Nucleic Acids ppt
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The document provides an overview of nucleic acids, including their history, structure, and classification. It details the four structural levels of nucleic acids and outlines differences between DNA and RNA, including their roles in cellular processes. The conclusion emphasizes the importance of nucleotides and nucleosides in genetic information transfer.
Nucleic Acids ppt
- 1. Subject: Biochemistry Topic : Nucleic acids Date : 27 September 2014
- 3. CONTENTS Introduction to Nucleic acids History of Nucleic acids Structure of Nucleic acids Description of Nucleic acids Chemical structure of DNA and RNA Classifications of Bases Sites of Nucleic acids Names of Nucleosides and Nucleotides Conclusion References
- 4. Structure of Nucleic acids NA structure is often divided into four different levels: Primary structure Secondary structure Tertiary structure Quaternary structure
- 5. Primary structure: consists of a linear sequence of nucleotides that are linked together by phosphodiester bond. Nucleotides consists of 3 components: Nitrogenous base 5-carbon sugar One or more phosphate groups
- 6. Secondary structure This is the set of interactions between bases. In DNA double helix, the two strands of DNA are held together by hydrogen bonds. The nucleotides on one strand base pairs with the nucleotide on the other strand. The secondary structure is responsible for the shape that the nucleic acid assumes.
- 7. Tertiary structure This is the locations of atoms in three-dimensional space, taking into consideration geometrical and steric constraits. A higher order than the secondary structure in which large scale folding in a linear polymer occurs and the entire chain is folded into a specific 3-dimensional shape.
- 8. Quaternary structure This is similar to that of protein quaternary structure. Although some of the concepts are not exactly the same. QS refers to a higher level of organization of nucleic acids moreover, it refers to the interactions of the nucleic acids with other molecules.
- 9. NNuucclleeiicc AAcciiddss Nucleic acids are molecules that store information for cellular growth and reproduction There are two types of nucleic acids: - deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) These are polymers consisting of long chains of monomers called nucleotides A nucleotide consists of a nitrogenous base, pentose sugar and a phosphate group.
- 10. DNA and RNA are nucleic acids, long, thread-like polymers made up of a linear array of monomers called nucleotides All nucleotides contain three components: 1. A nitrogen heterocyclic base 2. A pentose sugar 3. A phosphate residue
- 11. Ribonucleotides have a 2’-OH Deoxyribonucleotides have a 2’-H
- 12. Bases are classified as Pyrimidines or Purines
- 13. Nucleus Cytoplasm replication DNA transcription RNA (mRNA) translation Proteins
- 17. reverse transcription messenger RNA (mRNA) transfer RNA (tRNA) ribosomal RNA (rRNA)
- 18. Names of Nucleosides and Nucleotides
- 19. X-ray diffraction patterns produced by DNA fibers Rosalind Franklin and Maurice Wilkins
- 20. 1962 Nobel Prize in Physiology or Medicine for their discoveries concerning the molecular structure of nucleic acids and its significance for information transfer in living material" James Watson Francis Crick Maurice Wilkins
- 21. DDNNAA ccoonnffoorrmmaattiioonnss AA-- DDNNAA BB--DDNNAA ZZ--DDNNAA Helix Right-handed Right-handed Left-handed Width Widest Intermediate Narrowest Planes of bases planes of the base pairs inclined to the helix axis planes of the base pairs nearly perpendicular to the helix axis planes of the base pairs nearly perpendicular to the helix axis Central axis 6A hole along helix axis tiny central axis no internal spaces Major groove Narrow and deep Wide and deep No major groove Minor groove Wide and shallow Narrow and deep Narrow and deep
- 22. BB--DDNNAA Right-handed helix intermediate planes of the base pairs nearly perpendicular to the helix axis tiny central axis wide + deep major groove narrow + deep minor groove
- 23. DNA conformations AA-- DDNNAA Right-handed helix Widest planes of the base pairs inclined to the helix axis 6A hole along helix axis narrow + deep major groove Wide + shallow minor groove
- 24. DNA conformations ZZ--DDNNAA Left-handed helix Narrowest planes of the base pairs nearly perpendicular to the helix axis no internal spaces no major groove narrow + deep minor groove
- 25. BB AA ZZ
- 27. Direction of Replication The enzyme helicase unwinds several sections of parent DNA At each open DNA section, called a replication fork, DNA polymerase catalyzes the formation of 5’-3’ester bonds of the leading strand The lagging strand, which grows in the 3’-5’ direction, is synthesized in short sections called Okazaki fragments The Okazaki fragments are joined by DNA ligase to give a single 3’-5’ DNA strand
- 28. Ribonucleic Acid (RNA) RNA is much more abundant than DNA There are several important differences between RNA and DNA: - the pentose sugar in RNA is ribose, in DNA it’s deoxyribose - in RNA, uracil replaces the base thymine (U pairs with A) - RNA is single stranded while DNA is double stranded - RNA molecules are much smaller than DNA molecules There are three main types of RNA: - ribosomal (rRNA), messenger (mRNA) and transfer (tRNA)
- 29. Types of RNA
- 30. Ribosomal RNA and Messenger RNA Ribosomes are the sites of protein synthesis - they consist of ribosomal DNA (65%) and proteins (35%) - they have two subunits, a large one and a small one Messenger RNA carries the genetic code to the ribosomes - they are strands of RNA that are complementary to the DNA of the gene for the protein to be synthesized
- 31. Transfer RNA Transfer RNA translates the genetic code from the messenger RNA and brings specific amino acids to the ribosome for protein synthesis Each amino acid is recognized by one or more specific tRNA tRNA has a tertiary structure that is L-shaped - one end attaches to the amino acid and the other binds to the mRNA by a 3-base complimentary sequence
- 33. Important conclusion NUCLEIC ACIDS NUCLEOTIDES NUCLEOSIDES PHOSPHORIC ACID NITROGENOUS BASES SUGAR purines and pyrimidines ribose and deoxyribose A & G C,T & U
- 34. REFERENCES: CYTOLOGY BY S. CHANDS AND BIOCHEMISTRY TEXTBOOK BY U. SATYANARAYANA
Editor's Notes
- #14: The nucleus contains the cell’s DNA, which makes up the genome. The nucleus is surrounded by a nuclear envelope, two membrane bilayers Molecules come into and out of the nucleus through nuclear pores The inside of the nucleus is called the nucleoplasm. Chromatin is the name given to DNA complexed with proteins (histones) The nucleolus is a region where the DNA is concentrated for replication
- #20: Figure 6.6
- #33: "Dictionary" of amino acid code words in mRNAs. The codons are written in the 5′→3′ direction. The third base of each codon (in bold type) plays a lesser role in specifying an amino acid than the first two. The three termination codons are shaded in pink, the initiation codon AUG in green. All the amino acids except methionine and tryptophan have more than one codon. In most cases, codons that specify the same amino acid differ only at the third base.