Pharos university Faculty of Allied Medical SCIENCE Biochemistry 1 ( MGBC-101 )

1. Pharos universityFaculty of Allied Medical SCIENCEBiochemistry 1(MGBC-101) Dr. Tarek El Sewedy Department of Medical Laboratory Technology Faculty of Allied Medical Sciences

2. Lecture19/12/2013 Nucleic Acids Structure and Function

3. Intended Learning Outcomes • By the end of this lecture, students will learn: • Recognize the structure of nucleosides and nucleotide. • Identify functions of nucleotides. • Recognize the structure of DNA and RNA. • Learn Polymerase chain reaction (PCR) • Identify the biological importance of DNA and RNA.

4. Lecture Content • Nitrogenous bases (Purines and Pyrimidines) • Nucleosides • Nucleotides • Nucleic acids (DNA and RNA) Structure and function • Polymerase chain reaction

5. Nucleic Acid Structure

6. Purines and pyrimidine bases are nitrogen-containing heterocycles compounds whose rings contain both carbon and Nitrogen (hetero atoms). • The smaller pyrimidine has the longer name and the larger purine the shorter name A. Nitrogenous BasesPurines and pyrimidine

7. Nucleosides consist of nitrogenous base bound to a ribose (RNA) or deoxyribose sugar(DNA) via a glycosidic bond. B. Nucleosides

8. consists of a nucleoside (Nitrogenous base and sugar) bonded to one or more phosphate groups. C. Nucleotides

9. Nucleotides monophosphates

10. Nucleotides are the monomers or building blocks of nucleic acids (DNA and RNA). • Adenosine triphosphates ATP is the central cellular energy source. • Forming important coenzymes such as NAD+, NADP+, FAD and co A. • Intermediates in lipids, carbohydrates and protein biosynthetic reactions. • Cyclic nucleotides are 2nd messenger and regulators of many cellular metabolic pathways. Nucleotides Biological functions

11. Adenosine tri-phosphate (ATP) energy source for many reactions in living organisms. Phosphates are well-known high-energy molecules, meaning that high levels of energy are released when the phosphate groups are removed

12. D. NUCLEIC ACIDS DNA & RNA

13. They are polymers of nucleotides. They carry genetic information within cells. They are usually either single-stranded or double-stranded. D. NUCLEIC ACIDS They are made of three components, 1. nitrogenous bases (purines and pyrimidine) 2. 5-carbon sugars (Ribose in RNA or deoxyribose in DNA) 3. phosphate groups.

14. Forms of Nucleic acids Two-stranded double helix single stranded RNA DNA

15. Adenine, guanine, and cytosine are found in bothRNA and DNA, while thymine occurs only in DNA and uracil only in RNA.

16. Deoxyribose Sugar Ribose Sugar Difference between Ribose and Deoxyribose

17. (1) In RNA, the sugar moiety to which the phosphates and purine and pyrimidine bases are attached is riboserather than the 2′-deoxyribose of DNA. (2) The pyrimidine components of RNA differ from those of DNA. Although RNA contains the ribonucleotides of adenine, guanine, and cytosine, it does not possess thymine. Instead of thymine, RNA contains the ribonucleotide of uracil. (3) RNA exists as a single strand, whereas DNA exists as a double-stranded. (4) Since the RNA molecule is a single strand its guanine content does not necessarily equal its cytosine content, nor does its adenine content necessarily equal its uracil content. THE CHEMICAL NATURE OF RNA DIFFERS FROM THAT OF DNA

19. Base pairing • Base pairing between Adenosine (A) and Thymidine (T) involves the formation of twohydrogen bonds. • Three hydrogen bonds are formed between Cytosine (C) and Guanosine (G)

20. Double helix • The bases occupy the centeral core of helix • Sugar –phosphate run along external backbone. • Complementary base pairing (G binds C),(A binds T) • The length of DNA is measured by bp and Kb. Structure Characteristics of DNA

21. -The Main Function of DNA can be summarized in: Carrying the genetic information for all biological functions of the cell. FUNCTION of DNA

22. Function of RNA • Messenger RNA (mRNA) • Ribosomal RNA (rRNA) • Transfer RNA (tRNA) RNA plays essential role in Protein Biosynthesis Through the 3 types mentioned above

23. Although the structure of DNA is the same throughout all species of plants, animals and microorganisms, each individual organism looks different. This is due to the DNA base pairs sequence. Not only does this order make you a human rather than a dog or a monkey, it also makes each person unique. • Sequences of DNA differ from person to person, but every cell within the same person contains the same sequence of DNA. So, your hair, blood, skin and all of the other cells in your body are exactly the same at the molecular level. DNA similarity

24. Inside cells During DNA replication the two strands of the DNA must be separated from one another by enzymes called helicasesthat uses chemical energy (from ATP). • In the laboratory, DNA can be disrupted by heating DNA. The heating disrupts the hydrogen bonds between base pairs and thereby causes the strands to separate. • Separated complementary strands of nucleic acids spontaneously reassociate to form a double helix when the temperature is lowered below T m. This renaturationprocess is sometimes called annealing. • The ability to denature and reannealDNA in the laboratory provides a powerful tool for some molecular biology techniques such as Polymerase chain reaction (PCR). The DNA Double Helix Can Be Reversibly Melted (Denatured)

25. Polymerase Chain reaction PCR allows scientists to amplify and analyze bits of DNA from trace amounts of DNA samples. PCR is an essential element in DNA fingerprinting and in the sequencing of genes and entire genomes. Basically, It’s like a technique to photocopy pieces of DNA. In a matter of a few hours, a single DNA sequence can be amplified to millions of copies.

26. Typically, PCR consists of a series of 20-40 repeated temperature changes, called cycles, with each cycle commonly consisting of 3 discrete temperature steps • Denaturation. • Annealing. • Extension. PCR Procedures

27. Stage one is a hotstage called denaturationAt 90◦C temperature opens up the DNA for copying. • Stage two is a coolingor annealingthat permits the DNA to attach to chemicals needed to copy it. • Stage three is a warmtemperature cycle called the extension. It encourages the growth of the DNA strand. PCR Procedures

28. DNA template that contains the DNA region (target) to be amplified. • Two primers that are complementary to the 3' (three prime) ends of each of the sense and anti-sense strand of the DNA target. • Taq polymerase or another DNA polymerase with a temperature optimum at around 70 °C. • Deoxynucleoside triphosphates dNTPs, the building blocks from which the DNA polymerases synthesizes a new DNA strand. • Buffer solution, providing a suitable chemical environment for optimum activity and stability of the DNA polymerase. Requirements for PCR

29. Medicine: Detection of mutations in genes causing tumor. • Infectious disease: early diagnosis of viruses such as AIDS. • Forensic: Human DNA fingerprinting. • Research: identification of certain DNA or RNA regions. Applications of PCR

30. Write three points about : • i-Function of nucleotides • 1- • 2- • 3- • Correct the incorrect word: • Nucleosides are made from a ring of nitrogen, carbon and oxygen atoms together with a six-carbon sugar. • DNA is polymer of nucleotides and contains ribose sugar. Study Question

31. Choose: 1-Nucleotide consists of • a-Sugar+ Nitrogenous base+phosphate group • B- Nitrogenous base+phosphate group. • C- Sugar+ Nitrogenous base 2- DNA is polymer of • a-Nucleoside • b-Nucleotides • c-Nitrogenous base

32. Principles of Biochemistry, Donald J. Voet, Judith G. Voet, Charlotte W. pratt; Willey, 3rd ed. Suggested readings