Chapter 10 Notes

1. Chapter 10 Notes DNA and RNA

2. 10-1 DNA- History • Freidrich Miescher (1868) found nuclear material to be ½ protein & ½ unknown substance • 1890’s, unknown nuclear substance named DNA • Walter Sutton (1902) discovered DNA in chromosomes • Fredrick Griffith (1928) working with Streptococcus pneumoniae conducted transformation experiments of virulent & nonvirulent bacterial strains • Levene (1920’s) determined 3 parts of a nucleotide • Hershey & Chase (1952) used bacteriophages (viruses) to show that DNA, not protein, was the cell’s hereditary material • Rosalind Franklin (early 1950’s) used x-rays to photograph DNA crystals • Erwin Chargaff (1950’s) determined that the amount of A=T and amount of C=G in DNA; called Chargaff’s Rule • Watson & Crick discovered double helix shape of DNA (A pairs with T; C pairs with G) & built the 1st model

3. 10-1 DNA In 1928 Fredrick Griffith was studying the bacteria that cause pneumonia. - smooth  mouse dies - rough  mouse lives - heat killed smooth  mouse lives - above + rough  mouse dies

4. 10-1 DNA Heat-killed, disease-causing bacteria (smooth colonies) Harmless bacteria (rough colonies) Harmless bacteria (rough colonies) Control(no growth) Heat-killed, disease-causing bacteria (smooth colonies) Disease-causing bacteria (smooth colonies) Dies of pneumonia Dies of pneumonia Lives Lives Live, disease-causingbacteria (smooth colonies)

5. 10-1 DNA Griffith called this process transformation: one type of bacteria turned into another ex. rough turns into smooth Avery and other scientists found that DNA is the nucleic acid that stores and transmits the genetic information from one generation to the next

6. 10-2 DNA The two categories of nitrogenous bases are purines and pyrimidines Purines: double ring structure - adenine and guanine Pyrimidines: single ring structure - cytosine and thymine

7. 10-2 DNA DNA is like a ladder - the rungs are made of the nitrogenous bases - the backbone is formed by the sugar and phosphate groups Chargaff’s rule: [A] = [T]; [C] = [G]

8. 10-2 DNA Purines Pyrimidines Adenine Guanine Cytosine Thymine Phosphate group Deoxyribose

9. 10-2 DNA Nucleotide Hydrogen bonds Sugar-phosphate backbone Key Adenine (A) Thymine (T) Cytosine (C) Guanine (G)

10. Section Quiz Avery and other scientists discovered that • DNA is found in a protein coat. • DNA stores and transmits genetic information from one generation to the next. • transformation does not affect bacteria. • proteins transmit genetic information from one generation to the next.

11. Section Quiz DNA is a long molecule made of monomers called • nucleotides. • purines. • pyrimidines. • sugars.

12. Section Quiz Chargaff's rules state that the number of guanine nucleotides must equal the number of • cytosine nucleotides. • adenine nucleotides. • thymine nucleotides. • thymine plus adenine nucleotides.

13. Section Quiz In DNA, the following base pairs occur: • A with C, and G with T. • A with T, and C with G. • A with G, and C with T. • A with T, and C with T.

14. 10-3 Chromosomes and DNA Replication Prokaryotes have a single strand of DNA that forms a circle - found in the cytoplasm The DNA of eukaryotes is linear and forms many strands - found in the nucleus

15. 10-3 Chromosomes and DNA Replication Chromosome E. Coli Bacterium Bases on the Chromosomes

16. 10-3 Chromosomes and DNA Replication Eukaryotic DNA is tightly packed to form chromosomes - each chromosome contains both DNA and protein, packed together to form chromatin. - the DNA wraps around proteins called histones

17. 10-3 Chromosomes and DNA Replication Nucleosome Chromosome DNA double helix Coils Supercoils Histones

18. 10-3 Chromosomes and DNA Replication DNA Replication: the copying of DNA before a cell divides DNA polymerase: the enzyme used in replication

19. 10-3 Chromosomes and DNA Replication During DNA replication, the DNA separates into two strands, then produces two new complementary strands following the rules of base pairing. Each strand serves as a template for a new strand. DNA replication movie DNA replication movie 2

20. 10-3 Chromosomes and DNA Replication • Process by which DNA makes a copy of itself • Occurs during S phase of interphase before cell division • Extremely rapid and accurate (only 1 in a billion are incorrectly paired) • Requires many enzymes & ATP (energy) • Begins at special sites along DNA called origins of replication where 2 strands open & separate making  a replication fork

21. 10-3 Chromosomes and DNA Replication • ·Nucleotides added & new strand forms at replication forks • ·DNA helicase (enzyme) uncoils & breaks the weak hydrogen bonds between complementary bases (strands separate) • ·DNA polymerase adds new nucleotides to the exposed bases in the 5’ to 3’ direction • ·Leading strand (built toward replication fork)completed in one piece • ·Lagging strand (built moving away from the replication fork) is made in sections called Okazaki fragments

22. 10-3 Chromosomes and DNA Replication • ·DNA ligase helps join Okazaki segments together • ·DNA polymerase proofreads the new DNA checking for errors & repairing them; called excision repair ·Helicase recoils the two, new identical DNA molecules

23. 10-3 Chromosomes and DNA Replication

24. 10-3 Chromosomes and DNA Replication Original strand DNA polymerase New strand Growth DNA polymerase Growth Replication fork Replication fork New strand Original strand

25. Section Quiz In prokaryotic cells, DNA is found in the • cytoplasm. • nucleus. • ribosome. • cell membrane.

26. Section Quiz The first step in DNA replication is • producing two new strands. • separating the strands. • producing DNA polymerase. • correctly pairing bases.

27. Section Quiz A DNA molecule separates, and the sequence GCGAATTCG occurs in one strand. What is the base sequence on the other strand? • GCGAATTCG • CGCTTAAGC • TATCCGGAT • GATGGCCAG

28. Section Quiz In addition to carrying out the replication of DNA, the enzyme DNA polymerase also functions to • unzip the DNA molecule. • regulate the time copying occurs in the cell cycle. • “proofread” the new copies to minimize the number of mistakes. • wrap the new strands onto histone proteins.

29. 10-4 RNA and Protein Synthesis RNA, like DNA, consists of long chains of nucleotides. Three differences between DNA and RNA - the sugar is ribose - single stranded - contains uracil instead of thymine *base pairings are A-U and C-G

30. 10-4 RNA and Protein Synthesis

31. 10-4 RNA and Protein Synthesis Genes are coded DNA instructions that control the production of proteins. - each gene controls the production of a specific protein - DNA (gene)  specific RNA sequence  specific amino acid sequence

32. 10-4 RNA and Protein Synthesis There are three types of RNA: 1. messenger RNA (mRNA) 2. ribosomal RNA (rRNA) 3. transfer RNA (tRNA)

33. 10-4 RNA and Protein Synthesis

34. 10-4 Messenger RNA (mRNA) • Single, uncoiled, straight strand of nucleic acid • Found in the nucleus & cytoplasm • Copies DNA’s instructions & carries them to the ribosomes where proteins can be made • mRNA’s base sequence is translated into the amino acid sequence of a protein • Three consecutive bases on mRNA called a codon (e.g. UAA, CGC, AGU) • Reusable

35. 10-4 RNA and Protein Synthesis Ribosome Ribosomal RNA

36. 10-4 Ribosomal RNA (rRNA) • Globular shape • Helps make up the structure of the ribosomes • Ribosomes are the site of translation (making polypeptides) • rRNA & protein make up the large • & small subunits of ribosomes

37. 10-4 RNA and Protein Synthesis Amino acid Transfer RNA

38. 10-4 Transfer RNA (tRNA) • Single stranded molecule containing 80 nucleotides in the shape of a cloverleaf/hairpin • - Carries amino acids in the cytoplasm to ribosomes for protein assembly • Three bases on tRNA that are complementary • to a codon on mRNA are called anticodons(e.g. codon- UUA; anticodon- AAU) • - Amino Acid attachment site • across from anticodon site on tRNA • -Enters a ribosome & reads mRNA • codons and links together correct • sequence of amino acids to make • a protein • -Reusable

39. 10-4 Transcription Adenine (DNA and RNA) Cystosine (DNA and RNA) Guanine(DNA and RNA) Thymine (DNA only) Uracil (RNA only) RNApolymerase DNA RNA

40. 10-4 Transcription Transcription: the copying of the DNA into a complementary strand of RNA - uses the enzyme RNA polymerase During transcription, RNA polymerase binds to DNA and separates the DNA strands. RNA polymerase then uses one strand of DNA as a template from which nucleotides are assembled into a strand of RNA. The enzyme binds to the region DNA known as the promoter region.

41. 10-4 Transcription • DNA helicase (enzyme) uncoils the DNA molecule • RNA polymerase  (enzyme) binds to a region of DNA called the promoter which has the start codon AUG to code for the amino acid methionine • Promoters mark the beginning of a DNA chain in prokaryotes, but mark the beginning of 1 to several related genes in eukaryotes • The 2 DNA strands separate, but only one will serve as the template & be copied • Free nucleotides are joined to the template by RNA polymerase in the 5’ to 3’ directionto form the mRNA strand • mRNA sequence is built until the enzyme reaches an area on DNA called the termination signal • RNA polymerase breaks loose from DNA and the newly made mRNA • Eukaryotic mRNA is modified (unneeded sections snipped out by enzymes & rejoined) before leaving the nucleus through nuclear pores, but prokaryotic RNA is not All 3 types of RNA called transcripts are produced by this method

42. 10-4 RNA and Protein Synthesis RNA Editing Before it leaves the nucleus, RNA is edited. Splicing occurs by removing introns and fusing exons together.

43. 10-4 RNA and Protein Synthesis Transcription – Processing of Gene Information The Genetic Code The genetic code is read in three letter segments called codons. There are 64 different codon possibilities that code for only 20 amino acids -AUG is the start codon -there are 3 stop codons- UAA, UAG, UGA

44. 10-4 RNA and Protein Synthesis

45.  3 LetterAbbreviation  Amino Acid  Codons  Alanine  Ala  GCA GCC GCG GCU  Arginine  Arg  AGA AGG CGA CGC CGG CGU  Aspartic Acid  Asp  GAC GAU  Asparagine  Asn  AAC AAU  Cysteine  Cys  UGC UGU  Glutamic Acid  Glu  GAA GAG  Glutamine  Gln  CAA CAG  Glycine  Gly  GGA GGC GGG GGU  Histidine  His  CAC CAU  Isoleucine  Ile  AUA AUC AUU  Leucine  Leu  UUA UUG CUA CUC CUG CUU  Lysine  Lys  AAA AAG  Methionine  Met  AUG  Phenylalanine  Phe  UUC UUU  Proline  Pro  CCA CCC CCG CCU  Serine  Ser  AGC AGU UCA UCC UCG UCU  Threonine  Thr  ACA ACC ACG ACU  Tryptophan  Trp  UGG  Tyrosine  Tyr  UAC UAU  Valine  Val  GUA GUC GUG GUU  Start  AUG  UAA UAG UGA  Stop

46. 10-4 Translation Translation: the decoding of mRNA into an amino acid sequence During translation, the cell uses information from messenger RNA to produce proteins - anticodon: the three letter sequence on tRNA that binds with mRNA

47. 10-4 Translation • mRNA brings the copied DNA code from the nucleus to the cytoplasm • mRNA attaches to one end of a ribosome; called initiation • tRNAs attach the correct amino acid floating in the cytoplasm to themselves • tRNA with its attached amino acid has 2 binding sites where they join the ribosome • The tRNA anticodon “reads” & temporarily attaches to the mRNA codon in the ribosome • Two amino acids at a time are linked together by peptide bonds to make polypeptide -chains (protein subunits); called elongation • Ribosomes) move along the mRNA strand until they reach a stop codon (UAA, UGA, or UAG); called termination • 8. tRNA’s break loose from amino acid, leave the ribosome, & return to • cytoplasm to pick up another amino acid Protein Synthesis – Translation Animation

48. 10-4 Translation Lysine Phenylalanine tRNA Methionine Ribosome mRNA Start codon

49. 10-4 Translation Lysine tRNA Translation direction mRNA Ribosome

50. 10-4 Translation Polypeptide Ribosome tRNA mRNA