06 DNA Recombination

Question 1

_______ involves the cutting and pasting of a particular DNA sequence into the DNA of another organism, hence “recombining DNA”. It is widely used in medicine, research, agriculture, food industry, and biotechnology.

Answer 1

DNA recombination technology

Question 2

There are five major steps in recombinant DNA technology:

Answer 2

The gene of interest is obtained from the donor cells.

A suitable recipient DNA is isolated
.
The same restriction enzyme cuts open the recipient DNA so that the gene may be inserted.

The recombinant DNA is inserted into another cell

The cells with recombinant DNA are grown.

Question 3

• The DNA that will receive the gene of interest is called a ____.

Answer 3

vector

Question 4

• Usually, the bacterial _____ are chosen as the DNA that will receive the isolated gene. This is because of their availability.

Answer 4

plasmids

Question 5

• _______ ensure that the gene is incorporated well into the recipient DNA

Answer 5

DNA polymerase and ligase

Question 6

A _____such as heat or electricity is used to temporarily increase cell membrane permeability. This will increase chances of cells taking up the recombinant DNA.

Answer 6

shock stimulus

Question 7

A _____ is also usually incorporated with the recombinant DNA. This could code for traits such as fluorescence or drug resistance. The marker gene allows scientists to easily isolate only those cells that took up the recombinant DNA.

Answer 7

marker gene``

Question 8

However, recombinant DNA technology does not always produce good results. Recombinations may cause abnormalities or even death in the cells holding the recombinant DNA.

Question 9

______ occurs between DNA that have a lot of homology. This occurs in meiosis during the formation of egg and sperm cells, certain DNA damage repair processes, and in the maintenance of telomeres in the absence of telomerase.

Answer 9

Homologous recombination

Question 10

Three models have been proposed to understand the process of homologous recombination:

Answer 10

the Holiday model, Meselson-Radding model, and the double strand break repair model

Question 11

_____occurs between DNA that do not have much homology. As the name suggests, it involves certain sequences.

Answer 11

Site specific recombination

Question 12

In site specific recombination, ______recognize and bind to the target short sequences between two DNA. The strands are cut out and exchanged between the two DNA.

Answer 12

site-specific recombinases or SSRs

Question 13

Certain recombinase enzymes such as _____ in recombinases may also perform other abilities such as deleting and inverting the sequences.

Answer 13

Cyclilization

Question 14

_______is the moving of large sections of DNA from one DNA source (such as a chromosome) to another DNA. It is another term for homologous recombination.

Answer 14

Generalized recombination

Question 15

_____, which are specific eight-base sequence, exists periodically in most DNA sequences and serves as a recombinational hotspot. RecBCD unwinds the DNA until it reaches such a site.

Answer 15

Chi sites

Question 16

______ are products of DNA recombination.

Answer 16

Recombinant proteins

Question 17

____ is a manipulated form of native protein, which is generated in various ways in order to increase production of proteins, modify gene sequences, and manufacture useful commercial products.

Answer 17

Recombinant protein

Question 18

____ are bacteriophage genomes integrated into the host genome. Early investigators noticed that infection with this virus caused frequent mutations and therefore named it Mu for “mutator” phage.

Answer 18

Prophages

Question 19

They carry genetic material that they inject into bacteria. The genetic material can undergo either of the two pathways:

Answer 19

1. Lytic cycle

2. Lysogenic cycle

Question 20

The genetic material is used by the bacterial machinery to code for the bacteriophage proteins instead of the bacterial proteins necessary for the host cell. Phages are produced and the bacterial cell eventually lyses.

Answer 20

Lytic cycle

Question 21

The genetic material is integrated into the host DNA and gets included in the replication cycles that occur later on.
The genetic material may keep on getting replicated without being transcribed or translated to proteins.

Answer 21

Lysogenic cycle

Question 22

______are also called jumping genes. They are genes that move from one position to anther in the genome. Transposable elements
make up approximately 44% of the human genome.

Answer 22

Transposable genetic elements or transposons

Question 23

Mutations caused by transposable elements are linked to cancer and other diseases.

Question 24

_____ move via a copy-paste method. It starts as an RNA.

Answer 24

Retrotransposons

Question 25

.______ move via a cut and paste method

Answer 25

DNA transposons

Question 26

_______ are present on both strands of a DNA.

Answer 26

Replicative transposons

Question 27

General mechanism of transposition

Transposition
_____Form of genetic recombination that moves defined genetic elements called transposable elements or transposons from one DNA site to another.
- Occur either in two mechanisms: cut and paste transposition and replicative transposition.

Answer 27

Transposition

Question 28

General mechanism of transposition

• The recombinases responsible for transposition.

Answer 28

Transposase

Question 29

_______

• Carries a gene encoding their own transposase.
• May carry a few additional genes as well (e.g., antibiotic resistance genes).
• Ends are arranged as inverted repeats that ranges from about 25 to a few hundred base pairs and carry the recognition for transposes binding

Answer 29

Transposons (Jumping Genes)

Question 30

Two Mechanisms of Transposition:

Cut and Paste Transposition
Replicative Transposon

Question 31

Involves the excision of a transposon from its initial location in the genome followed by integration of the excised transposon into a new DNA site.

Answer 31

Cut and Paste Transposition