Question

1)Vitamin A and pro-vitamin A are molecules that contain only carbon and hydrogen atoms and do not have any amino acids. If scientists want to genetically engineer a plant to make pro-vitamin A, what type of gene or genes would the scientists need to insert in the plant cells? Would they insert a gene that codes for pro-vitamin A? If not, what type of molecule would the gene or genes have to code for? Explain your reasoning.

2)Scientists have identified genes for two enzymes needed to make pro-vitamin A. One of these genes comes from corn. If this gene from a corn plant is inserted in the DNA of a rice plant, will the sequence of amino acids in the protein produced by the rice plant be the same as the sequence of amino acids in the protein produced by the corn plant? In other words, will rice plants that have this gene produce the same enzyme as corn plants produce? Explain why or why not.

3)Once scientists have identified the genes for enzymes to produce provitamin A, how could they insert these genes in the DNA of rice plant cells? Suggest one possibility.

4)Would you recommend that scientists try to insert the genes for enzymes to produce pro-vitamin A into:

a. all the cells in a rice plant

b. the thousands of cells in each rice grain or

c. a small group of embryonic rice plant cells that can divide and develop into a rice plant?

Explain your reasoning.

5) To insert genes from one organism into a different organism, scientists often take advantage of the natural genetic engineering capabilities of bacteria or viruses. One type of bacteria genetically engineers plant cells by inserting part of its bacterial DNA into the plant cell DNA, thus producing recombinant DNA. The inserted bacterial genes code for proteins that:

• stimulate the genetically engineered plant cells to produce food molecules that only the bacteria can use
• stimulate these genetically engineered plant cells to divide and form a growth that bulges out from the stem or root.

Explain how this type of genetic engineering is useful for the bacterium.

Answer 1

Ans1) There are two types of vitamin A found in the diet. Known to be as vitamin A retinol and provitamin A beta carotene respectively.the food sources of the first is from the animal products and the later is from the plant based products.

Generally the retinol are obtained by the body from the conversion of carotene compounds found in egg yolk, butter, cream etc. And other form of retinol i.e. vitamin A is also known to be as vitamer retinal which aids/play a vital role in the transmission of light sensation in the retina of eye. And so, the deficiency of which leads to the Night blindness. This convertion of vitamer of vitamin A to vitamin A occurs via the consumption of animal products.

And the production of provitamin A is obtained from conversion of a precursor called beta carotene. From plant based products such as spinach, carrots, fruits- cantaloupe and apricot.

Beta carotene plays a vital role as an antioxidant which aids in the protection of oncocells against oxidation.

Therefore, if scientist want to insert a gene into the plant for the production of beta carotene provitaminA one should go with the biosynthetic pathway and should focus upon the genes encoding for it.

A research paper suggests that the insertion of genes to obtain the biosynthetic pathway for proper functioning and production of it would occur if we introduces the gene called Psy for phutoene synthase enzyme and beta-Icy gene for beta cyclase enzyme as a single combined transformation effort of cDNA coding respectively. From a plant called Nacissus pseudonarcissus. Under the control of a promoter of endosperm with a Bacterial phutoene desaturase. i.e. crtI from Erwinnia uredovora under constitutive 35s promoter control.

All of these above described combination covers the betacarotene synthesis carried out by the Psy and crtI gene alone. Along with the synthesis of xanthophyll.

Thenceforth, yes as from the above instance we can say that the scientist would insert genes that code for provitaminA.