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Metabolism Chemical reactions in life Convert Energy Enzymes*****

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Presentation on theme: "Metabolism Chemical reactions in life Convert Energy Enzymes*****"— Presentation transcript:

1 Metabolism Chemical reactions in life Convert Energy Enzymes*****
Store Energy Use Energy Enzymes***** Controls

2 Latin Allo Ana Cata Endo Exo Kine Lyse Thermo -

3 Terms Allosteric Anabolic Catabolic Endergonic Entropy Exergonic
Free energy Gibb’s Free Energy

4 Organisms and Energy Three types of energy organisms use:
Light – photons, waves Electrons – potential energy in chemical bonds Gradients – ‘push’ protons across a membrane and let them flow back

5 Learning Objectives: 1.B.1.a – Organisms share many conserved core processes and features and are widely distributed among organisms today. Metabolic pathways are conserved across all Domains Interpreted as evidence of evolution (descent with modification)

6 Shared Metabolic Processes and Features
All cells: Break and form chemical bonds Use ATP Many prokaryotes and all eukaryotes possess cytochrome c Almost all cells do aerobic respiration w/ETC Have similar enzymes for metabolism

7 2. A. 1 – All Living Systems Require Constant Input of Free Energy
2.A.1 – All Living Systems Require Constant Input of Free Energy. Life Requires a Highly Ordered System Order is maintained by constant input of free energy Loss of order or free energy results in death Increased disorder and entropy are offset by biological processes that maintain or increase order

8 Living systems do not violate the Second Law of Thermodynamics which states that entropy increases over time. Order is maintained by coupling reactions that increase entropy (and so have negative changes in free energy) with those that decrease entropy (and so have positive changes in free energy) Energy input must exceed free energy lost to entropy to maintain order and power cellular processes Energetically favorable exergonic reactions such as ATP-ADP, have a negative change in free energy can be used to maintain or increase order in a system by being coupled with reactions that have positive free-energy change.

9 Thermodynamics 1st law – energy cannot be created or destroyed.
Can be transformed, but does not go away 2nd law – Entropy; energy becomes less usable as it is transformed. Lost as unusable heat. Entropy increases as energy is transferred. Stuff goes from order to disorder.

10 Thermodynamics – ‘Free’ Energy
‘Free’ = ‘usable’ Organisms absorb usable energy (free energy) from light. They convert light (kinetic energy) to potential energy in chemical bonds (C-H); entropy of the environment increases. Cells maintain their organization by increasing the entropy of the universe (Earth).

11 Thermodynamics 10% law 2nd Law of Thermodynamics

12 Gibbs “Free” Energy Δ G = ΔH – TΔS G - Gibbs “free” energy
H – Enthalpy (the amount of usable energy in the system) T – Temperature in Kelvin (273 + C⁰) S - Entropy (disorder created by something being broken down) Usable energy = total energy – T x ‘lost’ energy Youtube – Gibbs free energy; Bozeman

13 Unstable (Capable of work) vs. Stable (no work)
G < 0 G = 0 A closed hydroelectric system

14 Catabolism (Hydrolysis Reaction)
Reactants Amount of energy released (G < 0) Free energy Energy Products Progress of the reaction Exergonic reaction: energy released

15 Anabolism (Dehydration Synthesis)
Products Amount of energy required (G > 0) Free energy Energy Reactants Progress of the reaction Endergonic reaction: energy required

16 Practice, Practice, Practice
An experiment determined that when a protein unfolds to its denatured (D) state from the original folded(F) state, the change in Enthalpy is ΔH = H(D) – H(F) = 56,000 joules/mol. Also the change in Entropy is ΔS = S(D) – S(F) = 178 joules/mol. At a temperature of 20⁰C, calculate the change in Free Energy ΔG, in j/mol, when the protein unfolds from its folded state. Show all your work and circle your final answer. Is this a spontaneous or non-spontaneous reaction?

17 ATP*** Phosphate bond is easily broken/formed

18 Energy Coupling To maintain organization, energy input must be greater than the free energy lost to entropy. Energy coupling – couple reactions that increase entropy (exergonic; negative changes in free energy) with those that decrease entropy (endergonic; positive changes in free energy) Ex. ADP-ATP cycle G < 0 G > 0

19 Potential vs Kinetic Energy
Potential energy - stored Chemical bonds of electrons (C-H) Identify potential and kinetic energy in the picture Short polymer Unlinked monomer Dehydration removes a water molecule, forming a new bond Longer polymer Dehydration reaction in the synthesis of a polymer

20 Chemical Reactions Two kinds of reactions:
Exergonic – net release of energy Fire, respiration Endergonic – net absorption of energy Photosynthesis Hydrolysis Dehydration synthesis

21 Metabolism – Types of Reactions
Anabolism - build up Store energy by assembling macromolecules (photosynthesis) Endergonic Catabolism - break down Release energy by breaking down molecules (digestion, respiration) Exergonic

22 Activation Energy Reactions are random collisions
Spontaneous, exergonic reaction; ΔG < 0 Most reactions require activation energy

23 Activation Energy Cells can only tolerate certain conditions
Not too hot, low electrical charge (why?) Cells need chemical reactions to be at low activation energy Catalyst – lowers activation energy Enzymes – biological catalysts

24 Rate of Reactions in Cells
Three factors affect rate of reaction in cells: Temperature – affects the speed at which molecules can collide (fast or slowly) Energy provided by the cell Enzymes - catalysts

25 Enzymes Catalysts – reduce activation energy** Globular proteins (700)
Specific conformational shape** Only catalyze one specific reaction Anabolic or catabolic Catalase catalyzes 40 million reactions per second

26 Transition state - reactants absorb energy
? Endergonic or exergonic? *** Transition state - reactants absorb energy

27 Progress of the reaction
. Course of reaction without enzyme EA without enzyme EA with enzyme is lower Reactants Free energy Course of reaction with enzyme DG is unaffected by enzyme Products Progress of the reaction

28 Enzymes Substrate – reactant enzyme acts upon
Active site - area on the enzyme where the substrate attaches Groove or pocket created by the specific folding of proteins Secondary, tertiary and/or quaternary

29 How Enzymes Work ‘Lock and Key’ = specificity
Induced fit model - enzyme changes shape when the substrate attaches to the active site making it easier for bonds to form or break

30 Factors That Affect Enzyme Activity
Correct environmental conditions pH, heat Cofactors Inhibitors

31 Correct Environmental Factors
Denature the enzyme (protein) Heat, pH, salinity Why?

32 Competitive Inhibition
Competitive inhibitors - resemble substrate, block active site Cyanide is a competitive inhibitor for catalase

33 Allosteric Control Allosteric control – the shape of an enzyme’s active site is controlled at another place on the enzyme Allosteric site has to be activated, (may be inhibited)

34 Feedback Inhibition Isoleucine – allosteric inhibitor Feedback Inhibition - end product of the pathway inhibits the pathway**** Prevents cells from wasting resources

35 Structure and Metabolism
Cells are organized Multi-enzyme complex - enzymes are positioned in a membrane Inner membrane of mitochondria, chloroplasts

36 Enzyme Cooperativity Cooperativity - one substrate molecule can activate all other subunits of an enzyme Only requires a small concentration of substrate to activate enzyme Phosphofructokinase Hemoglobin

37 Organisms use free energy to maintain organization, grow and reproduce:
Use various strategies to regulate temperature. Endothermy – use thermal energy to maintain homeostasis. Ectothermy – use external temperature to regulate and maintain temperature Elevated floral temperatures in some plants.

38 Relationship between metabolic rate per unit body mass and the size of multicellular organisms
Generally, the smaller the organisms, the higher the metabolic rate. Reproduction and rearing of offspring requires more free energy than just maintenance and growth. Different strategies in response to energy availability. Seasonal reproduction in animals and plants Life-history strategy (annuals, biennials, etc.) Diapause – eggs and/or development stop due to adverse conditions (insects, plants)


40 Energy Changes Affect Populations
Changes in free energy availability can result in changes in population size and or disruptions to an ecosystem Change in the producer level can affect the size and number of other trophic levels Change in energy resource (sunlight) can affect all trophic levels

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