1. Work these in your notebook For the multiple selection questions write down and explanation

2. What does a nucleosome consist of ? A.DNA and histones B.DNA and chromatin C.Chromatin and nucleotides D. Mature RNA and histones Which base is connected to its complementary base in a base pair by three hydrogen bonds? A.Uracil B.Thymine C.Guanine D. Adenine What is the distinction between highly repetitive DNA sequences and single-copy genes? A.The highly repetitive sequences have greater amounts of guanine. B.The highly repetitive sequences have greater amounts of cytosine. C.The highly repetitive sequences are not transcribed. D.The highly repetitive sequences are not replicated.

3. In the model of the DNA molecule shown below, which arrows point to covalent bonds? A.I, II and III only B.II, III and IV only C.I, III and IV only D.I, II and IV only

4. Outline the structure of nucleosomes. (2) (eight) histone (proteins); DNA wrapped around histones/nucleosome; further histone holding these together; Do not allow histone wrapped around DNA. Most of the DNA of a human cell is contained in the nucleus. Distinguish between unique and highly repetitive sequences in nuclear DNA. (5)

5. (b)Outline transcription in prokaryotes. [6]