ENZYMES

What’s an Enzyme? Enzymes are proteins. Enzymes are catalysts. Catalysts speed up chemical reactions End in –ase (Ex: sucrase, catalase) Without an enzyme! With an enzyme!

WARNING Superman had Kryptonite Enzymes have Acids (pH) Cold Temperatures Extreme Hot Temps slow down the enzyme and the chem. reaction

How do you speed up enzymes? Add more of the enzyme. Warm up the enzyme! Don’t warm it too much or something may happen

Chemical Reactions Reactants → (yield) Products Ex: Fe + O2 → rust

TYPES OF Chemical Reactions 1. Condensation (dehydration synthesis) means….. You pull out water to produce one single molecule from the original two molecules. Molecule + Molecule  One Larger Molecule + Water   2. Hydrolysis means……. To use water to break one molecule into two smaller molecules. One Larger Molecule + Water  Molecule + Molecule

Dehydration or hydrolysis?

Why do we need Enzymes? Speed up rate of chemical reaction by lowering the activation energy (energy needed to start chemical reaction) Without enzyme Activation energy without enzyme Activation Energy with enzyme Reactants With enzyme Products

How do ENZYMES work? The enzyme attaches to reactants The reactants that bind to the enzyme are known as the substrates. The part of the enzyme where the substrate attaches to the enzyme is called the active site. The shape of the active site only fits the shape of the substrate, like a lock fits a key. Only the correct substrate binds to the enzyme.

Lock-and-Key Mechanism- Enzymes can only bind to certain substrates Reactants/ Substrates Enzyme Lock-and-Key Mechanism- Enzymes can only bind to certain substrates

Once the enzyme and substrate are together, the enzyme holds the substrate so the reaction can occur. Once the reaction is over, the enzyme unlocks the product and the enzyme can start a new reaction with an identical substrate. Enzymes are not permanently changed or used up in reactions

A change in the pH of the enzyme can cause a change in the shape of the active site, therefore changing the activity of the enzyme.

Sucrase

Reactions can absorb energy OR release energy ENDERGONIC Reactions Figure 2-19 Chemical Reactions Reactions can absorb energy OR release energy Section 2-4 ENDERGONIC Reactions EXERGONIC Reactions Energy-Absorbing Reaction Energy-Releasing Reaction Products Activation energy Activation energy Reactants Reactants Products Go to Section:

Effect of Enzymes Reaction pathway without enzyme Activation energy Reactants Activation energy with enzyme Reaction pathway with enzyme Products Go to Section:

Factors that affect Enzyme Function Temperature pH Enzyme concentration Substrate concentration Salinity Activators Inhibitors catalase

Factors Affecting Enzyme Activity TEMPERATURE- the average kinetic energy a substance. Too much energy can cause an enzyme to unravel. If an enzyme unravels it is said to have DENATURED. Once an enzyme denatures it can’t be put back together again Not enough energy means that substrates don’t “bump” into the active site of the enzyme for the reaction to occur.

How would enzyme activity differ in endotherms vs ecotherms?

Factors Affecting Enzyme Activity pH- is the concentration of H+ ions in a solution H + ions interfere with bonds that hold the enzyme in it correct shape. More H+ (lower pH) means the enzyme with DENATURE.

Can you explain what is happening after every meal? pepsin trypsin pepsin reaction rate trypsin 1 2 3 4 5 6 7 8 9 10 11 12 13 14 pH

Factors affecting Enzyme Activity Substrate concentration As  substrate =  reaction rate more substrate = more frequently collide with enzyme Reaction rate levels off all enzymes have active site engaged enzyme is saturated maximum rate of reaction Why is it a good adaptation to organize the cell in organelles? Sequester enzymes with their substrates! substrate concentration reaction rate

Factors affecting enzyme function Enzyme concentration As  enzyme =  reaction rate more enzymes = more frequently collide with substrate Reaction rate levels off substrate becomes limiting factor not all enzyme molecules can find substrate Why is it a good adaptation to organize the cell in organelles? Sequester enzymes with their substrates! enzyme concentration reaction rate