________ 2H 2 O > 2H 2 O + O 2 2H + + 2O > H 2 O 2 Free radical- A highly reactive molecule that has _____________ electrons Can disrupt __________ of molecules Hydrogen peroxide _________ ROS= Reactive oxygen intermediate Ground Rules of Metabolism Chapter 5

Roundworm Experiments Add superoxide dismutase + catalase to diet or worms- Result- increased life span Diet also allowed worms genetically-engineered for susceptibility to free radicals to live normal life span

What is Energy? Capacity to do _____ Forms of energy –_________ energy –Kinetic energy –_________ energy

The first law of ____________ -energy cannot be _________ or destroyed. –It can be transferred and transformed –Plants transform light to _______ energy; they do not _________energy. The second law of _______________-every energy transformation must make the universe more ____________. __________ - a measure of _______, or randomness. Increased randomness = increased __________ Living cells convert organized energy to heat. Organisms are ________ of low entropy in an increasingly random universe.

__________ Energy _____ required Product has _____ energy than starting substances product with more energy (plus by-products 60 2 and 6H 2 O) ENERGY IN 612 ___________ Energy is released Products have _____ energy than starting substance ENERGY OUT energy-rich starting substance products with less energy 66 Types of reactions

The Role of ATP Cells “earn” ATP in ________reactions Cells “spend” ATP in _________ reactions ATP is produced by _________________ reactions carried out by enzymes in cellular _______________

Chemical Equilibrium HIGHLY SPONTANEOUS EQUILIBRIUM HIGHLY SPONTANEOUS RELATIVE CONCENTRATION OF PRODUCT RELATIVE CONCENTRATION OF REACTANT Which Way Will a Reaction Run?

Energy Relationships ATP BIOSYNTHETIC PATHWAYS (ANABOLIC) ENERGY INPUT DEGRADATIVE PATHWAYS (CATABOLIC) energy-poor products (such as carbon dioxide, water) large energy-rich molecules (fats, complex carbohydrates, proteins, nucleic acids) simple organic compounds (simple sugars, amino acids, fatty acids, nucleotides) ADP + P i _____________________ Energy Input

Types of Reaction Sequences BRANCHING PATHWAY: LINEAR PATHWAY:CYCLIC PATHWAY: ABCDE F KJI G NML H

A ________changes the rate of a reaction without being ________ by the reaction. –An ________ is a catalytic protein. Reactions do not _____________ enzyme molecules Enzymes regulate the movement of molecules through ________________. Most metabolic enzymes can catalyze a reaction in both the ________and __________ direction Enzymes speed up metabolic reactions by lowering ______________

Activation Energy For a reaction to occur, an energy barrier must be surmounted Enzymes make the energy barrier ____________ activation energy without enzyme activation energy with enzyme energy released by the reaction products starting substance

Induced-Fit Model two substrate molecules active sight substrates contacting active site of enzyme TRANSITION STATE (tightest binding but least stable) end product enzyme unchanged by the reaction Substrate molecules are brought together Substrates are oriented in ways that favor reaction Active sites may promote acid-base reactions Active sites may shut out water

Factors Influencing Enzyme Activity 1.___________ 2._________ 3.____________________ 4. ___________________ 5. __________________

1. Effect of Temperature Small increase in temperature increases ______ _____ High temperatures – disrupt ______ –destroy the shape of _________ 2. Effect of pH Usually ______ optimum range

4. Enzyme Helpers Called “______________” –Coenzymes ___________________________ Accept electrons and hydrogen ions; transfer them within cell Derived from ______________ –Metal ions Ferrous iron in cytochromes

Allosteric _______ allosteric inhibitor allosteric binding site vacant; active site can bind substrate active site altered, can’t bind substrate Allosteric ________ 5. Allosteric regulators

Cell Membranes Show ________________________ O 2, CO 2, and other small nonpolar molecules;and H 2 O C 6 H 12 O 6, and other large, polar (water-soluble) molecules; ions such as H +, Na +, CI -, Ca ++ ; plus H 2 O hydrogen-bonded to them X Cell membranes

Five types of molecular transport across a membrane 1.________- Passive movement of molecules down a concentration gradient 2.______________- The passive movement of molecules down its concentration gradient via a ___________________ 3.______________- The active transport of molecules against a concentration gradient 4.____________- engulf and devour 5.____________- engulf and discharge

Fig. 5.25a, p. 91 P energy input low high Concentration gradient DIFFUSION ACROSS LIPID BILAYER PASSIVE TRANSPORT facilitated diffusion ACTIVE TRANSPORT lipid bilayer Specific solutes pumped across, through transport proteins against gradient; requires energy boost Water-soluble molecules and ions diffuse through interior of transport proteins. No energy boost required. Lipid-soluble molecules and water molecules diffuse across

2. Faciliated Diffustion (Passive Transport) __________ proteins required _______ concentration gradient Solutes move both ways No ________ input 3. Active Transport Transport proteins required Requires energy (____) ________ concentration gradient unidirectional

Bulk Transport 4. ___________ 5. ___________

Osmosis Diffusion of water molecules across a ________________ membrane Side with the most solute molecules has the lowest water concentration _________ - having more solutes ________ - having same amount __________ - having fewer solutes

________ solution ___________ solution Plant cell in: “plump” cells “flaccid” cells