1. LOGO Course lecturer : Jasmin Šutković 3th June 2016 Organic Chemistry – Spring 2016 Lecture 14 Nucleic acids and protein synthesis

2. CHAPTER OUTLINE International University of Sarajevo Nucleosides and Nucleotides Nucleic Acids The DNA Double Helix Replication RNA Transcription The Genetic Code Translation and Protein Synthesis Book chapter 22

3. Introduction  WHETHER you are tall or short, fair-skinned or dark-complexioned, blue-eyed or brown-eyed, your unique characteristics are determined by the nucleic acid polymers that reside in the chromosomes of your cells.  The nucleic acid DNA stores the genetic information of a particular organism, while the nucleic acid RNA translates this genetic information into the synthesis of proteins needed by cells for proper function and development.  Even minor alterations in the nucleic acid sequence can have significant effects on an organism, sometimes resulting in devastating diseases like sickle cell anemia and cystic fibrosis.

4. NUCLEOSIDES AND NUCLEOTIDES  Nucleic acids are unbranched polymers composed of repeating monomers called nucleotides.  There are two types of nucleic acids. 1.DNA, deoxyribonucleic acid, stores the genetic information of an organism and transmits that information from one generation to another. 2.RNA, ribonucleic acid, translates the genetic information contained in DNA into proteins needed for all cellular functions. The nucleotide monomers that compose DNA and RNA consist of three components—a monosaccharide, a nitrogen-containing base, and a phosphate group.

5. About DNA  Found in Chromosomes  Humans have 46 – other species have different numbers  Chromosomes are divided into genes  A gene is a portion of the DNA molecule responsible for the synthesis of a single protein.

6. NUCLEOSIDES—JOINING A MONOSACCHARIDE AND A BASE The nucleotides of both DNA and RNA contain a five-membered ring monosaccharide, often called simply the sugar component. In RNA, the monosaccharide is the aldopentose D-ribose. In DNA the monosaccharide is D-2-deoxyribose, an aldopentose that lacks a hydroxyl group at C2.

7. Bases Only five common nitrogen-containing bases are present in nucleic acids. Three bases with one ring (cytosine, uracil, and thymine) are derived from the parent compound pyrimidine. Two bases with two rings (adenine and guanine) are derived from the parent compound purine. Each base is designated by a one-letter abbreviation.

9.  Nucleotides are formed by adding a phosphate group to the 5'-OH of a nucleoside.  Ribonucleotides are derived from ribose, while deoxyribonucleotides are derived from 2- deoxyribose. NUCLEOTIDES—JOINING A NUCLEOSIDE WITH A PHOSPHATE

12. NUCLEIC ACIDS Nucleic acids—both DNA and RNA—are polymers of nucleotides, formed by joining the 3'-OH group of one nucleotide with the 5'-phosphate of a second nucleotide in a phosphodiester linkage.

14. THE DNA DOUBLE HELIX  Our current understanding of the structure of DNA is based on the model proposed initially by James Watson and Francis Crick in 1953  DNA consists of two polynucleotide strands that wind into a right-handed double helix.

17. The double helix is stabilized by hydrogen bonding between the bases of the two DNA strands as shown in Figure 22.4. A purine base on one strand always hydrogen bonds with a pyrimidine base on the other strand. Two bases hydrogen bond together in a predictable manner, forming complementary base pairs. Adenine pairs with thymine using two hydrogen bonds, forming an A–T base pair. Cytosine pairs with guanine using three hydrogen bonds, forming a C– G base pair.

19. Central Dogma  What comes after...how we synyhesise the protein then?

20.  Each chromosome contains many genes, those portions of the DNA molecules that result in the synthesis of specific proteins.  We say that the genetic message of the DNA molecule is expressed in the protein. Only a small fraction (1–2%) of the DNA in a chromosome contains genetic messages or genes that result in protein synthesis.

21. REPLICATION

23. RNA While RNA is also composed of nucleotides, there are important differences between DNA and RNA.  In RNA, The sugar is ribose.  U (uracil) replaces T (thymine) as one of the bases.  RNA is single stranded. RNA molecules are much smaller than DNA molecules  Ribosomal RNA (rRNA)  Messenger RNA (mRNA)  Transfer RNA (tRNA)

24. TRANSCRIPTION  The conversion of the information in DNA to the synthesis of proteins begins with transcription— that is, the synthesis of messenger RNA from DNA.

25. The genetic code  From DNA to RNA....so how can small mRNA make a protein ? Its because the GENETIC CODE For example, the codon UAC in an mRNA molecule codes for the amino acid serine, and the codon UGC codes for the amino acid cysteine. The same genetic code occurs in almost all organisms from bacteria to whales to humans.

27. The translation of the information in messenger RNA to protein synthesis occurs in the ribosomes. Each type of RNA plays a role in protein synthesis.  mRNA contains the sequence of codons that determines the order of amino acids in the protein.  Individual tRNAs bring specifi c amino acids to add to the peptide chain.  rRNA contains binding sites that provide the platform on which protein synthesis occurs. Each individual tRNA contains an anticodon of three nucleotides that is complementary to th codon in mRNA and identifi es individual amino acids. For example, a codon of UCA in mRNA corresponds to an anticodon of AGU in a tRNA molecule, which identifi es serine as the amino acid. TRANSLATION AND PROTEIN SYNTHESIS

29. Mutations

30.  Final Exam (PowerPoint lecture 7-14)  Following the powerpoint read your book Accordingly !  All calculation problems may be in the exam  You can expect 10 questions!  Being your own calculator-no sharing allowed!!!!!