DNA and Protein Synthesis

MOLECULAR GENETICS I

(DNA and Protein Synthesis)

Read chapters 16-17 in Campbell.

Key Terms:

transformationreplication

bacteriophageadenine

guaninepurine

cytosinethymine

pyrimidinepolymerase

transcriptionmessenger RNA (mRNA)

uracilribosomal RNA (rRNA)

transfer RNA (tRNA)RNA polymerase

exon DNA polymerase

introntranslation

codonanticodon

P-siteA-site

addition mutationdeletion mutation

base substitution

Answer the following questions:

1.Cite two lines of experimental evidence to support the conclusion that DNA is the genetic material.

2.Draw a diagram of a nucleotide. Label the phosphate group, the sugar group, the 1' carbon, 3' carbon, and 5' carbon of the sugar. Explain how DNA nucleotides differ from RNA nucleotides.

3. Name the four nitrogenous bases found in DNA, and indicate which are pyrimidines (single-ring structures) and which are purines (double-ring structures).

Indicate the number of hydrogen bonds in a GC pair and an AT pair.

4.Draw the following sequence of bases on one DNA strand (3' TAC ATT TGC CGC CCG GGA TAT ATT GTT 5'), using a different color of ink

list the sequence on the complementary strand.

5.Discuss how the Watson-Crick model accounts for precise replication of genetic material, explain why one strand is copied continuously while the other is copied in discontinous segments, and name the enzymes that catalyze DNA replication.

6.Describe how repair enzymes act to correct mutations and errors that occur during replication.

7.List three ways in which RNA is different from DNA; name the three types of RNA and indicate where each is synthesized, and describe the function of each type of RNA.

8.Given the following sequence of bases on one DNA strand

(3' TAC ATT TGC CGC CCG GGA TAT ATT GTT TCC 5'), write the sequence of mRNA that would be transcribed from this DNA. Indicate the 5' and 3' ends of the transcript. State the role of the promoter, RNA polymerase, the start signal and the termination signal in the process.

9.Explain how transcription in prokaryotes differs from that in eukaryotes.

10. Describe how the genetic code is read by the ribosome. In doing so, explain the terms codon, anticodon, initiation codon, and termination codon.

11. Using the DNA and mRNA strand in #9, show the amino acid sequence that it

would produce.

12.Explain what mutatuions are. List three examples of different types of mutations, and indicate how mutations can be induced. Explain the relationship between mutagenicity and carcinogenicity.

13.Discuss possible definitions of the word "gene."

14.Give the percentage of the eukaryotic genome that is both transcribed and translated and contrast that with the percentage of the prokaryotic genome that is transcribed and translated. Explain the role of snRNP's in eukaryotes.