides

26 CP transfers P to make ATP

27 Glucose metabolism In cytoplasm In mitochondria

28 Fats as fuel Stored triglycerides (storage form of fats) are metabolized to generate ATP for: Low intensity exercise Exercise of long duration Ex: 10 hr. hike + moderate climb Abundant energy source, even in lean people Provides 2x more energy per gram as carbohydrate

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30 Distribution ATP/CP Carbohydrates Fats Protein

31 Energy use over time: Increasing intensity

32 Interpreting Data This graph illustrates how an enzyme catalyzes reactions in biological systems. From an energy standpoint is this reaction an endergonic or exergonic reaction? a) Endergonic b) Exergonic c) There is not enough information in this graph to decide the type of reaction.

33 Interpreting Data Which of the following represents the energy of activation after modification by an enzyme? A. B. C.

34 Which of the following represents the energy of activation after modification by an enzyme? A. Answer

35 Energy