1 WELCOME TO The Presentation

2 SUBMITTED By Md. Tanjir Islam

3 SUMMARY I mainly work on the structure, types of nucleic acid, brief description on DNA,RNA,their functions & try to make comparision between them. BY Md. Tanjir Islam

4 AREAS OF WORKS DONE BY THE MEMBERSNAME OF THE MEMBER WORK ON THE TOPICS SLIDE RANGE Introduction, Discovery of nucleic acid, Types, Distribution, STRUCTURE, Bases, Properties of pyrimidines & purines,Comparision between DNA & RNA, Introduction of DNA 1-19 Md. Tanjir Islam History,storage ,structure of single chain DNA 20-27 Structure of DNA(DNA Double Helix) 28-35 Introduction,storage,composition ,Types of RNA 36-40 mRNA,rRNA,tRNA Structure & Function 41-48

5 Introduction •Nucleic acids are large biological molecules essential for all known forms of life •Nucleic acids are the most important biological macromolecules •Although first discovered within the nucleus of eukaryotic cells, nucleic acids are now known to be found in all life forms as well as some nonliving entities, including within bacteria, archaea, mitochondria, chloroplasts, viruses and viroids. •Nucleic acids are involved in the storage and transfer of genetic information in all living organisms, including the simplest viruses.

6 Discovery of nucleic acidNucleic acids were discovered by Friedrich Miescher in 1869 Isolated what he called nuclein from the nuclei of pus cells Nuclein was shown to have acidic properties, hence it became called nucleic acid. Friedrich Miescher

7 Types of nucleic acid are foundTwo types of nucleic acid are found Deoxyribonucleic acid (DNA) Ribonucleic acid (RNA)

8 Distribution of nucleic acidsDNA is found in the nucleus with small amounts in mitochondria and chloroplasts. RNA is found throughout the cell.

9 NUCLEIC ACID STRUCTURENucleic acids are polynucleotides Nucleic acids are the third class of biopolymers (polysaccharides and proteins being the others) These are polymers consisting of long chains of monomers called nucleotides The monomeric units for nucleic acids are nucleotides

10 Nucleotides are made up of three structural subunitsA Nitrogenous Base (purine or pyrimidine) A Five-Carbon Sugar(ribose or deoxyribose) A Phosphate Group

11 General Structure Of Nucleotides

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13 Nitrogen Bases The nitrogen bases in nucleotides consist of two general types: - purines: adenine (A) and guanine (G) - pyrimidines: cytosine (C), thymine (T) and Uracil (U) Purine – aromatic organic compound that consists of a pyrimidine ring and an imadazole ring (C3H4N2). Pyrimidine – aromatic organic compound with 2 nitrogens at C1 & C3 of a six membered ring.

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15 Pentose Sugars There are two related pentose sugars:- RNA contains ribose - DNA contains deoxyribose The sugars have their carbon atoms numbered with primes to distinguish them from the nitrogen bases.

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17 Properties of pyrimidines & purinesPyrimidine conformations are planar; purines are somewhat puckered - Plain pyrimidines and purines have low solubility (not many polar bonds) - Cytosine, Thymine, Uracil, Guanine, and Adenine are more soluble because they have many polar groups that are available for hydrogen bonding. - Because they are aromatic, pyrimidines and purines can all absorb UV light. - DNA & RNA concentration in a sample can be found by measuring UV absorbance.

18 Comparision between DNA & RNAProperties DNA RNA Stands for DeoxyriboNucleicAcid RiboNucleicAcid Predominant Structure Typically a double- stranded molecule with a long chain of nucleotides A single-stranded molecule in most of its biological roles and has a shorter chain of nucleotides Bases four different bases: adenine, guanine, cytosine and thymine four different bases: adenine, guanine, cytosine, and uracil Pairing of Bases A-T(Adenine-Thymine), G-C(Guanine-Cytosine) A-U(Adenine-Uracil), G-C(Guanine-Cytosine) Sugars deoxyribose ribose Job/Role Medium of long-term storage and transmission of genetic information transfer the genetic code need for the creation of proteins from the nucleus to the ribosome. this process prevents the DNA

19 DNA DNA stands for deoxyribose nucleic acidThis chemical substance is present in the nucleus of all cells in all living organisms DNA controls all the chemical changes which take place in cells The kind of cell which is formed, (muscle, blood,nerve etc) is controlled by DNA The kind of organism which is produced (buttercup,giraffe, herring, human etc) is controlled by DNA

20 A HISTORY OF DNA Discovery of the DNA double helixA. Frederick Griffith – Discovers that a factor in diseased bacteria can transform harmless bacteria into deadly bacteria (1928) B.Rosalind Franklin - X-ray photo of DNA. (1952) C.Watson and Crick - described the DNA molecule from Franklin’s X-ray.(1953)

21 DNA In The human Genome The human genome (diploid) consists of about 6 x 109 base pairs of DNA. The DNA is divided into chromosomes that each contain a linear double-helical DNA molecule of about 200 x 106 base pairs. Prior to cell division, the DNA condenses into discrete chromosomes, visible by microscopy. A diploid cell has 46 chromosomes; 22 pairs of ‘normal’ chromosomes and 2 sex chromosomes

22 Storage of DNA In eukaryotic cells (animals, plants, fungi) DNA is stored in the nucleus, which is separated from the rest of the cell by a semipermeable membrane The DNA is only organized into chromosomes during cell replication Between replications, the DNA is stored in a compact ball called chromatin, and is wrapped around proteins called histones to form nucleosomes

23 DNA is a very large molecule made up of a longchain of sub-units The sub-units are called nucleotides Each nucleotide is made up of a sugar called deoxyribose a phosphate group -PO4 and an organic base

24 Ribose is a sugar, like glucose, but with only fivecarbon atoms in its molecule Deoxyribose is almost the same but lacks one oxygen atom Both molecules may be represented by the symbol

25 The most common organic bases areAdenine (A) Thymine (T) Cytosine (C) Guanine (G)

26 PO4 The deoxyribose, the phosphate and one of the basesNucleotides The deoxyribose, the phosphate and one of the bases Combine to form a nucleotide adenine deoxyribose PO4 It is the phosphate group which gives DNA its acidic properties

27 Structure of Single DNA ChainDNA is a long chain of deoxyribose units linked by phosphodiester links. The phosphate on the 5’ carbon is linked to the –OH on the 3’ carbon along the chain. On each deoxyribose there is a base. The chain has two ends. The 5’ end and the 3’ end. It is not symmetrical. The primary sequence is the linear sequence of the bases. By convention, the nucleotide sequence is specified in the 5’ to 3’ direction.

28 Single DNA chain

29 Structure of DNA:The Double HelixJames D. Watson and Francis H. C. Crick proposed a structure for DNA in 1953. Watson and Crick's structure was based on: •Chargaff's observations •X-ray crystallographic data of Maurice Wilkins and Rosalind Franklin •Model building

30 Watson and Crick proposed a double-stranded structure for DNA in which a purine or pyrimidine base in one chain is hydrogen bonded to its complement in the other. Gives proper Chargaff ratios (A=T and G=C) Because each pair contains one purine and one pyrimidine, the A---T and G---C distances between strands are approximately equal. Complementarity between strands suggests a mechanism for copying genetic information.

31 DNA Double Helix P O 1 2 3 4 5 P O 1 2 3 4 5 G C T A

32 DNA Double Helix “Rungs of ladder” Nitrogenous Base (A,T,G or C)“Legs of ladder” Phosphate & Sugar Backbone

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34 Advantages to Double HelixStability---protects bases from attack by H2O soluble compounds and H2O itself. Provides easy mechanism for replica

35 Ribonucleic Acid Ribonucleic Acid – polymer of nucleic acids (polynucleotide) Functions as template for translating genes into proteins, transfers amino acids to the ribosome site on a growing polypeptide chain, etc. Unlike DNA, RNA is single-stranded and consists of a shorter nucleotide chain. Hydroxyl group on the ribose causes RNA to be less stable than DNA because it is easier to undergo hydrolysis. - Contains Adenine, Guanine, Cytosine, and Uracil

36 Structure of RNA Single stranded Ribose Sugar 5 carbon sugarPhosphate group

37 The bases in RNA are: adenine (A), guanine (G), cytosine (C), uracil (U).

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40 Ribosomal RNA: rRNA is a type of RNA that is a component of ribosomes and plays a role in the process of translation (making protein from nucleic acid sequence). Ribosomal RNAs (rRNAs) are found in association with several proteins as components of the ribosomes-the complex structures that serve as the sites for protein synthesis. There are three distinct size species of rRNA (23S. 16S. and 5S) in prokaryotic cells and four rRNA size species (28S. 18S. 5.8S. and 5S) In the eukaryotic cytosol. rRNAs species make up 80% of the total RNA in the cell.

41 Transfer RNA: tRNAs are RNA molecules that provide the means of translating the genetic code. One end of the tRNA contains a three nucleotide sequence called the anticodon loop that is complementary to the codon of the mRNA. The other end of the tRNA is covalently attached to a specific amino acid. Transfer RNAs (tRNAs), the smallest of the three major species of RNA molecules (4S), have between 74 and 95 nucleotide residues. tRNAs species make up about 15 % of the total RNA in the cell. The tRNA molecules contain unusual bases e.g. dihydrouracil, and have extensive intrachain base-pairing (Figure 1). Each tRNA serves as an 'adaptor" molecule that carries its specific amino acid-covalently attached to its 3’ end-to the site of protein synthesis.

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43 Messenger RNA : Messenger RNAs are RNA molecules that carry the "message" from the DNA to the ribosomes to be translated into protein. The "message" in mRNA is carried in groups of three nucleotides called codons. Each codon specifies one amino acid in a protein according to the rules of the genetic code. Messenger RNA (mRNA) comprises only about 5 % of RNA in the cell. It is the most heterogeneous type of RNA in size (500 to 6000 nucleotides) and base sequence. The mRNA carries genetic information from the nuclear DNA to the cytosol where it is used as the template for protein synthesis. Special structural characteristics of eukaryotic mRNA (but not prokaryotic) include a long sequence of adenine nucleotides (a 'poly-A tail) on the 3’ -end of the RNA chain plus a 'cap' on the 5’ -end consisting of a molecule of 7-methylguanosine attached 'backward' (5'5') through a triphosphate linkage (Figure 2).

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45 The two main processes involved in protein synthesis are- the formation of mRNA from DNA (transcription) - the conversion by tRNA to protein at the ribosome (translation) Transcription takes place in the nucleus, while translation takes place in the cytoplasm Genetic information is transcribed to form mRNA much the same way it is replicated during cell division

46 REFERENCES(1) Marks Basic Principle Of Biochemistry.Lehninger Principle Of Biochemistry. Harpers Biochemistry. ABC Of Biochemistry- Dr. Mozamal. Pharmaceutical Biotechnology-S.P Vyas & V.k Dixit. Wilson Gisvolts Medicinal Chemistry.

47 REFERENCES(2) Adams, R. L., J. T. Knowler and D. P. Leader 1992 The Biochemistry of Nucleic Acids . 11th Ed. Chapman and Hall. Atkins J. F. and H. F. Noller 1993 Bringing RNA into View: RNA and its roles in Biology. Biological Science Curriculum Study (BSCS) Colorado Springs. (retrieved Jan 2005). Burton Z. F. and J. M. Kaguni Experiments in Molecular Biology: Biochemical Applications. Academic Press Snyder L. and W. Champness 2003 Molecular Genetics of Bacteria 2nd Ed. ASM Press Alberts B., D. Bray, J. Lewis, M. Rarr, K. Roberts, and J. D. Watson 1994 Molecular Biology of the Cell, 3rd Edition Garland Publishing Inc.

48 THANK YOU