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Nucleic acids

Nucleic acids. Nucleosides & Nucleotides Nucleic Acids DNA & Replication RNA & Transcription Genetic Code & Protein Synthesis Genetic Mutations Recombinant DNA Viruses. Nucleic acids. Nucleic acids : Maintain genetic information Determine Protein Synthesis

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Nucleic acids

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  1. Nucleic acids • Nucleosides & Nucleotides • Nucleic Acids • DNA & Replication • RNA & Transcription • Genetic Code & Protein Synthesis • Genetic Mutations • Recombinant DNA • Viruses

  2. Nucleic acids • Nucleic acids: • Maintain genetic information • Determine Protein Synthesis • DNA = deoxyribonucleic acid • “Master Copy” for most cell information. • Template for RNA • RNA = ribonucleic acid • Transfers information from DNA • Template for Proteins

  3. Nucleic Acids • In chromosomes • (in nucleus) Have genes 1 gene 1 enzyme Enzymes determine external & internal characteristics

  4. NUCLEIC ACIDS • Long chains (polymers) of repeating nucleotides. • Each nucleotide has 3 parts: A heterocyclic Amine Base A sugar A phosphate unit

  5. Nucleotide = phosphate + sugar + base Phosphate Base Sugar -N-glycosidic linkage Nucleoside = sugar + base

  6. Nucleic Acids • Nucleic Acids = polymers of Nucleotides. base B B B B B B P S P S P S P S P S P S phosphate sugar

  7. O O HOCH2 HOCH2 OH OH H H H H H H H H OH OH OH H THE SUGAR PART • The major difference between RNA and DNA is the different form of sugar used. Ribose C5H10O5 in RNA DeoxyRibose C5H10O4 in DNA The difference is at carbon #2.

  8. The Nitrogenous Bases • 5 bases used fall in two classes • Purines & Pyrimidines A double ring (6 & 5 members) A single ring (6 membered)

  9. The Nitrogenous Bases Purines: • Pyrimidines: Adenine (A) Guanine (G) Thiamine (T) In DNA only Uracil (U) In RNA only Cytosine (C)

  10. Nucleotides deoxyadenosine 5’ monophosphate (dAMP) Name based on sugar & base names followed by the # of phosphates..

  11. NH2 | C N N C CH O | O -- P -- O -- || O H C C N N - CH2 NH2 | O C N C H O | O -- P -- O -- || O C C H O N - CH2 O || O C N N H C CH O | O -- P -- O -- || O C C N H2N N - CH2 O || O CH3 C N H C O | O -- P -- O -- || O C C H O - N CH2 O OH Primary structure Similar to proteins with their peptide bonds and side groups. • Phosphate bonds • link DNA or RNA • nucleotides together • in a linear sequence.

  12. DNA - Primary Structure

  13. H - N N O | | N - H N N N N O | | N - H H3C H H O | | N | N - H N N N O | | N N Base pairing and H-bonding H- bonding between purines and pyrimidines.. guanine cytosine thymine adenine

  14. DNA - Secondary Structure • Complementary Base Pairing • Guanine pairs with Cytosine • Position of H bonds and distance match

  15. DNA - Secondary Structure • Complementary Base Pairing • Adenine pairs with Thymine • Position of H bonds and distance match

  16. C G T A G C C G A T Hydrogen bonding Each base wants to form either two or three hydrogen bonds. That’s why only certain bases will form pairs.

  17. Sugar-phosphate backbone DNA coils around outsideof attached bases like a spiral stair case. Results in a double helix structure.

  18. The double helix One complete twist is 3.4 nm The combination of the stairstep sugar-phosphate backbone and the bonding between pairs results in a double helix. 2 nm between strands Distance between bases = 0.34 nm

  19. DNA - Secondary Structure • Complementary Base Pairing

  20. The actual chain is like a coiled spring. • It is something similar to what happens when protein chains form an alpha helix. • It is the sequence (order) of the amines coming off of the backbone that give us all our genetic information • Just like the sequence of words in a sentence give it meaning. • Of the like in words meaning just sentence a give sequence it. (Get my meaning ? )

  21. Crick and Watson • (1962 Nobel Prize) • Proposed the basic structure of DNA • 2 strands wrap around each other • Strands are connected by H-bonds between the amines. • Like steps of a spiral staircase

  22. Chromosomes Chromosomes consists of DNA strands coiled around protein - histomes. The acidic DNA’s are attracted to the basic histones.

  23. It also was clear in the 1960s that the chromosomes of cells

  24. Chromosomes • The normal number of chromosome pairs varies among the species. • Animal Pairs Plant Pairs • Man 23 Onion 8 • Cat 30 Rice 14 • Mouse 20 Rye 7 • Rabbit 22 Tomato 12 • Honeybee, White pine 12 • male 8 Adder’s 1262 • female 16 tounge fern

  25. DNA: Self - Replication • When a cell nucleus divides, the bridging hydrogen bonds break (with the aid of enzymes) and the intertwined strands unwind from each other. • The amines left sticking out from each strand are now free to pick up new partners from the plentiful supply present in the cell.

  26. DNA Replication

  27. Replication of DNA Replication occurs on both halves in opposite directions.

  28. DNA Replication

  29. DNA Replication Okazaki fragments

  30. DNA Replication Okazaki fragments

  31. It is the linear sequence of paired bases (amines) along the DNA molecule that constitutes the Genetic Code. • Each series of amines that codes for a particular protein is called aGene.

  32. Flow of genetic information DNA Replication Transcription Flow of information is one way only. RNA Translation Protein

  33. RNA • Single strands of nucleotides where ribose is used in the sugar-phosphate backbone. • Several secondary structures (types) based on the particular role it plays. • RNA is produced by transcription of genes along a strand of DNA. • DNA may contain all the information but RNA does all of the work. (Kinda like the architect and the engineer. Or better yet, the teacher and the student. )

  34. Classes of RNA • Messenger RNA - mRNA • It carries a copy of the genetic information contained in DNA. Used as pattern to make proteins.

  35. RNA - THE MESSENGER (m/RNA) • DNA in the nucleus of the cell directs the sythesis of an RNA molecule. • The RNAwill carry the sequence of amines found on a particular portion of the DNA • Only a portion of a DNA strand is used to make any given RNA. • There needs to be a way to start and stop transcription. • The DNA has systems of promoter and termination base sequences.

  36. RNA synthesis In the first step, RNA polymerase binds to apromotor sequence on the DNA chain. This insures that transcription occurs in the correct direction. The initial reaction is to separate the two DNA strands.

  37. RNA synthesis initiation sequence termination sequence ‘Special’ base sequences in the DNA indicate where RNA synthesis starts and stops.

  38. RNA synthesis Once the termination sequence is reached, the new RNA molecule and the RNA synthase are released. The DNA recoils.

  39. The messenger RNA (mRNA) move outside the nucleus to the cytoplasm where Ribosomes are anxiously awaiting their arrival. 60 S rRNA 40 S rRNA Nucleus

  40. The messenger RNA (mRNA) move outside the nucleus to the cytoplasm where Ribosomes are anxiously awaiting their arrival. 60 S rRNA 40 S rRNA Nucleus

  41. The messenger RNA (mRNA) move outside the nucleus to the cytoplasm where Ribosomes are anxiously awaiting their arrival. 60 S rRNA 40 S rRNA Nucleus

  42. The messenger RNA (mRNA) move outside the nucleus to the cytoplasm where Ribosomes are anxiously awaiting their arrival. 60 S rRNA 40 S rRNA Nucleus

  43. 60 S rRNA 40 S Ribosomal RNA – rRNA: Platform for protein synthesis. Holds mRNA in place and helps assemble proteins. rRNA

  44. 60 S UUG AUG GCU AUG 3’ 5’ • The Ribosomes are like train stations • The mRNA is the train slowly moving through the station. rRNA Codons mRNA rRNA 40 S

  45. Transfer RNA - tRNA = • relatively small compared to other RNA’s (70-90 bases.) • transports amino acids to site of protein synthesis.

  46. Anticodons on t-RNA Site of amino acid attachment Point of attachment to mRNA Three base anticodon site

  47. Amino acid codons alanine GCA, GCC, GCG GCU, AGA, AGG arginine AGA, AGG, CGA CGC, CGG, CGU asparagine AAC, AAU aspartate GAC, GAU cysteine UGC, UGU glutamate GAA, GAG glutamine CAA, CAG glycine GAA, GCC, GGG GGU histidine CAC, CAU isoleucine AUA, AUC, AUU leucine CUA, CUC, CUG CUU, UUA, UUG lysine AAA, AAG methionine AUG phenylalanine UUC, UUU proline CCA, CCC CCG, CCU serine UCA, UCC UCG, UCU AGC, AGU threonine ACA, ACC ACG, ACU tryptophan UGG tyrosine UCA, UCU valine GUA, GUC GUG, GUU

  48. activated AA fMET anticodon C A G Protein Synthesis1: Activation • Each AA is activated by reacting with an ATP • The activated AA is then attached to particular tRNA... (with the correct anticodon)

  49. Aa + adenosine 5’ triphosphate (ATP)

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