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LECTURE PRESENTATIONS For CAMPBELL BIOLOGY, NINTH EDITION Jane B. Reece, Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Robert.

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Presentation on theme: "LECTURE PRESENTATIONS For CAMPBELL BIOLOGY, NINTH EDITION Jane B. Reece, Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Robert."— Presentation transcript:

1 LECTURE PRESENTATIONS For CAMPBELL BIOLOGY, NINTH EDITION Jane B. Reece, Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Robert B. Jackson © 2011 Pearson Education, Inc. Lectures by Erin Barley Kathleen Fitzpatrick Carbon and the Molecular Diversity of Life Chapter 4

2 Overview: Carbon: The Backbone of Life living organisms consist mostly of carbon-based compounds carbon is unparalleled in its ability to form large, complex, and diverse molecules proteins, DNA, carbohydrates, and other molecules that distinguish living matter are all composed of carbon compounds

3 Molecules of Life: the chemicals used in metabolic reactions or those that are produced by them can be classified into 2 groups: 1. Inorganic 2. Organic

4 Inorganic Compounds è water è oxygen,carbon dioxide è inorganic salts Organic Compounds è what three elements make up an organic compound?

5 Organic Compounds always contain carbon, oxygen and hydrogen

6 Concept 4.2: Carbon atoms can form diverse molecules by bonding to four other atoms electron configuration is the key to an atom’s characteristics electron configuration determines the kinds and number of bonds an atom will form with other atoms

7 The Formation of Bonds with Carbon with four valence electron - carbon can form four covalent bonds with a variety of atoms this ability makes large, complex molecules possible in molecules with multiple carbons, each carbon bonded to four other atoms has a tetrahedral shape however, when two carbon atoms are joined by a double bond, the atoms joined to the carbons are in the same plane as the carbons

8 Figure 4.3 Name and Comment Molecular Formula (a) Methane (b) Ethane CH 4 Ball-and- Stick Model Space-Filling Model (c) Ethene (ethylene) C2H6C2H6 C2H4C2H4 Structural Formula

9 the valences of carbon and its most frequent partners (hydrogen, oxygen, and nitrogen) are the “building code” that governs the architecture of living molecules Hydrogen (valence  1) Oxygen (valence  2) Nitrogen (valence  3) Carbon (valence  4) Urea

10 Molecular Diversity Arising from Carbon Skeleton Variation

11 (a) Length Ethane 1-Butene (c) Double bond position 2-Butene Propane (b) Branching(d) Presence of rings Butane 2-Methylpropane (isobutane) Cyclohexane Benzene Carbon chains form the skeletons of most organic molecules Carbon chains vary in length and shape

12 Hydrocarbons Hydrocarbons are organic molecules consisting of only carbon and hydrogen many organic molecules, such as fats, have hydrocarbon components hydrocarbons can undergo reactions that release a large amount of energy Nucleus Fat droplets (b) A fat molecule(a) Part of a human adipose cell 10  m

13 Isomers variation in the architecture of organic molecules can be seen as isomers isomers are compounds with the same molecular formula but different structures and properties –structural isomers have different covalent arrangements of their atoms –cis-trans isomers have the same covalent bonds but differ in spatial arrangements –enantiomers are isomers that are mirror images of each other (a) Structural isomers (b) Cis-trans isomers (c) Enantiomers cis isomer: The two Xs are on the same side. trans isomer: The two Xs are on opposite sides. CO 2 H CH 3 H NH 2 L isomer NH 2 CH 3 H D isomer


15 Drug Ibuprofen Albuterol Condition Effective Enantiomer Ineffective Enantiomer Pain; inflammation Asthma S-IbuprofenR-Ibuprofen R-Albuterol S-Albuterol enantiomers are important in the pharmaceutical industry two enantiomers of a drug may have different effects usually only one isomer is biologically active differing effects of enantiomers demonstrate that organisms are sensitive to even subtle variations in molecules

16 Concept 4.3: A few functional groups are key to the functioning of biological molecules distinctive properties of organic molecules depend on the carbon skeleton and on the molecular components attached to it a number of characteristic functional groups can replace the hydrogens attached to skeletons of organic molecules the number and arrangement of functional groups give each molecule its unique properties Estradiol Testosterone

17 Example: Modification of Hydrocarbons modification of a hydrocarbon with functional groups can turn a non-polar hydrocarbon into a structure with polar characteristics the functional groups usually contain O, N, P or S hydrocarbon + carboxyl group  “hydrophilic” due to the electronegativity of the oxygen atom C H C H H C H H C H H O OH carboxyl group = hydrophilic C H C H H C H H C H H O O-O- de-protonated carboxyl group

18 The seven functional groups that are most important in the chemistry of life: –Hydroxyl group = negative charge –Carbonyl group –Carboxyl group = negative charge –Amino group = positive charge –Sulfhydryl –Sulfate group = negative charge –Phosphate group = negative charge –Methyl group

19 STRUCTURE CHEMICAL GROUP Hydroxyl NAME OF COMPOUND EXAMPLE Ethanol Alcohols (Their specific names usually end in -ol.) (may be written HO—) Carbonyl Ketones if the carbonyl group is within a carbon skeleton Aldehydes if the carbonyl group is at the end of the carbon skeleton Carboxyl Acetic acid Acetone Propanal Carboxylic acids, or organic acids FUNCTIONAL PROPERTIES Is polar as a result of the electrons spending more time near the electronegative oxygen atom. Can form hydrogen bonds with water molecules, helping dissolve organic compounds such as sugars. A ketone and an aldehyde may be structural isomers with different properties, as is the case for acetone and propanal. Ketone and aldehyde groups are also found in sugars, giving rise to two major groups of sugars: ketoses (containing ketone groups) and aldoses (containing aldehyde groups). Found in cells in the ionized form with a charge of 1  and called a carboxylate ion. Nonionized Ionized Acts as an acid; can donate an H + because the covalent bond between oxygen and hydrogen is so polar: Hydrophilic

20 AminoSulfhydrylPhosphateMethyl Methylated compounds Organic phosphates (may be written HS—) Thiols Amines Glycine Cysteine Acts as a base; can pick up an H + from the surrounding solution (water, in living organisms): NonionizedIonized Found in cells in the ionized form with a charge of 1+. Two sulfhydryl groups can react, forming a covalent bond. This “cross-linking” helps stabilize protein structure. Cross-linking of cysteines in hair proteins maintains the curliness or straightness of hair. Straight hair can be “permanently” curled by shaping it around curlers and then breaking and re-forming the cross-linking bonds. Contributes negative charge to the molecule of which it is a part (2– when at the end of a molecule, as above; 1– when located internally in a chain of phosphates). Molecules containing phosphate groups have the potential to react with water, releasing energy. Arrangement of methyl groups in male and female sex hormones affects their shape and function. Addition of a methyl group to DNA, or to molecules bound to DNA, affects the expression of genes. Glycerol phosphate 5-Methyl cytidine Hydrophilic -the H+ of a carboxyl group is often picked up by the NH2  NH3+ -creates a zwitterion

21 Organic macromolecules : 1. carbohydrates 2. lipids 3. proteins 4. nucleic acids


23 Figure 5.2 (a) Dehydration reaction: synthesizing a polymer Short polymer Unlinked monomer Dehydration removes a water molecule, forming a new bond. Longer polymer (b) Hydrolysis: breaking down a polymer Hydrolysis adds a water molecule, breaking a bond

24 1. Carbohydrates: provide energy to cells can be stored as reserve energy supply (humans = glycogen) supply “building materials” to build certain cell structures e.g. cell wall of plants water soluble = hydrophilic characterized H - C - OH (ratio C:H ~ 1:2) e.g. glucose C 6 H 12 O 6 sucrose C 12 H 22 O 12 classified by size: simple sugars – saccharides complex – polysaccharides monosaccharides disaccharides

25 carbohydrates are classified many ways: 1. the location of the carbonyl group (as aldose or ketose) -aldose = carbonyl group (C=O) is at the end of the carbon skeleton -ketose – carbonyl is within the carbon skeleton 2. the number of carbons in the carbon skeleton -e.g. five carbon sugars = pentose (ribose and deoxyribose) -e.g. six carbon = hexose (glucose, fructose and galactose) 3. also by the number of subunits – simple saccharides (sugars) and complex polysaccharides

26 A. Simple carbohydrates – mono and disaccharides monosaccharides = single saccharide subunit in which the # of carbon atoms is low - from 3 to 7 - formula: C:2H:O glucose and galactose with their carbonyls at the end are aldose sugars glucose and galactose only differ with respect to their arrangements of H and OH groups at one carbon!! (see purple boxes) fructose is a ketose sugar Aldose (Aldehyde Sugar) Ketose (Ketone Sugar) Hexoses: 6-carbon sugars (C 6 H 12 O 6 ) Glucose GalactoseFructose

27 Monosaccharides : - in aqueous solutions – the monosaccharides are not linear -they form rings -three ways to represent the ring structure of a monosaccharide 1.Molecular ring form 3. Simplest form 2. Abbreviated ring structure

28 Glucose, Fructose and Galactose beta-glucose (OH above the ring plane) alpha-glucose (OH below the ring plane) beta-galactose (isomer of glucose at the 4 carbon)

29 A. Simple carbohydrates disaccharide = two monosaccharides bound together -form by a dehydration synthesis reaction to form a glycosidic linkage -broken up by a hydrolysis reaction e.g. glucose + glucose = maltose e.g. glucose + fructose = sucrose e.g. glucose + galactose = lactose

30 B. Complex carbohydrates: built of simple carbohydrates to form macromolecules multiple, repeating monomers or “building blocks”  polymer some serve as storage materials – hydrolyzed into individual monosaccharides for sugars others serve as structural or building materials

31 Storage Polysaccharides Starch & Glycogen = storage polysaccharides stored by plants and animals as a future sugar supply starch = storage form of glucose found in plants simplest ones are joined by 1-4 linkages (e.g. amylose) helical and unbranched in conformation stored within plastids – e.g. chloroplast some are more complex – with branch points (1-6 linkages) – e.g. amylopectin hydrolyzed into glucose by enzymes – found in both plants and animals (a) Starch: a plant polysaccharide (b) Glycogen: an animal polysaccharide Chloroplast Starch granules Mitochondria Glycogen granules Amylopectin Amylose Glycogen 1  m 0.5  m glycogen = storage form of glucose found in animals very highly branched hydrolyzed into glucose (in liver)

32 cellulose -major component of the tough wall of plant cells polymer of glucose, but the glycosidic linkages differ the difference is because there are two ring forms for glucose: alpha (  ) and beta (  ) –when glucose forms a ring – the OH group at carbon 1 can either be positioned above or below the plane of the ring –above – beta form –below – alpha form –starch – all glucoses are in the alpha form –cellulose – all glucoses are in the beta form – which makes every other glucose upside down Structural Polysaccharides (a)  and  glucose ring structures  Glucose  Glucose (b) Starch: 1–4 linkage of  glucose monomers (c) Cellulose: 1–4 linkage of  glucose monomers

33 cellulose differs from starch in many ways: –unlike starch – cellulose is not helical or branched –some OH groups on its glucose monomers are free to hydrogen bond with OHs from neighbouring cellulose molecules –results in cellulose molecules grouped parallel to one another = called microfibrils –strong cable-like building material – found in the cell wall of plants –enzymes that digest starch are unable to break the beta linkages of cellulose because of their different shapes –prokaryotes possess cellulase large numbers of these bacteria in the gut of herbivores –humans unable to hydrolyze cellulose – “insoluble fiber” cellulose “scrapes” the lining of the GI tract and causes the production of mucus (aids in smooth passage of other food through the GI tract) Cell wall Microfibril Cellulose microfibrils in a plant cell wall Cellulose molecules  Glucose monomer 10  m 0.5  m


35 Lipids many types –1. triglycerides = fats and oils –2. phospholipids –3. steroids cholesterol – animal cell membranes, basis for steroid hormones bile salts - digestion vitamin D – calcium regulation Adrenocorticosteroid hormones Sex hormones –4. Eicanosoids prostaglandins leukotrienes –5. Others fatty acids carotenes – synthesis of vitamin A vitamin E – wound healing vitamin K – blood clotting lipoproteins – HDL and LDL waxes and pigments

36 2. Lipids A. Fats energy supply most plentiful lipids in your body composed of C, H and O “building blocks” = 3 fatty acid chains (hydrocarbons usually from 16 to 18 carbons) PLUS 1 glycerol molecule fatty acid glycerol portion fatty acid portion

37 © 2011 Pearson Education, Inc. formed through dehydration synthesis reactions to form an ester linkage the three fatty acids joined to glycerol creates a triacylglycerol, or triglyceride fats separate from water because water molecules form hydrogen bonds with each other and exclude the fats (a) One of three dehydration reactions in the synthesis of a fat Fatty acid (in this case, palmitic acid) Glycerol (b) Fat molecule (triacylglycerol) Ester linkage

38 fatty acids -differ in chain length with each fat -differ in the location and number of double bonds within the hydrocarbon chains 1. single C bonds - saturated 2. double C bonds - unsaturated monounsaturated: 1 double bond polyunsaturated: 2 or more double bonds Saturated fatty acids have the maximum number of hydrogen atoms possible and no double bonds Unsaturated fatty acids have one or more double bonds

39 (a) Saturated fat (b) Unsaturated fat Structural formula of a saturated fat molecule Space-filling model of stearic acid, a saturated fatty acid Structural formula of an unsaturated fat molecule Space-filling model of oleic acid, an unsaturated fatty acid Cis double bond causes bending. at room temperature – the molecules of a saturated fat are packed closely together the fatty acid tails are more flexible forms a solid the molecules of an unsaturated fat cannot pack closely together enough to solidify the C=C bonds produce a “kink” in the fatty acid chain making it difficult to pack them together if the fat contains one fatty acid that is unsaturated – then the fat is considered unsaturated in hydrogenated oils – the unsaturated fats have been chemically converted to saturated by adding hydrogens prevents their separation into an oil form – keeps them solid

40 -a gram of fat stores twice as much energy vs. a gram of a polysaccharide like starch -adipose tissue evolved due to animal movement -much less bulky than polysaccharides like starch -although plants did evolve oils in their seeds to decrease the amount of space needed for the energy required -some fatty acids cannot be made by the body and must be taken in through food = essential fatty acids e.g omega-3 fatty acids -polyunsaturated fatty acids -important in regulating cholesterol levels (lower LDL levels in the blood) -increase calcium utilization by body - reduce inflammation (arthritis?) - promote wound healing


42 B. Phospholipids when added to water – self-assemble and form a form a phospholipid bilayer – major component of the plasma membrane similar to fat molecules - glycerol + 2 fatty acids modified through the replacement of one FA with a phosphate group (negative electrical charge) phosphate gp  hydrophilic “head” fatty acid gps  hydrophobic “tails”

43 C. Steroids backbone is called cholesterol = 4 fused carbon rings synthesized in the liver diversity through attached functional groups e.g. testosterone, estrogen aldosterone


45 3. Proteins nearly every dynamic function of a living organism depends on proteins Greek – proteios = “first place” more than 50% of the dry mass of most cells numerous roles: structural – support of cells and tissues storage - energy source transport across cell membranes hormones and their receptors – signaling chemical messengers - signaling antibodies - defense metabolic role - enzymes

46 Figure 5.15-a Enzymatic proteins Defensive proteins Storage proteins Transport proteins Enzyme Virus Antibodies Bacterium Ovalbumin Amino acids for embryo Transport protein Cell membrane Function: Selective acceleration of chemical reactions Example: Digestive enzymes catalyze the hydrolysis of bonds in food molecules. Function: Protection against disease Example: Antibodies inactivate and help destroy viruses and bacteria. Function: Storage of amino acidsFunction: Transport of substances 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. 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.

47 Figure 5.15-b 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 High blood sugar Normal blood sugar Insulin secreted Signaling molecules Receptor protein Muscle tissue Actin Myosin 100  m 60  m Collagen Connective tissue 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. 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. 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.

48 life would not be possible without enzymes enzymes are a type of protein that acts as a catalyst to speed up chemical reactions function relies upon their 3D conformation and the physical environment they are working in

49 3. Proteins building blocks = amino acids 22 amino acids available for human protein synthesis –20 of them are coded for by our DNA the R group give the amino acid a unique physical and chemical character divided into three groups –polar amino acids –non-polar amino acids –electrically charged amino acids –basic or acidic Side chain (R group) Amino group Carboxyl group  carbon a.a. = amino group at 1 end, carboxyl at the other - between is a single C called the alpha carbon -the alpha carbon is assymetrical and is bound to: 1. H atom 2. R group

50 the 20 amino acids coded by DNA: 1.non-polar: 1.Methionine – Met or M 2.Phenylalanine – Phe or F 3.Tryptophan – Trp or W 4.Proline – Pro or P 5.Glycine – Gly or G 6.Alanine – Ala or A 7.Valine – Val or V 8.Leucine – Leu or L 9.Isoleucine – Iso or I 2.polar: 1.Serine – Ser or S 2.Threonine – Thr or T 3.Cysteine – Cys or C 4.Tyrosine – Tyr or Y 5.Asparagine – Asp or N 6.Glutamine – Glu or Q 3.acidic 1.Aspartic acid – Asp or D 2.Glutamic acid – Glut or E 4.basic 1.Lysine – Lys or K 2.Arginine – Arg or R 3.Histidine – His or H

51 amino acids joined together by a dehydration synthesis reaction forming a peptide bond = between the NH 2 of 1 a.a. and the COOH of the next amino acid 2 a.a.  dipeptide 3 a.a.  tripeptide 4 or more a.a.  polypeptide Figure 5.17 Peptide bond New peptide bond forming Side chains Back- bone Amino end (N-terminus) Peptide bond Carboxyl end (C-terminus)

52 the 3D architecture is critical to protein function 3D shape is determined by the sequence of amino acids -i.e. the chemical properties of the amino acid can determine whether the protein will twist or kink or be linear -when a cell forms a polypeptide – it spontaneously begins to fold (takes no energy) -folding is driven by the bonds between different regions of the pp chain -the types of bonds depend on the amino acid sequence BUT – the physical environment can also affect 3D shape e.g. pH, salt, temperature IMPORTANT: polypeptide does not mean protein!!!! polypeptides have 4 types of structures or conformations which affect their ultimate function (b) A space-filling model (a) A ribbon model

53 Protein conformation: 1.primary - a.a. sequence of polypeptides e.g. transthyretin – 127 amino acids -sequence is determined by the genetic code found in the DNA -if randomly created – then a 127 AA polypeptide could be made different ways!!

54 Secondary structure Tertiary structure Quaternary structure Hydrogen bond  helix  pleated sheet  strand Hydrogen bond Transthyretin polypeptide Transthyretin protein

55 2. secondary – sections of the AA chain fold into  -helical coils or  -pleated sheets -found in most proteins -the result of H bonding - O and N atoms have partial negative charges -the weakly positive H atom attached to the N is attracted to the positive O of a nearby AA -alpha helix – produced by H bonding every 4 th AA -beta pleated sheet – H bonding between two or more regions of the PP lying side by side

56 3. tertiary – secondary structure folds into a unique 3D shape -tertiary conformation is superimposed on the secondary structure -gives rise to the overall 3D shape and function of the protein -results from interactions between the R groups Secondary structure Tertiary structure Hydrogen bond  helix  pleated sheet  strand Hydrogen bond

57 -one interaction = hydrophobic interactions -non-polar AAs face in when the protein folds -due to hydrophobic interaction with water -van der Waals keep these AAs close together -other interactions: -hydrogen bonding -between polar AAs -between the +ve and –ve charges of the acidic and basic AAs (ionic bond) Hydrogen bond Disulfide bridge Polypeptide backbone Ionic bond Hydrophobic interactions and van der Waals interactions -3D shape is reinforced through the formation of disulfide bridges

58 4. quaternary = joining of 2 or more polypeptides chains -aggregate into one function macromolecule -individual polypeptide chains are called subunits Collagen Hemoglobin Heme Iron  subunit  subunit

59 MEDICAL APPLICATION: Sickle-Cell Disease: A Change in Primary Structure A slight change in primary structure can affect a protein’s structure and ability to function Sickle-cell disease, an inherited blood disorder, results from a single amino acid substitution in the protein hemoglobin Primary Structure Secondary and Tertiary Structures Quaternary Structure Function Red Blood Cell Shape  subunit     Exposed hydrophobic region Molecules do not associate with one another; each carries oxygen. Molecules crystallize into a fiber; capacity to carry oxygen is reduced. Sickle-cell hemoglobin Normal hemoglobin 10  m Sickle-cell hemoglobin Normal hemoglobin    

60 Protein Folding in the Cell © 2011 Pearson Education, Inc. the AA sequence of more than 10 million proteins is now known the 3D structure of more than 20,000 proteins are also known –used to predict a protein’s structure from its primary structure BUT – the folding process is not straightforward –most proteins probably go through several stages on their way to a stable structure one thing is known – that initial protein folding is spontaneous

61 Protein Folding in the Cell © 2011 Pearson Education, Inc. The cap attaches, causing the cylinder to change shape in such a way that it creates a hydrophilic environment for the folding of the polypeptide. Cap Polypeptide Correctly folded protein Chaperonin (fully assembled) Steps of Chaperonin Action: An unfolded poly- peptide enters the cylinder from one end. The cap comes off, and the properly folded protein is released Chaperonins –proteins that assist the proper folding of other proteins –don’t fold the protein –detects when a protein is mis-folded and targets it for destruction –found in the cytoplasm and in the endoplasmic reticulum –made of a ‘cap’ on top a ‘hollow cylinder’ –the cylinder keeps the protein protected while it folds spontaneously –other monitoring systems also exist to verify folding –destruction of the mis-folded protein – by a proteosome diseases such as Alzheimer’s, Parkinson’s, and mad cow disease are associated with mis-folded proteins

62 Protein Folding in the Cell determining 3D protein structure uses a branch of science called X-ray crystallography –the molecule is crystallized –the atoms of the molecule diffract the X-rays –diffraction pattern is analyzed by computer software and a 3D ribbon structure is generated – known as bioinformatices another method is nuclear magnetic resonance (NMR) spectroscopy - does not require protein crystallization Diffracted X-rays X-ray source X-ray beam Crystal Digital detectorX-ray diffraction pattern RNADNA RNA polymerase II EXPERIMENT RESULTS

63 4. Nucleic acids known as DNA, RNA C,H,O,N,P building blocks = nucleotides or nucleic acids Sugar-phosphate backbone 5 end 5C5C 3C3C 5C5C 3C3C 3 end (a) Polynucleotide, or nucleic acid (b) Nucleotide Phosphate group Sugar (pentose) Nucleoside Nitrogenous base 5C5C 3C3C 1C1C nucleotide: 5 carbon sugar (pentose)  phosphate group (negative charge) located at the 5’ carbon  organic base located at the 1’ carbon  sugar and the base is known as a nucleoside  bases: 5 types: adenine (A) cytosine (C) guanine (G) thymine (T) uracil (U)

64 Nitrogenous bases Cytosine (C) Thymine (T, in DNA) Uracil (U, in RNA) Adenine (A) Guanine (G) Sugars Deoxyribose (in DNA) Ribose (in RNA) (c) Nucleoside components Pyrimidines Purines  There are two families of nitrogenous bases 1. Pyrimidines (cytosine, thymine, and uracil) have a single six-membered ring 2. Purines (adenine and guanine) have a six- membered ring fused to a five-membered ring

65 polynucleotide chain - formed by a phosphodiester bond between the phosphate (5’) of 1 n.t. and the sugar of the next (3’) -phosphodiester bond is comprised of a phosphate group linking two sugars two major types of nucleic acids: 1. RNA sugar = ribose 2. DNA sugar = deoxyribose ribosedeoxyribose HOCH 2 H OH H O HOCH 2 HH H O OH so a DNA/RNA chain “grows” in one direction only -5’ to 3’ Sugar-phosphate backbone 5 end 5C5C 3C3C 5C5C 3C3C 3 end (a) Polynucleotide, or nucleic acid phosphodiester bond

66 A. RNA single polynucleotide chain bases: A, C, G and uracil (U) in place of T 3 major types: mRNA tRNA rRNA B. DNA double polynucleotide chain = double helix 2 chains held by hydrogen bonds between the bases bases pair up in a complementary fashion A = T C G sense strand (5’ to 3’) anti-sense strand

67 c. ATP  individual n.t’s can have metabolic functions e.g. adenosine = adenine + ribose -adenine modified by adding three phosphates  major source of ATP = breakdown of glucose 1 glucose molecule 36 ATP glycolysis Kreb’s cycle oxidative phosphorylation

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