Cell walls commonly are classified into two major types. This classification is based not on structural or biochemical differences;

A) primary walls and

B) secondary walls

i) walls formed during cell growth

ii) walls that are formed after cell enlargement stops

iii) multilayered walls that are strengthened and waterproofed by lignin

iv) Usually they are thin and simple, but some times may be thick and multilayered, such as those found in collenchyma or in the epidermis

v) highly specialized in structure and composition, reflecting the differentiated state of the cell

Which of the following is the correctly represents features of primary and secondary walls?

TLS Online TPP Program

#Question id: 13083

#Unit 13. Methods in Biology

The genomic DNA of an organism is digested with two restriction enzymes; one of the, PstI (CTGCA/G), while the other., MseI (T/TAA). This would generate the following 3 types of DNA fragments: 

(1) both ends cleaved by PstI (Pst-Pst), 

(2) both ends cleaved by MseI (Mse-Mse), and 

(3) one end generated by each of the two enzymes (Pst-Mse). 

the most frequent fragments in decreasing order,

TLS Online TPP Program

#Question id: 13084

#Unit 13. Methods in Biology

Statement: In a modified version of AFLP, the selection of fragments using biotin-streptavidin binding is avoided.

Explanations: I. The fragments are ligated to the appropriate adapters and used for PCR amplification using two AFLP primers, each primer having a single selection nucleotide; this is called preamplification step.

II. The PCR products from this preamplificated step are diluted and used as template for second PCR amplification.

TLS Online TPP Program

#Question id: 13085

#Unit 13. Methods in Biology

The most common microsatellite sequence encountered in human genome is the sequence 

TLS Online TPP Program

#Question id: 13086

#Unit 13. Methods in Biology

Which group of VNTRs are tandem are frequently distributed in all eukaryotic genomes (except yeast) examined so far. They show a large, stable 'polymorphism due to variation in the number of repeat units and are almost 'ideal as molecular markers for genome mapping.

TLS Online TPP Program

#Question id: 13087

#Unit 13. Methods in Biology

To express a yeast gene in E. coli, your task is to design a strategy to insert the yeast gene into the bacterial plasmid. Below is a map of the area of the yeast genome surrounding the gene in which you are interested.

 

The distance between each tick mark placed on the line above is 100 bases in length

Below are the enzymes you can use, with their specific cut sites shown 5’-XXXXXX-3’ 3’-XXXXXX-5’

 

The plasmid is 5,000 bases long and the two farthest restriction enzyme sites are 200 bases apart. The plasmid has an ampicillin resistance gene somewhere on the plasmid distal from the restriction cut sites.

                              

Which of the following restriction enzyme is the best choice for you use to design a way to get the insert into the vector?

TLS Online TPP Program

#Question id: 13088

#Unit 13. Methods in Biology

To express a yeast gene in E. coli, your task is to design a strategy to insert the yeast gene into the bacterial plasmid. Below is a map of the area of the yeast genome surrounding the gene in which you are interested.

 

The distance between each tick mark placed on the line above is 100 bases in length

Below are the enzymes you can use, with their specific cut sites shown 5’-XXXXXX-3’ 3’-XXXXXX-5’

 

The plasmid is 5,000 bases long and the two farthest restriction enzyme sites are 200 bases apart. The plasmid has an ampicillin resistance gene somewhere on the plasmid distal from the restriction cut sites.

                              

You do the digestion of the insert and the vector and then ligate the two digestions together. You then transform the ligation into bacteria and select for ampicillin resistance. You get three colonies on your transformation plate. You isolate plasmid from each one and cut each plasmid with the enzyme XbaI. You then run your three digestions on an agarose gel and see the following patterns of bands. Describe what each plasmid actually was that was contained in each of the three colonies.

 

What is the Colony 1’s plasmid is;