Question 1

In this procedure, PCR products are blotted in a nylon filter and hybridized with specific probes that allow the distinction of the different known alleles.

Accepted Answer

Blotting PCR products in a nylon filter and hybridizing with specific probes is a characteristic of sequence-specific oligonucleotide probes (SSOP). SSOP can distinguish between different known alleles based on their specific probe hybridization patterns.

Question 2

All of the following make up three branches of molecular biology related to transfusion medicine except:

Accepted Answer

The three branches of molecular biology related to transfusion medicine are molecular genetics, biotechnology, and molecular diagnostics. Paternity is not directly related to transfusion medicine, although it may involve similar techniques such as DNA sequencing and analysis.

Question 3

Which of the following is representative of the "central dogma" of molecular biology?

Accepted Answer

The central dogma of molecular biology states that the information stored in DNA is transcribed into RNA, and then translated into proteins. Therefore, the basic information of life flows from DNA to RNA to proteins, as stated in choice A. Choice B is incorrect because RNA cannot reverse transcribe to DNA in the central dogma. Choice C is incorrect as proteins cannot transmit information to genes, and choice D is incorrect as amino acids are the building blocks of proteins and do not contain genetic information.

Question 4

Restriction endonucleases are characterized as being palindromic. What is meant by this term?

Accepted Answer

Palindromic refers to a sequence that reads the same backwards and forwards. In the case of restriction endonucleases, the recognition sequence is palindromic because it reads the same on both strands of the double helix when read in the same 5' to 3' direction.

Question 5

In DNA cloning, the DNA fragment of interest carried by the______________  is introduced into a host cell.

Accepted Answer

The answer of In DNA cloning, the DNA fragment of...

Question 6

Which of the following statements regarding the DNA molecule is false?

Accepted Answer

Adenine always pairs with thymine in DNA, not with uracil.

Question 7

Which of the following are described as bacterial circular genetic elements that replicate independently from the chromosome and are capable of conferring bacterial resistance to certain antibiotics in DNA cloning?

Accepted Answer

Plasmids are circular genetic elements that replicate independently from the chromosome and can carry genes for antibiotic resistance, making them commonly used in DNA cloning as a tool for introducing genes into bacteria. Introns are non-coding sequences of DNA found within genes, extrons are the coding sequences within genes, and codons are the three-letter codes within DNA that correspond to specific amino acids.

Question 8

Which of the following sequences is recognized by ecoRI?

Accepted Answer

ecoRI recognizes and cuts the sequence 5'GAATTC3'. This sequence contains the specific recognition site for the enzyme, which is a palindrome – meaning it reads the same way in both directions (in this case, GAATTC and CTTAAG). Choice B (5'CTCTTG3') does not contain the ecoRI recognition site. Choice C (5'CGCG3') is a palindromic sequence, but it does not contain the necessary nucleotides for ecoRI recognition. Choice D (5'AGCT3') also does not contain the ecoRI recognition site.

Question 9

In this technique, fluorescent probes are used to detect homologous DNA or RNA sequences in chromosomes or intact cells.

Accepted Answer

FISH (Fluorescence In Situ Hybridization) is a technique that uses fluorescent probes to detect specific DNA or RNA sequences in chromosomes or intact cells. It allows visualization of specific genes or chromosomes in their natural environment, providing important information about their location, arrangement, and potential abnormalities. PCR amplifies specific DNA fragments, RFLP (Restriction Fragment Length Polymorphism) detects differences in the lengths of DNA fragments produced by specific enzymes, and DNA sequencing determines the exact sequence of nucleotides in a DNA molecule. None of these techniques directly visualize DNA or chromosomes in cells or tissues.

Question 10

A codon consists of how many nucleotides?

Accepted Answer

A codon consists of 3 nucleotides, which code for a specific amino acid. There are 64 possible codons, each of which codes for one of the 20 amino acids used in protein synthesis.

Question 11

Which of the following is not consistent with the structure of DNA?

Accepted Answer

The double helix of DNA consists of two strands of nucleotides that run in opposite directions and are antiparallel, not parallel. This antiparallel orientation allows for base pairing between complementary nucleotides along the strands.

Question 12

What are ddNTPs?

Accepted Answer

ddNTPs are dideoxyribonucleoside triphosphates, which lack the 3'-OH group and cause chain termination during DNA sequencing.

Question 13

______________ are regions of DNA interspersed in the human genome formed by variable tandem repeats of short nucleotide sequences used in DNA fingerprinting.

Accepted Answer

Minisatellites are regions of DNA interspersed in the human genome formed by variable tandem repeats of short nucleotide sequences. These regions are commonly used in DNA fingerprinting or DNA profiling. Macrosatellites, Platelet satellites, and Chromatids are not relevant to this concept.

Question 14

How does the Northern blotting technique differ from the Southern blotting technique?

Accepted Answer

The Northern blotting technique detects RNA rather than DNA, whereas the Southern blotting technique detects DNA.

Question 15

How can genomic DNA be obtained?

Accepted Answer

The answer of How can genomic DNA be obtained?
...

Question 16

Which of the following is false regarding the Southern blotting technique?

Accepted Answer

The positions of the membrane-bound fragments in Southern blotting correspond to their positions as separated by size on the gel electrophoresis, not different positions. The transfer process does not alter the relative positions of the fragments.

Question 17

Which of the following is representative of the lagging strand in DNA replication?

Accepted Answer

The lagging strand is synthesized discontinuously in short fragments called Okazaki fragments. RNA primers are required to start each Okazaki fragment synthesis. RNA polymerase catalyzes a primer (made of RNA nucleotides) that provides the 3'OH, to which DNA polymerase III can add nucleotides in the 5' to 3' direction.

Question 18

What is the function of helicases and gyrases in the polymerase chain reaction?

Accepted Answer

Helicases are enzymes that are responsible for unwinding the double-stranded DNA molecule into single strands, which is an essential step in the polymerase chain reaction. Gyrases are enzymes that alter the topology of DNA by introducing negative supercoils, which can help to alleviate the tension that builds up as a result of the unwinding of DNA by helicases. However, gyrases are not typically used in the polymerase chain reaction.

Question 19

All of the following are examples of recombinant proteins used in transfusion medicine except:

Accepted Answer

The answer of All of the following are examples of...

Question 20

Gel electrophoresis is a useful tool in DNA cloning. At a neutral pH, when voltage is applied, DNA fragments will migrate toward the anode because:

Accepted Answer

DNA is negatively charged due to its phosphate backbone, which contains negatively charged phosphate groups. This causes fragments to migrate towards the positively charged anode during gel electrophoresis.

Quiz 4: Concepts in Molecular Biology