1 / 63

Higher Level

Nucleic Acid Structure. Higher Level. Nucleotides. Nucleotides are carbon ring structures containing nitrogen linked to a 5-carbon sugar (a ribose) 5-carbon sugar is either a ribose or a deoxyribose In eukaryotic cells nucleic acids are either: Deoxyribose nucleic acids (DNA)

ata
Download Presentation

Higher Level

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Nucleic Acid Structure Higher Level

  2. Nucleotides • Nucleotides are carbon ring structures containing nitrogen linked to a 5-carbon sugar (a ribose) • 5-carbon sugar is either a ribose or a deoxyribose • In eukaryotic cells nucleic acids are either: Deoxyribose nucleic acids (DNA) Ribose nucleic acids (RNA)

  3. Coding and Non Coding Parts of Nucleotides • Non coding Structures = Sugar + Phosphate • Coding Structures = Base Sequences

  4. Structure of a Nucleotide • The Phosphate group and the Sugar form the sides of the DNA strand

  5. OH Base NH2 - P HO O H+ H O N N N N Phosphate H CH2 5’ O 1’ 4’ 3’ 2’ Sugar OH H OH ANucleotide

  6. Building DNA – Video and Activity http://www.zerobio.com/drag_gr9/DNA/dna.htm

  7. Nucleotides • The 4 DNA nucleotides • A & G = Purines • T & C = Pyrimidines

  8. To help you remember… • Purines = • the Attorney General is PURE • Pyrimidines = have the letter y • pYrimidines = thYmine and cYtosine

  9. Purine Bases • Adenine and Guanine Double ringed molecular structures Known as Purine Bases

  10. Pyrimidine Bases • Thymine and Cytosine Single ringed structures Known as Pyrimidine bases

  11. NH2 Thymine (DNA) Uracil (RNA) CH3 Adenine N N N N N O N N NH N O O O N O O NH NH N N N O NH2 NH2 Guanine Cytosine NH2 N N Purines Pyrimidines

  12. Base Numbers Number of Purine Bases = Number of Pyramidine Bases This led to the discovery of Base Pairing

  13. Cytosine N O O N N N N Guanine H H O N H N N N H H Base PairingGuanine And Cytosine - + + - - + Three Hydrogen Bonds

  14. H H + N - Adenine Thymine CH3 H - + N N N N N N O O N Base PairingAdenine And Thymine Two Hydrogen Bonds

  15. - + - Thymine CH3 H + + N N N N N O N O N Guanine O H N H H Base PairingGuanine And Thymine

  16. DNA 3’Hydroxyl group CH3 OH O NH2 H OH P HO O HN N N N O 5’Phosphate group O N N CH2 O O CH2 O NH2 B A S E S HO P O H O N H2N O H O H P HO O N O N N NH O SUGAR-PHOSPHATE BACKBONE N N O H2O H2O NH2 N O O CH2 N O CH2 N O HN N O HO P H2N H O O H H P HO O 5’Phosphate group O CH2 O O CH2 O 3’Hydroxyl group O HO P OH H HO

  17. The Watson - Crick Model Of DNA - - AT - - CG - - GC - - TA - - 3.4 nm 1 nm - - - - GC TA - - CG - - AT - - - - AT - - CG - - GC - - 0.34 nm TA - - Minor groove Major groove

  18. What have you learned Can you ……………… • Outline the simple structure of DNA • Name the four bases and the base pairs in DNA • Distinguish between coding and non coding structures • Define triplet base code • Outline the structure of RNA • Name the bases in RNA • Discuss the replication of DNA

  19. PROTEIN SYNTHESIS Higher Level

  20. Lesson Objectives At the end of this lesson you should be able to • Outline the steps in protein synthesis • Understand DNA contains the code for protein • Understand that enzymes unwind the DNA • Understand this code is transcribed to mRNA • Know the role of RNA polymerase • Know the role of a codon 7. Know the code is translated on the ribosome 8. Know the ribosome is composed of subunits 9. Understand the amino acids are assembled in the correct order determined by the codons on mRNA to synthesise the protein

  21. Lesson Objectives (cont.) At the end of this lesson you should be able to: 10. Understand a stop codon on mRNA signals the release of the protein 11. Know that the protein folds into its functional shape 12. Give the location of protein synthesis 13. Understand the molecular involvement of DNA, mRNA, tRNA, rRNA and amino acids in the process of protein synthesis

  22. For Protein Synthesis You need: • A supply of amino acids – cytoplasm • Instructions as how to join the amino acids together – genetic code • An assembly line – ribosomes • A messenger to carry information from DNA to ribosomes - mRNA

  23. Protein Synthesis - Steps 3 stages: 1. Initiation 2. Transcription 3. Translation • Remember: DNA  RNA  Protein

  24. RNA is composed of 3 parts • Ribose: smaller sugar than deoxyribose of DNA • Phosphate • 4 Nitrogenous Bases A,G,U,C RNA is single stranded and thus smaller & able to leave the nucleus of the cell

  25. Nuclear membrane DNA Transcription RNA Processing mRNA Ribosome Translation Protein DNA  RNA Protein Transcription Translation Eukaryotic Cell

  26. DNA Transcription mRNA Ribosome Translation Protein DNA  RNA Protein Prokaryotic Cell – No nucleus

  27. Learning Check • What is RNA composed of? • How does RNA(ribonucleic acid) differ from DNA (deoxyribonucleic acid)? • What are the three stages in Protein synthesis?

  28. Nuclear membrane DNA Transcription RNA Processing mRNA Ribosome Translation Protein 1. Transcription Eukaryotic Cell

  29. 1. Transcription • The transfer of information in the nucleus from a DNA molecule to an RNA molecule. • Only oneDNA strand serves as the template • When complete, mRNA molecule is released into the cytoplasm

  30. Video Clip available in extra material folder

  31. Transcription • Takes places in the nucleus of the cellThe process by which the information from DNA is transferred to RNA. DNA uncoils and unzips. • The exposed DNA bases are matched up with RNA bases in the nucleus to form mRNA.

  32. DNA RNA Polymerase mRNA 1. Transcription Enzyme

  33. A U G G G C U U A A A G C A G U G C A C G U U • This is a molecule of messenger RNA. • It was made in the nucleus by transcription from a DNA molecule. codon mRNA molecule

  34. Learning Check • What type of RNA molecule is responsible for taking the DNA copy from the nucleus into the cytoplasm • What parts of the cell do you find RNA in? • Can you outline the stages in transcription?

  35. mRNA • Takes place in the nucleus of the cellThe process by which the information from DNA is transferred to RNA. DNA uncoils and unzips. • The exposed DNA bases are matched up with RNA bases in the nucleus to form mRNA.

  36. Types of RNA • Three types ofRNA: A. messenger RNA (mRNA) B. transfer RNA (tRNA) C. ribosomal RNA (rRNA) • Remember: all produced in thenucleus!

  37. A. Messenger RNA (mRNA) • Carries the information for a specific protein. • Made up of 500 to 1000 nucleotides long. • Made up of codons(sequence of three bases) • Each codon is specific for one amino acid.

  38. start codon A U G G G C U C C A U C G G C G C A U A A mRNA codon 1 codon 2 codon 3 codon 4 codon 5 codon 6 codon 7 stop codon protein methionine glycine serine isoleucine glycine alanine Primary structure of a protein aa2 aa3 aa4 aa5 aa6 aa1 peptide bonds A. Messenger RNA (mRNA)

  39. B. Transfer RNA (tRNA) • Made up of 75 to 80 nucleotides long. • Picks up the appropriate amino acid floating in the cytoplasm • Transports amino acids to the mRNA. • Has anticodons that are complementary to mRNAcodons. • Recognizes the appropriate codons on the mRNA and bonds to them with H-bonds.

  40. C. Ribosomal RNA (rRNA) • Made up of rRNA is 100 to 3000 nucleotides long. • Important structural component of a ribosome. • Associates with proteins to form ribosomes.

  41. Ribosomes • Large and small subunits. • Composed of rRNA (40%) and proteins (60%). • Both units come together and help bind the mRNA and tRNA.

  42. mRNA A U G C U A C U U C G Ribosomes Large subunit Small subunit

  43. Learning Check • What are the three types of RNA? • Where is each type produced? • What is the function of each type of RNA?

  44. Nuclear membrane DNA Transcription Pre-mRNA RNA Processing mRNA Ribosome Translation Protein 3. Translation Eukaryotic Cell

  45. Video Clip available in extra material folder

  46. 3. Translation • Synthesis of proteins in the cytoplasm • Involves the following: 1. mRNA (codons) 2. tRNA (anticodons) 3. rRNA 4. ribosomes 5. amino acids

  47. Translation • In the cytoplasm, translation occurs.The mRNA binds to a ribosome. • The strand of mRNA is pulled through the ribosome three bases at a time, in triplets. • Each of these triplets on the mRNA strand is called a codon.

  48. A U G G G C U U A A A G C A G U G C A C G U U • This is a molecule of messenger RNA. • It was made in the nucleus by transcription from a DNA molecule. codon mRNA molecule

  49. ribosome A U G G G C U U A A A G C A G U G C A C G U U A ribosome on the rough endoplasmic reticulum attaches to the mRNA molecule.

  50. Amino acid tRNA molecule anticodon U A C A U G G G C U U A A A G C A G U G C A C G U U A transfer RNA molecule arrives. It brings an amino acid to the first three bases (codon) on the mRNA. The three unpaired bases (anticodon) on the tRNA link up with the codon.

More Related