Molecular Basis of Inheritance quiz

The number of base pairs in one turn of the B-DNA helix is about:

Griffith's transformation experiment used:

In the Hershey and Chase experiment, radioactive phosphorus was found in:

The enzyme that joins Okazaki fragments is:

Which RNA polymerase transcribes hnRNA in eukaryotes?

The initiator codon AUG codes for:

In the lac operon, the z gene codes for:

The ribozyme that catalyses peptide bond formation in bacteria is:

Histones are rich in:

According to the Human Genome Project, the chromosome with the fewest genes is:

Why is DNA a better genetic material than RNA? Give two reasons. (2 marks)

Distinguish between euchromatin and heterochromatin. (2 marks)

Why is the genetic code called degenerate and unambiguous? (2 marks)

What is the role of the 5' cap and the poly-A tail in eukaryotic mRNA? (2 marks)

What is meant by charging of tRNA? (2 marks)

Why is replication continuous on one strand and discontinuous on the other? (2 marks)

What are untranslated regions (UTRs)? Where are they located? (2 marks)

Name the three stop codons. Why do they not code for any amino acid? (2 marks)

State two applications of DNA fingerprinting. (2 marks)

What are SNPs? How many were identified in the human genome? (2 marks)

A DNA molecule has 30% guanine. Calculate the percentage of each other base. If it has 5,000 nucleotides in total, calculate the number of adenine nucleotides. (3 marks)

Bacteriophage lambda has 48,502 bp. Calculate the length of its DNA in micrometres (distance between base pairs 0.34 nm) and the number of complete helical turns. (3 marks)

A mammalian cell's DNA of 6.6 x 10^9 bp is packed into nucleosomes, each with about 200 bp (including linker DNA). Calculate the approximate number of nucleosomes in the cell. (3 marks)

An mRNA has 150 nucleotides between the start codon AUG (inclusive) and the stop codon (exclusive). How many amino acids will the polypeptide have? How many tRNA molecules are needed if each tRNA brings one amino acid? (3 marks)

In Meselson and Stahl's experiment, after four generations in 14N medium, calculate the fraction of DNA molecules that are hybrid and the fraction that are light. (3 marks)

Read the passage and answer the questions. Frederick Griffith injected mice with live R strain bacteria, live S strain bacteria, heat-killed S strain bacteria, and a mixture of heat-killed S and live R strain bacteria. Mice died in two of the four cases, and live S bacteria were recovered from the mixture. (i) In which two cases did the mice die? (ii) What did Griffith conclude? (iii) Which scientists later identified the transforming principle as DNA? (5 marks)

Read the passage and answer the questions. A segment of DNA has the template strand 3'-TAC GGA CCT ATT-5'. During transcription, RNA polymerase uses this strand to make mRNA. (i) Write the coding strand and the mRNA. (ii) Write the amino acid sequence using: AUG Met, CCU Pro, GGA Gly, UAA stop. (iii) What would happen if the third base of the second codon in the template were changed so that the codon in mRNA became CCC (also coding for proline)? (5 marks)

Read the passage and answer the questions. E. coli cells growing in a medium with glucose were transferred to a medium containing only lactose. After some time, the cells began producing beta-galactosidase, permease and transacetylase. (i) What is lactose called in this context? (ii) How does it switch on the genes? (iii) Why are the genes switched off when lactose is used up? (5 marks)

Read the passage and answer the questions. In a paternity dispute, a court ordered DNA tests of the child, the mother and two alleged fathers. The bands obtained after Southern blotting with a VNTR probe were compared. (i) Name the technique and its principle. (ii) What is the source of DNA for the test? (iii) How will the result identify the biological father? (5 marks)

Read the passage and answer the questions. The Human Genome Project began in 1990 and was completed in 2003. It found that the human genome has about 3,164.7 million nucleotide bases, that less than 2% codes for proteins, and that 99.9% of bases are the same in all people. (i) Name two goals of the project. (ii) What is the average size of a gene and which is the largest known gene? (iii) Name two methodologies used in the project. (5 marks)

Describe the structure of DNA according to the Watson and Crick model with a labelled diagram, and explain the packaging of DNA in eukaryotic cells. (6 marks)

Describe the Meselson and Stahl experiment with labelled diagrams of the centrifuge bands after each generation. Explain how it proves semiconservative replication. (6 marks)

Explain transcription in bacteria and eukaryotes. Draw a labelled diagram of a transcription unit and show the processing of hnRNA into mRNA. (6 marks)

Describe the process of translation with labelled diagrams showing initiation, elongation and termination on a ribosome. (6 marks)

Describe the steps in DNA fingerprinting with a flowchart, and explain its applications in forensic science and population studies. (6 marks)