1. DNA, RNA structure 2. DNA replication 3. Transcription, translation

1. 1. DNA, RNA structure 2. DNA replication 3. Transcription, translation

2. DNA and RNA are polymers of nucleotides • 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 Polynucleotide Sugar-phosphate backbone

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

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

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

6. Untwisting and replication of DNA • each strand is a template for a new strand helicase DNA polymerase

7. 5 end 3 end P • Each strand of the double helix is oriented in the opposite direction P P P P P P P 3 end 5 end

8. 3 DNA polymerasemolecule 5 5 end Daughter strandsynthesizedcontinuously Parental DNA 5 3 Daughter strandsynthesizedin pieces • DNA polymerase works in only one direction 3 P 5 • Telomere sequences are lost with each replication. • Cancer, aging telomeres 5 P 3 DNA ligase Overall direction of replication

9. The information constituting an organism’s genotype is carried in its sequence of bases • The DNA is transcribed into RNA, which is translated into the polypeptide DNA TRANSCRIPTION RNA TRANSLATION Protein

10. Transcription produces genetic messages in the form of mRNA RNA nucleotide RNApolymerase Direction oftranscription Templatestrand of DNA Newly made RNA

11. RNA polymerase DNA of gene Promoter DNA Terminator DNA Initiation • RNA nucleotides line up along one strand of DNA, following the base-pairing rules • single-stranded messenger RNA peels away and DNA strands rejoin • occurs in nucleus • In transcription, DNA helix unzips Elongation Termination GrowingRNA Completed RNA RNApolymerase

12. Translation of nucleic acids into amino acids • The “words” of the DNA “language” are triplets of bases called codons • The codons in a gene specify the amino acid sequence of a polypeptide

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

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

15. Each tRNA molecule has a triplet anticodon on one end and an amino acid attachment site on the other Amino acidattachment site Anticodon

16. 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

17. Mutations can change the meaning of genes • Mutations are changes in the DNA base sequence • caused by errors in DNA replication or by mutagens

18. 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