Question

Introns are known to contain stop codons (UAA, UGA, or UAG), yet these codons do not interrupt the coding of a particular protein. Why?

	a.	More than one stop codon is needed to stop transcription.
	b.	Exons are spliced out of mRNA before translation.
	c.	These triplets do not cause termination in gene expression.
	d.	Stop codons are only required for termination of mRNA synthesis.
	e.	Introns are removed from mRNA before translation

A(n) _____ is located upstream of a gene's coding region.

	a.	origin of replication
	b.	stop codon
	c.	start codon
	d.	promoter
	e.	3' UTR

Transcription results in the production of (select all that apply):

	a.	mRNA
	b.	Okazaki fragments
	c.	rRNA
	d.	tRNA
	e.	DNA
	f.	polypeptides
	g.	RNA polymerase
	h.	enzymes

Below is a double-stranded prokaryotic sequence of DNA encoding a complete short peptide. The -10 consensus sequence is underlined and the corresponding mRNA is below.

5’ TTATAACCCTGAAGTCATTGAATCGGTCGCTGG AACGTTAAGCATTATA 3’

3’ AATATTGGGACTTCAGTAACTTAGCCAGCGACC TTGCAATTCGTAATAT 5’

5’ CCGAUUCAAUGACUUCAGGGUUAUAA 3’

Which strand is the coding strand?

	a.	top strand
	b.	bottom strand

Below is a double-stranded prokaryotic sequence of DNA encoding a complete short peptide. The -10 consensus sequence is underlined and the corresponding mRNA is below.

5’ TTATAACCCTGAAGTCATTGAATCGGTCGCTGG AACGTTAAGCATTATA 3’

3’ AATATTGGGACTTCAGTAACTTAGCCAGCGACC TTGCAATTCGTAATAT 5’

5’ CCGAUUCAAUGACUUCAGGGUUAUAA 3’

Transcription occurs from ____________.

	a.	right to left
	b.	left to right

Below is a double-stranded prokaryotic sequence of DNA encoding a complete short peptide. The -10 consensus sequence is underlined and the corresponding mRNA is below.

5’ TTATAACCCTGAAGTCATTGAATCGGTCGCTGG AACGTTAAGCATTATA 3’

3’ AATATTGGGACTTCAGTAACTTAGCCAGCGACC TTGCAATTCGTAATAT 5’

Mark the codon that corresponds to the first translated codon below.

5' CCAUUCAAUGACUUCAGGGUUAUAA 3'

Answer 1

1). E). Introns are removed from mRNA before translation

Explanation: Introns are removed from mRNA before translation. So, there would be no effect of any nucleotides of introns on protein synthesis.

2). D. Promoter

Explanation:

The promoter region is immediately upstream of the coding sequence

3). A). mRNA

4). A. Top strand

5). A. Right to left

6). AUG

Translation starts at first codon, AUG which represents methionine amino acid. The underlined codon in the given below sequence is the first codon.

mRNA = 5' CCAUUCAAUGACUUCAGGGUUAUAA 3'