BIOCHEMISTRY PRELIMINARY INTRODUCTION TO BIOCHEMISTRY Biochemistry - Chemistry of life - Study of life processes, structures, mechanisms, reactions at the molecular level - Chemistry, Biology, & Genetics Vitalism Theory - Idea that substances and processes associated with living organisms did not behave according to the known laws of physics and chemistry - Organic vs. Inorganic Evidences for Vitalism - Only living things have a high degree of complexity - Only living things extract, transform and utilize energy from their environment - Only living things are capable of self assembly and self replication Origins of Biochemistry: a challenge to vitalism and… Famous Dead Scientists 1. Friedrich Wohler (19th century) - Synthesized urea from inorganic substance—ammonium cyanate. 2. Eduard Buchner and Hans Buchner (1897) - found that glucose + dead yeast cells are still able to undergo fermentation, demonstrating that reactions can occur in vitro. 3. Emil Fischer (1894) - Each enzyme can only catalyze specific complex molecules called substrates. - proposed the lock and key theory, which states that enzymes have a specific shape that directly correlates to the shape of the substrate. 4. James Batcheller Sumner - studied the enzyme urease, which breaks down urea into ammonia and carbon dioxide - An enzyme is protein 5. Gregor Mendel (mid-1900) - Started describing genes. - Father of Genetics 6. Oswald Avery, Colin McLeod, Maclyn McCarty (1944) - identified DNA as information molecules 7. James Watson (still alive) and Francis Crick (1953) - proposed the structure of the DNA - In 1958 Crick proposed the central dogma of biology - DNA -> RNA (mRNA) -> Protein Replication -> Transcription -> Translation Areas of Biochemistry - Biomolecules. Structure and function of biological macromolecules - Metabolism - Catabolism: Destructive phase - Complex substance to subunits (simpler substance) - Anabolism: Constructive phase - From simpler substance to complex substance - Molecular Genetics - How life is replicated - Regulation of protein synthesis Objective of Biochemistry - determine how the collections of inanimate molecules that constitute living organisms interact with each other to maintain and perpetuate life Scope of Biochemistry - LIFE. chemistry of living matter in its different phases of activity, from the smallest microorganisms such as viruses to the most complex ones as human - Virus: has either DNA or RNA - Cell: has both DNA and RNA Chemical Reactions Occurring in Living Organism Oxidation - gains oxygen or loses hydrogen/electron ⇀ aerobic oxidation – takes place in the presence of oxygen ⇀ anaerobic oxidation – occurs in the absence of oxygen Reduction - gains hydrogen/electron or loses oxygen Condensation - Dehydration synthesis(union) - Removal of water Central Dogma - Flow of information IGANO, CIENNA CHARRISE 1 TRANSES: BIOCHEMISTRY Hydrolysis - Lysis = splitting - Large molecules broken down Cell Size - Most cells are relatively small because as size increases, volume increases much more rapidly. - Cell size and shape are related cell functions. A Scale of Visibility Transfer Reactions a. Phosphorylation - addition of phosphate group b. Transamination - transfer of amino group c. Acetylation - addition of acyl group d. Transmethylation - transfer of methyl group Decarboxylation - Removal of carboxyl group Uses of Biochemistry The results of biochemical research are used extensively in the world outside the laboratory - Agriculture - Pharmacology and Toxicology - Medical Sciences - Clinical Chemistry - Nutrition THE CELL AND ITS CHEMISTRY Cells - Basic functional and structural unit of life All living things are composed of cells, cell parts, or cell products - Organisms may be: - Unicellular: prokaryotes - Multicellular: human Cell theory - All organisms are composed of one or more cells. - Cells are the smallest living units of all living organisms. - Cells arise only by division of a previously existing cell. - Cells vary in size and shapes. Cell Requirements - Genetic material - Single circular molecule of DNA in prokaryotes - Double helix located in nucleus in eukaryotes - Cytoplasm - Fills cell interior (sugars, amino acids, proteins, organelles) - Plasma Membrane - Encloses the cell Classification of Cells There are two major types of cells - Prokaryotic - lacks a nucleus and does not have an extensive system of internal membranes - all bacteria and archaea have this cell type - Eukaryotic - has a nucleus and has internal membrane-bounded compartments - all organisms other than bacteria or archaea have this cell type Prokaryotic Cells Prokaryotes are the simplest cellular organisms. They have a plasma membrane surrounding a cytoplasm without interior compartments (some bacteria have additional outer layers to the plasma membrane) Cell wall - comprised of carbohydrates to confer rigid structure Capsule may surround the cell wall Cytoplasm is uniform with little or no internal support framework Ribosomes (sites for protein synthesis) are scattered throughout the cytoplasm Nucleoid region (an area of the cell where DNA is localized) not membrane-bounded, so not a true nucleus Flagellum (plural, flagellae) is a threadlike structure made of protein fibers that extends from the cell surface may be one or many aids in locomotion and feeding Pilus (plural, pili) is a short flagellum aids in attaching to substrates and in exchanging genetic information between cells IGANO, CIENNA CHARRISE 2 TRANSES: BIOCHEMISTRY The Plasma Membrane The plasma membrane is conceptualized by the fluid mosaic model–a sheet of lipids with embedded proteins. The lipid layer forms the foundation of the membrane. The fat molecules comprising the lipid layers are called phospholipids. A phospholipid has a polar head and two non- polar tails The polar region contains a phosphate chemical group and is water-soluble The non-polar region is comprised of fatty acids and is water-insoluble Eukaryotic Cells Eukaryotic cells are larger and more complex than prokaryotic cells. They have a plasma membrane encasing the cytoplasm, internal membranes form compartments called organelles. The cytoplasm is semi-fluid and contains a network of protein fibers that form a scaffold called a cytoskeleton. Nucleus - a membrane-bounded compartment for DNA that gives eukaryotes (literally, “true-nut”) their name Endomembrane system - gives rise to the internal membranes found in the cell. Each compartment can provide specific conditions favoring a particular process. The cells of plants, fungi, and many protists have a cell wall beyond the plasma membrane All plants and many protists contain organelles called chloroplasts Plants contain a central vacuole only animal cells contain centrioles - A lipid bilayer forms spontaneously whenever a collection of phospholipids is placed in water - The interior of the lipid bilayer is completely nonpolar no water-soluble molecules can freely cross through it cholesterol is also found in the interior it affects the fluid nature of the membrane its accumulation in the walls of blood vessels can cause plaques plaques lead to cardiovascular disease Another major component of the membrane is a collection of membrane proteins some proteins form channels that span the membrane these are called transmembrane proteins other proteins are integrated into the structure of the membrane for example, cell surface proteins are attached to the outer surface of the membrane and act as markers Proteins are embedded within the lipid bilayer - - IGANO, CIENNA CHARRISE 3 TRANSES: BIOCHEMISTRY The Nucleus: The Cell’s Control Center The nucleus is the command and control center of the cell it also stores hereditary information The nuclear surface is bounded by a doublemembrane called the nuclear envelope groups of proteins form openings called nuclear pores that permit proteins and RNA to pass in and out of the nucleus The DNA of eukaryotes is packaged into segments and associated with protein this complex is called a chromosome the proteins enable the DNA to be wound tightly and condense during cell division when the cell is not dividing, the chromosomes exist as threadlike strands called chromatin protein synthesis occurs when the DNA is in the chromatin form The cell builds proteins on structures called ribosomes ribosomes consist of ribosomal RNA (rRNA) and several different kinds of proteins Ribosomes are assembled in a region of the nucleus called the nucleolus The Endomembrane System The endoplasmic reticulum (ER) is an extensive system of internal membranes some of the membranes form channels and interconnections other portions become isolated spaces enclosed by membranes these spaces are known as vesicles The portion of the ER dedicated to protein synthesis is called the rough ER the surface of this region looks pebbly the rough spots are due to embedded ribosomes The portion of the ER that aids in the manufacture of carbohydrates and lipids is called the smooth ER the surface of this region looks smooth because embedded ribosomes are scarce - After synthesis in the ER, the newly-made molecules are passed to the Golgi bodies Golgi bodies are flattened stacks of membranes scattered through the cytoplasm their numbers vary depending on the cell their function is to collect, package, and distribute molecules manufactured in the cell the Golgi bodies of a cell are collectively called the Golgi complex - The ER and Golgi complex function together as a transport system in the cell IGANO, CIENNA CHARRISE 4 TRANSES: BIOCHEMISTRY - The Golgi complex also gives rise to lysosomes these membrane-bound structures contain enzymes that the cell uses to break down macromolecules worn-out cell parts are broken down and their components recycled to form new parts particles that the cell has ingested are also digested Organelles That Harvest Energy Eukaryotic cells contain energy harvesting organelles that contain their own DNA these organelles appear to have been derived from ancient bacteria that were taken up by eukaryotic cells these organelles include mitochondria and chloroplasts Mitochondria are cellular powerhouses Sites for chemical reactions called oxidative metabolism The organelle is surrounded by two membranes - Chloroplasts are the sites of photosynthesis The organelle is also surrounded by two membranes - Both mitochondria and chloroplasts possess their own molecule of circular DNA They cannot be grown free of the cell they are totally dependent on the cells within which they occur The theory of endosymbiosis states that some organelles evolved from a symbiosis in which one cell of a prokaryotic species was engulfed by and lived inside of a cell of another species of prokaryote that was a precursor to eukaryotes the engulfed species provided their hosts with advantages because of special metabolic activities the modern organelles of mitochondria and chloroplasts are believed to be found in the eukaryotic descendants of these endosymbiotic prokaryotes - - In addition to the double membranes and circular DNA found in mitochondria and chloroplasts, there is a lot of other evidence supporting endosymbiotic theory mitochondria are about the same size as modern bacteria the cristae in mitochondria resemble folded membranes in modern bacteria mitochondrial ribosomes are similar to modern bacterial ribosomes in size and structure mitochondria divide by fission, just like modern bacteria The Cytoskeleton and Related Structures The cytoskeleton is comprised of an internal framework of protein fibers that anchors organelles to fixed locations supports the shape of the cell helps organize ribosomes and enzymes needed for synthesis activities The cytoskeleton is dynamic and its components are continually being rearranged Three different types of protein fibers comprise the cytoskeleton Intermediate filaments thick ropes of intertwined protein Microtubules hollow tubes made up of the protein tubulin Microfilaments long, slender microfilaments made up of the protein actin The protein fibers of the cytoskeleton - IGANO, CIENNA CHARRISE Centrioles are complex structures that assemble microtubules in animal cells and the cells of most protists they occur in pairs they are found near the nuclear envelope they are composed of microtubules 5 TRANSES: BIOCHEMISTRY - - Cellular motion is associated with the movement of actin microfilaments and/or microtubules some cells “crawl” by coordinating the rearrangement of actin microfilaments some cells swim by coordinating the beating of microtubules grouped together to form flagella or cilia Cilia and Flagella are hairlike structures projecting from the cell that function to move the cell by their movements Cilium (Cilia) - the short, numerous appendages Flagellum (Flagella) – the longer, less numerous appendages Eukaryotic Cell Surfaces and Junctions Cells interact with their environments and with each other via their surfaces. Plant cells are supported by rigid cell walls made largely of cellulose. Plant cells connected by plasmodesmata. Animal cells are embedded in an extracellular matrix consisting mainly of glycoprotein. This matrix is responsible for binding cells together in tissues. - Manufacture Nucleus, ribosomes, RER, SER, Golgi complex Breakdown Lysosomes, peroxisomes, vacuoles Energy Processing Chloroplasts, mitochondria Support, Movement and Communication Between Cells Cytoskeleton, cell walls, extracellular matrix, junctions Transport of Materials Passive Transport: does not require energy. Moves along concentration gradient Diffusion Osmosis Facilitated Diffusion Active Transport: requires energy. Endocytosis Exocytosis Diffusion and Osmosis Movement of water and nutrients into a cell or elimination of wastes out of cell is essential for survival This movement occurs across a biological membrane in one of three ways diffusion membrane folding transport through membrane proteins Molecules move in a random fashion but there is a tendency to produce uniform mixtures The net movement of molecules from an area of higher concentration to an area of lower concentration is termed diffusion Molecules diffuse down a concentration gradient from higher to lower concentrations diffusion ends when equilibrium is reached Diffusion IGANO, CIENNA CHARRISE 6 TRANSES: BIOCHEMISTRY - The concentration of all molecules dissolved in a solution is called the osmotic concentration of the solution if the osmotic concentrations of two solutions is equal, the solutions are each called isotonic if two solutions have unequal osmotic concentration, the solution with the higher solute concentration is said to be hypertonic, and the solution with the lower solute concentration is said to be hypotonic Movement of water by osmosis into a cell causes pressure called osmotic pressure enough pressure may cause a cell to swell and burst osmotic pressure explains why so many cell types are reinforced by cell walls Osmotic pressure in plants and animal cells **Osmos means to push Forms of Endocytosis Phagocytosis is endocytosis of particulate (solid) matter. “eat” Pinocytosis is endocytosis of liquid matter. “drink” Exocytosis Chemistry of Life Inorganic Compounds Water Gases Minerals Organic Compounds Carbohydrates Proteins Lipids Nucleic acids Vitamins Hydrogen Bonds Give Water Unique Properties Water is essential for life the chemistry of life is water chemistr Water is a polar molecule water can form hydrogen bonds hydrogen bonding confers on water many different special properties Heat Storage water temperature changes slowly and holds temperature well Ice Formation few hydrogen bonds break at low temperatures water becomes less dense as it freezes because hydrogen bonds stabilize and hold water molecules farther apart High Heat of Vaporization water requires tremendous energy to vaporize because of all the hydrogen bonds that must be broken when water vaporizes, it takes this heat energy with it, allowing for evaporative cooling Ice formation IGANO, CIENNA CHARRISE 7 TRANSES: BIOCHEMISTRY - - Water molecules are attracted to other polar Molecules cohesion – when one water molecule is attracted to another water molecule adhesion – when polar molecules other than water stick to a water molecule High polarity in solution, water molecules tend to form the maximum number of hydrogen bonds hydrophilic molecules are attracted to water and dissolve easily in it these molecules are also polar and can form hydrogen bonds hydrophobic molecules are repelled by water and do not dissolve these molecules are nonpolar and do not form hydrogen bonds - - Pure water has a pH of 7 there are equal amounts of [H+] relative to [OH-] Acid – any substance that dissociates in water and increases the [H+] acidic solutions have pH values below 7 Base – any substance that combines with [H+] when dissolved in water basic solutions have pH values above 7 The pH in most living cells and their environments is fairly close to 7 (6.9–7.3) proteins involved in metabolism are sensitive to any pH changes Organisms use buffers to minimize pH disturbances a buffer is a chemical substance that takes up or releases hydrogen ions Organic compounds Biomolecules - associated with living things. Organic molecules Carbohydrates – major source of energy (a.k.a. sugars) Proteins – for tissue repair Lipids – constituents of membranes, also a source of energy (a.k.a. Oils and fats) Nucleic Acids – genetic material and for protein synthesis CARBOHYDRATES Water Ionizes The covalent bond within a sometimes breaks spontaneously water molecule H2O ↔ OH- + H+ - This produces a positively hydrogen ion (H+) and a negatively charged hydroxide ion (OH-) The amount of ionized hydrogen from water in a solution can be measured as pH The pH scale is logarithmic, which means that a pH scale difference of 1 unit actually represents a 10-fold change in hydrogen ion concentration Carbohydrates provide energy through oxidation serve as a form of stored chemical energy supply carbon for the synthesis of cell components form part of the structures of some cells and tissues a molecule that contains the elements CHO in a 1:2:1 ratio sizes vary (simple and complex carbohydrates) building block is simple sugar or monosaccharide Carbohydrates or saccharides (saccharon) are polyhydroxy aldehydes or ketones, or substances that yield such compounds on hydrolysis An aldehyde is an organic compound in which the carbonyl group is attached to a carbon atom at the end of a carbon chain. A ketone is an organic compound in which the carbonyl group is attached to a carbon atom within the carbon chain. Stereochemistry of Carbohydrates Two Forms of Glyceraldehyde (enantiomers)—not the same as each other; one enantiomer cannot be superimposed on the other. Enantiomers are mirror images of each other. D-glyceraldehyde IGANO, CIENNA CHARRISE 8 TRANSES: BIOCHEMISTRY - L-glyceraldchyde - Chiral Carbons any carbon atom which is connected to four different groups will be CHIRAL, and will have two nonsuperimposable mirror images (The mirror images are called enantiomers) An achiral object is identical with (superimposable on) its mirror image. - 2 raised to n Rule when a molecule has more than one chiral carbon, each carbon can possibly be arranged in either the right-hand or left-hand form, thus if there are n chiral carbons, there are 2n possible stereoisomers Fischer Projection are a convenient way to represent mirror images in two dimensions Place the carbonyl group at or near the top and the last achiral carbon at the bottom Naming Stereoisomers look at the chiral carbon farthest from the carbonyl group: if the hydroxyl group points to right when the carbonyl is up, it is the D-isomer if the hydroxyl group points to left when the carbonyl is up, it is the L-isomer The presence of an aldehyde is indicated by the prefix aldo- and an ketone by the prefix ketoProperties of Monosaccharides (Carbohydrates) monosaccharides & disaccharides are white crystalline substance; starches are amorphous powder; cellulose is fibrous solubility to ordinary solvents is inversely proportional to the complexity of their structures monosaccharides & disaccharides are sweet; starch and cellulose are tasteless Reducing power - the potential or power of any substance to reduce another substance. Substance is able to donate electrons. Fermentation - Sugar undergoing fermentation (with yeast) produces ethyl alcohol and carbon dioxide Osazone formation - The reaction (oxidation) between three moles of phenylhydrazine and one mole of aldose produces a crystalline product known as phenylosazone Action of alkalis - Strong alkalies, like strong acids, decompose the sugars. This process identifies the reducing property of sugar Action of acids - acid-catalyzed aldolized glycosides hydrolyzed back to alcohol & sugar Oxidation Oxidized to carboxyl/COOH Chiral Carbon Atoms - Classes of Carbohydrates A. Monosaccharides simplest of the carbohydrates,since they contain only one polyhydroxy aldehyde or ketone Monosaccharides are classified according to the number of carbon atoms they contain: 3 carbon atoms - triose 4 carbon atoms - tetrose 5 carbon atoms - pentose 6 carbon atoms - hexose IGANO, CIENNA CHARRISE - Reduction - Reduced to sugar alcohol monosaccharides do not usually exist in solution in their "open-chain" forms an alcohol group can add into the carbonyl group in the same molecule to form a pyranose ring containing a stable hemiacetal (aldehyde) or hemiketal (ketone) Haworth projection is a common way of writing a structural formula of sugars (monosaccharides and disaccharides) with an unpretentious three-dimensional perspective. Pyranose Ring (piattos) 9 TRANSES: BIOCHEMISTRY - - B. C. Formation of Phosphate Esters Phosphate Esters a class of organophosphorus compounds with the general structure O=P(OR) 3, a central phosphate molecule with alkyl or aromatic substituents. phosphate esters can form at the 6-carbon of aldohexose and ketohexose sugar-phosphate backbone of DNA & RNA, ATP Monosaccharide derivatives Deoxy sugars Sugars that have had hydroxyl group replaced with hydrogen atom Amino sugars Sugars where hydroxyl group is replaced with an amino group Alcohol sugars Polyhydric alcohols (polyols) formed when the carbonyl group of the monosaccharide is reduced to hydroxyl group (one -OH/hydroxyl group attached to each carbon) Carboxylic Acid sugars A carbonyl or hydroxyl group is oxidized to a carboxylic acid group Common Monosaccharides Glucose Fructose Galactose Oligosaccharides Contain 2-10 monosaccharide units Disaccharides Two monosaccharides linked together through a glycosidic linkage D. IGANO, CIENNA CHARRISE Common Disaccharides Sucrose table sugar glucose + fructose Lactose found in mammary milk glucose + galactose Maltose found in molasse used to ferment beer glucose + glucose Polysaccharides Contains hundreds/thousands carbohydrate units Not reducing sugar Two types: Homopolysaccharides - one type of monosaccharides Heteropolysaccharides - multiple types of monosaccharides Starch polymer consisting of glucose units insoluble in water because of high molecular weight forms of starch: 1. Amylose unbranched chains connected by (1-4) glycosidic linkages 10-20% in plants amylose chain is flexible enough to allow the molecules to twist into shape of a helix 2. Amylopectin consists of long chains of glucose connected by (1-4) glycosidic linkages, with (1-6) branches every 24 to 30 glucose units along the chain 80-90% of the starch in plants is in this form 10 TRANSES: BIOCHEMISTRY - - Glycogen aka animal starch structurally similar to amylopectin, containing both (1-4) and (1-6) glycosidic linkages abundant in the liver and muscles on hydrolysis, it forms glucose Cellulose polymer consisting of long, unbranched chains of glucose connected by (1-4) glycosidic linkages most important structural polysaccharide; single most abundant organic compound on earth dietary fiber - - - AMINO ACIDS AND PROTEINS Proteins are complex macromolecules that are polymers of many subunits called amino acids roles in living things catalysts-enzymes hormones transport molecules key part of structures muscle action immune response visual process operation of the nervous system Proteins come in all shapes and sizes Functional group gives amino acids their chemical identity Basic Structure of an Amino Acid Things to remember about amino acids: only 20 L-amino acids are used to make proteins; AA are joined by peptide bonds side chains or side groups are what distinguish amino acids from each other amino acids can exist as zwitterions (a molecule or ion having separate positively and negatively charged groups) - - Amino Acids these are small molecules with a simple basic structure, a carbon atom to which three groups are added amino group (-NH2) carboxyl group (-COOH) IGANO, CIENNA CHARRISE Writing AA starts from C-terminus Classification of Amino Acids: I. Polarity polar acidic basic neutral nonpolar II. R group acidic basic neutral III. Nutrition essential non-essential N-terminus 11 to TRANSES: BIOCHEMISTRY Polypeptide Count the amino acid residue To find the peptide bond locate the carbonyl Proteins structure protein structure is complex the order of the amino acids that form the polypeptide affects how the protein folds together the way that a polypeptide folds to form the protein determines the protein's function some proteins are comprised of more than one polypeptide Primary Protein Structure Sequence of a chain of amino acids - Secondary Protein Structure Local folding of the polypeptide chain into helices or sheets - Tertiary Protein Structure Three-dimensional folding pattern protein due to side chain interactions Proteins the covalent bond linking two amino acids together is called a peptide bond the assembled polymer is called polypeptide IGANO, CIENNA CHARRISE of 12 a TRANSES: BIOCHEMISTRY - Quaternary Protein Structure protein consisting of more than one amino acid chain Properties of proteins very large molecules have characteristic amino acid composition some proteins contain prosthetic group generally tasteless, mostly colorless insoluble in non-polar solvents; varied degrees of solubility in water, salt solution, dilute acids and bases Amphoteric - able to react both as a base and as an acid very reactive and highly specific Classifications of proteins I. According to structure simple proteins compound proteins II. According to shape globular fibrous III. According to function contractile defense enzymes regulatory storage structural transport Enzymes Parts Apoenzyme enzymatically inactive protein part of an enzyme, which requires a cofactor for its activity Cofactor a non-protein chemical compound or metallic ion that is required for an enzyme's role as a catalyst Proenzyme or zymogen a biologically inactive substance which is metabolized into an enzyme. Coenzyme organic compounds required by many enzymes for catalytic activity Enzymes Nomenclature Trivial System based on the substrate of the enzyme and the type of reaction catalyzed use of -ase ending International Enzyme Commission groups enzymes into six classes Main Classes of Enzymes Proteins Denaturation changes to the environment of the protein may cause it to unfold or denature increased temperature or lower pH affects hydrogen bonding, which is involved in the folding process a denatured protein is inactive Properties of Enzymes enzymes are proteins enzymes are catalysts enzymes are highly specific Chemical Reactions All chemical reactions require an initial input of energy called activation energy reactions become more likely to happen if their activation energy is lowered this process is called catalysis catalyzed reactions proceed must faster than non-catalyzed reactions ENZYMES Main Classes of Enzymes What are enzymes? Catalysts substances that speed up chemical reactions enzymes are specific for one particular reaction or group of related reactions many reactions cannot occur without the correct enzyme present General Characteristics of Enzymes Enzymes are well-suited to their roles in three major ways: they have enormous catalytic power they are highly specific their activity can be regulated IGANO, CIENNA CHARRISE 13 TRANSES: BIOCHEMISTRY How Enzymes Work enzymes bind specifically to a molecule and stress the bonds to make the reaction more likely to proceed active site is the site on the enzyme that binds to a reactant binding site is the site on the reactant where the enzyme binds the binding of the reactant to an enzyme causes the enzyme's shape to change slightly - leading to an "induced fit" the enzyme lowers the activation energy for the reaction the enzyme is unaffected by the chemical reaction and can be reused Mechanism of Enzyme Action Lock and Key Theory enzymes have a specific shape that directly correlates to the shape of the substrate. Induced Fit Theory an enzyme's shape and conformation changing over time in response to substrate binding. How cells regulate enzymes? Cells can control enzymes by altering their shape Repressors feedback inhibition Activators Enzyme Inhibition a decrease in enzyme-related processes, enzyme production, or enzyme activity. How Enzymes Work Temperature and pH affect enzyme activity enzymes function within an optimum temperature range enzymes function within an optimal pH range IGANO, CIENNA CHARRISE 14
