Question 1

Why does centrifugation at high speeds proceed in a near vacuum?

Accepted Answer

Centrifugation at high speeds can generate a significant amount of heat due to frictional resistance between the rotor and the surrounding air molecules. This can lead to denaturation or degradation of sensitive biomolecules being separated. Therefore, reducing the frictional resistance by carrying out the procedure in a near vacuum can minimize these effects and improve the accuracy of the separation. Additionally, a near vacuum can reduce the air drag force acting on the rotor, allowing it to spin at higher speeds without becoming unstable or unbalanced.

Question 2

How do DNA molecules place themselves in a C_SCl equilibrium gradient?

Accepted Answer

DNA molecules stop permanently at the point in the gradient where their buoyant density equals the density of the CsCl solution, allowing them to be separated based on density differences.

Question 3

What is the name of the process by which recombinant DNA gets into bacteria after being picked up from the surrounding medium?

Accepted Answer

The process by which recombinant DNA gets into bacteria after being picked up from the surrounding medium is called transformation. Transduction involves the transfer of genetic material from one bacterium to another through a virus, transmutation refers to the changing of one element into another through radioactive decay, transjunction is not a biological term, and transition refers to a change from one state or form to another.

Question 4

Another name for short,single-stranded nucleic acid molecules is _________.

Accepted Answer

Short, single-stranded nucleic acid molecules are called oligonucleotides. Option A and B are not correct terminologies used in science. Option C refers to long chains of nucleotides, not short, single-stranded ones. Option E is not a known term in science.

Question 5

Why does the S value alone not provide a measure of molecular mass?

Accepted Answer

The S value alone does not provide a measure of molecular mass because the velocity at which a particle moves through a liquid column depends on various factors, including its shape. Therefore, a particle with the same S value but a different shape would have a different molecular mass.

Question 6

When DNAs from two different organisms are incubated together,some duplexes are formed by DNA strands from the two species.What indicates that such duplexes are less stable than those between strands from the same organism?

Accepted Answer

The melting temperature of DNA duplexes indicates their stability. Since heterogeneous duplexes (formed between DNA strands from two different organisms) are less stable due to differences in base pairing and sequences, they will have a lower melting temperature compared to homogeneous duplexes (formed between DNA strands from the same organism). Therefore, choice A is the correct answer.

Question 7

What is the name of a piece of DNA containing sequences derived from more than one organism?

Accepted Answer

Recombinant DNA is a piece of DNA that contains sequences from more than one organism that have been artificially combined. This is often done in genetic engineering in order to produce specific traits or proteins. The other options (combinational DNA, combined DNA, cloned DNA, and recreational DNA) are not commonly used or accurate names for this type of DNA.

Question 8

Nowadays,how are double-stranded molecules of DNA synthesized for use in experimental procedures?

Accepted Answer

DNA synthesizers can chemically synthesize complementary single-stranded DNA molecules, which can then be hybridized together to produce double-stranded DNA. This method is commonly used in modern DNA synthesis technologies. Options A, B, D, and E are not relevant to the synthesis of double-stranded DNA molecules for experimental procedures.

Question 9

A small,circular,double-stranded DNA molecule that is separate from the main bacterial chromosome is called a(n)___________.

Accepted Answer

The definition provided refers to a plasmid. Plasmids are small, circular, double-stranded DNA molecules that exist independently of the main bacterial chromosome. They often carry genes that provide a selective advantage to the bacterium, such as antibiotic resistance or the ability to produce toxins.

Question 10

What step must first be carried out before one can amplify RNA templates?

Accepted Answer

Before RNA templates can be amplified, they must first be converted to complementary DNAs using reverse transcriptase, which is then used as a template for amplification using a polymerase chain reaction (PCR).

Question 11

How are double-stranded hybrids released from hydroxylapatite columns?

Accepted Answer

Increasing the elution buffer concentration will help in releasing the double-stranded hybrids from the hydroxylapatite column as it will cause the binding affinity of DNA to the column to weaken, thereby facilitating the elution of the DNA.

Question 12

What is the process of transferring single-stranded DNA from a gel to a nitrocellulose membrane called?

Accepted Answer

The process of transferring single-stranded DNA from a gel to a nitrocellulose membrane is called blotting. This technique is commonly known as Southern blotting when the DNA is from a genomic source, Northern blotting when it's from RNA, and Western blotting when it's from protein.

Question 13

What is the name of the procedure in which single-stranded DNA molecules are separated by electrophoresis,immobilized on a nitrocellulose filter and then hybridized with labeled,single-stranded DNA probes?

Accepted Answer

This is the definition of a Southern blot. It is used to detect specific DNA sequences in a sample. The separated DNA fragments are transferred from the gel to a nitrocellulose filter, where they are hybridized with labeled, single-stranded DNA probes.

Question 14

During the cloning procedure,what is the purpose of inserting genes into a bacterium that give it resistance to antibiotics?

Accepted Answer

The purpose of inserting genes into a bacterium that give it resistance to antibiotics is to allow researchers to select for those cells that contain a recombinant plasmid. By adding antibiotics to the culture media, only cells that have taken up the plasmid containing the antibiotic resistance gene will survive and grow, allowing for the selection of cells that have successfully undergone the cloning procedure.

Question 15

Nucleic acid hybridization techniques are based on the observation that ______________.

Accepted Answer

Nucleic acid hybridization techniques make use of the fact that two single-stranded nucleic acid molecules of complementary base sequence can form a stable, double-stranded hybrid. This property is the basis for many diagnostic and analytical methods in molecular biology, such as Southern blotting, Northern blotting, and in situ hybridization.

Question 16

Which of the following is a technique used to encourage bacteria to take up DNA from the surrounding culture medium?

Accepted Answer

The technique used to encourage bacteria to take up DNA from the surrounding culture medium is known as transformation. Pretreatment of bacteria with CaCl2 (calcium ions) followed by a brief heat shock (42°C) increases the permeability of bacterial cell walls, allowing foreign DNA to be taken up more efficiently. Therefore, choice C, pretreatment of bacteria with CaCl2 ions followed by a brief heat shock, is the correct option.

Question 17

What is defined as a technique for producing large quantities of a specific DNA sequence? One can make millions of copies of recombinant DNA in a short period of time from one or a few initial copies.

Accepted Answer

DNA cloning is defined as the technique for producing large quantities of a specific DNA sequence. It involves inserting a specific DNA sequence into a vector (such as a plasmid) and replicating it in a host cell. This results in the production of many copies of the inserted DNA sequence.

Question 18

How big are the sites recognized by most restriction enzymes?

Accepted Answer

The answer of How big are the sites recognized by...

Question 19

How are probes labeled with a radioactive isotope detected?

Accepted Answer

Autoradiography involves exposing a photographic emulsion to the emitted radiation from the probe labeled with a radioactive isotope. The radiation causes the emulsion to darken, creating a visible signal that can be detected and localized. Fluorescence, color changes, SEM, and TEM are not commonly used to detect probes labeled with radioactive isotopes.

Question 20

Nowadays,how are longer synthetic molecules of DNA synthesized for use in experimental procedures?

Accepted Answer

The answer of Nowadays,how are longer synthetic molecules of DNA...

Quiz 18: Techniques in Cell and Molecular Biology

Why does centrifugation at high speeds proceed in a near vacuum?

How do DNA molecules place themselves in a C_SCl equilibrium gradient?

What is the name of the process by which recombinant DNA gets into bacteria after being picked up from the surrounding medium?

Another name for short,single-stranded nucleic acid molecules is _________.

Why does the S value alone not provide a measure of molecular mass?

When DNAs from two different organisms are incubated together,some duplexes are formed by DNA strands from the two species.What indicates that such duplexes are less stable than those between strands from the same organism?

What is the name of a piece of DNA containing sequences derived from more than one organism?

Nowadays,how are double-stranded molecules of DNA synthesized for use in experimental procedures?

A small,circular,double-stranded DNA molecule that is separate from the main bacterial chromosome is called a(n) ___________.

What step must first be carried out before one can amplify RNA templates?

How are double-stranded hybrids released from hydroxylapatite columns?

What is the process of transferring single-stranded DNA from a gel to a nitrocellulose membrane called?

What is the name of the procedure in which single-stranded DNA molecules are separated by electrophoresis,immobilized on a nitrocellulose filter and then hybridized with labeled,single-stranded DNA probes?

During the cloning procedure,what is the purpose of inserting genes into a bacterium that give it resistance to antibiotics?

Nucleic acid hybridization techniques are based on the observation that ______________.

Which of the following is a technique used to encourage bacteria to take up DNA from the surrounding culture medium?

What is defined as a technique for producing large quantities of a specific DNA sequence? One can make millions of copies of recombinant DNA in a short period of time from one or a few initial copies.

How big are the sites recognized by most restriction enzymes?

How are probes labeled with a radioactive isotope detected?

Nowadays,how are longer synthetic molecules of DNA synthesized for use in experimental procedures?

Quiz 18: Techniques in Cell and Molecular Biology

Why does centrifugation at high speeds proceed in a near vacuum?

How do DNA molecules place themselves in a CSCl equilibrium gradient?

What is the name of the process by which recombinant DNA gets into bacteria after being picked up from the surrounding medium?

Another name for short,single-stranded nucleic acid molecules is _________.

Why does the S value alone not provide a measure of molecular mass?

When DNAs from two different organisms are incubated together,some duplexes are formed by DNA strands from the two species.What indicates that such duplexes are less stable than those between strands from the same organism?

What is the name of a piece of DNA containing sequences derived from more than one organism?

Nowadays,how are double-stranded molecules of DNA synthesized for use in experimental procedures?

A small,circular,double-stranded DNA molecule that is separate from the main bacterial chromosome is called a(n) ___________.

What step must first be carried out before one can amplify RNA templates?

How are double-stranded hybrids released from hydroxylapatite columns?

What is the process of transferring single-stranded DNA from a gel to a nitrocellulose membrane called?

What is the name of the procedure in which single-stranded DNA molecules are separated by electrophoresis,immobilized on a nitrocellulose filter and then hybridized with labeled,single-stranded DNA probes?

During the cloning procedure,what is the purpose of inserting genes into a bacterium that give it resistance to antibiotics?

Nucleic acid hybridization techniques are based on the observation that ______________.

Which of the following is a technique used to encourage bacteria to take up DNA from the surrounding culture medium?

What is defined as a technique for producing large quantities of a specific DNA sequence? One can make millions of copies of recombinant DNA in a short period of time from one or a few initial copies.

How big are the sites recognized by most restriction enzymes?

How are probes labeled with a radioactive isotope detected?

Nowadays,how are longer synthetic molecules of DNA synthesized for use in experimental procedures?

How do DNA molecules place themselves in a C_SCl equilibrium gradient?