Molecular Genetics

Who used X-ray diffraction to determine the shape of DNA?

• Watson and Crick

• Hershey and Chase

• Pauling and Corey

• Wilkins and Franklin

During DNA replication, the function of RNA primers is to:

• serve as a binding site for DNA ligase

• serve as starting points for DNA strand elongation by DNA polymerase III in prokaryotes

• serve as starting points for DNA strand elongation by DNA polymerase I in the 3' - 5' direction

• open replication bubbles

Which statement is true, based on the findings of Erwin Chargaff?

• The ratio of adenine to thymine in all organisms is constant.

• The amount of adenine in all organisms is constant.

• The ratio of adenine to cytosine in all organisms is constant.

• The ratio of adenine to thymine varies among organisms.

During DNA replication, one of the new strands of DNA is synthesized continuously. The other strand is synthesized as a number of separate fragments of DNA that are subsequently linked by DNA ligase. Why does this occur?

• RNA primers only anneal to one of the parental strands of DNA.

• One of the parental strands is unwound slower than the other by helicase.

• DNA polymerase III only synthesizes DNA in the 3' - 5' direction.

• DNA polymerase III only synthesizes DNA in the 5' - 3' direction.

Why is DNA replication considered to be semiconservative?

• Each original DNA strands makes a copy of its complementary base pair.

• Each original DNA strands makes a copy of itself.

• It keeps half of the old nucleotides.

• None of these

Why is DNA polymerase I used in prokaryotes?

• to repair damage to DNA base pairs

• to remove DNA sequences to form plasmids

• to fill in gaps between Okazaki fragments along the lagging strand

• to add DNA nucleotides to build new strands

Which statement about telomeres is true?

• They prevent the loss of genes from the ends of chromosomes during replication.

• They are associated with aging.

• They are repeating DNA sequences at the ends of chromosomes.

• All are correct

Telomeres are absent in prokaryotes because

• prokaryotes are single celled and cannot age.

• the circular chromosome in prokaryotes has no end.

• plasmids have the same function in prokaryotes.

• prokaryotes lack telemerase.

What is the central dogma?

• the flow of genetic information from RNA to amino acids to DNA

• the flow of genetic information from proteins to amino acids to DNA

• the flow of genetic information from RNA to DNA to proteins

• the flow of genetic information from DNA to RNA to proteins

Which of the following correctly describes the order in which cell components function during protein synthesis?

• RNA polymerase, mRNA, ribosome, tRNA

• DNA polymerase, mRNA, ribosome, tRNA

• mRNA, RNA polymerase, ribosome, tRNA

• RNA polymerase, mRNA, tRNA, ribosome