3/2 Daily Catalyst Pg. 86 Energy

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Presentation transcript:

3/2 Daily Catalyst Pg. 86 Energy 1. The Tasmanian devil suffers from a form of facial cancer (F). The frequency of the cancer in a population is 37%. Determine the allele of the f gene. 2. Thylakoids contain a large amount of ___________________. 3. List the products of the light reaction and the dark reaction.

1. The Tasmanian devil suffers from a form of facial cancer (F) 1. The Tasmanian devil suffers from a form of facial cancer (F). The frequency of the cancer in a population is 37%. Determine the allele of the f gene. P2= 37% (.37) P= .61 p+q=1 .61+q=1 q= .39

3/2 Daily Catalyst Pg. 86 Energy 2. Thylakoids contain a large amount of ___________________. Chlorophyll (in the photosystems) 3. List the products of the light reaction and the dark reaction. O2, NADPH, and ATP Glucose

3/2 Agenda Pg. 86 Energy Daily Catalyst Class Business Reading quiz Energy notes Intro to enzymes Review quiz #21

3/2 Reading Quiz 1. An enzyme is what type of molecule? 2. Define activation energy. 3. What is the unstable condition molecules are in? 4. When bonds are broken, __________ is released.

An Introduction to Metabolism Chapter 8 An Introduction to Metabolism

Key Concepts An organism’s metabolism transforms matter and energy, subject to the laws of thermodynamics The free-energy change of a reaction tells us whether the reaction occurs spontaneously

Some organisms convert energy to light, as in bioluminescence Video Clip

Concept 8.1: An organism’s metabolism transforms matter and energy, subject to the laws of thermodynamics So let’s talk about the law of thermodynamics and metabolism.

Key Point #1: Metabolism The the sum of an organism’s chemical reactions that take place in a cell interactions between molecules

Metabolic Pathways A metabolic pathway: Begins with a specific molecule (reactant) and ends with a product Catalyzed by a specific enzyme Catalyzed? To speed up a reaction. Enzyme 1 Enzyme 2 Enzyme 3 A B C D Reaction 1 Reaction 2 Reaction 3 Starting molecule Product

Key Point #2: Catabolic pathways Break down complex molecules into simpler compounds Release energy Some pathways break down molecules

Key Point #3: Anabolic pathways Build complicated molecules from simpler ones Consume energy

So what is energy? Key Point #4: Energy Definition: Is the capacity to cause change To do work Exists in various forms Energy cannot be created nor destroyed

Types of energy Kinetic energy Potential energy Is the energy associated with motion Potential energy Is stored in the location of matter Includes chemical energy stored in molecular structure (ATP)

Energy can be converted from one form to another On the platform, a diver has more potential energy. Diving converts potential energy to kinetic energy. Climbing up converts kinetic energy of muscle movement to potential energy. In the water, a diver has less potential energy. Figure 8.2 We are considered energy transformers because the chemical was from the plants we ate that made their enregy through photosynthesis.

An example of energy conversion The chemical (potential) energy in food will be converted to the kinetic energy of the cheetah’s movement. Chemical energy What happens to the er

Exergonic Key Point #5: Exergonic/exothermic reactions Release of free energy Spontaneous Reactants Products Energy Progress of the reaction Amount of energy released (∆G <0) Free energy

Key Point #6: Endergonic/endothermic reactions Absorbs free energy from its surroundings nonspontaneous Energy Products Amount of energy released (∆G>0) Reactants Progress of the reaction Free energy

Exergonic reactions power the endergonic

A cell does three main kinds of work: Concept 8.3: ATP powers cellular work by coupling exergonic reactions to endergonic reactions A cell does three main kinds of work: Mechanical- movement Transport-transportation Chemical- synthesis of polymers

The Structure and Hydrolysis of ATP ATP (adenosine triphosphate) Cell’s energy Figure 8.8 O CH2 H OH N C HC NH2 Adenine Ribose Phosphate groups - CH

Energy coupling Pairing reactions together Is a key feature in the way cells manage their energy resources to do this work

Energy is released from ATP When the terminal phosphate bond is broken Potential energy (chemical energy) When the terminal phosphate bond is broken P Adenosine triphosphate (ATP) H2O + Energy Inorganic phosphate Adenosine diphosphate (ADP) P i

ATP hydrolysis can be coupled to other reactions Endergonic reaction: ∆G is positive, reaction is not spontaneous ∆G = +3.4 kcal/mol Glu ∆G = + 7.3 kcal/mol ATP H2O + NH3 ADP NH2 Glutamic acid Ammonia Glutamine Exergonic reaction: ∆ G is negative, reaction is spontaneous P Coupled reactions: Overall ∆G is negative; together, reactions are spontaneous ∆G = –3.9 kcal/mol Figure 8.10 The breaking down of ATP or removing a phosphate group.

How ATP Performs Work ATP drives endergonic reactions By phosphorylation, transferring a phosphate to other molecules The molecule gets phosphorylated

The three types of cellular work are powered by the hydrolysis of ATP (c) Chemical work: ATP phosphorylates key reactants P Membrane protein Motor protein P i Protein moved (a) Mechanical work: ATP phosphorylates motor proteins ATP (b) Transport work: ATP phosphorylates transport proteins Solute transported Glu NH3 NH2 + Reactants: Glutamic acid and ammonia Product (glutamine) made ADP

Quiz #21 Directions: Review your assigned question. Be ready to share out the correct answer with your classmates and tell us why the right answer is what it is. Time: 5 minutes Noise: 1 (with a partner)

Question # Reviewer 1 Daquine 2 Kordell 3 Travia 4 5 Yennifer 6 Teresa 7 Tiana 8 Bristin 9 Kiandria 10 Taylor 11 Anthony 12 Quinshelle 13 Tiffany 14 Daniel 15 John 16 Annie

Concept 8.4: Enzymes speed up metabolic reactions by lowering energy barriers A catalyst Is a chemical agent that speeds up a reaction without being consumed by the reaction

An enzyme A protein that acts like a catalyst

How do enzymes speed up a reaction?

The Activation Barrier Energy is needed to break and make bonds. This is what we call a reaction.

The activation energy, EA Is the initial amount of energy needed to start a reaction Heat

The energy profile for an exergonic reaction Free energy Progress of the reaction ∆G < O EA A B C D Reactants Transition state Products

I mentioned heat before as the energy source I mentioned heat before as the energy source. Why is heat not always the best option in a cell?

How Enzymes Lower the EA Barrier  

The effect of enzymes on reaction rate Progress of the reaction Products Course of reaction without enzyme Reactants with enzyme EA EA with is lower ∆G is unaffected by enzyme Free energy Figure 8.15

Substrate Specificity of Enzymes Enzyme binds to the substrate. enzyme-substrate complex

Can the substrate bind anywhere? The active site Is the region on the enzyme where the substrate binds Figure 8.16 Substate Active site Enzyme (a)

Induced fit of a substrate Once met, the active site changes shape so that the substrate fits even better. Figure 8.16 (b) Enzyme- substrate complex

Reusable

The catalytic cycle of an enzyme Substrates Products Enzyme Enzyme-substrate complex 1 Substrates enter active site; enzyme changes shape so its active site embraces the substrates (induced fit). 2 Substrates held in active site by weak interactions, such as hydrogen bonds and ionic bonds. 3 Active site (and R groups of its amino acids) can lower EA and speed up a reaction by • acting as a template for substrate orientation, • stressing the substrates and stabilizing the transition state, • providing a favorable microenvironment, • participating directly in the catalytic reaction. 4 Substrates are Converted into Products. 5 Products are Released. 6 Active site Is available for two new substrate Mole. Figure 8.17

Enzymes help the substrate reach the transition state by straining substrate bonds so they break easily.

The active site can lower an EA barrier by Orienting substrates correctly Straining substrate bonds Providing a favorable microenvironment Covalently bonding to the substrate

Enzyme activity Enzyme activity also relies on the substrate concentration. Increase [substrate] = increase E-S complex Eventually the solution will be saturated and more enzymes will be needed.

Effects of Local Conditions on Enzyme Activity The activity of an enzyme Is affected by general environmental factors

Effects of Temperature and pH Each enzyme Has an optimal temperature in which it can function Figure 8.18 Optimal temperature for enzyme of thermophilic Rate of reaction 20 40 80 100 Temperature (Cº) (a) Optimal temperature for two enzymes typical human enzyme (heat-tolerant) bacteria

Has an optimal pH in which it can function Figure 8.18 Rate of reaction (b) Optimal pH for two enzymes Optimal pH for pepsin (stomach enzyme) Optimal pH for trypsin (intestinal enzyme) 1 2 3 4 5 6 7 8 9

Cofactors Cofactors Coenzymes Are nonprotein enzyme helpers Are organic cofactors

Enzyme Inhibitors Competitive inhibitors Bind to the active site of an enzyme, competing with the substrate Figure 8.19 (b) Competitive inhibition A competitive inhibitor mimics the substrate, competing for the active site. Competitive inhibitor A substrate can bind normally to the active site of an enzyme. Substrate Active site Enzyme (a) Normal binding

Noncompetitive inhibitors Bind to another part of an enzyme, changing the function Figure 8.19 A noncompetitive inhibitor binds to the enzyme away from the active site, altering the conformation of the enzyme so that its active site no longer functions. Noncompetitive inhibitor (c) Noncompetitive inhibition

Concept 8.5: Regulation of enzyme activity helps control metabolism A cell’s metabolic pathways Must be tightly regulated

Allosteric Regulation of Enzymes Is the term used to describe any case in which a protein’s function at one site is affected by binding of a regulatory molecule at another site Regulatory molecules bind to specific sites (allosteric sites) and change the shape of the protein. Inhibit or stimulate

Allosteric Activation and Inhibition Many enzymes are allosterically regulated

They change shape when regulatory molecules bind to specific sites, affecting function Stabilized inactive form Allosteric activater stabilizes active from Allosteric enyzme with four subunits Active site (one of four) Regulatory site (one of four) Active form Activator Stabilized active form Allosteric activater stabilizes active form Inhibitor Inactive form Non- functional active site (a) Allosteric activators and inhibitors. In the cell, activators and inhibitors dissociate when at low concentrations. The enzyme can then oscillate again. Oscillation Figure 8.20

Cooperativity Is a form of allosteric regulation that can amplify enzyme activity Figure 8.20 Binding of one substrate molecule to active site of one subunit locks all subunits in active conformation. Substrate Inactive form Stabilized active form (b) Cooperativity: another type of allosteric activation. Note that the inactive form shown on the left oscillates back and forth with the active form when the active form is not stabilized by substrate.

Feedback Inhibition In feedback inhibition The end product of a metabolic pathway shuts down the pathway

Feedback inhibition Figure 8.21 Initial substrate (threonine) Active site available Isoleucine used up by cell Feedback inhibition Isoleucine binds to allosteric site Active site of enzyme 1 no longer binds threonine; pathway is switched off Initial substrate (threonine) Threonine in active site Enzyme 1 (threonine deaminase) Intermediate A Intermediate B Intermediate C Intermediate D Enzyme 2 Enzyme 3 Enzyme 4 Enzyme 5 End product (isoleucine) Figure 8.21

Specific Localization of Enzymes Within the Cell Within the cell, enzymes may be Grouped into complexes Incorporated into membranes

Contained inside organelles 1 µm Mitochondria, sites of cellular respiraion Figure 8.22