Biology Exam 2

A mutation that replaces one amino acid in a protein with another is called a ___ mutation.

Missense

Uracil forms a complementary pair with ___ in RNA and ___ in DNA.

adenine; adenine

The two molecules that alternate to form the backbone of a polynucleotide chain are:

sugar and phosphate

Which of the following nucleotide sequences represents the complement to the DNA strand 5'-AGATCCG-3' ?

3'-TCTAGGC-5'

If 20% of the bases in a DNA molecule are found to be adenines, what percentage would be guanine?

30%

Initiation of transcription requires:

A promoter sequence

Where is the amino acid binding site located on the tRNA molecule?

At the 3' end of the molecule

A researcher adds an enzyme to a tube containing DNA. When she returns later, the DNA has been cut into several smaller pieces. She likely added a ___ enzyme.

Restriction

DNA ligase links two ___ DNA fragments by ___ bonds.

linear; covalent

Deletion of ___ bases of DNA in the coding region of a gene would NOT cause a frameshift mutation.

3

Why does synthesis only proceed in the 5' to 3' direction?

Because DNA polymerases can only add nucleotides to the 3' end of a polynucleotide strand

How does the lac repressor block transcription of the lac operon?

By binding to the operator

Pre-mRNA is longer than the corresponding mature forms of mRNA. That is because pre-mRNA contains ____ and are found in ___ cells.

Introns; only eukaryotic

RNA differs from DNA in all of the following except:

RNA contains cytosine

Translational controls regulate:

The rate at which a protein is produced

Bacterial gene regulation occurs mainly at the ___ level.

Transcriptional

In the trp operon, the repressor actively binds to the operator when:

Tryptophan binds to an allosteric site on the repressor

Which of the following is made from a DNA template?

mRNA, tRNA, and rRNA

Which of the following best describes semiconservative replication?

A DNA molecule consists of one parental strand and one new strand

Which of the following causes the unwinding of the DNA double helix?

DNA helicase

During replication, which of the following adds new nucleotides to a growing DNA chain?

DNA polymerase

Introns in pre-mRNA are known to:

Undergo splicing, whereby they are removed from the mRNA

The operator of the lac operon is located:

between the promoter and the structural genes

Lactose induces the transcription of the lactose operon by:

binding to the allosteric site of the repressor after being converted to allolactose

The gene that encodes for the repressor protein of the lac operon is:

constitutive

In polymerase chain reaction technology, the two strands of DNA are separated by:

heating them

Increasing the stability of a particular mRNA ___ the expression of its corresponding protein.

increases

A mutation in the coding region of a gene occurs such that the RNA produced from that gene changes a codon from a 5'-UGG-3' to a 5'-UGA-3'. This would be an example of a ___ mutation.

nonsense

RNA synthesis is also known as:

transcription

If a human mRNA molecule were placed into a mouse cell, it would be:

translated into the protein that is found in humans