Unit 5 Test (Biotechnology)

Question 1

What are the three natural molecules and processes scientists use to manipulate DNA?

Answer 1

Restriction enzymes, gel electrophoresis, and DNA ligase.

Question 2

What do restriction enzymes do?

Answer 2

They cut double stranded DNA molecules into smaller, non-infectious fragments.

Question 3

How do restriction enzymes work?

Answer 3

By breaking the bonds of the DNA backbone in between the 3’ hydroxyl group of one nucleotide and the 5’ poshphate group of another nucleotide.

Question 4

What is the restriction site?

Answer 4

The site at which restriction enzymes cleave specif sequences of bases.

Question 5

How does methylation affect restriction enzymes?

Answer 5

A methyl group can be attached to a host bacterial DNA’s restriction site to prevent restriction enzymes from cleaving when not necessary.

Question 6

What does gel electrophoresis do?

Answer 6

It separates DNA fragments that have been cut with a restriction enzyme.

Question 7

How does gel electrophoresis work?

Answer 7

DNA fragments will be placed into a semisolid gel, and an electric field will be applied. The DNA will then move across the gel due to its negatively charged phosphate groups, leading to separation between the small fragments.

Question 8

What information does gel electrophoresis give us?

Answer 8

The number of DNA fragments, the size of those fragments, and the relative abundance of a fragment.

Question 9

What does DNA ligase do?

Answer 9

It catalyzes the joining of DNA fragments to form recombinant DNA.

Question 10

How does DNA ligase work?

Answer 10

It creates phosphodiester bonds between DNA fragments.

Question 11

What is a genomic library?

Answer 11

A collection of DNA fragments that comprise the genome of an organism.

Question 12

What is a cDNA library?

Answer 12

A smaller DNA library made only of the genes transcribed in a particular tissue. This library is made from complementary DNA.

Question 13

How are cDNA libraries made?

Answer 13

mRNA is isolated from cells, and cDNA copies are made by complementary base pairing. This reaction is catalyzed by reverse transcriptase.

Question 14

What is a stem cell?

Answer 14

An unspecialized cell that divides into specialized cells.

Question 15

What is an expression vector used for?

Answer 15

They introduce a specific gene into a target cell so that the protein can actually be expressed in the cell.

Question 16

What is a cloning vector used for?

Answer 16

Cloning a DNA fragment by inserting a plasmid cloning vector into a bacterial host and allowing it to multiply.

Question 17

What are BAC/YAC (bacterial artificial chromosomes/yeast artificial chromosomes)?

Answer 17

Artificial vectors that can carry a greater amount of DNA than some naturally occurring vectors.

Question 18

What are reporter genes used for?

Answer 18

They help select or identify the host cell that contains the recombinant DNA (ex: ampicillin).

Question 19

What is DNA-DNA hybridization?

Answer 19

A fragment of DNA that has a radioactive tag attached to it is allowed to adhere to other pieces of DNA in order find a particular corresponding sequence.

Question 20

What is a transfer filter?

Answer 20

Placing a filter on a culture plate to make a blot of the colonies that are growing on that plate. A blot is an imprint that allows the filter to pick up the colonies in the same pattern that they were found on the plate.

Question 21

What is a southern blot?

Answer 21

A process that can identify a gene of interest from a DNA molecule that was separated through gel electrophoresis.

Question 22

Microarray analysis

Answer 22

Thousands of known DNA sequences are attached to a solid surface, and each genes is labeled with a color. The cDNA from a cell or tissue will then be hybridized to the array of probe DNA in order to determine the set of genes expressed in different cells.

Question 23

What is colony hybridization?

Answer 23

A process by which a labeled DNA probe is used to scan a DNA library.

Question 24

What is gene mapping?

Answer 24

Using recombination frequencies to determine the physical arrangement of genes.

Question 25

What is DNA sequencing?

Answer 25

Using a manual or automated machine to determine the order of bases based on overlapping sequences.

Question 26

What is vitro mutagenesis?

Answer 26

Mutated forms of 
a gene are reinserted into the original species to look for malfunctions in gene expression.

Question 27

How does PCR work?

Answer 27

It amplifies a particular segment of DNA without the need of using another organism.

Question 28

What is denaturation of DNA?

Answer 28

Heating of a double-stranded piece of DNA until the hydrogen bonds
 break and the strands separate.

Question 29

What is RNA interference?

Answer 29

Using small double stranded RNA, called silencing RNA (siRNA), to target mRNA for breakdown. In doing so, the expression of a undesired protein can be prevented.

Question 30

What is bottom-up sequencing?

Answer 30

First, DNA is amplified and sheared into small fragments. The DNA is then sequenced. A database will search for sequences that overlap in their reads and then pair them up to form contigs (A set of overlapping DNA segments). The DNA sequence of an entire genome can then be determined.

Question 31

What is restriction fragment length polymorphism (RFLP)?

Answer 31

DNA is cut by specific restriction enzymes into small fragments. The fragments are run on an agarose gel and then labeled with an RFLP probe in a southern blot. This is used to either determine if two individuals have the same genotype, or if an individual has a particular disease.