2. DNA Replication & Protein Synthesis

3. DNA Replication

4. Conservative, semi-conservative or dispersive?

5. The Meselson-Stahl Experiment Each strand of DNA acts as a template for synthesising a new one.

6. Protein Synthesis Objectives: * state that a gene is a sequence of nucleotides as part of a DNA molecule, which codes for a polypeptide; **describe the way in which the nucleotide sequence codes for the amino acid sequence in a polypeptide; ***explain that, as enzymes are proteins, their synthesis is controlled by DNA

7. 1. The DNA double helix ‘unzips’ and the hydrogen bonds between the bases break. 2. Free nucleotides in the nucleus are activated by 2 extra phosphates. P P 3. The bases of the active nucleotides pair up with their complementary base on the DNA template. 4. DNA polymerase links the sugar and phosphate groups of neighbouring nucleotides together.

8. Protein Synthesis DNA  RNA  amino acids

10. http://www- class.unl.edu/biochem/gp2/m_biology/a nimation/gene/gene_a1.html http://www- class.unl.edu/biochem/gp2/m_biology/a nimation/gene/gene_a1.html describe how the information on DNA is used to construct polypeptides, including the role of messenger RNA, transfer RNA and the ribosomes

11. Comparison of DNA, mRNA and tRNA FeatureDNAmRNAtRNA Double/Single Size Shape Sugar Bases Quantity in cells Stability

12. Comparison of DNA, mRNA and tRNA FeatureDNAmRNAtRNA Double/SingleDoubleSingle SizeLargestVariableSmaller ShapeDouble helixSingle helixClover shape SugarDeoxyriboseRibose BasesA, G, T, CA, G, U, C Quantity in cellsConstant (gametes) Varies StabilityVery stableUnstableMore stable than mRNA, less than DNA

13. Transcription – In the nucleus

15. . Translation – In the cytoplasm

17. Summary

18. Compare the relationship between DNA and nucleotide with amino acids and protein

19. RNA polymerase binds to the promoter region This initiates transcription RNA polymerase uncoils the DNA Only one strand is used, the template strand Free nucleoside triphosphates bond to their complementary bases on the template strand Adenine binds to uracil instead of thymine As the nucleoside triphosphates bind they become nucleotides and release energy by losing two phosphate groups The mRNA is built in a 5'→3' direction RNA polymerase forms covalent bonds between the nucleotides and keeps moving along the DNA until it reaches the terminator The terminator signals the RNA polymerase to stop transcription RNA polymerase is released and mRNA separates from the DNA The DNA rewinds

20. The Triplet Code

21. http://www.ibguides.com/bi ology/notes/transcription-hl