# DBT JRF 2020 — Question 143

Exam: DBT JRF 2020 · Section: B · Topic: Biotechnology · Difficulty: Easy

## Question

'Golden rice' is genetically engineered by altering the biosynthetic pathway for the production of

## Options

- **A.** carotenoids
- **B.** chlorophylls
- **C.** phycocyanins
- **D.** flavonoids

## Answer

Option A

## Explanation

Golden Rice' was developed at ETH Zurich by Ingo Potrykus and Peter Beyer (2000, published in Science). Rationale: rice (Oryza sativa) endosperm lacks $\beta$ -carotene (provitamin A). Genetic modification: Three transgenes introduced into Japonica rice: (1) psy (phytoene synthase) from Narcissus (daffodil) or Zea mays — converts GGPP to phytoene; (2) crtI (carotene desaturase) from Erwinia uredovora (Pantoea ananatis) — converts phytoene to lycopene (4 desaturation steps); (3) lcy $\beta$ (lycopene $\beta$ -cyclase) is already present in rice endosperm (converts lycopene → $\beta$ -carotene). Golden Rice 2 (2005) uses psy from maize, producing 23× more $\beta$ -carotene (37 $\mu$ g/g dry weight). $\beta$ -Carotene is a carotenoid (tetraterpene pigment). Not chlorophyll, phycocyanin, or flavonoids.

Source: https://mypyqbuddy.com/questions/golden-rice-is-genetically-engineered-by-altering-the-6a05a8a02adafec4702932a7