Essential Elements of Biochemistry BCHM 3050 Dr Srikripa Chandrasekaran Lecture 2 9 15 Notes Nucleotides I II III Definition Classification A DNA and RNA are 2 nucleic acids B They are made up from bases C Overall because of the charge and structure of the DNA and RNA they are still called nucleic acids 1 They have acidic properties even though they are composed of 2 DNA lacks an oxygen compared to RNA 3 DNA is the blueprint of life and the most important molecule for bases life 4 RNA is a middle man it is a messenger it takes information from DNA and coverts it into proteins Molecular Components of Nucleotides A Made nucleotides together make up the structure of DNA B Sugars have carbons and hydroxyl groups connected to them they form a ring like structure C Pentose sugar 5 sided ring D Deoxyribose sugar lacks the second oxygen on the bottom that ribose sugar has ribose sugar has 2 OH on the bottom while deoxyribose sugar has 1 OH and 1 H Purines vs Pyrimidines A Purines are larger have 2 rings B Pyrimidines are smaller have 1 ring C Deamination products of regular purines they are constantly removed and replaced with regular purines they are intermediates D Removal of the amino group happens in the presence of water E Xanthine is derived from guanine hypoxanthine is derived from adenine F Purines are bigger pyrimidines are smaller G Purines adenine guanine xanthine hypoxanthine H Pyrimidines thymine cytosine uracil I Thymine is the only base with a methyl group J Thymine is only present in DNA not RNA Uracil is only present in RNA not DNA IV K Adenine bonds with Thymine Guanine bonds with Cytosine Nucleoside A Nucleoside nucleotide without the phosphate group just contains the nitrogenous base and the sugar B A bonds with T G bonds with C C Carbon atom 1 of the sugar attaches to the base 1 D Glycosidic linkages are generally present between sugars glycosidic linkages connect the sugar and the base together E Carbon atom 2 and 3 have OH attached to them in ribose sugar in RNA F Carbon atom 2 lacks an oxygen in deoxyribose sugar in DNA carbon atom 3 has an OH in deoxyribose sugar in DNA G Ribose sugar adenine base in RNA Adenosine H Deoxyribose sugar adenine base in DNA Deoxyadenosine I Ribose sugar cytosine base in RNA Cytidine J Deoxyribose sugar cytosine base in DNA Deoxycytidine K Cannot have just regular thymidine can only have deoxythymidine because thymine is only present in DNA not RNA V Some Interesting Nitrogenous Bases A Adenosine is an inhibitory neurotransmitter that binds to the adenosine receptor Adenosine accumulates during wakefulness and helps promote sleepiness especially following sleep deprivation B Theobromine and theophylline are enriched in tea and coca C Caffeine is enriched in coffee D These compounds are all derived from nitrogenous bases and they have many medical uses VI Nucleotides A Nucleotides nitrogenous base a sugar one or more phosphates B Phosphate group is in the 5th carbon position nucleotide C Hydroxyl group OH that is usually on the 5th carbon is replaced by the phosphate group D Phosphoester bond forms between carboxylic acid groups and hydroxyl groups E Monophosphate 1 phosphate group F Diphosphate 2 phosphate groups G Triphosphate 3 phosphate groups VII Metabolic Functions of Nucleotides VIII A ATP is one of the most important molecules for organisms because it provides us with energy B ATP is the energy currency of the cell C Cellular respiration is a catabolic reaction D The energy produced is used to make more ATP Significance of G A B Exergonic reaction releases energy so the G free energy is G difference in energy between the reactant and the product negative these reactions are favorable or spontaneous C Endergonic reactions are scavenger reactions the G free energy is positive IX D Breaking down ATP is an exergonic reaction Cyclic AMP Cyclic GMP A cGMP mediated nitric oxide signaling is a relatively new signal cascade especially in plants 2 B Much is known about cAMP mediated signaling C cAMP cyclic AMP D E the amount of pain that we feel is controlled by cGMP N2O is laughing gas it is now being introduced as an anesthetic for child birth NO is pain The purines form the cyclic compounds F G They modulate blood pressure 3
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