Question 1

A gene containing three exons would have how many introns?

Accepted Answer

Since exons are distinctly separated by introns, a three-exon gene would have to contain at least two introns.

Question 2

Which genes are actively undergoing transcription during mitosis?

Accepted Answer

None. There are essentially no active transcriptional processes occurring during mitosis because as cells enter mitosis, the chromosomes become highly condensed so they can be distributed to daughter cells. In mitotic cells at metaphase, the DNA will have been condensed approximately ten-thousand-fold. This highly condensed DNA can no longer serve as a template for RNA synthesis. and transcription ceases during mitosis.

Question 3

The ENCODE project revealed that as much as 75% of the genome in humans is actually transcribed into RNA. Most of this is non‒protein-coding RNA. Which of the following include two new classes of noncoding RNA discovered by the ENCODE project?

Accepted Answer

A)   mRNA and tRNA
B)   rRNA and snRNA
C)   Pre-mRNA and hnRNA
D)   MicroRNA and lncRNA D

Question 4

The ENCODE Project revealed that as much as 75% of the human genome is transcribed.

Accepted Answer

A) True 
 B)False

Question 5

Which statement describes centromeric sequences in humans?

Accepted Answer

A)   They consist of two short conserved sequences, CDEI/III, separated by 78-86 base pairs.
B)   They consist of a central core of unique-sequence DNA, flanked by tandem repeats of three repetitive sequence elements.
C)   They consist of A/T-rich  α\alphaα -satellite DNA, spanning 1-5 million base pairs.
D)   They consist of two satellite sequences, transposable elements, and nonrepetitive DNA, spanning hundreds of kilobases.

Question 6

In some breeds of dogs, the premature termination of bone growth results in short legs. In these breeds, the mRNA encoding by the gene responsible for leg length undergoes _______ and gets inserted into a LINE where its expression is impaired.

Accepted Answer

The answer of In some breeds of dogs, the premature...

Question 7

Introns were discovered when mRNA for adenovirus protein expressed in mammalian cells was hybridized to single-stranded virus DNA coding for that mRNA. When the complexes were observed under the electron microscope,

Accepted Answer

A)   a completely double-stranded hybrid was seen.
B)   a partial hybrid with loops of mRNA extending from the hybrid regions was seen.
C)   a partial hybrid with loops of DNA extending from the hybrid regions was seen.
D)   no hybrid was seen, because the introns had been removed.

Question 8

Introns constitute about what percentage of the average human gene?

Accepted Answer

A)   3%
B)   40%
C)   60%
D)   90%

Question 9

Nuclease digestion of chromatin occurs at sites separated by approximately 200 base pairs because

Accepted Answer

A)   an AT-rich region occurs every 200 base pairs.
B)   nucleosomes are spaced 200 base pairs apart.
C)   a restriction nuclease site occurs every 200 base pairs.
D)   two turns of the DNA around the nucleosome consist of 200 base pairs.

Question 10

Pseudogenes are

Accepted Answer

A)   genes that code for an RNA but do not code for a protein.
B)   nonfunctional gene copies.
C)   inactive genes.
D)   genes containing variant sequences.

Question 11

Partial digestion of chromatin with micrococcal nuclease was found to yield DNA fragments approximately 200 base pairs long. What accounts for this phenomenon?

Accepted Answer

A)   The low pH environment of the nucleus renders the nuclease able to cut only in 200-base-pair increments.
B)   This result suggests that the binding of proteins to DNA in chromatin protects regions of DNA from nuclease digestion.
C)   This is a random phenomenon, and its significance is unknown.
D)   The nuclease cleaves at specific DNA sequences that occur every 200 base pairs in the genome.

Question 12

A centromere is a

Accepted Answer

A)   region of euchromatin devoid of histones.
B)   sequence at the end of chromatids.
C)   region where proteins bind to form kinetochores.
D)   specific, repeated DNA sequence.

Question 13

Because telomeres are longer in the cells of infants than they are in older people, it has been hypothesized that telomere length determines a cell's life expectancy. Thus, some believe that finding a way to extend the length of telomeres in older people would extend their life expectancy. What is a possible problem with this approach?

Accepted Answer

The answer of Because telomeres are longer in the cells...

Question 14

A "complete" sequence of the Drosophila genome has recently been obtained; that is, the part of the genome that lies within euchromatin (and only that part) has been sequenced. Why would sequencing be focused on euchromatin, and why is the acquisition of the Drosophila genome sequence now considered to be virtually complete?

Accepted Answer

The answer of A "complete" sequence of the Drosophila genome...

Question 15

Different proteins may be produced from the same gene through the process of _______.

Accepted Answer

The answer of Different proteins may be produced from the...

Question 16

The specialized sequences at the ends of eukaryotic chromosomes are called _______.

Accepted Answer

The answer of The specialized sequences at the ends of...

Question 17

Retrotransposons and retroviruses share similar mechanisms by encoding which of the following enzymes?

Accepted Answer

A)   Reverse transcriptase and RNA polymerase
B)   Reverse transcriptase and integrase
C)   RNA polymerase and integrase
D)   DNA polymerase and integrase

Question 18

SINEs and LINEs are types of _______ DNA sequences.

Accepted Answer

The answer of SINEs and LINEs are types of _______...

Question 19

Epigenetic inheritance is the transfer from parent to progeny of information that is not encoded in DNA sequences.

Accepted Answer