2. What are proteins? Constructed from 20 different amino acids Involved in almost all cellular functions including:

3. Antibodies that defend the body from germs Contractile proteins that are responsible for movement Enzymes that speed up chemical reactions

4. What’s the Big Deal about DNA? DNA codes for RNA which guides the synthesis of proteins Remember, proteins are the building blocks of cells

5. DNA is too large to leave the nucleus and guide instruction so:

6. It makes a copy of itself to send out called: RNA

7. RNA: ribonucleic acid Nucleic acid The principle molecule that carries out the instructions coded in DNA

8. RNA

9. RNA differs from DNA in 3 ways:

10. The sugar in RNA is ribose, not deoxyribose

11. It is single stranded

12. Contains the base uracil instead of thymine (U bonds with A)

13. Types of RNA:

14. Molecular Genetics Messenger RNA (mRNA)  Long strands of RNA nucleotides that are formed complementary to one strand of DNA 12.3 DNA, RNA, and Protein Chapter 12

15. Transfer RNA (tRNA) Smaller segments of RNA nucleotides that transport amino acids to the ribosome

16.  Ribosomal RNA (rRNA)  Associates with proteins to form ribosomes in the cytoplasm, contain no genetic info.

17. http://www.youtube.com/watch?v=NJxobgkP EAo

18. Transcription Transcription: process by which RNA is made Part of the nucleotide sequence of a DNA molecule is copied into RNA Occurs in the nucleus

19. Steps of Transcription DNA is unzipped in the nucleus by an enzyme Another enzyme, RNA polymerase, bonds “free nucleotides” to the exposed bases

21. Adenine bonds with uracil (A to U) and guanine bonds to cytosine This chain is called mRNA

22. Consists of multiple codons

23. Codon: group of 3 nucleotides in mRNA that specify one amino acid Ex. AAA CAC GGU reads as 3 codons AAA codes for the amino acid lysine CAC codes for the amino acid histidine Pg. 338

24. Molecular Genetics 12.3 DNA, RNA, and Protein Chapter 12

25. Suppose the DNA strand is CGT-ACG-AAA, what is the mRNA strand? 20 different amino acids make up proteins

27. Molecular Genetics Chapter 12

28. Translation Translation: nucleotides in mRNA are decoded into a sequence of amino acids in a protein Occurs after transcription in the cytoplasm Involves the ribosomes

29. Steps of Translation mRNA leaves the nucleus and attaches to the ribosomes, where it acts as a pattern to line up amino acids –Each triplet codon codes for an amino acid

30. The ribosome reads each triplet codon (on the mRNA)

31. Transfer RNA (tRNA) brings amino acids to the complementary codon on the mRNA –This is called the anti-condon

33. The ribosome bonds the amino acid to the previous amino acid tRNA moves off into the cytoplasm to pick up another amino acid

34. Amino acids are scattered throughout the cytoplasm

37. Each tRNA can only deliver one type of amino acid When the protein is assembled, the mRNA breaks up and becomes free nucleotides again A stop codon releases the polypeptide (protein)

38. Molecular Genetics 12.3 DNA, RNA, and Protein Chapter 12

39. Molecular Genetics Chapter 12

40. Molecular Genetics Mutation  A permanent change that occurs in a cell’s DNA is called a mutation. 12.4 Gene Regulation and Mutation Chapter 12

41. Types of mutations: Substitution Insertion Deletion

42. Point Mutation Substitution: When one base is exchanged for another Ex. Normal: AUG CCT GAT CCC Substitution: AUG CCA GAT CCC

43. Substitution could lead to a change in amino acid sequence or no change at all

46. Insertion Insertion: Addition of nucleotide in the DNA sequence EX. Normal: AUG CCT GAT CCC Insertion: AUG GCC TGA TCC C

47. INSERTION

48. Deletion Loss of a nucleotide in the DNA sequence EX. Normal: AUG CCT GAT CCC Deletion: AUG CTG ATC CC

50. Both insertion mutations and deletion mutations change the multiples of 3 from the point of insertion or deletion Frameshift mutations both insertion and deletion are called this

51. Molecular Genetics 12.4 Gene Regulation and Mutation Chapter 12

52. Molecular Genetics Body-cell v. Sex-cell Mutation  Somatic cell mutations are not passed on to the next generation.  Mutations that occur in sex cells are passed on to the organism’s offspring and will be present in every cell of the offspring. 12.4 Gene Regulation and Mutation Chapter 12