AP Biology Discussion Notes Wednesday 9/14/2016

Goals for Today: Be able to describe how polymers are broken & built Be able to describe Protein structure & Function Be able to describe enzyme structure and function.

9/14 Question of the Day: IDENTIFY the four Biomolecules?

Organic Chemistry - the chemistry of _________ All organic compounds contain: ____ BIOTIC ABIOTIC is the reverse true? give an example

The Molecules of Life All living things are made up of four classes of large biological molecules: carbohydrates, lipids, proteins, and nucleic acids Macromolecules are large molecules composed of thousands of covalently connected atoms Molecular structure and function are inseparable

Macromolecules are polymers, built from monomers A polymer is a long molecule consisting of many similar building blocks These small building-block molecules are called monomers Three of the four classes of life’s organic molecules are polymers Carbohydrates Proteins Nucleic acids

The Synthesis and Breakdown of Polymers A dehydration synthesis occurs when two monomers bond together through the loss of a water molecule Polymers are disassembled to monomers by hydrolysis, a reaction that is essentially the reverse of the dehydration reaction

(a) Dehydration reaction: synthesizing a polymer Figure 5.2a (a) Dehydration reaction: synthesizing a polymer 1 2 3 Short polymer Unlinked monomer Dehydration removes a water molecule, forming a new bond. Figure 5.2 The synthesis and breakdown of polymers. 1 2 3 4 Longer polymer

(b) Hydrolysis: breaking down a polymer Figure 5.2b (b) Hydrolysis: breaking down a polymer 1 2 3 4 Hydrolysis adds a water molecule, breaking a bond. Figure 5.2 The synthesis and breakdown of polymers. 1 2 3

The Diversity of Polymers Each cell has thousands of different macromolecules Macromolecules vary among cells of an organism, between individuals, vary more within a species, and vary even more between species An immense variety of polymers can be built from a small set of monomers *Think alphabet & words HO

Characteristics of Proteins Comes from the greek proteios, meaning first or primary 50% of the dry weight of each cell is protein - instrumental in almost everything organsims do.

Proteins Proteins account for more than 50% of the dry mass of most cells Protein functions include structural support, storage, transport, cellular communications, movement, and defense against foreign substances

Amino Acids - building blocks of proteins Amine Group Carboxyl Group “ACID” End “AMINO” End

Where do we get proteins or the building blocks of proteins? Foods! What kind of foods? Comes from the greek proteios, meaning first or primary 50% of the dry weight of each cell is protein - instrumental in almost everything organsims do.

High Protein Foods

Jobs of Proteins Defense Storage Transport Cellular communication/Coordination Movement Structural support Speeding up chemical reactions Comes from the greek proteios, meaning first or primary 50% of the dry weight of each cell is protein - instrumental in almost everything organsims do.

Enzymatic proteins Enzyme Figure 5.15a Enzymatic proteins Function: Selective acceleration of chemical reactions Example: Digestive enzymes catalyze the hydrolysis of bonds in food molecules. Enzyme Figure 5.15 An overview of protein functions.

Storage proteins Ovalbumin Amino acids for embryo Figure 5.15b Storage proteins Function: Storage of amino acids Examples: Casein, the protein of milk, is the major source of amino acids for baby mammals. Plants have storage proteins in their seeds. Ovalbumin is the protein of egg white, used as an amino acid source for the developing embryo. Figure 5.15 An overview of protein functions. Ovalbumin Amino acids for embryo

Hormonal proteins Insulin secreted High blood sugar Normal blood sugar Figure 5.15c Hormonal proteins Function: Coordination of an organism’s activities Example: Insulin, a hormone secreted by the pancreas, causes other tissues to take up glucose, thus regulating blood sugar concentration Figure 5.15 An overview of protein functions. Insulin secreted High blood sugar Normal blood sugar

Contractile and motor proteins Figure 5.15d Contractile and motor proteins Function: Movement Examples: Motor proteins are responsible for the undulations of cilia and flagella. Actin and myosin proteins are responsible for the contraction of muscles. Actin Myosin Figure 5.15 An overview of protein functions. Muscle tissue 100 m

Defensive proteins Antibodies Virus Bacterium Figure 5.15e Defensive proteins Function: Protection against disease Example: Antibodies inactivate and help destroy viruses and bacteria. Antibodies Virus Bacterium Figure 5.15 An overview of protein functions.

Transport proteins Transport protein Cell membrane Figure 5.15f Transport proteins Function: Transport of substances Examples: Hemoglobin, the iron-containing protein of vertebrate blood, transports oxygen from the lungs to other parts of the body. Other proteins transport molecules across cell membranes. Transport protein Figure 5.15 An overview of protein functions. Cell membrane

Figure 5.15g Receptor proteins Function: Response of cell to chemical stimuli Example: Receptors built into the membrane of a nerve cell detect signaling molecules released by other nerve cells. Receptor protein Signaling molecules Figure 5.15 An overview of protein functions.

Structural proteins Collagen Connective tissue 60 m Function: Support Figure 5.15h Structural proteins Function: Support Examples: Keratin is the protein of hair, horns, feathers, and other skin appendages. Insects and spiders use silk fibers to make their cocoons and webs, respectively. Collagen and elastin proteins provide a fibrous framework in animal connective tissues. Collagen Figure 5.15 An overview of protein functions. Connective tissue 60 m

Enzymes -- protein catalysts Catalyst - chemical agent that speeds up chemical reactions without being consumed by the reaction. Let’s Draw one! 

Enzymes -- Metabolic Proteins Substrate - what the enzyme acts on. Active Site

Enzymes -- Metabolic Proteins Active Site - place on the enzyme where the reaction takes place. Active Site Where the substrate binds

Enzymes -- Metabolic Proteins This shows the “induced-fit model” of enzyme activity. Each enzyme is very specific and only works on one or a few chemical reactions. Active Site *Structure & function are correlated at all levels of organization Each enzyme has a unique shape which means it has a unique function!

How a CATABOLIC Enzyme Works

How an ANABOLIC Enzyme Works Produc

What Enzymes Actually Do Enzymes lower the “activation energy” of a reaction. Enzymes lower the “activation energy” of a reaction. The ΔG of the reaction does not change, but the rate of the reaction does. The ΔG of the reaction does not change, but the rate of the reaction does.

anOTHER type of enzyme….

Allosteric Enzymes “Allo-” = “Other” site Allosteric site “-ster” = Site/space Other than active site!!!

Allosteric Enzymes “Enzymes might be too helpful!? Well, not really, but when a chemical reaction doesn’t need to be done the allosteric site can function like an on/off switch to turn the enzyme “off” Other Site/space

Allosteric Enzymes Competitive inhibitor – another chemical that competes with the substrate for active site Other Site/space

Allosteric Enzymes Non-Competitive inhibitor – does NOT compete for active site. Binds to the allosteric site changing the shape of active site so substrate can’t bind. Other Site/space

Characteristics of Enzymes •Are PROTEINS •Are made of the elements: •Are built of ________ ________ •They are reusable •They have an ACTIVE SITE •Two kinds: CATABOLIC and ANABOLIC •Some are also ALLOSTERIC Could catabolic/anabolic enzymes be allosteric? YES YES YES Ask what proteins are made of (amino acid, CHON(s)) Ask if an allosteric enzyme can also be catabolic/anabolic – absolutely All enzymes are either Catabolic or Anabolic (They help build or they help break), having an allosteric site is just an additional feature of some enzymes that allows for a binding site for a non-competitive inhibitor.

Characteristics of Enzymes So much good…. •They speed up reactions—sometimes as much as a million times! •They lower the Ea of a reaction They are physically flexible, and change shape when contacted Explain what E sub a means – activation energy

What is this graph showing? Ask students to talk to a neighbor and describe what is happening in the graph.

Characteristics of Enzymes …..comes with a price. They are VERY specific to a particular substrate They are VERY picky about pH and temperature They can become “denatured” at pH and temperature extremes Discuss what it means to be “denatured” and explain the loss of shape with a loss of organization – tie to them theme of emergent properties – when we lose the organization we lose the emergent properties.

Questions on enzymes?