Nucleic Acid Structure and Function PDF

NUCLEIC ACID STRUCTURE AND 1. PYRIMIDINES - one (1) ring, six FUNCTION (6) atoms Building blocks: 2. PURINES - two (2) rings, nine (9) Amino acids – proteins (peptide bonds) atoms Monosaccharides – carbohydrate...

NUCLEIC ACID STRUCTURE AND 1. PYRIMIDINES - one (1) ring, six FUNCTION (6) atoms Building blocks: 2. PURINES - two (2) rings, nine (9) Amino acids – proteins (peptide bonds) atoms Monosaccharides – carbohydrates (glycosidic bond) Fatty acid (it varies) – lipids Nucleotides – nucleic acids (DNA and RNA) Nucleic Acids - biomolecules responsible for transfer of genetic information - They are polymers of repeating Nitrogenous Bases unit called NUCLEOTIDE Pyrimidine: uracil (U), thymine (T), cytosine - Also involved in energy (C ) metabolism, like ATP, UTP, GTP Uracil (U) - RNA only DNA - always stays in the nucleus Thymine (T)- DNA only - In eukaryotes Cytosine (C ) - Both DNA and RNA - Ex: plants, and animals RNA - in cytoplasm In prokaryotes Nucleotides - monomers used in nucleic acids. Composed of nitrogenous base, pentose sugar, phosphate group NITROGENOUS BASES - There are two types of heterocyclic, nitrogenous bases, depending on the parent Pyrimidine(one ring): compound they were derived Uracil, O double bonds from. Thymine, has CH3 Cytosine, has NH2 Purine (two rings): Nitrogenous bases - are linked to C1 of Adenine, has NH2, NO O double bonds the pentose (1’) via glycosidic bond Guanine, has O double bond and H2N Nucleosides - nitrogenous bases linked to pentose are referred to as this PENTOSE SUGAR - two pentose sugar are used for Phosphate groups - are li;ked to C5 of nucleotides: ribose, 2-Deoxyribose the pentose (5’) via an ester bond - Mono, di, tri Ribose- for RNA, has “OH” in carbon 2 2-Deoxyribose - for DNA, has “H” in carbon 2 PHOSPHATE GROUP - are derived from phosphoric acid NOMENCLATURE (H3PO4) - Under cellular conditions, it exists its ionic form, HPO4^2- Nucleotides - are linked through their sugar and phosphate groups, referred to as nucleic acid backbone. In nucleotides, the bonds that link the three groups use the carbon atoms of the NUCLEOTIDE STRUCTURE pentose sugar as reference. Pentose carbons - are designated with a number and a prime  - Refers to the single strand nucleotide sequence, written from 5’ to 3’ Secondary structure - Refers to double stranded helix NUCLEIC ACID STRUCTURE structure Nucleotides are linked through their sugar - One strand runs from 5’ to 3’ and and phosphate groups, referred to as other runs from 3’ to 5’ (anti- nucleic acid backbone parallel) - Stabilized by HYDROGEN BONDS Note: the structure alternate as - Backbone is oriented OUTwards Phosphate-sugar-phosphate-sugar - Bases are oriented INwards Depending if it is DNA or RNA DNA STRUCTURE DNA backbone: phosphate-Deoxyribose View ppt for image RNA backbone: Phosphate-ribose BASE PAIRING Nucleotides are linked from 3’ carbon to In double stranded DNA (dsDNA) the 5’ carbon The nitrogenous base on one strand are always paired with their complementary 5’ end - nucleotide with free phosphate bases on the other strand group 3’ end - nucleotide with free OH group Guanine is always paired to cytosine with three (3) hydrogen bonds) Nucleic acids are written from 5’ to 3’ Adenine is always paired with thymine DEOXYRIBONUCLEIC ACID (DNA) with two (2) hydrogen bonds - Nitrogenous bases: G, C, A, T EXAMPLE: - Pentose sugar: 2-Deoxyribose SsDNA: 5’-A-A-T-G-C-A-G-C-T-3’ - Found in the nucleus complement: 3’-T-T-A-C-G-T-C-G-A-5’ - For storage and transfer of genetic information ssDNA: - Passed from one cell to another 5’-A-A-G-C-T-A-G-C-T-T-A-C-T-3’ during cell division complement: 3’-T-T-C-G-A-T-C-G-A-A-T-G-A-3’ Primary structure In dsDNA:  - %A = %T rRNA: form the ribosome - %G=%C ex: human DNA contains 30% adenine, 30% thymines, 20% guanine, and 20% cytosine RIBONUCLEIC ACID (RNA) - nitrogenous bases: G, C< A, U Messenger RNA (mRNA) - pentose sugar: Ribose - carries information from DNA inside the NUCLEUS - found in ALL parts of the cell - takes the DNA to ribosomes for - for protein synthesis protein synthesis - less stable than DNA - mRNA sequence is used by Primary structure ribosome as the basis for amino - A similar to DNA, refers to the acid sequence of proteins single strand nucleotide sequence, written from 5’ to 3’ Note: each codon has three nucleotides secondary structure: Transfer RNA (tRNA) - refer to the folding of a single - delivers amino acids to the sites RNA strand for protein synthesis - stabilized by hydrogen bonds - Smallest RNA molecules (75-90 between complementary bases nucleotide units) - ‘clover-leaf’ like structure - L-shaped 3D structure TYPES OF RNA - There are three main RNA Ribosomal RNA ( rRNA) molecules that are involved in the - component of ribosomes conversion of genetic information - allow proper binding of mRNA into protein products. when it enters the ribosome - the three main roles: messenger - has a large and small subunit RNA (mRNA), transfer RNA (tRNA), Ribosomal RNA (rRNA) -___________ mRNA: Encodes proteins look at ppt for the pictures tRNA: Acts as adapter between mRNA and amino acids