1. Nucleic Acids, DNA Replication, and Protein Synthesis
November 3, 2007
Bio099
Timberlake Chapter 17
Martinin Pages 54-55

2. Nucleic Acids: The Big Picture

3. Two Types of Nucleic Acids
DNA
Deoxyribonucleic acid

4. Two Types of Nucleic Acids
DNA
Deoxyribonucleic acid
RNA
Ribonucleic acid

5. Nucleotide The monomer of nucleic acids

6. Molecular Components of the nucleotide
Pentose sugar
DNA
RNA

7. Molecular Components of the nucleotide
Pentose sugar
Phosphate group

8. Molecular Components of the nucleotide
Pentose sugar
Phosphate group
Nitrogenous bases
purine pyrimidine

9. Nitrogenous Bases
BASES OF DNA
BASES OF RNA

10. Nucleoside

11. Primary Structure of Nucleic Acids
Nucleotides are bound together to form nucleic acids.

12. Primary Structure of Nucleic Acids
Nucleotides are bound together to form nucleic acids.
The sequence of bases is like an instruction manual that can be read by the cell.

13. Secondary Structure of Nucleic Acids
DNA:
The Double Helix
The vertical blue strand represents the sugar and phosphate group and the inner horizontal bands represent the nitrogenous bases

14. Secondary Structure of Nucleic Acids
DNA:
The Double Helix
Complementary base pairs

15. Secondary Structure of Nucleic Acids
DNA:
The Double Helix
Complementary base pairs
Helical

16. Secondary Structure of Nucleic Acids
RNA:
Single stranded, but loopy in structure

17. Review
What are the 2 types of nucleic acids?

18. Review
What are the 2 types of nucleic acids?
RNA and DNA

19. Review What are the 2 types of nucleic acids?
RNA and DNA
What molecules makes up the “backbone” of a nucleic acid?

20. Review What are the 2 types of nucleic acids?
RNA and DNA
What molecules makes up the “backbone” of a nucleic acid?
phosphate and sugar

21. Review What are the 2 types of nucleic acids?
RNA and DNA
What molecules makes up the “backbone” of a nucleic acid?
phosphate and sugar
What is one difference between RNA and DNA?

22. Review What are the 2 types of nucleic acids?
RNA and DNA
What molecules makes up the “backbone” of a nucleic acid?
phosphate and sugar
What is one difference between RNA and DNA?
secondary structure (double stranded helix vs. single stranded)
nitrogenous bases (RNA uses uracil instead of thyamine)

23. DNA Replication
Each time a cell divides, its entire genome must be copied and passed on to the new cell.

24. DNA Replication
1 double helix replicates to give 2 new double helixes

25. DNA Replication 1 double helix replicates to give 2 new double helixes
The 2 new DNA molecules are made of 1 OLD and 1 NEW polynucleotide strands

26. The Steps of DNA Replication
The two DNA strands are unwound with the help of the enzyme HELICASE which facilitates the breaking of the chemical bonds between the molecules.

27. The Steps of DNA Replication
DNA POLYMERASE helps to form bonds between the nucleotides of the newly formed strand.

28. Review
What must happen before a cell divides?

29. Review
What must happen before a cell divides?
DNA replication

30. Review What must happen before a cell divides?
DNA replication
What enzyme helps to unwind the DNA so it can be copied?

31. Review What must happen before a cell divides?
DNA replication
What enzyme helps to unwind the DNA so it can be copied?
Helicase

32. Protein Synthesis The Big Picture
DNA
(instructions)
RNA
(copy of instructions)
Protein
(result of following instructions)

33. Protein Synthesis requires 3 types of RNA
DNA
RNA
Protein

34. Three Types of RNA messenger RNA (mRNA) copy of a gene (DNA)
leaves nucleus
to carry genetic
information to
the ribosome for
protein synthesis

35. Three Types of RNA
ribosomal RNA (rRNA)
part of the ribosome

36. Three Types of RNA transfer RNA (tRNA) transfers the amino acids
to the ribosome for
protein synthesis.

37. Steps of Protein Synthesis
Transcription of the genetic material.
making the mRNA.

38. Steps of Protein Synthesis
Transcription of the genetic material.
making the mRNA.
Why is it a good idea to make a copy of the DNA to leave the nucleus?

39. Steps of Protein Synthesis
The mRNA travels to the cytoplasm.

40. Steps of Protein Synthesis
Translation of the mRNA
The word translation is used because the language is changing from nucleic acids to amino acids.
A genetic code is used by the cell to translate the genetic material (mRNA) into a protein
3 nucleotides of mRNA make a codon
that translates to a specific amino acid,
or a start or stop message during
protein synthesis.

41. Steps of Protein Synthesis
Translation of the mRNA is initiated with a start codon.

42. Steps of Protein Synthesis
Translation of the genetic material continues and the polypeptide gets longer.

43. Steps of Protein Synthesis
Termination occurs when a stop codon is reached.

44. Review
What is transcription?

45. Review
What is transcription?
copying a gene (DNA) into mRNA

46. Review What is transcription?
copying a gene (DNA) into mRNA
_________ is the process that creates a protein from a strand of mRNA.

47. Review What is transcription?
copying a gene (DNA) into mRNA
_________ is the process that creates a protein from a strand of mRNA.
translation

48. Review What is transcription?
copying a gene (DNA) into mRNA
_________ is the process that creates a protein from a strand of mRNA.
translation
What type of mRNA carries the amino acids to the ribosome during translation?

49. Review What is transcription?
copying a gene (DNA) into mRNA
_________ is the process that creates a protein from a strand of mRNA.
translation
What type of mRNA carries the amino acids to the ribosome during translation?
transfer (t) RNA

50. Genetic Mutations
Mutations are changes in the sequence of nucleotides in DNA. U G A U G C

51. How would this mutation impact protein translation?
Genetic Mutations
Mutations are changes in the sequence of nucleotides in DNA. U G A U G C
How would this mutation impact protein translation?

52. Genetic Mutations
Mutations are changes in the sequence of nucleotides in DNA.
Mutations within a gene can alter the sequence of amino acids in a protein causing changes, or lack of protein function. U G A U G C

53. Types of Mutations
Substitution

54. Types of Mutations
Substitution

55. Types of Mutations
Frameshift

56. Genetic Mutations and Disease
A mutation in the gene that encodes the protein leptin leads to marked obesity in rodents and humans.

57. Genetic Diseases
For more examples of genetic diseases caused by mutations see Timberlake Table 17.5