BIOLOGY FORM 5 CHAPTER 5 - 5.3 A (DNA)
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The document provides a history of discoveries related to DNA and genetics. It describes experiments in the 1940s-1950s that proved DNA is the genetic material responsible for inheritance. It details discoveries such as DNA's double helix structure and base pairing rules. The document also summarizes the mapping of the human genome and benefits of understanding the genome sequence.
BIOLOGY FORM 5 CHAPTER 5 - 5.3 A (DNA)
- 2. History • Before the 1940’s scientists didn’t know what material caused inheritance. • They suspected it was either DNA or proteins.
- 3. History • A series of experiments proved that DNA was the genetic material responsible for inheritance.
- 4. History • In 1952, Alfred Hershey and Martha Chase did an experiment using a virus that infects E. coli bacteria. • The experiment proved that DNA and not protein is the factor that influences inheritance.
- 5. History • Erwin Chargaff discovered the base pairing rules and ratios for different species. • Adenine pairs with Thymine • Cytosine pairs with Guanine.
- 6. History • Rosalind Franklin & Maurice Wilkins had taken the 1st pictures of DNA using X-ray crystallization
- 7. This proved that DNA had a helical shape.
- 8. History • The Nobel Prize in Medicine 1962 Francis Harry Compton Crick James Dewey Watson Maurice Hugh Frederick Wilkins Rosalind Franklin (Died of cancer 1958)
- 9. Watson Crick Wilkins has become a historical footnote and Watson & Crick are remembered as the Fathers of DNA
- 10. James Watson & Francis Crick 1953 • Constructed a model for DNA structure • Awarded the Nobel Prize in 1962
- 13. • Important Note: Most DNA is found in the nucleus. Small amounts of DNA are found in the mitochondria organelle (mtDNA) –Learn more abaout mtDNA at http://en.wikipedia.org/wiki/Mitochondrial_DNA
- 14. Chromosome – thread like twisted structure found in the nucleus
- 15. http://www.brooklyn.cuny.edu/bc/ahp/LAD/C4/C4_Chromosomes.html Chromosomes are made up of protein and DNA
- 16. Genes • A basic unit of inheritance • Occupies a specific position (locus) in a chromosome
- 17. DNA Gene -a segment of DNA -that determines a trait -Eg. eye colour
- 18. • The molecule of DNA - two strands coiled together to form a “double helix”. Right hand twist
- 19. • Each of the two strands is made up of small units called nucelotides.
- 20. Each nucleotide is itself made up of three chemical groups: 1.Phosphate 2.Sugar 3.Nitrogenous base
- 21. There are four different kinds of base 1.Adenine (A) 2.Guanine (G) 3.Cytosine (C) 4.Thymine (T)
- 22. C always pairs with G A always pairs with T
- 23. The 2 strands of DNA are held together by the hydrogen bonds between the complimentary bases.
- 24. The sequence of bases, (the order of A G C and T’s) carries the information that the genes contain. • Sequence of three bases – codon • Codon - code for a specific amino acid. • Amino acids make up proteins from which all living things are made.
- 25. • Some codons actually carry instructions like full stops to end messages, or starting points.
- 26. DNA REPLICATION
- 27. DNA • During S stage in interphase, DNA replicates itself.
- 28. DNA • You end up with 2 identical strands of DNA.
- 29. Gene Protein Gene = segment of DNA = specifies the sequence of amino acids in a polypeptide chain of a protein. Every gene is a code for a particular protein.
- 31. RNA • Function: obtain information from DNA & synthesizes proteins
- 32. RNA - 4 differences from DNA 1. Single strand instead of double strand 2. Ribose instead of deoxyribose 3. Uracil instead of thymine 1. No helix structure
- 33. 3 types of RNA 1. mRNA (messenger): takes a message from the nucleus to the ribosomes in the cytoplasm 2. tRNA (transfer): transfers amino acids to the ribosomes 3. rRNA (ribosomal): along with proteins, makes up the ribosomes where polypeptides are synthesized.
- 34. Genes code for RNA RNA codes for protein.
- 35. Transcription - mRNA is made from DNA & goes to the ribosome Translation - Proteins are made from the message on the mRNA
- 36. Translation • At the ribosome, amino acids (AA) are linked together to form specific proteins. • The amino acid sequence is directed by the mRNA molecule. ribosome Amino acids
- 37. VIDEO FROM DNA TO PROTEIN
- 38. A chromosome is a long sequence
- 40. • Scientists have recently completed mapping the position of every base in human DNA. • This massive project is called the Human Genome Project
- 41. Human Genome Project Aim: Determine the entire sequence of the human genome. Problem: It’s really big! 3 billion base pairs
- 42. Model organisms Phil Hieter Sequenced / in progress:
- 43. Two Different Groups Worked to Obtain the DNA Sequence of the Human Genome • The HGP is a multinational consortium established by government research agencies and funded publicly. • Celera Genomics is a private company whose former CEO, J. Craig Venter, ran an independent sequencing project.
- 44. Published • The International Human Genome Sequencing Consortium published their results in Nature, 409 (6822): 860-921, 2001. “Initial Sequencing and Analysis of the Human Genome” • Celera Genomics published their results in Science, Vol 291(5507): 1304-1351, 2001. – “The Sequence of the Human Genome”
- 45. Completion of the genome “Working Draft” Completion expected April 2003 “Complete”
- 46. Benefit - Identification of genes that cause disease - Diagnoses, treatments and possible prevention of many ailment - Screen genetic disorder - Track genes that is responsible for certain disease - Test compatibility for potential organ donor DNA samples –– hhaaiirr,, ssaalliivvaa,, bblloooodd,, sseemmeenn
- 47. Genome Sequencing Genome: 3 Gb Cut genome into large pieces Clone into BACs: 100 kb Order based on sequence features (markers) = mapping Cut again Assemble entire sequence …TTGTAAGTGAGAACAGGACGTATGTGGTTTTCTACTCCTGTGTT… TTGTAAGTGAGAACA Sequence AGAACAGGACGTATGTGGT TGTGGTTTTCTACTCC CTACTCCTGTGTT Assemble each BAC
- 48. What does the sequence mean? TCACAATTTAGACATCTAGTCTTCCACTTAAGCATATTTAGATTGTTTCCAGTTTTCAGCTTTTATGACTAAATCTTCTAAAATTGTTTTTCCCTAAATGTATATTTTAATTTGTCTCAGGAGTAGAATTTCTGAGTCATAAAGCGG TCATATGTATAAATTTTAGGTGCCTCATAGCTCTTCAAATAGTCATCCCATTTTATACATCCAGGCAATATATGAGAGTTCTTGGTGCTCCACATCTTAGCTAGGATTTGATGTCAACCAGTCTCTTTAATTTAGATATTCTAGTAC ATACAAAATAATACCTCAGTGTAACCTCTGTTTGTATTTCCCTTGATTAACTGATGCTGAGCACATCTTCATGTGCTTATTGACCATTAATTAGTCTTATTTGTTAAATGTCTCAAATATTTTATACAGTTTTACATTGTGTTATTC ATTTTTTAAAAAATTCATTTTAGGTTATATGTATGTGTGTGTCAAAGTGTGTGTACATCTATTTGATATATGTATGTCTATATATTCTGGATACCATCTCTGTTTCATGCATTGCATATATATTTGCCTATTTAGTGGTTTATCTTT TCATTTTCTTTTGGTATCTTTTCATTAGAAATGTTATTTATTTTGAGTAAGTAACATTTAATATATTCTGTAACATTTAATGAATCATTTTATGTTATGTTTAGTATTAAATTTCTGAAAACATTCTATGTATTCTACTAGAATTGT CATAATTTTATCTTTTATATACATTGATATTTTTATGTCAAATATGTAGGTATGTGATATTATGCACATGGTTTTAATTCAGTTAATTGTTCTTCCAGATGTTTGTACCATTCCAACATCATTTAAATCATTAAATGAAAAGCCTTT CCTTACTAGCTAGCCAGCTTTGAAAATCCATTCATAGGGTTTGTGTTAATATATTTTTGTTCTTTTTTTTCCTTTCTACTGATCTCTTTATATTAATACCTACTGTGGCTTTATATGAAGTCATGGAATAATACGTAGTAAGCCCTC TAACACTGTTCTGTTACTGTTGTTATTGTTTTCTCAGGGTACTTTGAAATATTCGAGATTTTATTATTTTTTAGTAGCCTAGATTTCAAGATTGTTTTGACGATCAATTTTTGAATCAATTGTCAATATTTTTAGTAATAAAATGAT GATTTTTGATTGGAAATACATTAAATCTATAAGCCAAATTGGAGATTATTGATATATTAACAAAAATGAGTTTTCCAGTCCATGAATGTATGCACATTATAAAATTCATTCTTAAGTATGTCATTTTTTAAGTTTTAGTTTCAGCAG TATATGTTTGTTACATAGGTAAACTCCTGTCATGGGGGTTAGTTGTACAGGTTATTTTATCATCCAGGCATAAAGCCCAGTACCCAGTAGTTATCTTTTCTGCTCCTCTCCCTCCTGTCACCCTCCACTCTCAAGTAGACCCCAGTT TCTGTTGTTCTCTTCTTTGCATTAATGACTTCTCATCATTTAGATTGCACTTGTAAGTGAGAACAGGACGTATGTGGTTTTCTACTCCTGTGTTAGTTTGCTAAGGATAACCACCTCCATCTCCATCCATGTTCCCACAAAAGACAT GATCTCCTTTTTTATGGCTGCATATTATTCCATGGTATATATGTACCACATTTTCTTTATCCAATCTGTCATTGATGGACATTTAGGTTGTTTCCACATCATTGCCGTTGTAAATACTGCTGCAGTGAATATTCGTGTGTATGTCTT TATGGTAGAATGATTTATATTCCTCTGGGTATATTTCCAAGTAATGGGATGGTTGGGTCAAATGGTAATTCTGCTTTTAGCTTTTTGAGGAATTGCCATATTGCCTTTCACAACGGTTGAACTAATTTATACTCCCAAGAGTGTATA AGTTGTTCCTTTTTCTCTGCAACCTCGACATCACCTGTTATTTATGACTTTTATATAATAGCCATTCTGCTGGTCTGAGATGGTATCTCATTATGATTTTGATTTGCATTTCTCTAATGCTCAGTGATATTGAGCTTGGCTGCATAT ATGTCTTCTTTTAAAAATATCTGTTCATGTCCTTTGCCTAATTTATAACGGGGTTGTTTGTTTTTCTCTTGTAAATTTGTTTAAGTTCCTTATAGATTCTAGGTATTAAACCTTTTTTCAGAGGCGTGGCTTGCAAATATTTTCTCC CATTCTATAGGTTGTCTGTTTATTCTGTTGATAGTTTCCCTTGCTGTGCAGAAGCTCTTAACTTTAATTAGATCCGACTTGTCAATTTTTGCTTTGGTCGCAATTGCTTTTGATGTTATTGTCGTGAAATCTTTGCTAGTTCTTAGG TCCAGGATGATATTGCCCAAGTTGTCTTCCAGGGCTTTTATAATTTTGGATTTTACATTTAAGTCTTAATATATTTATTAAATTTGTTAGGGTTTCAGGATACAAGGACAATATAGCAGCAAACAATGTAAAAGTAAAATCTGAAAA ATAATAGAAAACAGTTTAATTGAACACTTTACCATTATGTAATGCCCTTCTTTGTCTTTCCTGATCTTTGTTGGTTTGAAGTTCAAAAAAGACAAACTTAATGGTACAATAGGTATTGTAGATTTCAGGACTTTCTGTATAAAATAT TTTGTATATATGAATAGATCATTTTTTATTTCCAGTCTTTAAACATTTTCTTAACATTTTCTTCTATTGCTTCACTTCACTCGCTAGGACCATCAGGACAGTGTTGAACAGAAATTGTCAGACTGATCATCACAACTTTTTCTAGAT TTTAGAAGGAAATTTTTCTTTATTTCAACATAAAGCAGCATGTTAATGCCAAGTTTTAATATGTGTTATCAGATTGAAATTTTTTTGTATATTTCTACATTACCAAGAATTTTTAGCAAGAGTTTTTGTTGAGTTTTAATTTAAAAA TCATTTGTTAATTTCATCTGATTTTTTTATTTCTCTTTTTACCTTAAGAGATTAAACTGACTACAGATTGAATATAAACAAACAAACAAACAAACAAAAACTCTAAAATGCTGTGGATCAACACCACTTAGTAATTTGTATACTTGG ATTCAATTTGCTGAAATTTTGTTAGACATTTTTGCGTCGATATTTATGAGGGATGTTGATCTGTAAAAGTATTAAAATGCCTTTGACAGATTTTGATAGCAGTGTTATTCTGGCCTAATAAATCAAACTGAGGTATGATCCTTCCTT TTCTATTTCTTAATAGCATTTTTAAAATTGGTGGTTTTTTCCTTCCTTAGTGAAATTTACCAGCAAAGTAACAGGCCTTATATTTCTCTTGTGGAAATATTTTAATTTCAAATTAATGGTATTTTGTTCTTGTAGGGTGGTAATTTT CTCTGTGTTTGGTCTTAATGGACTCTTAGCTGATCACCCAGTTACTCAGCGAGGTCTCTTCACTCTGGAAGAGCTGGAACTCCAGTGTGTTTTAGTGCAGCATGACCACGGGTATTACCGTTCAACATTTAGGCTTTATCAGTGATA ACTATTTGTCCTCATGGAGTTTTTGCCGCTGGGCCTACACAGTTTAGGCTTCAGCTTAGAACACATAATGAATTCTTATGCAGATTTCTGCCCACCTTTGACCTTTCATGATTTCCTCTTCTTGGGTAAGCTGCCTTATTAATCTGA TACACTTCAGCAGTCCAGAACTACACTCTTTCCCTTCTCTGCTCTTGGAGATGACTCTTTTGTCTGAGATTCACTTTGCTGTGCTGAAAAAGAAAAGTGCTTCAAGGAAGATACCAAGGAAAATCACAGGGCTCATTTATGTATTTC TCTTCTTTCAAGGACTACAGCTTTGTGTTGCCTATGTTCAATTTCTGAAAATAATTAGAGCATATATACTCTGTGTGAGAAGGCAAATCCAGACAGTTAGTTTGTATGACTAGAAGCAGAAGTCTACATGGAGAATTTTACTTAACT GTGTTATAGTTTCTTTAATTATTTCAAGAGTATGTTTAATGTTCCACAGATCTCATTCTATAAATCTTTATCATCTTAGAGCTCTGATACTATTTAGAATTACTATTCCTTCAAATAAGAGATTAGAAACAGGGTTATATTTGGGGT AGGTTGACTTACTTTTCTGGGAACCAAAGCATATTAAATTGACCAGTTTTAACACACTTCTATGTATGCACAAAGATATATATTTACATTCTGCAAAATCATTCTTTCCTTTTTGAATTTGAAAAGGATCTTTGGTATACAGATATT CAATAGCCAGCCTGAAGATTCATTTGAATTCATTTAATGTTTAGATTCACTACATGAAATGATCCAGAAGAGAGTACTCAAATATAAGTATCTATAACGATGGAAATATACATCTCCACTGCCCAAGATGGTAGTCATGAGTCAATA TTGATCATGTGAGACGTGGCAAGTGTTACTCAGGGTCTCAATATTTAAATGTATTAAGCTTTAATTAATGTAAATTTGAATTTAGCAAAACATGTATAGCTTGTGGTTACTGTTTTATTCAGTGCCAATATAGAACATTTCCATGAT TACAGAAAGTTATCTTAGAATACTCAGTTCTGGACTATTTTATCTGGCTAAATTAAATGTTAAAATATTACAAATTCATCTTCAGGCTGGCTGTTGAATATTTTTATAGCAAAAGTCATTTATAAATTTAAAACTCAAATAATTATC TTTTTCAATATGTAAAATATGTCTTTACATATTCTACTCCCTTCTTACATACATATTCTGATGTAACATAGGTATTCTCTTATTCATGCACACTGAAATGACAACATAAATAATTTTACTAAGTGTCACCATATAAAAAACTTTGAA CAAAATCAGATTATATCACTGTGGATATTTCTATTTTGAACTAACTTAGATGATAATTTTAATCTATATCCTAGATGAACTTTAAATCAATAAAATCTCTCAATGGTGTTATAAATCTCAAGCCATTAGCCACTGATTATCCCATTT TTATTCTTTTCATATTAATTTTATTGCCATGTATGAATGCTGTAGCATCCATGTTTAAATACTAGTTAACAAAATGCACTGGCATCAGATACAATAAGGATGAAATGAGATATAATTAGGACTCTGGTAACACACATAAAATTGGAA AGATACCCTGAAATTCAAGCCAAGAAGATATTTATCCAGCTTATTTTATTTTGAGACAGAGTCTTGCTCTCTCACTCAGGCTGGAGTGCAGTGGACCATTCTAGGCTCGCTCCAACCTCTGTCTCCCAAATTGAAGTAATTCTCGTG CCTCAATCTCCCGAGTAGCTGGGATTACAGGCATGTGTCACCAAGCCTGGCTGATTTTTGTAGTTTTAGTAGAGACGGGGTTTCACCATGATGGCCAGGCTGGTCTTGAACTCCTGGCCTCAAGTGACTGGAACACCTCGGCCTCCT AAAGTGCTGGGATTACAGACGAGAGCCACTGAACAGCTTTGATCCAACTTATTTGGATGAATGAGTTACATATTTTACATTAAATCTGTTATTGTGATAATTCTTCATGTTATTTTCCATGTATAGATTTATATATAATGTAATTTT AATTTTTTTTCACCGGAGAGTATAAACAACAATTATTTTATAAACAGGATAATAAAAATAAGACAAAAATTGTTGAAATGTCTTCATTTGACTACTAACTTTTTACATGTTTGTTACTTTGAAGCTGTTATCAATACTTGTGATGTA TTACAATTAAGTAAAGATTTAAAGATGCCATTTTTAACTTATTATGACACAAAGTCTATAAATTCTTATATTTTGAGATTTGTATTTAAATAACTTGTGAAATTTAATTTTAAAATAAAATTTCTTCTATGGATTGGTCTTCAATCG AGGCATAAAAAGGAATATAACAGTGTGGCACTATAACTTCTATATTGAATTTCTATATTATTTAACACAATTATAATTTTGCTAATGAATTGTAATGTTTTTAAAAAGCTAGGTGAATTTTATTAAATTCATTACATGGCGATAACA CAGAGAAAACATTTTGGGGATTCTTTTAAAATGGTATGTACAAAAGCTTAAAAGTTGTTATGTAGTGGCAGAGATAAAAAAGTAAAACAAAAAAAAGCTTAAAAGTTTGCTTTACTATTTATAGGCTCATAAGTGTAAGTGTGCCAG AAAATGAAAAAGAAAGGAGAGAAATTATAAATAACTGTGTGGAAAACACAGATAAAGCATAAAGATAGAATATAAAGATAGAAGCATTTTAATATGAGGCAGTGATGGCTTTTTGAAGAATCCCAACTAAGGACCTACTTTTAGTTA ATAAATAATATGTTTCTAATCCCTATATTGTCCACAGCAACCTTTTTAGGACATGGAGCAGTGACTATGAGTGCCAGAAGGCAAGAGTAGAAGCAATTGTAAAATCATGAACACTAGTTTGTAAAATCCTCACTGAGATATAATATC TGTTTGCCTCTACCTTAGAATTATTAATGTCTTGAGGGCTGGGA A very small piece of chromosome 21
- 49. Genomic structure • 3 GB • ~50% repetitive • Only 3% protein coding!
- 50. www.nature.com The age of complete genomic sequences
- 51. TTHHEE EENNDD
Editor's Notes
- #51: This is just a simple schematic to try and put us all on the same page with regard to what I’m talking about. A person’s genome or “book of life” as it is sometimes referred to is our entire genetic endowment. First there are Trillions of cells within the body and for the most part each cell contains 46 chromosomes or approximately 2 meters of DNA if stretched out. These chromosomes contain approximately 3 billion DNA subunits or nucleotides. These nucleotides are A, C, T, or G. Strings of these nucleotides make up the genes and based on current estimates there are roughly 30,000 genes encoding proteins that perform all the functions required for the human body.