To release chemical energy to perform work…cells must break and make chemical bonds = chemical reaction

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All cells have them

They lower the activation energy of chemical reactions..they are catalysts

They are reusable

They work properly in certain conditions ◦ At certain temperatures, certain pH range, certain salinity, etc.

The name of the enzyme usually ends in ase ◦ Catalase, sucrase, lactase, etc.

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Free Energy

Progress of the reaction

Reactants

Products

Free energy of activation

Without Enzyme

With Enzyme

Specific enzymes catalyze specific reactions http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_enzymes_work.html

http://highered.mcgraw-hill.com/sites/0072507470/student_view0/chapter25/animation__enzyme_action_and_the_hydrolysis_of_sucrose.html

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The structure of an enzyme has a small area called an Active Site

The active site brings the substrate and enzyme closer together

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Reactant molecule of a reaction. What fits into the active site.

This is how it goes… ◦ The substrate fits into the active site of an enzyme, activation

energy is lowered, chemical reaction from substrate to product occurs, the product breaks away from the enzyme.

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Enzyme changes shape when it binds its substrate

Once the newly formed molecules (or products) break away from the enzyme, the enzyme is unchanged.

Many reactions are reversible (two molecules combine to form one, one molecule broken to form two)

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Enzyme reactions can be faster at higher temps but above certain temps, out of a certain pH range, or without certain ions…enzymes can unfold or Denature.

Denaturation renders the enzyme useless.

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Inhibitors

Allosteric factors

pH

Temperature

Salinity (salt concentration)

Enzyme concentration

Substrate concentration

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Competitive Inhibitors- have similar structure to the enzymes substrate, so they compete with the substrate for the active site of an enzyme.

Noncompetitive Inhibitors- do not attach to the active site and block the enzyme-substrate complex from forming. They react with portions of the active site, which results in the changing of its shape so that it can no longer bind with the substrate.

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Some enzymes have special areas other than active site…regulatory site. Any molecule that attaches to the regulatory site is called an allosteric factor.

Join with regulatory site and change the shape of the entire enzyme preventing it from binding with the substrate.

Not all allosteric factors are bad, some actually bring the enzyme and substrate together.

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Coenzyme ◦ Non protein

◦ Organic

◦ Assists enzyme with chemical reactions

◦ Vitamins

Cofactors ◦ Non protein

◦ Organic or Inorganic

◦ Assists enzyme with catalyzing chemical reactions

◦ Zinc, magnesium

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Enzymes function best in a particular pH.

If too many ions (H+ or OH-) are present, the enzyme may denature (unfold).

To a certain extent, high temps increases the rate of an enzymes activity. Too high temperatures.. the enzyme can denature.

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For a given enzyme concentration, the rate of reaction increases with increasing substrate concentration up to a point, above which any further increase in substrate concentration produces no significant change in reaction rate. This is because the active sites of the enzyme molecules at any given moment are virtually saturated with substrate.

To avoid wasting energy, ATP binds an enzyme in catabolism that shuts the enzyme off, effectively shifting the cell to an anabolic state.

This process is called feedback inhibition.

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The sum total of all chemical reactions that take place in a cell or organism.

2 Types: ◦ Synthesis (Anabolic reactions): forming larger, more complex

molecules from smaller less complex ones (ex: starch from glucose, protein from amino acids)

◦ Decomposition (Catabolic reactions): larger molecules break down into smaller molecules (ex: glycogen to glucose)

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Metabolic reactions, which consume energy to build complicated molecules from

simpler compounds are Endergonic

Ex: Photosynthesis 6CO2 + 6H2O C6H12O6 + 6O2

SUN light

energy

(glucose)

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Metabolic reactions that release energy by breaking down complex molecules in simpler ones are Exergonic

Ex: Cellular Respiration

C6H12O6 + 6O2 6CO2 + 6H2O +

ATP (glucose)

energy

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Oxygen is a common electron acceptor in living systems, so loss of electrons is termed oxidation. An oxidized substance loses energy.

The gain of electrons is called reduction and a reduced substance gains energy.

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Oxidation-Reduction (Redox) Reactions Oxidation - Chemical reaction that results in removal of one or more electrons from an atom, ion, or compound; oxidation of one substance occurs simultaneously with reduction of another. Reduction - Chemical reaction that results in addition of one or more electrons to an atom, ion, or compound. Reduction of one substance occurs simultaneously with oxidation of another.

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Components:

1. adenine: nitrogenous base

2. ribose: five carbon sugar

3.phosphate group: chain of 3

ribose

adenine

P P P

phosphate group

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Three phosphate groups- energy is stored in the LAST bond between the last two phosphate groups

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Organisms use enzymes to break down energy-rich glucose to release its potential energy

This energy is trapped and stored in the form of adenosine triphosphate(ATP)

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It is estimated that each cell will generate and consume approximately 10,000,000 molecules of ATP per second

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ATP + H2O ADP + P (exergonic)

Hydrolysis

(add water)

P P P

Adenosine triphosphate (ATP)

P P P +

Adenosine diphosphate (ADP)

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Energy Used by

Cells

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ADP + P ATP + H2O (endergonic)

P P P

Adenosine triphosphate (ATP)

P P P +

Adenosine diphosphate (ADP)

Dehydration (Remove H2O

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Energy is restored in Chemical Bonds

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1. Physical or Mechanical Digestion Chew Tear Grind Mash Mix

2. Chemical Digestion Catabolic reactions – breakdown complex

food molecules into simpler ones that can be used by cells

Enzymatic hydrolysis

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◦Ingestion

◦Movement

◦Digestion

◦Absorption

◦Further digestion

Extracellular: Happens outside of the cells

Intracellular: Happens inside the cells

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Intracellular- hydrolysis of food inside vacuoles cell engulfs food- phagocytosis and fuse with vacuoles that have lysosomes. Sponges are an example.

Extracellular- breakdown of food in compartments that are continuous with outside of body.

Muscular pharynx that sucks food in

Passes through esophagus Stored and moistened in crop Mechanical digestion happens

in muscular gizzard which adds sand

Further digestion and absorption happens in the intestine with lots of surface area!

Several digestive chambers grouped into 3 regions ◦ Foregut ◦ Midgut ◦ Hindgut

◦ Food is moistened and stored

in crop but most digestion happens in midgut. Gastric cecae are the pouches that function in absorption and digestion.

Three separate chambers: ◦ Crop

◦ Stomach

◦ Gizzard

Herbivores

Deal with high fiber diet

◦ Hind Gut Fermentation ( also horses, guinea pigs and chinchillas)

◦ They are crepuscular (eat at dawn and dusk)

◦ Have a large blind sac called cecum located where the SI and LI meet- same as our appendix- but this contains healthy bacteria, yeast etc.

◦ Eats pellets ( double digestion!) C oprophagy

Mechanical digestion occurs here

Saliva is produced from salivary glands ◦ Contains digestive enzyme: salivary amylase

◦ Chemical digestion begins here

◦ Salivary amylase breaks down complex carbohydrates (polysaccharides) into smaller and smaller carbohydrates (disaccharides).

When food is chewed, balled up in mouth it is called a bolus.

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Peristalsis: wave like

Contractions that move

Food through the entire

digestive

system

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Flap like structure that prevents the bolus of food or drink from

entering the trachea (airway).

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Acidic environment

Muscles surround the stomach to

mix and churn food.

Mixture becomes liquid here..it’s called chyme

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When food enters here, a hormone called gastrin is released.

Gastrin causes the cells here to release gastric juices – contains enzymes, HCl acid, and mucus

The enzyme in gastric juice is Pepsin. Pepsin comes from Pepsinogen (HCl converts it)

Pepsin breaks down Protein (polypeptides) into smaller polypeptides.

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•Approximately 6 feet long •Small intestine is lined with Villi •Villi are fingerlike projections that increase the surface area of the SI •Each villi contains Capillaries (tiny blood vessels) that will absorb small molecules into the bloodstream. •All things: simple sugars, amino acids, fatty acids, glycerol, minerals, and vitamins get into the bloodstream this way.

Small Intestine

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Chemical digestion is completed here.

Pancreatic juices & liver juices are released into the small intestine.

Pancreatic juice contains enzymes

◦Trypsin, lipase, amylase, nuclease

◦Also contains bicarbonate

Liver juice is Bile

◦Bile emulsifies (breaks down) fat

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Flag like structure

Large gland but also has digestive function.

Pancreatic juice leaves pancreas through the pancreatic duct into the small intestine

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Secretes Pancreatic Juice

Into the small intestine

Pancreatic Juice contains

enzymes ◦ Trypsin – breaks down proteins

◦ Lipase – breaks down lipids

◦ Amylase – breaks down carbs

◦ Nuclease – breaks down nucleic acids

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The enzyme Trypsin (type of protease) breaks down small polypeptides into amino acids.

Bile helps to break down lipids so they can be broken down further. Bile comes from liver.

Lipase is the enzyme that completely breaks down lipids

Amylase is the enzyme that breaks small carbohydrates into simple sugars (glucose)

Nuclease is the enzyme that breaks nucleic acids into nucleotides to be recycled in the body.

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Liver makes Bile

Bile is stored in the Gallbladder

Bile is released into the small intestine when a fatty meal reaches the small intestine

Bile emulsifies or helps break up lipids so they can be broken down further

by the lipase enzyme.

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Enzyme Action Where in Digestive System?

Salivary Amylase

Polysaccharides into dissacharides

Mouth

Pepsin Polypeptides into smaller polypeptides

Stomach

Trypsin Small polypeptides into amino acids

Secreted from pancreas Works in Small Intestine

Lipase Lipids into glycerols and fatty acids **need bile from liver first to help break down lipids**

Secreted from pancreas Works in Small Intestine

Amylase Small polysaccharides & disaccharides into simple sugars

Secreted from pancreas Works in Small Intestine

Nuclease Nucleic acids into Nucleotides

Secreted from pancreas Works in Small Intestine 60

Beginning is the Cecum – ileocecal valve allows undigested material from SI to enter the LI.

Ascending, Transverse,

and Descending colon

Sigmoid Colon

Rectum

Anus

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About 4.5 feet long

All undigested material from the SI comes here.

Main function is Water Reabsorption

Bacteria live here (normal gut flora)

Bacteria finish breaking things down to produce vitamins, minerals, gases.

Feces is formed from the leftovers.

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