Chapter 12: DNA , RNA, and Proteins

1. Chapter 12: DNA, RNA, and Proteins

2. I. DNA A. DNA— deoxyribonucleic acid; determines an organism’s traits by controlling when proteins in the body are made 1. Proteins and enzymes —control most aspects of cellular function in an organism

3. I. DNA B. Structure of DNA 1. Made of long chains of nucleotides a. 3 parts of a nucleotide: - phosphate group - simple sugar (deoxyribose) - nitrogen base

4. I. DNA b. 4 types of nitrogen bases: - adenine (A) - guanine (G) - cytosine (C) - thymine (T) Guanine (G) Cytosine (C) Thymine (T) Adenine (A)

5. I. DNA c. Complementarybasepairs: • - A pairs with T • - G pairs with C Guanine (G) Cytosine (C) Thymine (T) Adenine (A) d. Nucleotides join together in long chains to formnucleic acids.

6. I. DNA 2. All organisms are made up of the same nucleotides, just in different order a. Example: All words are made up of the same letters, just in different order

7. II. What does DNA look like? A. Discovered by James Watson and Francis Crick in 1953. 1. Double Helix — double stranded, twisted ladder shape of DNA 2. If DNA is a ladder: a. Sugarandphosphate groups form the backbone or the sides of the ladder b. Nitrogen bases form the rungs of the ladder.

8. II. What does DNA look like? James Watson and Francis Crick

9. II. What does DNA look like? 3. Individual nucleotides are joined by covalent bonds. 4. Nitrogen bases in the middle of the helix are joined by hydrogen bonds.

10. II. What does DNA look like? B. How does DNA fit in the cell? 1. Think about it! The DNA strand can be incredibly LONG! Human DNA molecules contain up to 4,639,221,000 base pairs. That means there is about 1-2 meters of DNA in each cell. How can it be kept in such a small area?

11. II. What does DNA look like? 2. The solution: a. Chromatin is made of DNA packed around histone proteins. b. During interphase, these are dispersed and uncoiled. When cells enter prophase, they pack tightly to form chromosomes.

12. III. Replication A. DNA Replication - Whenever a cell divides, the DNA must be copied before it splits 1. DNA helicase, an enzyme, unzips the double helix (breaks the hydrogen bonds) to form two single strands still joined at the replication forks. Replication Fork Replication Fork DNA helicase DNA helicase

13. III. Replication 2. DNA polymerase, an enzyme, adds new nucleotides to each single strand according to their complementary base pairs a. DNA polymerase also “proofreads” for errors Replication Fork Replication Fork DNA polymerase DNA helicase DNA helicase

14. III. Replication 3. DNA Ligase, an enzyme, reseals the gaps remaining in the sugar/phosphate backbone to finish. Replication Fork Replication Fork DNA polymerase DNA ligase DNA helicase DNA helicase

15. III. Replication 4. END RESULT: 2 new and identical molecules of DNA are formed a. 1 strand made of “old” DNA b. 1 strand made of “new” DNA

16. III. Replication New DNA molecule Original DNA Strand Free Nucleotides New DNA molecule New DNA Strand Original DNA Strand Original DNA

17. III. Replication DNA Replication Replication

18. III. Replication 5. Example Complementary Base Pairing a. (Find each complementary base pair for the strand of DNA) A—C—T—A—G—A—C—C—T—A—G—T | | | | | | | | | | | | T G A T C T G G A T C A

19. III. Replication 6. Example of DNA Replication a. (Unzip the following molecule of DNA, and write the two new strands of DNA that would result from the replication) b. Original DNA Molecule C—G—T—C—A—T—C—G—C—A—A—T—G | | | | | | | | | | | | | G—C—A—G—T—A—G—C—G—T—T—A—C Molecule #1 C—G—T—C—A—T—C—G—C—A—A—T—G | | | | | | | | | | | | | G—C—A—G—T—A—G—C—G—T—T—A—C Molecule #2 C—G—T—C—A—T—C—G—C—A—A—T—G | | | | | | | | | | | | | G—C—A—G—T—A—G—C—G—T—T—A—C

20. IV. From DNA to Protein • DNA- Double stranded nucleic acid that is stored in the nucleusof the cell. • 1. Gene- piece of DNA that controls a specific trait

21. IV. From DNA to Protein B. RNA - a single stranded nucleic acid found all over the cell (nucleus, cytoplasm, and ribosome) 1. Made of long chains of nucleotides: a. 3 parts of a nucleotide— -phosphate group - simple sugar (ribose) - nitrogen base

22. IV. From DNA to Protein b. 5 types of Nitrogen Bases - adenine (A) - guanine (G) - cytosine (C) - thymine (T) - Uracil (U) c. Complementary base pairs • - A pairs with U • - T pairs with A • - G pairs with C d. Nucleotides join together in long chains to formnucleic acids.

23. IV. From DNA to Protein 2. Three Types of RNA a. Messenger RNA (mRNA)- carries the information from the DNA in the nucleus to the rest of the cell Codon

24. IV. From DNA to Protein Transfer RNA molecule Amino acid b. Transfer RNA (tRNA)- helps build proteins by carrying amino acids to ribosomes, following instructions coded for in the mRNA. • Each tRNA carries only ONE type of amino acid • The code of the tRNA is complementary to the mRNA. Chain of RNA nucleotides Anticodon

25. IV. From DNA to Protein c. Ribosomal RNA (rRNA)- the site of protein synthesis; makes up the ribosome

26. IV. From DNA to Protein C. DNA/RNA Comparison

27. IV. From DNA to Protein

28. IV. From DNA to Protein D. Protein Synthesis - Using genetic information in DNA to make proteins DNA RNA Protein transcription translation

29. IV. From DNA to Protein E. Steps of Protein Synthesis 1. Transcription - Process of making mRNA from DNA a. Why? DNA can’t leave nucleus but RNA can

30. IV. From DNA to Protein b. Steps of Transcription 1. RNA polymerase, an enzyme, unzips the double helix of DNA inside the nucleus and uses it as a template to create a complementary mRNA strand

31. IV. From DNA to Protein 2. RNA editing occurs • Introns- sections of the DNA that don’t code for proteins are cut from the mRNA • Exons- sections of the DNA that code for proteins are left on the mRNA

32. IV. From DNA to Protein 3. DNA rezips and mRNA leaves nucleus and goes to the cytoplasm to find a ribosome for protein synthesis

33. IV. From DNA to Protein c. Example: Transcribe the DNA into mRNA. • A C C A T G A C C T G A C T T A C • U G G U A C U G G A C U G A A U G

34. IV. From DNA to Protein 2. Translation: Making chains of amino acids (proteins) by reading/translating mRNA codons (a group of 3 nucleotides) in the ribosome a. The amino acid sequence determines the structure and function of proteins codon

35. IV. From DNA to Protein b. Steps of Translation 1. mRNA travels to ribosome with a message from the DNA and attaches to the rRNA. 2. 3. 2. 1.

36. IV. From DNA to Protein 2. As each mRNA codon moves over the ribosome, it is matched with its complementary tRNA anticodon, which is carrying amino acids. 2. 3. 2. 1.

37. IV. From DNA to Protein 3. Inside the ribosome, peptidase, an enzyme, helps form peptide bonds joining amino acids to make proteins and tRNA is released to go find another amino acid 2. 3. 2. 1.

38. IV. From DNA to Protein c. Example: Translate the mRNA into proteins (USE CODON CHART!) • mRNA = A U G C A U G G A A G C U G A • amino acid chain =

40. IV. From DNA to Protein

41. IV. From DNA to Protein

42. IV. From DNA to Protein d. There are 20 amino acids created from a combination of the 4 nitrogen bases - Each mRNA codon specifies a different tRNA anticodon to bring amino acids to join to the protein - Every different combination of amino acids forms new proteins Methionine Alanine Peptide bond

43. IV. From DNA to Protein • Special Codons - some codons signal start or stop • AUG (methoinine) = start building protein • UAA, UAG, and UGA = stop building protein Stop codon

45. Transcription vs. Translation 3. Transcription/Translation Comparison

46. V. Mutations A. Mutation - Mistake or change in DNA sequence 1. The change in the DNA is HUGE since the codon is changed a. If the codons are affected, the amino acidsand proteins for the cell are also affected.

47. V. Mutations B. Types of Mutations 1. Point Mutation- change in a SINGLE base pair in DNA a. Substitution Mutation - one nitrogen base is replaced with another - Example: ACTAGGCAC to ACTAGTCAC - Results in a change of one codon

48. Types of Gene Mutations mRNA Normal Protein mRNA Point mutation Protein

49. V. Mutations b. Frameshift Mutation - ONE base is added or deleted from DNA, and it shifts the reading of codons - Example: Addition Mutation: ACTAGGCAC to ACTAGGGCAC Deletion Mutation: ACTAGGCAC to ACTAGCAC - Results in EVERY codon after the mutation to change. - Original Protein: Meth-Lys-Phenyl-Gly-Ala- Leu - Mutated protein: Meth-Lys-Leu-Ala-Hist- Cys

50. Types of Gene Mutations Without mutation Frameshift mutation mRNA Protein Deletion of U