Unit 4: Enzymes

It is Just Chemistry…Really FAST Chemistry All living things require chemistry to exist: – Photosynthesis (making sugars) – Glycolysis (breaking sugars) – Making ATP (energy units) How long does it take for a chemical reaction to occur in a living thing? – 2.3 billion years How long does the same reaction take with an enzyme? – Less than 1 second Life CANNOT exist without enzymes 4.5 billion years

What is an Enzyme? Biological catalysts  a catalyst used in biochemistry – Name always says what is does – ATP synthase = “Make ATP” – Alcohol dehydrogenase = “Take H from alcohol” – Always end in “ase” Catalyst  a substance that speeds up a chemical reaction but is NOT affected by it – Never changed so it cannot be used up – Can reach a limit on how fast they can work Enzymes are made of proteins – Few made from RNA (ribosome)

What do Enzymes do? 10,000s of enzymes in a cell 1) Anabolic enzymes: Build complex molecules – Photosynthesis changes CO 2 into C 6 H 12 O 6 (sugar) 2) Catabolic enzymes: Break apart complex molecules – Glycolysis breaks sugar apart to make ATP (energy units) 3) Transformation enzymes: Change one substance into another substance – Yeast add H+ to compounds to make alcohol

Enzyme Structures Lock and Key Model: Substrate  substance the enzyme is designed for (Key) Enzyme  binds with substrates to combines them, break them apart, or change them (Lock) Active site  site in enzyme that is designed to match the shape of the substrate (Key Hole) The Key (substrate) fits in the Lock (enzyme) by entering the Key Hole (active site) Only if the Key (substrate) fits the Key Hole (active site) will the Lock (enzyme) work

Enzymatic Rates Enzymes can be used over and over; only a few enzymes are needed to react with lots of substrate How can we increase the reaction rate? – Add more enzymes (share the work) Why does this rate stop increasing? – Enzyme can only work so fast – It takes time to do each reaction – All enzymes have a maximum efficiency

Enzymatic Rates: Temperature What drives enzymatic rates? – Kinetic energy Kinetic energy  random movement in all atoms – Substrates and enzymes randomly move around and eventually join together How can we increase kinetic energy in atoms? – Give them more energy by increasing temperature

Optimum Temperature All enzyme reactions slow down at low temps and increase at higher temps What happens when the temperature gets too high? – Enzyme stops working (denatures) Protein bonds  chemical bonds making holding the enzyme in a specific shape – High temps break these bonds; enzyme unfolds and cant work (denature) Optimum temperature  the temp. an enzymatic rate is highest without denaturing the enzyme – Fungi and plants  40 o C – Humans  37 o C – Some bacteria  90 o C

Optimum pH pH can affect the peptide bonds of an enzyme too Optimum pH  the pH where the enzymatic rate is highest without denaturing the enzyme – Varies greatly in the body Blood pH = 7.4 Stomach pH = 2 If you fix the pH and temp. of a denatured enzyme, can it be used again? – Sometimes. Some proteins can renature. Most proteins cannot.

The Properties of Enzymes 5 Major Properties: 1)Enzymes are made of proteins 2)Enzymes catalyze one specific reaction 3)Enzymes, being catalysts, can be reused many times 4)Enzymes are influenced by temperatures (all have an optimum temperature) 5)Enzymes are influences by pH (all have an optimum pH)

Using Enzymes Enzymes from living things can be used in production: – Medicine – Food – Fuel – Materials General types: 1)Proteases  break apart proteins 2)Lipases  break apart fats 3)Amylases  break down sugars 4)Cellulous  break down cellulose (cell wall)

Making Medicine Penicillin is an antibiotic that can kill many types of bacteria – Fungi Penicillium makes it through fermentation (breaking down sugar without Oxygen) Fermentation Process  – Penicillium added to large vessel full of sugar and nutrients – Stirrer mixes up insides – Water-cooled jacket keeps vessel at 24 o C – Probes keep pH at 6.5 After 6 days of this, penicillin can be drained from mixture Cleaned and sent to hospitals

Homework Study to Exam on Units 1-4 on 10/8 Cell Projects due 10/11 Quizlets for Units 3 and 4 Homework papers on Unit 2, 3, and 4