C11- DNA and Genes

1. C11- DNA and Genes Chapter 11

2. Contents • 11-1 DNA: The Molecule of Heredity • 11-2 From DNA to Protein • Protein Synthesis video • 11-3 Genetic Changes

3. 11-1 DNA: The Molecule of Heredity • Genetic info in DNA controls organism’s traits

4. 11-1 DNA: The Molecule of Heredity • Genetic info in DNA controls organism’s traits • Determines structure of proteins built

5. 11-1 DNA: The Molecule of Heredity • Genetic info in DNA controls organism’s traits • Determines structure of proteins built • Hershey & Chase (1952) used radioactively tagged viruses to infect bacteria and proved DNA is genetic material

6. 11-1 DNA: The Molecule of Heredity • Genetic info in DNA controls organism’s traits • Determines structure of proteins built • Hershey & Chase (1952) used radioactively tagged viruses to infect bacteria and proved DNA is genetic material

7. Nucleotide Structure • DNA polymer of repeating units called nucleotides.

8. Nucleotide Structure • DNA polymer of repeating units called nucleotides. • 3 parts • Simple sugar • Phosphate • Phosphorus w/ 4 O • Nitrogenous base

9. Nucleotide Structure • DNA polymer of repeating units called nucleotides. • 3 parts • Simple sugar • Phosphate • Phosphorus w/ 4 O • Nitrogenous base • C ring w/ 1 or more N & a base • Adenine (A) • Cytosine (C) • Guanine (G) • Thymine (T)

10. Nucleotides • Join in long chains • with phosphates connecting • to sugar of next unit • to form a backbone

11. Nucleotides • Join in long chains • with phosphates connecting • to sugar of next unit • to form a backbone • with the bases sticking out like the teeth of a zipper. • Adenine = Thymine • Guanine = Cytosine

12. Structure of DNA • James Watson & Francis Crick (1953) unraveled the structure of DNA. • Double Helix structure

13. Nucleotide Sequence • Forms unique genetic information of organism

14. Nucleotide Sequence • Forms unique genetic information of organism • Can be used to determine evolutionary relationships between organisms

15. Nucleotide Sequence • Forms unique genetic information of organism • Can be used to determine evolutionary relationships between organisms • Or familial relationships • DNA can identify victims or criminals

16. Replication of DNA • Copies DNA in chromosome during interphase

17. Replication of DNA • Copies DNA in chromosome during interphase • Enzyme breaks the hydrogen bond between bases

18. Replication of DNA • Copies DNA in chromosome during interphase • Enzyme breaks the hydrogen bond between bases • Complimentary base pairing allows duplication

19. Replication of DNA • Copies DNA in chromosome during interphase • Enzyme breaks the hydrogen bond between bases • Complimentary base pairing allows duplication • Each strand is a template

20. 11-2 From DNA to Protein • DNA controls the production of proteins. • Proteins are key cell structures & regulators of cell functions.

21. 11-2 From DNA to Protein • DNA controls the production of proteins. • Proteins are key cell structures & regulators of cell functions. • RNA, another nucleic acid carries out DNA’s instructions

22. 11-2 From DNA to Protein • DNA controls the production of proteins. • Proteins are key cell structures & regulators of cell functions. • RNA, another nucleic acid carries out DNA’s instructions • Structure differs 3 ways • Single-stranded • Sugar is ribose • Uracil replaces thymine

23. Three Types of RNA • Protein assembly line: • Messenger RNA (m-RNA) • Ribosomal RNA (r-RNA) • Transfer-RNA (t-RNA)

24. Three Types of RNA • Protein assembly line: • Messenger RNA (m-RNA) • Brings instructions from DNA to ribosome in the cytoplasm • Ribosomal RNA (r-RNA) • Transfer-RNA (t-RNA)

25. Three Types of RNA • Protein assembly line: • Messenger RNA (m-RNA) • Brings instructions from DNA to ribosome in the cytoplasm • Ribosomal RNA (r-RNA) • Reads instructions to assemble protein by binding to m-RNA • Transfer-RNA (t-RNA)

26. Three Types of RNA • Protein assembly line: • Messenger RNA (m-RNA) • Brings instructions from DNA to ribosome in the cytoplasm • Ribosomal RNA (r-RNA) • Reads instructions to assemble protein by binding to m-RNA • Transfer-RNA (t-RNA) • Delivers amino acids for assembly to ribosome

27. Transcription • Occurs in the nucleus by enzymes copying part of the DNA • Enzyme unzips DNA • Assembles single-strand copy

28. Transcription • Occurs in the nucleus by enzymes copying part of the DNA • Enzyme unzips DNA • Assembles single-strand copy • DNA rezips after m-RNA detaches

29. Transcription • Occurs in the nucleus by enzymes copying part of the DNA • Enzyme unzips DNA • Assembles single-strand copy • DNA rezips after m-RNA detaches • m-RNA leaves nucleus by nuclear pore to enter cytoplasm

30. Transcription • Occurs in the nucleus by enzymes copying part of the DNA • Enzyme unzips DNA • Assembles single-strand copy • DNA rezips after m-RNA detaches • m-RNA leaves nucleus by nuclear pore to enter cytoplasm • Carries instructions to ribosome

31. Translation • Occurs in the ribosome • Process of converting series of bases into chain of amino acids forming a protein

32. Translation • Occurs in the ribosome • Process of converting series of bases into chain of amino acids forming a protein • r-RNA reads sequence of 3 bases (codon)

33. Translation • Occurs in the ribosome • Process of converting series of bases into chain of amino acids forming a protein • r-RNA reads sequence of 3 bases (codon) • t-RNA anticodon matches up with the codon from m-RNA and supplies the amino acid needed

34. Translation • Occurs in the ribosome • Process of converting series of bases into chain of amino acids forming a protein • r-RNA reads sequence of 3 bases (codon) • t-RNA anticodon matches up with the codon from m-RNA and supplies the amino acid needed • Ribosome translates the next codon until finished assembling the protein

35. RNA & Protein Synthesis

36. RNA Processing • Introns- noncoding nucleotide sequences • Exons- expressed sections of nucleotides • Enzymes cut out the introns & paste the exons together

37. Genetic Code • Amino acids are the building blocks of proteins. • A sequence of 3 nucleotide bases code for each of the 20 amino acids. • 64 different codons in m-RNA • AUG start codon • UAA stop codon • All organisms use the same genetic code.

38. Translating the m-RNA Code • T-RNA leaves amino acid in position to form peptide bond with previous amino acid

39. Translating the m-RNA Code • T-RNA leaves amino acid in position to form peptide bond with previous amino acid • The ribosome continues to assemble amino acids until stop codon is reached.

40. Translating the m-RNA Code • T-RNA leaves amino acid in position to form peptide bond with previous amino acid • The ribosome continues to assemble amino acids until stop codon is reached. • Translation is complete

41. Translating the m-RNA Code • T-RNA leaves amino acid in position to form peptide bond with previous amino acid • The ribosome continues to assemble amino acids until stop codon is reached. • Translation is complete • Amino acid chain is released & twists into complex folded shape of protein

42. Translating the m-RNA Code • T-RNA leaves amino acid in position to form peptide bond with previous amino acid • The ribosome continues to assemble amino acids until stop codon is reached. • Translation is complete • Amino acid chain is released & twists into complex folded shape of protein • Become enzymes & structures

43. 11-3 Genetic Changes • Mutation- any change in DNA sequence • Caused by errors in • Replication • Translation • Cell division • Or by external agents such as UV or chemical exposure

44. Mutations in Reproductive Cells • Changes in the sequence of nucleotides can cause: • Altered gene in offspring • New traits • Nonfunctional protein with structural or functional problems in cells • Embryo may not survive • Positive effect

45. Mutations in Body Cells • Does not pass on to offspring • May cause problems for the individual • Impair function of the cell • Contributes to aging • Can cause cancer by making cells reproduce rapidly

46. Effects of Point Mutations • Point mutation - Change in a single base pair in DNA • Can change entire structure of the protein • Error may or may not affect protein function • Ex. Sickle cell anemia

47. Frameshift Mutations • A single base is added to or deleted from DNA • Shifts the reading of the codons by one base • Nearly every amino acid after the insertion or deletion will be changed

48. Chromosomal Alterations • Chromosomal mutations • Deletions -Parts break & are lost during mitosis or meiosis • Insertions- Parts rejoin incorrectly • Inversions- Rejoin backwards • Translocations- Join other chromosomes • Common in plants

49. Causes of Mutations • Mutagens- agents that cause change in DNA • Radiation • X-rays • Gamma rays • Ultraviolet light • Nuclear radiation • Chemicals • Dioxins • Asbestos • Benzene • Formaldehyde • High temperatures 6-legged frog aflatoxin

50. Repairing DNA • Repair mechanisms have evolved: • Enzymes proofread DNA & replace incorrect nucleotides. • The greater the exposure to the mutation, the less likely it can be corrected. • Limit exposure to mutagens.