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Deoxyribonucleic Acid ( DNA ) Stanley Mikles, 2009.

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Presentation on theme: "Deoxyribonucleic Acid ( DNA ) Stanley Mikles, 2009."— Presentation transcript:

1 Deoxyribonucleic Acid ( DNA ) Stanley Mikles, 2009

2 DNA is a polymer a is a long chain molecule made up of many smaller molecules a polymer is a long chain molecule made up of many smaller molecules

3 a DNA polymer is a long chain of nucleotides

4 Parts of a nucleotide Deoxyribose sugar Nitrogen base Phosphate

5 PO O HO Phosphate HO

6 CC O CC HH H HH OH Deoxyribose Sugar

7 CC N C O OH NH 2 N Nitrogen Base

8 1.Deoxyribose sugar Composition of a Nucleotide 2.phosphate group nitrogenous base a.thymine b.adenine c.cytosine d.guanine

9 O O CH 3 H H N N Thymine

10 N H N N N Adenine H N H

11 N O H H N N Cytosine H

12 O H N N N Guanine H N H N H

13 N N N N O CH 2 OHH PO O HO O NH H H O Deoxyribose Guanine Phosphate 1 of 4 possible Nucleotides (one of 4 possible nitrogen bases)

14 Steps of Replication of DNA B.enzymes break hydrogen bonds between nitrogen bases A.molecule untwists C.other enzymes bond new nucleotides to the split strand of the DNA (enzyme: DNA polymerase) D.Result is 2 separate identical molecules of DNA E.new molecules of DNA retwist

15 A G T T A C G A C A T G C G G A T T A A C C G C G A C T A A A T C T C A A TG C T G T A C G C C T A A T T G G C G C T G A T T T A G

16 T C A A TG C T G T A C G C C T A A T T G G C G C T G A T T T A G T C A A TG C T G T A C G C C T A A T T G G C G C T G A T T T A G A G T T A C G A C A T G C G G A T T A A C C G C G A C T A A A T C

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18 Making Proteins from DNA Proteins are polymers of amino acids. Proteins are long molecules made up of amino acids molecules. Remember: a polymer is a long chain molecule made up of many smaller molecules “Protein Synthesis”

19 The whole point of DNA is to be a template for making proteins.

20 There are 20 amino acids.

21 1 st Base in the Codon 2 nd Base in the Codon3 rd Base in the codon UCAG UPhenylalanineSerineTyrosineCysteineU PhenylalanineSerineTyrosineCysteineC LeucineSerineStop A LeucineSerineStopTryptophanG CLeucineProlineHistadineArginineU LeucineProlineHistadineArginineC LeucineProlineGlutamineArginineA LeucineProlineGlutamineArginineG AIsoleucineThreonineAsparagineSerineU IsoleucineThreonineAsparagineSerineC IsoleucineThreonineLysineArginineA Methionine (start)ThreonineLysineArginineG GValineAlanineAspartateGlycineU ValineAlanineAspartateGlycineC ValineAlanineGlutamateGlycineA ValineAlanineGlutamateGlycineG

22 Transcription of DNA to RNA (Think of transcription like re-writing a language into another form. It is the same language.)

23 Ribonucleic Acid Single stranded Has uracil in place of thymine Three types of RNA

24 Messenger RNA mRNA Transfer RNA tRNA Ribosomal RNA rRNA

25 1.Enzyme unzips DNA molecule at the start codon and stopping at the first stop codon. Steps of Transcription A G T T A C G A C A T G C G G A T T A A C C G C G A C T A A A T T A C G C C T A A T T G G C G C T G A T TT C A A TG C T G T A

26 DNA polymerase cuts bonds between nitrogen bases

27 A G T T A C G A C A T G C G G A T T A A C C G C G A C T A A A T T A C G C C T A A T T G G C G C T G A T T T C A A TG C T G T A 2.Free RNA nucleotides in Nucleoplasm form complementary base pairs on DNA strand forming an mRNA (messenger RNA) strand A U G C G G AU U A U C C G C G U C U A A

28 RNA nucleotides bonding to DNA

29 A G T T A C G A C A T G C G G A T T A A C C G C G A C T A A A T T A C G C C T A A T T G G C G C T G A T TT C A A TG C T G T A A U G C G G AU U A U C C G C G U C U A A 3.mRNA strand breaks away from DNA by enzyme action

30 T A A G T T A C G A C A T G C G G A T T A A C C G C G A C T A A A T T A C G C C T A A T T G G C G C T G A T T T C A A TG C T G 4.DNA re-zips as mRNA breaks off.

31 mRNA strand breaks away

32 DNA Rezips

33 B.RNA Processing 1.Not all nucleotides in DNA code for making proteins. 2.Some regions of a DNA molecule do not code for anything. 3.These regions are called introns (intervening regions). 4.Regions that do contain information for coding for proteins are called exons.

34 5.When mRNA in transcribed from DNA, both introns and exons are copied. a.The introns must be removed from the mRNA before it can function as a protein b.Enzymes in nucleoplasm cut out the introns and paste mRNA back together. 6.mRNA then leaves the nucleus

35 From RNA to protein translation: changing mRNA code into a protein: a sequence of amino acids

36 Think of translation as re-writing a message into another language. The message is the same, but the language is different.

37 1.Transfer ribonucleic acid (tRNA) a.about 75 nucleotides long b.twisted so that only three nucleotides are available for bonding c.one tRNA for one amino acid

38 A U G C G G A U U A U C C G C G U C U A A Met

39 Transfer Ribonucleic Acid tRNA Amino Acid Anticodon

40 PhenylalanineSerineTyrosineCysteine LeucineProlineHistadineTryptophan IsoleucineThreonineGlutamineArginine MethionineAlanineAsparagineGlycine ValineLysine Aspartate Glutamate 20 Amino Acids Scientists have found a few more amino acids, like pyrrolysine and selenocysteine, that help to build proteins.

41 1 st Base in the Codon 2 nd Base in the Codon3 rd Base in the codon UCAG UPheSerTryCysU PheSerTryCysC LeuSerStop A LeuSerStopTrpG CLeuProHisArgU LeuProHisArgC LeuProGlnArgA LeuProGlnArgG AIleThrAsnSerU IleThrAsnSerC IleThrLysArgA Met (start)ThrLysArgG GValAlaAspGlyU ValAlaAspGlyC ValAlaGluGlyA ValAlaGluGlyG

42 2.start codon on mRNA strand attaches to ribosome

43 3.tRNA molecules, each carrying an amino acid, approach ribosome 4.tRNA molecules with complementary anticodon pairs with mRNA codon. 5.tRNA remains until next tRNA arrives

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45 6.mRNA shifts along ribosome to next codon 7.Next tRNA molecule carrying the amino acid that possesses the complimentary anticodon bonds

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47 8.An enzyme joins the two amino acids forming a amino acids forming a peptide between them bond between them 9.tRNA from 1st amino acid falls away

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49 10.process continues until ribosome reaches stop codon bringing about termination

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51 11. enzyme breaks off last tRNA 12.result is a chain of amino acids: polypeptide: protein

52 The End!

53 The End? Not Quite!

54 Control of Gene Expression Gene A segment of a chromosome that controls (codes for) the production of a certain protein.

55 Protein: Gene Expression: large, complex polymer of amino acids which provides structure for tissues and helps carry out cell metabolism. the production of the protein that the gene is coded for, which then allows for the operation of that protein.

56 Genetic ChangesMutation: any mistake in DNA or RNA sequence of nucleotides

57 Mutation: Results of Mutation: Failure to produce protein Production of wrong protein Over production of protein whether right or wrong

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59 point mutation: change in a single base pair

60 frame shift mutation a.additions b.deletions

61 Chromosomal mutations 1.parts broken off or lost during mitosis or meiosis 2.re-joining wrong 3.join backward 4.effects: incorrect distribution of genes to gametes during meiosis a.deletions b.insertions c.inversions

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64 Causes of Mutations mutagen: any agent that can cause a change in the DNA A.radiation 1.X-rays 2.gamma rays 3.ultraviolet rays B.chemicals 1.dioxin 2.asbestos 3.benzene 4.formaldehyde 5.alcohol C.high temperatures

65 Repairing DNA

66 The End!

67 The End? Not Quite!

68 The search for knowledge continues!

69 Controversies about DNA


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