Question 1

Why does a genomic library need more clones than what would be estimated by calculations to be complete?

Accepted Answer

A genomic library needs more clones than what would be estimated by calculations to be complete because there is a significant probability that some sequences would not be represented in a library if it was only the calculated size. This is because of the heterogeneity of genomic DNA and the possibility of genomic regions that are difficult to amplify or clone. Therefore, increasing the number of clones increases the likelihood of capturing all the genomic sequences.

Question 2

What enzyme is necessary for the copying of mRNA sequence into DNA during cDNA library construction?

Accepted Answer

Reverse transcriptase is responsible for copying the mRNA sequence into cDNA during cDNA library construction. This enzyme is able to synthesize a DNA strand using an RNA template, which is essential for generating cDNA libraries from mRNA. RNA polymerase is involved in the transcription of DNA into RNA, and DNA polymerase is involved in replication of DNA. Restriction endonucleases are enzymes that cleave DNA at specific sites and are not involved in cDNA library construction.

Question 3

What is the function of the amp^r gene in a vector?

Accepted Answer

The amp^r gene provides resistance to the antibiotic ampicillin, allowing for the selection of bacteria that have successfully taken up the vector containing this gene.

Question 4

How do bacteria protect their own DNA from the restriction enzymes they produce?

Accepted Answer

Bacteria protect their own DNA from the restriction enzymes they produce by adding methyl groups to recognition sequences in their DNA, which block digestion by restriction enzymes. This is called methylation and serves as a defense mechanism against the endonucleases.

Question 5

What information cannot be determined from the DNA sequence of a cDNA clone?

Accepted Answer

The sequence of the promoter cannot be determined from the DNA sequence of a cDNA clone because cDNA is synthesized from mRNA, which does not include promoter regions. Promoters are located upstream of the transcription start site in the genomic DNA, not in the mRNA.

Question 6

How are open reading frames or exons predicted from genomic sequence?

Accepted Answer

The answer of How are open reading frames or exons...

Question 7

Pseudogenes are evidence for

Accepted Answer

Pseudogenes are non-functional copies of genes that have been duplicated, often as a result of gene duplications. Therefore, their presence is evidence for gene duplications.

Question 8

How are the genes in the $\beta$-globin locus different from each other?

Accepted Answer

The answer of How are the genes in the $\beta$-globin...

Question 9

In gel electrophoresis of DNA, fragments move at different rates because they have different

Accepted Answer

The fragments move at different rates due to their sizes. Smaller fragments move faster through the gel, while larger fragments move more slowly. The other choices are not likely to affect the movement of DNA fragments in gel electrophoresis.

Question 10

Which of the following is an example of a recombinant DNA molecule?

Accepted Answer

A genomic fragment of human DNA ligated to a bacterial plasmid vector is an example of a recombinant DNA molecule. This is because it involves the combination of DNA from two different sources (human and bacterial) through the use of molecular biology techniques such as restriction enzymes and ligases. The resulting molecule contains genetic information from both sources and is known as a recombinant DNA molecule. The other options do not involve the combination of DNA from different sources and therefore are not examples of recombinant DNA molecules.

Question 11

What is the advantage of having different forms of hemoglobin?

Accepted Answer

The different forms of hemoglobin are adapted to most efficiently carry oxygen in the different stage of development. For example, fetal hemoglobin has a higher affinity for oxygen than adult hemoglobin, which allows for efficient transfer of oxygen from mother to fetus. Different forms of hemoglobin also allow for adaptability in different environmental conditions such as high altitude, where some individuals may have a different form of hemoglobin adapted to low oxygen levels. Therefore, the advantage of having different forms of hemoglobin is the ability to efficiently transport oxygen in different contexts.

Question 12

In Sanger sequencing, what causes DNA synthesis to terminate at a specific base?

Accepted Answer

In Sanger sequencing, dideoxy nucleotides (ddNTPs) are used along with normal nucleotides (dNTPs) during DNA synthesis. Dideoxy nucleotides lack a hydroxyl group at the 3' position, which is required for further nucleotide addition during DNA synthesis. This results in termination of DNA synthesis at the specific base where the ddNTP is incorporated. The incorporation of ddNTPs occurs at a low ratio compared to dNTPs, resulting in a series of synthesized DNA fragments with different lengths ending specifically at each base.

Question 13

Which choice is NOT a characteristic of a plasmid used as a cloning vector?

Accepted Answer

Plasmids used as cloning vectors do not integrate into the host chromosome. They may replicate separately as extrachromosomal entities within the host cell.

Question 14

Use the BLAST tool at http://blast.ncbi.nlm.nih.gov/Blast.cgi and click "Protein blast" to find out the identity of the protein with the following amino acid sequence: CCKHPEAKRM PCAEDYLSVV LNQLCVLHEK TPVSDRVTKC CTESLVNRRP

Accepted Answer

By entering the amino acid sequence into the Protein Blast tool, the top hit is human serum albumin with a score of 285 bits and 100% query coverage. There are no significant hits to any of the other protein options.

Question 15

The BLAST suite of programs can be used to

Accepted Answer

The BLAST suite of programs is commonly used to compare a nucleotide or amino acid sequence to databases from a variety of species in order to identify homologous sequences and gain insights into evolutionary relationships or functional conservation. The other options listed (displaying reading frames, finding tissue expression, analyzing microarray data, and the word "tubulin") are unrelated to BLAST.

Question 16

What proportion of the genome is comprised of the exome?

Accepted Answer

The answer of What proportion of the genome is comprised...

Question 17

Reverse transcriptase is an enzyme made by

Accepted Answer

Reverse transcriptase is an enzyme made by retroviruses, which are RNA viruses that use the enzyme to convert their RNA genome into DNA before integrating it into the host cell's chromosome.

Question 18

Where do restriction enzymes come from, and what is their normal physiological function?

Accepted Answer

Restriction enzymes are produced by bacteria as a defense mechanism against viral invasion. They cut foreign DNA at specific sites, while leaving their own DNA unharmed. This helps to prevent viral DNA from replicating and taking over the bacterial cell.

Question 19

What is one difference between using restriction endonucleases and mechanical shearing of DNA?

Accepted Answer

Restriction endonucleases are enzymes that recognize and cleave DNA at specific target sequences. Therefore, they digest DNA at known specific sites. On the other hand, mechanical shearing involves physically breaking DNA at random locations, resulting in fragments of various sizes.

Question 20

If DNA had 5 different bases, a restriction enzyme with a 4-base recognition sequence would predicted to digest the DNA approximately every

Accepted Answer

A four-base recognition sequence means that the enzyme would recognize and cut at every possible combination of those four bases. With 5 different bases, there would be a total of 5^4 = 625 possible recognition sites. Therefore, the DNA would be predicted to be digested approximately every 625 base pairs.

Quiz 9: Digital Analysis of Genomes

Why does a genomic library need more clones than what would be estimated by calculations to be complete?

What enzyme is necessary for the copying of mRNA sequence into DNA during cDNA library construction?

What is the function of the amp^r gene in a vector?

How do bacteria protect their own DNA from the restriction enzymes they produce?

What information cannot be determined from the DNA sequence of a cDNA clone?

How are open reading frames or exons predicted from genomic sequence?

Pseudogenes are evidence for

How are the genes in the $\beta$ -globin locus different from each other?

In gel electrophoresis of DNA, fragments move at different rates because they have different

Which of the following is an example of a recombinant DNA molecule?

What is the advantage of having different forms of hemoglobin?

In Sanger sequencing, what causes DNA synthesis to terminate at a specific base?

Which choice is NOT a characteristic of a plasmid used as a cloning vector?

Use the BLAST tool at http://blast.ncbi.nlm.nih.gov/Blast.cgi and click "Protein blast" to find out the identity of the protein with the following amino acid sequence: CCKHPEAKRM PCAEDYLSVV LNQLCVLHEK TPVSDRVTKC CTESLVNRRP

The BLAST suite of programs can be used to

What proportion of the genome is comprised of the exome?

Reverse transcriptase is an enzyme made by

Where do restriction enzymes come from, and what is their normal physiological function?

What is one difference between using restriction endonucleases and mechanical shearing of DNA?

If DNA had 5 different bases, a restriction enzyme with a 4-base recognition sequence would predicted to digest the DNA approximately every

Quiz 9: Digital Analysis of Genomes

Why does a genomic library need more clones than what would be estimated by calculations to be complete?

What enzyme is necessary for the copying of mRNA sequence into DNA during cDNA library construction?

What is the function of the ampr gene in a vector?

How do bacteria protect their own DNA from the restriction enzymes they produce?

What information cannot be determined from the DNA sequence of a cDNA clone?

How are open reading frames or exons predicted from genomic sequence?

Pseudogenes are evidence for

How are the genes in the β\betaβ -globin locus different from each other?

In gel electrophoresis of DNA, fragments move at different rates because they have different

Which of the following is an example of a recombinant DNA molecule?

What is the advantage of having different forms of hemoglobin?

In Sanger sequencing, what causes DNA synthesis to terminate at a specific base?

Which choice is NOT a characteristic of a plasmid used as a cloning vector?

Use the BLAST tool at http://blast.ncbi.nlm.nih.gov/Blast.cgi and click "Protein blast" to find out the identity of the protein with the following amino acid sequence: CCKHPEAKRM PCAEDYLSVV LNQLCVLHEK TPVSDRVTKC CTESLVNRRP

The BLAST suite of programs can be used to

What proportion of the genome is comprised of the exome?

Reverse transcriptase is an enzyme made by

Where do restriction enzymes come from, and what is their normal physiological function?

What is one difference between using restriction endonucleases and mechanical shearing of DNA?

If DNA had 5 different bases, a restriction enzyme with a 4-base recognition sequence would predicted to digest the DNA approximately every

What is the function of the amp^r gene in a vector?

How are the genes in the $\beta$ -globin locus different from each other?