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Biology lecture 5
- 4. DNA RNA Protein Prokaryotic Cell Transcription Translation DNA mRNA Ribosome Protein
- 5. DNA RNA Protein Eukaryotic Cell Nuclear membrane Transcription RNA Processing Translation DNA Pre-mRNA mRNA Ribosome Protein
- 11. DNA Nucleotide
- 15. Anti-Parallel Strands of DNA
- 16. DNA Replication
- 18. Two New, Identical DNA Strands Result from Replication
- 19. Another View of Replication
- 20. RNA
- 22. Structure of RNA
- 24. Making a Protein
- 32. Transcription
- 36. DNA pre-mRNA RNA Polymerase
- 40. RNA Processing pre-RNA molecule intron intron exon exon exon exon exon exon Mature RNA molecule exon exon exon intron intron splicesome splicesome
- 42. Messenger RNA (mRNA) methionine glycine serine isoleucine glycine alanine stop codon protein A U G G G C U C C A U C G G C G C A U A A mRNA start codon Primary structure of a protein aa1 aa2 aa3 aa4 aa5 aa6 peptide bonds codon 2 codon 3 codon 4 codon 5 codon 6 codon 7 codon 1
- 44. Transfer RNA (tRNA) amino acid attachment site U A C anticodon methionine amino acid
- 47. Ribosomes P Site A Site Large subunit Small subunit mRNA A U G C U A C U U C G
- 50. mRNA Codons Join the Ribosome P Site A Site Large subunit Small subunit mRNA A U G C U A C U U C G
- 51. Initiation mRNA A U G C U A C U U C G A anticodon hydrogen bonds codon 2-tRNA G aa2 A U 1-tRNA U A C aa1
- 52. mRNA A U G C U A C U U C G 1-tRNA 2-tRNA U A C G aa1 aa2 A U A anticodon hydrogen bonds codon peptide bond Elongation 3-tRNA G A A aa3
- 53. mRNA A U G C U A C U U C G 1-tRNA 2-tRNA U A C G aa1 aa2 A U A peptide bond Ribosomes move over one codon (leaves) 3-tRNA G A A aa3
- 54. mRNA A U G C U A C U U C G 2-tRNA G aa1 aa2 A U A peptide bonds 3-tRNA G A A aa3 A C U 4-tRNA G C U aa4
- 55. mRNA A U G C U A C U U C G 2-tRNA G aa1 aa2 A U A peptide bonds 3-tRNA G A A aa3 A C U (leaves) Ribosomes move over one codon 4-tRNA G C U aa4
- 56. mRNA G C U A C U U C G aa1 aa2 A peptide bonds 3-tRNA G A A aa3 4-tRNA G C U aa4 A C U U G A 5-tRNA aa5
- 57. mRNA G C U A C U U C G aa1 aa2 A peptide bonds 3-tRNA G A A aa3 4-tRNA G C U aa4 A C U Ribosomes move over one codon U G A 5-tRNA aa5
- 58. mRNA A C A U G U aa1 aa2 U primary structure of a protein aa3 200-tRNA aa4 U A G aa5 C U aa200 aa199 terminator or stop codon Termination
- 64. One ribosome from the RER
- 66. A ribosome
Notes de l'éditeur
- Notice that the 3’ and 5’ refer to a numbering system for the carbon atoms that make up the sugar.
- On the left is the DNA double helix. When the helix is unwound, a ladder configuration shows that the uprights are composed of sugar and phosphate molecules and the rungs are complementary bases. Notice that the bases in DNA pair in such a way that the phosphate-sugar groups are oriented in different directions. This means that the strands of DNA end up running antiparallel to one another, with the 3’ end of one strand opposite the 5’ end of the other strand.
- DNA polymerase is an enzyme.
- Replication is called semiconservative because each new double helix is composed of an old (parental) strand and a new (daughter) strand.
- Use of the ladder configuration better illustrates how complementary nucleotides available in the cell pair with those of each old strand before they are joined together to form a daughter strand.
- Like DNA, RNA is a polymer of nucleotides. In an RNA nucleotide, the sugar ribose is attached to a phosphate molecule and to a base, either G, U, A, or C. Notice that in RNA, the base uracil replaces thymine as one of the pyrimidine bases. RNA is single-stranded, whereas DNA is double-stranded.
- The fact that the genetic code is about universal in living things suggests that the code dates back to the first organisms on earth and that all living things are related.
- Notice that in this chart, each of the codons (white rectangles) is composed of three letters representing the first base, second base, and third base. For example, find the rectangle where C for the first base and A for the second base intersect. You will see that U, C, A, or G can be the third base. CAU and CAC are codons for histidine; CAA and CAG are codons for glutamine.
- Transcription occurs when DNA acts as a template for mRNA synthesis. Translation occurs when the sequence of the mRNA codons determines the sequence of amino acids in a protein.
- During transcription, complementary RNA is made from a DNA template. A portion of DNA unwinds and unzips at the point of attachment of RNA polymerase. A strand of mRNA is produced when complementary bases join in the order dictated by the sequence of bases in DNA. Transcription occurs in the nucleus, and the mRNA passes out of the nucleus to enter the cytoplasm.