DNA metabolism 1-1-14.pdf

Textbooks Lehninger Principles of Genetics A conceptual Biochemistry Approach 5th or 6th edition Fourth Edition Dr. Suheir Ereqat 2023-2024  Cen...

Textbooks Lehninger Principles of Genetics A conceptual Biochemistry Approach 5th or 6th edition Fourth Edition Dr. Suheir Ereqat 2023-2024  Central dogma of Molecular Biology DNA>>>>RNA>>>>protein Dr. Suheir Ereqat 2023-2024  What is DNA? Deoxyribonucleic acid, is a complex molecule that contains all of the information necessary to build and maintain an organism (specify the structure and function of living things ) The primary unit of heredity in organisms of all types. Dr. Suheir Ereqat 2023-2024  REVISION DNA Structure Dr. Suheir Ereqat 2023-2024  DNA The structure of DNA can be considered at three hierarchical levels: the primary structure of DNA is its nucleotide sequence the secondary structure is the double- stranded helix the tertiary structure refers to higher-order folding that allows DNA to be packed Dr. Suheir Ereqat 2023-2024  All nucleotides have a common structure A nucleotide present in RNA The pentoses in nucleic acids Dr. Suheir Ereqat 2023-2024  Remember HOW the Carbons Are Numbered! Phosphate Group O 5 CH2 O=P-O O O N Nitrogenous base C4 C1 (A, G, C, or T) Sugar Nitrogen 9 of purines and (deoxyribose) 1 of pyrimidines are C3 C 2 Dr. Suheir Ereqat 2023-2024 bonded to C1 of ribose or deoxyribose “Bases” 2 purine bases Adenine: A Guanine: G A G Bases Pyrimidines Purines C T U 2 pyrimidine bases (in DNA) Cytosine: C Thymine: T or Uracil: U Dr. Suheir Ereqat 2023-2024 (in RNA, instead of Thymine)  DNA Two strands coiled called a double helix Sides made of a pentose sugar Deoxyribose bonded to phosphate (PO4) groups by phosphodiester bonds Center made of nitrogen bases bonded together by weak hydrogen bonds Dr. Suheir Ereqat 2023-2024 Nucleotide subunits are linked together by phosphodiester bonds This nucleic acid chain is represented as ( 5’ C-A-G 3’ ) always in 5’ to 3’ direction left to right. 5’ phosphate group on the 5’ of the sugar and a 3’ hydroxyl of the sugar Dr. Suheir Ereqat 2023-2024  Polynucleotide 5-phosphate group of one nucleotide unit is joined to the 3-hydroxyl group of the next nucleotide, creating a phosphodiester linkage Dr. Suheir Ereqat 2023-2024 Watson (left) and Crick (right) provided a three dimensional model of the structure of DNA. Dr. Suheir Ereqat 2023-2024 Native DNA is a double helix of complementary antiparallel chains held together by: 1- Hydrogen bonding between complementary base pairs (A-T or G-C) 2- Hydrophobic interactions between planar bases/ stacked adjacent bases. This contributes to the stability of the double helix. Dr. Suheir Ereqat 2023-2024 DNA Double Helix “Rungs of ladder” Nitrogenous Base (A,T,G or C) “Legs of ladder” Phosphate & Sugar Backbone Dr. Suheir Ereqat 2023-2024