Quiz 3

You subject two different size linear DNA fragments to standard polyacrylamide gel electrophoresis. What can you predict about their behavior?

Both fragments will move downwards in the gel; the smaller fragment will move further down.

We have defined cloning a gene as:

Making many identical copies of a DNA molecule by inserting it into a plasmid.

Restriction endonucleases:

Are Hydrolases that recognize specific short DNA sequences.

To begin transcription:

General transcription factors and RNA polymerase bind at the promoter region while activator proteins bind to the enhancer region.

In eukaryotes pre-mRNA:

• Is capped at the 3’ end and polyadenylated at the 5’ end.

• Is spliced after it exits the nucleus through the nuclear pores.

• Is capped and polyadenylated after it is released from the

• RNA polymerase.

• Is folded into three dimensional molecules in the nucleolus.
  A: None of the above

You isolate total nuclear chromatin from human cells, extract away all the chromatin proteins and perform in vitro metabolic labelling by adding radioactive p32-labelled deoxynucleotides to tag/label the B-globin gene. What are the minimum factors you need to generate the labelled DNA in the test tube?

Ability to denature and anneal the DNA double strand, a primer complementary to a portion of Bglobin gene, DNA polymerase.

Match the following RNA categories to their descriptions:
A. Spliceosome Ribozymes involved in mRNA processing
B. Adaptors between mRNA triple codon and amino acids during translation C. Ribosome ribozymes involved in protein synthesis
D. RNA that codes for protein

rRNA
rRNA
snRNA
U2 or U4 RNA

• rRNA C

• rRNA B

• snRNA A

• U2 or U4 RNA A

T/F: The key enzyme in making a cDNA library is reverse transcriptase, since RNA is the starting material and a complementary DNA needs to be made.

True

T/F: Proteins can be denatured and nucleic acids cannot be denatured.

False

T/F: During splicing, the branch point has a dideoxy nucleotide that forms a new phosphodiester bond with a 5’ consensus sequence nucleotide.

False

T/F: On any chromosome, either of the DNA double helix strands may serve as “template” for the transcription of specific genes.

True

The gene for a given eukaryotic protein is transcribed only once into a single complementary mRNA molecule which is then translated repeatedly on polyribosomes in the cytoplasm.

False