Enzymes: Proteins with Purpose!! What is an eNzyme? VIP! Very Important ProteiN. Enzymes help speed chemical reactions* in the body. *Catalyst is the term for anything that speeds reactions. Why should you care? Without enzymes all the chemical reactions we need for life would occur too slowly or not at all. What are enzymes like? They are specifically shaped to bind to specific reactants (substrates). Their shape determines their function. How do enzymes work? • Lock and Key

Substrates fit active site. Like a key into a lock. • Induced fit

Active site forms around substrate when it contacts enzyme.

*Enzymes are named with –ase ending.

Protease enzymes act on protein, lipase enzymes act on lipids and amylase enzymes work on amylose.

How do enzymes help reactions to happen?

Enzymes help substrates react by lowering the energy it takes to start a reaction. (Activation energy). Enzymes do NOT add energy to a reaction. Why is shape important to an enzyme? The shape of active site has to fit the substrate or reaction won’t happen. Shape determines the specificity of an enzyme. Enzymes work on only one substrate type.

What environmental conditions can alter the shape of an enzyme?

pH and Temperature can change how protein folds up…changes shape.

Activation energy

Activation Energy + enzyme

Denaturation: Enzyme begins to change shape as conditions move away from optimal. It starts to “melt”! What else can affect how fast an enzyme can do its job? Maximum rate • Enzyme concentration

Adding more enzyme will speed Up the rate until the lack Of substrate limits it. • Substrate Concentration

Adding more substrate will speed up The rate until enzymes can’t go any faster. Why are enzymes present in such small quantities in a cell?

Optimal Conditions Each enzyme has an optimal (best) pH and temperature in which they have highest activity.

• Recycling: Enzymes are reused after product is formed. They are unchanged by the reaction.

How does the process of nutrition use enzymes? • Hydrolysis reactions (digestion)

Large molecules broken down into smaller pieces.

• Dehydration synthesis reactions (synthesis for short) Small molecules are joined to form larger

molecules Summary:

1. An enzyme is a 3-D_ Protein molecule. 2. The ___Shape__ of an enzyme determines its function. 3. An enzyme binds a substrate at its __active site __in

order to produce the __Product._ 4. An enzyme works best at certain pH and __ Temperature conditions. (Optimal) 5. An enzyme is considered a catalyst because it _speeds_

the rate of a reaction without being __Changed_ itself. 6. The life process of nutrition involves _Hydrolysis _because

organic food molecules are being _broken down __ to fit into the tiny cells of the body.

Reused

During the trip through the digestive system large organic food molecules are broken down into their building blocks (monomers) by enzymes. This process is called hydrolysis or digestion.

1. Visual recognition of hydrolysis(digestion). 1 large molecule breaks apart into smaller ones. 2. Molecular level look at hydrolysis: Water is added to

break apart food. Hydro = H2O lysis = break up OH H + + H2O Hydrolysis of a disaccharide produces 2 monosaccharides + H2O

Hydrolysis of a dipeptide produces 2 amino acids.

O

H H

OH

OH

H H

NCC OH NCC H NCC NCC

A Closer Look at Enzyme Aided Reactions

B. Synthesis Reactions After Food monomers are absorbed by cells they are used either for energy or as building blocks for more complex new molecules. Using the food monomers for energy is called _________________. Using the simple food monomers to build more complex new molecules is called ______________.

1. Visual recognition of synthesis. +H2O Small molecules join to produce 1 larger molecule, releasing water.

Hydrolysis of carbohydrates occurs in the mouth and the small intestine

Hydrolysis of proteins occurs in the stomach and small intestine.

Hydrolysis of Fats occurs only in the small intestine.

Where does your food get hydrolyzed (digested)?

2. Molecular level look at synthesis. Water is lost so it is called Dehydration synthesis

Notice that before and after synthesis, oxygen has two bonds, hydrogen has one and carbon has four. How many should nitrogen have below? ___ The bond between 2 amino acids is called a peptide bond. Amino acids continue to be added to dipeptide forming a polypeptide which folds into a specific shape.

This process continues adding glucose molecules to form a polysaccharide called glycogen. Where in the body is this glycogen building reaction happening? Liver & muscles.

Where in the cell does this reaction take place? Ribosome

NCC

Human Digestive System (favorites video clip)

Two Types of Digestion: Mechanical- Food broken apart to smaller pieces Occurs in: 1. Mouth with teeth 2. Stomach with churning 3. Small intestine Bile turns fat to droplets Chemical- Enzymes chemically break down food Occurs in: 1. Mouth Carbohydrates-disaccharides 2. Stomach Proteins - dipeptides 3. Small intestine-Carbs, Proteins and Fats all

digested to their monomers.

Epiglottis (flap)

Salivary glands

Mouth to Toilet Notes Digestive System: Breaks down food into pieces that will pass through the cell membranes of your body cells. Organs food Passes through

Salivary Glands Secrete enzymes and water into mouth

Mouth-ingests food

Teeth Mechanically grind food into smaller pieces of food.

Pharynx Back of mouth where esophagus and trachea openings are.

Epiglottis-flap which closes over trachea. Prevents choking.

Esophagus-long tube. Food moves down via peristalsis. Muscles contract above, relax below the bolus.

Carbohydrates Disaccharides Cellulose

Lipids (Fats)

Protein

Salivary Amylase Enzymes Hydrolyze amylose(starch) into disaccharides

Cardiac Sphincter

Accessory Glands/Organ

Peristalsis

Stomach Water-Added to food making chyme Hydrochloric Acid- Unfolds proteins Protease Enzymes- Hydrolyze proteins forming dipeptides and amino acids

Disaccharides Cellulose

Lipids (Fats)

Protein Dipeptides

Pyloric Sphincter

Small Intestine Chemical Digestion- Intestinal enzymes Complete digestion of all foods to their monomers. Villi-Absorption Fingerlike projections 1-Increase the surface area 2-Have thin membranes allowing rapid diffusion 3-Are close to blood vessels. Lacteals collect fat. All the rest goes into blood.

Liver-Mechanical Digestion Bile- made by Liver-soapy-NOT an ENZYME!! Gall Bladder-Stores the

bile until its needed. Emulsification- Fat is

broken up into little fat droplets by Bile.

Pancreas-Chemical digestion & neutralization Digestive Enzymes*-added to small intestine, finish digesting all foods. *Protease, amylase & lipase Buffers- Neutralize stomach acid.

Disaccharide Monosaccharide Cellulose Dipeptides Amino Acids

Hydrolysis of a polypeptide

Fat Fat Droplets

Fat 3 Fatty Acids and Glycerol

Elimination of Feces Disorders: Ulcers-hole in stomach lining. Heartburn-acid moving up into esophagus

Cellulose= Undigestable plant fiber

Water removed

Large Intestine- Removes water from undigested food forming solid feces. Rectum- Stores feces until it is eliminated

Anal Sphincter

Alimentary Canal Organs (Digestive tract) Mouth pharynx epiglottis Esophagus Stomach Small Intestine Large Intestine Rectum

Accessory Organs Salivary Glands Liver Pancreas

Bacteria Feed on undigested food. Provide vitamin K which is absorbed into the blood.

Digestive System Jobs Ingestion- Taking in food Digestion- Breaking food down Absorption-VILLI Moving food into Blood by diffusion Elimination- Undigested food exits body

1. Write a C in the box for each organ in which carbohydrates are digested. 2. Write a P in the box for each organ in which proteins are digested. 3. Write an F in the box for each organ in which fats are digested. 4. Write H2O in the box for the organ which removes excess water. 5. Write an “A” in the box of the accessory organs and glands.

Where does most digestion occur? _________________________________

Pam savors the tasty flavors of olive oil, cheese, crispy crust and chicken as she chews her

white pizza from Guidas. Her teeth mechanically digest the pizza into successively smaller pieces while her salivary amylase enzymes work to chemically digest the amylose starch in the crust into mono and disaccharides. She swallows and the pizza travels down the esophagus by peristalsis, through the cardiac sphincter and into the stomach. The churning muscles of the stomach continue the mechanical digestion of all the food while protease enzymes chemically digest the chicken and cheese protein into dipeptides and amino acids. The, now liquid, pizza is squirted through the pyloric sphincter into the small intestine, where it is mixed with bile which was produced by the liver and stored in a part of the liver called the gall bladder. The bile mechanically emulsifies the large fat molecules into smaller droplets. The pancreas and walls of the small intestine secrete a variety of amylases, proteases and lipases to complete the chemical digestion of the carbohydrates, fats and proteins. Once these food groups are reduced to their monomers; monosaccharides, fatty acids, glycerols and amino acids, they can pass through the lining of the small intestine and into the blood stream by diffusion. Specialized cells in the lining of the small intestine called villi, increase the surface area of the small intestine and help speed diffusion of the nutrients into the blood stream. The absorbed nutrients are whisked away to the liver for toxin screening and then sent to the heart to be pumped to all the cells in the body. The undigested food travels via peristalsis into the large intestine where water is reabsorbed leaving solid feces. The feces exit the body through the final anal sphincter. This process is called elimination and is not considered to be a part of the life process of excretion because the food never entered the body cells and therefore cannot be considered metabolic waste.

When you understand this, you are ready for the next exam!

Nutrition Unit