DNA, RNA, Amino Acids, Proteins, and Genes!

1. DNA, RNA, Amino Acids, Proteins, and Genes!

2. DNA • DNA is a nucleic acid, made of long chains of nucleotides Phosphate group Nitrogenous base Nitrogenous base(A, G, C, or T) Sugar Phosphategroup Nucleotide Thymine (T) Sugar(deoxyribose) DNA nucleotide Figure 10.2A Polynucleotide Sugar-phosphate backbone

3. DNA has four kinds of bases, A, T, C, and G Thymine (T) Cytosine (C) Adenine (A) Guanine (G) Figure 10.2B

4. different sugar • Uracil instead of Thymine • Single strand • RNA is also a nucleic acid Nitrogenous base(A, G, C, or U) Phosphategroup Uracil (U) Sugar(ribose) Figure 10.2C, D

5. DNA is a double-stranded helix • James Watson and Francis Crick worked out the three-dimensional structure of DNA, based on work by Rosalind Franklin Figure 10.3A, B

6. Hydrogen bond • Hydrogen bonds between bases hold the strands together: A and T, C and G Ribbon model Partial chemical structure Computer model Figure 10.3D

7. Untwisting and replication of DNA • each strand is a template for a new strand Figure 10.4B

8. The information constituting an organism’s genotype is carried in its sequence of bases • The DNA is transcribed into RNA, which is translated into a protein DNA TRANSCRIPTION RNA TRANSLATION Protein Figure 10.6A

9. RNA transcripts of DNA

10. Translation of nucleic acids into amino acids • The “words” of the DNA “language” are three bases in a row called codons • The codons in a gene specify the amino acid sequence of a protein

11. Gene 1 Gene 3 DNA molecule Gene 2 DNA strand TRANSCRIPTION RNA Codon TRANSLATION Polypeptide Amino acid Figure 10.7

12. Virtually all organisms share the same genetic code “unity of life” Second Base U C A G UUU UCU UAU UGU U tyr phe cys UUC UCC UAC UGC C ser U UUA UCA UAA stop UGA stop A leu UUG UCG UAG stop UGG trp G CUU CCU CAU CGU U his CUC CCC CAC CGC C pro arg leu C CUA CCA CAA CGA A gln CUG CCG CAG CGG G First Base Third Base AUU ACU AAU AGU U ser asn AUC ACC AAC AGC C ile thr A AUA ACA A AAA AGA lys arg AGG AUG ACG AAG G met (start) GUU GCU GAU GGU U asp GUC GCC GAC GGC C val G ala gly GUA GCA GAA GGA A glu GUG GCG GAG GGG G

13. Transcribed strand • An exercise in translating the genetic code DNA Transcription RNA Startcodon Stopcodon Translation Polypeptide Figure 10.8B

14. Transfer RNA molecules serve as interpreters during translation Amino acid attachment site • In the cytoplasm, a ribosome attaches to the mRNA and translates its message into a polypeptide • The process is aided by transfer RNAs Hydrogen bond RNA polynucleotide chain Anticodon Figure 10.11A

15. Ribosomes build proteins Next amino acidto be added topolypeptide Growingpolypeptide tRNA molecules P site A site Growingpolypeptide Largesubunit tRNA P A mRNA mRNAbindingsite Codons mRNA Smallsubunit Figure 10.12A-C

16. mRNA, a specific tRNA, and the ribosome subunits assemble during initiation Largeribosomalsubunit Initiator tRNA P site A site Startcodon Small ribosomalsubunit mRNA 1 2 Figure 10.13B

17. Elongation • The mRNA moves a codon at a time relative to the ribosome • A tRNA pairs with each codon, adding an amino acid to the growing polypeptide • A STOP codon causes the mRNA-ribosome complex to fall apart

18. Amino acid Polypeptide Asite P site Anticodon mRNA 1 Codon recognition mRNAmovement Stopcodon Newpeptidebond 2 Peptide bond formation 3 Translocation Figure 10.14

19. Table 14.2 Types of RNA Type of RNA Functions in Function Messenger RNA (mRNA) Nucleus, migrates to ribosomes in cytoplasm Carries DNA sequence information to ribosomes Transfer RNA (tRNA) Cytoplasm Provides linkage between mRNA and amino acids; transfers amino acids to ribosomes Cytoplasm Ribosomal RNA (rRNA) Structural component of ribosomes

20. Review: The flow of genetic information in the cell is DNARNAprotein • The sequence of codons in DNA spells out the primary structure of a polypeptide • Polypeptides form proteins that cells and organisms use

21. Mutations can change the meaning of genes • Mutations are changes in the DNA base sequence • caused by errors in DNA replication or by mutagens • change of a single DNA nucleotide causes sickle-cell disease

22. Normal hemoglobin DNA Mutant hemoglobin DNA mRNA mRNA Normal hemoglobin Sickle-cell hemoglobin Glu Val Figure 10.16A

23. NORMAL GENE • Types of mutations mRNA Protein Met Lys Phe Gly Ala BASE SUBSTITUTION Met Lys Phe Ser Ala Missing BASE DELETION Met Lys Leu Ala His Figure 10.16B

24. Chromosomal changes can be large or small Deletion Homologouschromosomes Duplication Inversion Reciprocaltranslocation Nonhomologouschromosomes Figure 8.23A, B

25. TRANSCRIPTION DNA Stage mRNA istranscribed from aDNA template. 1 mRNA RNApolymerase • Summary of transcription and translation Amino acid TRANSLATION Stage Each amino acid attaches to its proper tRNA with the help of a specific enzyme and ATP. 2 Enzyme tRNA Initiator tRNA Anticodon Stage Initiation of polypeptide synthesis 3 Largeribosomalsubunit The mRNA, the first tRNA, and the ribosomal subunits come together. Start Codon Smallribosomalsubunit mRNA Figure 10.15

26. Newpeptidebondforming Growing polypeptide Stage Elongation 4 A succession of tRNAs add their amino acids to the polypeptide chain as the mRNA is moved through the ribosome, one codon at a time. Codons mRNA Polypeptide Stage Termination 5 The ribosome recognizes a stop codon. The poly-peptide is terminated and released. Stop Codon Figure 10.15 (continued)