Updated By SaraNextGen

On March 11, 2024, 11:35 AM

Question 2:

Make a chart (with diagrammatic representation) showing a restriction enzyme, the substrate DNA on which it acts, the site at which it cuts DNA and the product it produces.

ANSWER:

The name of the restriction enzyme is Bam H 1.

Question 3:

From what you have learnt, can you tell whether enzymes are bigger or DNA is bigger in molecular size? How did you know?

ANSWER:

Enzymes are smaller in size than DNA molecules. This is because DNA contains genetic information for the development and functioning of all living organisms. It contains instructions for the synthesis of proteins and DNA molecules. On the other hand, enzymes are proteins which are synthesised from a small stretch of DNA known as ‘genes’, which are involved in the production of the polypeptide chain.

Question 4:

What would be the molar concentration of human DNA in a human cell? Consult your teacher.

ANSWER:

The molar concentration of human DNA in a human diploid cell is as follows:

⇒ Total number of chromosomes × 6.023 × 10²³

⇒ 46 × 6.023 × 10_­­­²³

⇒ 2.77 ×10¹⁸ Moles

Hence, the molar concentration of DNA in each diploid cell in humans is 2.77 × 10 ²³ moles.

Question 5:

Do eukaryotic cells have restriction endonucleases? Justify your answer.

ANSWER:

No, eukaryotic cells do not have restriction endonucleases. This is because the DNA of eukaryotes is highly methylated by a modification enzyme, called methylase. Methylation protects the DNA from the activity of restriction enzymes .These enzymes are present in prokaryotic cells where they help prevent the invasion of DNA by virus.

Question 6:

Besides better aeration and mixing properties, what other advantages do stirred tank bioreactors have over shake flasks?

ANSWER:

The shake flask method is used for a small-scale production of biotechnological products in a laboratory. On the other hand, stirred tank bioreactors are used for a large-scale production of biotechnology products.

Stirred tank bioreactors have several advantages over shake flasks:

(1) Small volumes of culture can be taken out from the reactor for sampling or testing.

(2) It has a foam breaker for regulating the foam.

(3) It has a control system that regulates the temperature and pH.

Question 7:

Collect 5 examples of palindromic DNA sequences by consulting your teacher. Better try to create a palindromic sequence by following base-pair rules.

ANSWER:

The palindromic sequence is a certain sequence of the DNA that reads the same whether read from 5^’ → 3^’ direction or from 3^’→ 5^’ direction. They are the site for the action of restriction enzymes. Most restriction enzymes are palindromic sequences.

Five examples of palindromic sequences are:

Question 8:

Can you recall meiosis and indicate at what stage a recombinant DNA is made?

ANSWER:

Meiosis is a process that involves the reduction in the amount of genetic material. It is two types, namely meiosis I and meiosis II. During the pachytene stage of prophase I, crossing over of chromosomes takes place where the exchange of segments between non-sister chromatids of homlogous chromosomes takes place. This results in the formation of recombinant DNA.

Question 9:

Can you think and answer how a reporter enzyme can be used to monitor transformation of host cells by foreign DNA in addition to a selectable marker?

ANSWER:

A reporter gene can be used to monitor the transformation of host cells by foreign DNA. They act as a selectable marker to determine whether the host cell has taken up the foreign DNA or the foreign gene gets expressed in the cell. The researchers place the reporter gene and the foreign gene in the same DNA construct. Then, this combined DNA construct is inserted in the cell. Here, the reporter gene is used as a selectable marker to find out the successful uptake of genes of interest (foreign genes). An example of reporter genes includes lac Z gene, which encodes a green fluorescent protein in a jelly fish.