macromolecules
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Macromolecules. Organic compounds Contain both hydrogen and carbon Large molecules composed of smaller subunits Carbohydrates Proteins Lipids Nucleic Acids . Carbohydrates (Sugars). Bio-molecule consisting of carbon, oxygen, and hydrogen. - PowerPoint PPT PresentationTRANSCRIPT
Macromolecules• Organic compounds– Contain both hydrogen and carbon
• Large molecules composed of smaller subunits– Carbohydrates– Proteins– Lipids– Nucleic Acids
Carbohydrates (Sugars)• Bio-molecule consisting of
carbon, oxygen, and hydrogen.
• General molecular formula (CnH₂nOn) (C₆H₁₂O₆)
• Roles– Energy storage - plants – Structural support in cells and
tissues • Hydrophilic • Pentose/Hexose ring
structure
Monosaccharides• Simplest type of
carbohydrate• Used as primary energy
source for cellular metabolism (making ATP)
• 1 sugar unit – Glucose – grape sugar,
blood sugar– Fructose – honey, fruit
juices
Monosaccharides• Most Common– 3 carbon (linear) – triose– 5 carbon – pentose ring– 6 carbon – hexose ring
• Why?– Folding into a ring
occurs through a reaction between carbonyl group and hydroxy l group
• Link together to form disaccharides
Glucose• Linear and ring structures• Hexose ring– Two possible arrangements
• α - glucose• Β – glucose
– Isomers – same molecular formula, different structural formula• Carbon atoms have assigned numbers– Used when discussing structures of sugars
Linkages are designated α or β from the position of the –OH group on the 1 carbon
Disaccharides• Consist of two monosaccharides – Maltose – used to make beer – Sucrose – simple sugar found in
plant sap– Lactose – milk
• Used as energy sources and building blocks for larger molecules
• Joined together by a dehydration synthesis reaction
• Glycosidic bond – links monosaccharides together
• Common carbon linkages – 1 4 1 2– 1 3 1 6
Polysaccharides• Complex carbohydrate/polymer– Chain of hundreds to thousands of monosaccharides
(monomers) with many subunits– Unbranched – side chains – Branched – single chain
Polysaccharides• Assembled by dehydration reaction– Glycosidic linkage– Polymerization – linkage of identical or various monomers to
form long chains• Linear unbranched – hydrogen bonds form between molecules
• Polar • Hydrophilic• Non-soluble in water
Examples Amylose – soluble component of
starch α- glucose chains
Glycogen – energy storage in animals α- glucose chains
Cellulose – main component of plant cell walls β- glucose chains
Chitin – hard exoskeleton of insect and crustaceans
Lipids• Non-polar • Made up of mostly
carbon and hydrogen • Not polymers• Do not dissolve in water• Roles – Formation of cell
membranes – Energy source – Hormones – Vitamins
• 5 main categories – Fatty acids – Fats – Phospholipids – Steroids – Waxes
Fatty Acids• Derivative of most lipids
(structural backbone)• Consists of– Single hydrocarbon
chain (14 to 22)– Carboxyl functional
group at one end (-COOH)
– Gives the fatty acid its acidic properties
• As chain length increases, insolubility in water increases
Fatty Acids• Saturated – Max number of hydrogen
atoms attached to carbons– Single bonds throughout the
carbon chain– Solid at room temp
• Unsaturated– Formation of double bonds in
carbon chain– Monounsaturated – one
double bond– Polyunsaturated – many
double bonds– Causes a bent formation in
molecule – Liquid at room temp
Cis and Trans Fats• Presence of a double
bond (unsaturated)• Cis – Naturally occuring– Good for health– Forms kinks in carbon
chain• Trans– Artificially produced– Found in processed foods– Raise bad cholesterol
(LDL) – Forms straight chains
Fats • Consists of
– 1 to 3 fatty acid chains– Glycerol
• Dehydration synthesis– Hydroxyl group of
glycerol and carboxyl group of fatty acid
• Can have identical/different fatty acid chains
• Hydrophobic• Ester linkage forms
between FA chain and glycerol
Triglycerides • Most well known fat• Contains 3 fatty acid chains• Stored energy (food) in fat cells • Liver produces triglycerides for extra energy or for production of
Lipoproteins • Yield more than twice as much energy as carbohydrates• Normal blood level – less than 150 mg/dL
Phospholipids• Consists of– 2 fatty acid chains
(hydrophobic) – Glycerol – Phosphate group • contains a polar
unit (hydrophilic)
• Amphipathic – Contains both
hydrophobic and hydrophilic regions
Phospholipids• Roles– Lipid bilayer of cell
membranes – Hydrophilic end faces
toward water– Hydrophobic end
faces inward• Unsaturated tail
makes membrane more permeable to water and small molecules
Steroids
• Consists of – Four fused carbon ring– Side group
• Sterols– Most abundant – Consists of • Single polar –OH group • Non – polar hydrocarbon chain
– Amphipathic molecule– Eg; Cholesterol , Phytosterols
Cholesterol• Formed in the liver • Structural component of
plasma membrane (nearly half)
• Amphipathic• Function– Maintains integrity of
membrane– Proper membrane
permeability/fluidity– Fatty acid
transport/metabolism– Production of hormones, bile
salts, and vitamins
Cholesterol • Can’t dissolve in
blood• Transported by
carriers • Types
– LDL – low density lipoprotein
– Promote cardiovascular disease
– HDL – high density lipoprotein
– “Good” cholesterol– removes cholesterol
from artery– Eliminated in liver
Sex Hormones• Control development of sexual traits and sex cells – Eg; testosterone, estrogen, progesterone
Waxes• Consist of – Long fatty acid chains– Alcohol molecule or Carbon
ring• Hydrophobic• Extremely non-polar• Soft Solids• Functions– Waterproof coating on various
plant and animal parts– Cutin – plants conserve water
and fights disease– Beeswax – production of
honeycomb
Proteins• Polymer with many subunits• Composed of Amino Acids
(monomers)• Folded into a 3-D structure
– Primary Secondary– Tertiary Quaternary
• Folding allows protein to function
• Structure specifies function of protein
• Formed by dehydration reaction• Peptide bonds link amino acids
together
Amino Acids• 20 different amino acids– 8 essential - supplied by
diet• Contain:– Central carbon– Amino group (-NH₂)– Carboxyl group (-COOH)– R group
• R groups give each amino acids specific characteristics– Polarity, acidity
Amino Acids
Peptide Bond• Covalent bond between
(NH₂) group of one amino acid and (COOH) group of another.
• Amino acids are only added to the C-terminal of a growing peptide
• Peptide– String of 1-49 amino acids– Contains no side branches
• Polypeptide– String of 50 or more amino
acids
Proteins• Structural – framework support
(hair, tendon, ligaments)• Defensive – infection fighters
(antibodies)• Signal – messenger (hormones)• Carrier – transport of materials
(hemoglobin)• Recognition and Receptor –
cellular markers (major histocompatability complex)
• Enzyme – catalyst (amylase)• Motile – movement (actin and
myosin)
Protein Structure• Primary Structure 1⁰– Linear sequence of amino acids in polypeptide chain– Changing one amino acid with change overall structure
of protein
Protein Structure • Secondary Structure • Polypeptides fold or coil
into patterns• Result of hydrogen bonding– β-pleated sheets
• Side-by-side alignment• (Eg; strength of silk)
– α-helix • Coil that is held together by
hydrogen bonds between every 4th amino acid
• (Eg; filamentous proteins, transmembrane proteins)
Protein Structure• Tertiary Structure 3⁰• 3-D shape of a polypeptide chain• Intermolecular reactions of
amino acid R groups determines shape
• Include• Ionic bonds• Hydrogen bonds• Hydrophobic interactions
– Non-polar side groups cluster when introduced to water
• Disulfide bridges– Bond formed from two cysteine
amino acids (-SH group)– Stabilizes proteins shape
Protein Structure • Quaternary Structure 4⁰– Composed of 2 or more
polypeptides– Functional proteins– Forms subunits – Same bonds and forces
as tertiary structure
Protein Prosthetic Groups• Non-protein components– Metal ions (Fe²⁺ Mg²⁺)
• Needed for protein to function• Hemoglobin– 4 polypetide chains each with a
heme groups – Each group has s single iron ion
(Fe²⁺) – Oxygen binds to heme groups via
(Fe²⁺)– How many molecules of O₂ can
hemoglobin carry at one time?
Protein Denaturation• When a protein loses its 3-D structure• Often irreversible • Extreme temperatures• pH• Chemcials
Enzymes• 3-D biological catalyst• Protein • Used in reactions– Speeds up a chemical
reaction – Is not consumed – Does not change products
of the reaction– Lowers activation energy
of reaction• Energy required to start a
chemical reaction
• Eg. Catalase breaks down the build up of hydrogen peroxide in the body
Reactants →Products
Types of Enzymes Three types of enzymes 1. Metabolic Enzymes
- body produces that work in blood, tissues, and organs
2. Digestive Enzymes - break down food into usable material
3. Food Enzymes - contained in raw food
Enzyme Groups and Functions• Enzymes can be divided into 6 main groups 1. Hydrolases – break down proteins, carbohydrates,
and fats during the process of digestion 2. Isomerases – rearrange chemical groups within the
same molecules 3. Ligases – form bonds between two substrate
molecules 4. Lyases – form double bonds between atoms 5. Oxidoreductases – facilitate REDOX reactions 6. Transferases – transfer chemical groups from one
molecule to another
Enzyme Cycle
Factors That Affect Enzyme Activity• Enzyme and substrate concentration– Increasing enzyme concentration increases rate of
reaction– Increasing substrate increases rate of reaction to a point
called saturation level
Factors That Affect Enzyme Activity• Temperature– Increasing temperature increases rate of reaction
(collision between enzyme and substrate)– 40⁰C or higher - enzyme begins to denature
Factors That Affect Enzyme Activity• pH– Optimal enzyme pH is 7 (most)• Increasing or decreasing pH from optimal
value decreases rate of reaction
Enzyme Function• http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_enzymes_work.html
• http://www.youtube.com/watch?v=hoBhOdQV7vw&list=PLBAC6D002DBAE5224
• Binds substrate (reactant or reactants) at the active site (pocket in enzyme)– Forms an enzyme-substrate complex– Enzyme changes shape to better bind substrate• Induced-fit model
Cofactors and Coenzymes• Enzymes require them
to function properly– Cofactor• Non-protein group that
binds to an enzyme• Often metals (Fe²⁺ Cu²⁺)
– Coenzyme• Organic • Derived from water-
soluble vitamins• Shuttle molecules from
enzyme to another• Eg. NAD⁺
Enzyme Inhibition• Bind to an enzyme lowering the rate at which an
enzyme catalyzes a reaction • Occur at different locations on enzyme– Competitive– Non-competitive– Allosteric
Competitive Inhibition• Competes with
normal substrate to bind at the active site of enzyme
• Penicillin (bacterial cell walls)
• Protease Inhibitors (HIV)
Non-competitive Inhibition • Sometimes irreversible • Binds to enzyme at a
location other than the active site
• Changes shape of enzyme (substrate cannot bind)
• Cyanide
Allosteric Inhibition/Activation • Regulates enzyme activity
via feedback• Helps maintain
homeostasis in cell • Increases or decreases
enzymatic activity depending on concentration of product (turn enzyme “on” or “off”)
• Use allosteric regulators– Inhibits or activates enzyme– Bind to enzyme at an
allosteric site – Can be competitive and
non-competitive
Nucleic Acids• Polynucleotide chains
serve as assembly instructions for all proteins in living organisms
• DNA – deoxyribonucleic acid– Stores hereditary
information• RNA – Ribonucleic acid
– Hereditary molecule of some viruses
– Involved in protein synthesis
• Composed of nucleotides • Linked by a
phosphodiester bond
Nucleotides• Consists of– Nitrogenous base
• Uracil (U), thymine (T), cytosine (C), adenine (A), guanine (G)
– Sugar– Phosphate groups
• Functions– Data storage– Energy currency (ATP)– Cellular communication (cAMP,
ATP)– Co-enzyme catalysis
Nitrogenous Bases• 2 types– Pyrimidines• Uracil (U), Thymine (T), Cytosine (C)
– Purines • Adenine (A), Guanine (G)
Phosphodiester Bond• Links nucleotides
together– Phosphate bridge forms
between the 5’ carbon of one sugar and the 3’ carbon of the next sugar.
– Forms the backbone of a nucleic acid chain
– Nitrogenous bases project from the backbone
DNA• Consists of – Deoxyribose sugar– Phosphate group– A, T, C, G
• Double stranded molecule (Double Helix)– Two strands of DNA run antiparallel to each
other (opposite direction)– 5’ to 3’ – 5’ is the end with the phosphate group– 3’ is where deoxyribose sugar is located
• Nitrogenous bases– Held together by hydrogen bonds– A pairs with T ( forms double bond)– C pairs with G (forms a triple bond) – A to T and C to G is known as
complementary base pairing
RNA• Consists of– Ribose sugar– Phosphate group – A, U, C, G
• Single stranded molecule• Converts information stored in DNA into proteins