Ch.14 Bio (Topic7)

The enzyme polynucleotide phosphorylase randomly assembles nucleotides into a polynucleotide polymer.You add polynucleotide phosphorylase to a solution of adenosine triphosphate and guanosine triphosphate. How many artificial mRNA 3 nucleotide codons would be possible?

8

The genetic code is essentially the same for all organisms. From this, one can logically assume which of the following?

A gene from an organism can theoretically be expressed by any other organism

A transfer RNA (#1) attached to the amino acid lysine enters the ribosome. The lysine binds to the growing polypeptide on the other tRNA (#2) already in the ribosome. Where does tRNA #2 move to after this bonding of lysine to the polypeptide?

E site

Which small-scale mutation would be most likely to have a catastrophic effect on the functioning of a protein?

a base deletion near the start of a gene

A frameshift mutation could result from

either an insertion or a deletion of a base

What type of bonding is responsible for maintaining the shape of the tRNA molecule in the figure?

hydrogen bonding between base pairs

Which component of the complex described enters the exit tunnel through the large subunit of the ribosome?

newly formed polypeptide

A particular triplet of bases in the coding sequence of DNA is AAA. The anticodon on the tRNA that binds the mRNA codon is

uuu

You add polynucleotide phosphorylase to a solution of ATP, GTP, and UTP. How many artificial mRNA 3 nucleotide codons would be possible?

27

A possible sequence of nucleotides in the template strand of DNA that would code for the polypeptide sequence Phe-Leu-Ile-Val would be

3' AAA-GAA-TAA-CAA 5'.

RNA polymerase moves in which direction along the DNA?

3' to 5' along the template strand

which direction does the RNA polymerase move?

3' → 5' along the template strand

The nitrogenous base adenine is found in all members of which group?

ATP, RNA, and DNA

Why might a point mutation in DNA make a difference in the level of a protein's activity?

It might substitute a different amino acid in the active site.

Suppose that an error in transcription alters the formation of a single tRNA molecule in a cell. The altered tRNA still attaches to the same amino acid (Phe), but its anticodon loop has the sequence AAU, which binds to the mRNA codon UUA (usually specifying leucine, Leu). What will be the effect on translation in this cell?

One altered tRNA molecule will be relatively inconsequential because it will compete with many "normal" ones.

The most commonly occurring mutation in people with cystic fibrosis is a deletion of a single codon. This results in

a polypeptide missing an amino acid

What amino acid sequence will be generated, based on the following mRNA codon sequence?5' AUG-UCU-UCG-UUA-UCC-UUG 3'

met-ser-ser-leu-ser-leu