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Nucleic Acid Structure and Organization

Nucleic Acid Structure and Organization. Asmarinah Department of Medical Biology. Nucleic acid. - Macromolecules consisting of a chain of nucleotides joined together by phosphodiester bonds. divided into: DNA (Deoxyribonucleic acid) molecules RNA (Ribonucleic acid) molecules.

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Nucleic Acid Structure and Organization

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  1. Nucleic Acid Structure and Organization Asmarinah Department of Medical Biology

  2. Nucleic acid - Macromolecules consisting of a chain of nucleotides joined together by phosphodiester bonds • divided into: • DNA (Deoxyribonucleic acid) molecules • RNA (Ribonucleic acid) molecules

  3. DNA and its building • DNA is made from subunits, called nucleotides • Each nucleotide consisting of • Sugar (deoxyribose) • Phosphate • Base: Adenine • Thymine • Guanine • Cytosine

  4. DNA - Gene A gene is defined as a segment of DNA that contains the insctruction for making a particular protein

  5. ● DNA molecules are organized into chromosome ● Chromosome: A DNA molecule with its attendant proteins that moves as an independent units during mitosis and meiosis Before DNA replication, each chromosome consists of a single DNA molecule plus protein, is called a chromatid After replication, each chromosome consists of two identical DNA molecule plus proteins; this are called sister chromatids ● Chromatin: DNA plus the proteins that package it within the cell nucleus

  6. A B C • The principal structural features of chromosome • An electron micrograph of human mitotic chromosomes • A diagram of various classes of human chromosomes

  7. Chromatin packing occurs on several levels

  8. Structural organization of nucleosome Nucleosome contains Octameric histon protein & DNA double helix

  9. Genome The totality of genetic information belonging to a cell or an organism; in particular, the DNA that carries this information Genomics The science of studying the DNA sequences and properties of entire genomes

  10. Human Genome Each human chromosome has a unique banding pattern

  11. The Organization of human genome

  12. Conserved gene order in chromosome between the human (a) and mouse (b) genome

  13. Closely related species can have very different chromosome numbers

  14. Chromosomes from many eucaryotes (including human) contain a large excess of interspersed DNA that does not seem to carry critical information, called junk DNA • This DNA may not be important, but can play a role: - as spacer material - for long-term evolution of the species - for the proper expression of genes Bacteria and some single-celled eucaryotes have especially compact genomes. The complete nucleotide sequence of their genomes reveals that DNA molecules are little more than strings of closely packed genes

  15. Mitochondrial DNA • Chromosome No. 25 • Genome  circular double stranded DNA • Maternal inherited • Mito DNA : 16.569 bp Nuclear DNA : 3 x 109 bp

  16. The structure of mitochondria • contains two membranes: • * outer mitochondrial membrane • * inner mitochondrial membrane • There is two aqueous compartment: • * Matrix, within the interior • * Intermembrane space, between • OMM and IMM

  17. Role of mitochondria produce ATP 5 respiration enzyme complexes complex I (NADH oxydoreductase : Ubiquinone) complex II (suksinat oxydoreductase : ubiquinone) complex III (ubiquinol oxydoreductase : sitokrom c) complex IV (Cytocrome c oxydase) complex V (ATPsynthase).

  18. The genome of E. coli • E.coli strain K-12 has 4.639.221 nucleotides pairs • A diagram of the E. coli genome. E. Coli genome is circular that forms a single, closed loop. Yellow or orange bars shows protein-coding genes Green arrows indicate genes encoding only RNA molecules

  19. Genetic differences between pathogen and nonpathogen bacteria

  20. Example: Genetic organization of Vibrio cholerae A. Vibrio cholerae has two circular chromosomes, that each of its has distinct origin of replication (oriC1 & oriC2) CTXφ locus carriers the gene for cholera toxin VPI island contains gene for factors required for intestinal colonization B. Map of CTXφ locus consist of: - core region: gene for cholera toxin ctxA & ctxB gene for involving of virulence (ace & zot) - repeated sequence RS2 & RS1 that involved chromosomal insertion of bacteriophage genome

  21. Schematic drawings of several types of viral genomes

  22. RNA • Polymer formed from covalently linked ribonucleotide monomer • Type of RNA: • mRNA = messenger RNA, code for protein • rRNA = ribosomal RNA, form basic structure of ribosome and catalyze protein synthesis • tRNA = tranfer RNA, central to protein synthesis as adaptors between mRNA and amino acids

  23. snRNA = small nuclear RNA, function an variety of nuclear process • snoRNA = small nucleolar RNA, used to process and chemically modify rRNA • scaRNA = small cajal RNA, used to modify snoRNA and snRNA • miRNA = microRNA, regulate gene expression typically by blocking translation of selective mRNA • siRNA = small interfering RNA, turn off gene expression by directing degradation of selective mRNA and the establishment of compact chromatin structure

  24. mRNA

  25. References: • Albert et al., 2008. Molecular biology of the cell. 5th ed. • Albert et al., 2004. Essential of cell biology. • Pollard and Earnshaw. 2004. Cell biology.

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