Question

Q. 1. (i) What is a plasmid ?

(ii) What is meant by ADA deficiency ? How is gene

therapy a solution to this problem ? Why is it not a

permanent cure ?​

Answer 1

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ᴘʟᴀsᴍɪᴅs ᴀʀᴇ ᴇxᴛʀᴀ-ᴄʜʀᴏᴍᴏsᴏᴍᴀʟ, sᴇʟғ-ʀᴇᴘʟɪᴄᴀᴛɪɴɢ, ᴜsᴜᴀʟʟʏ ᴄɪʀᴄᴜʟᴀʀ ᴅᴏᴜʙʟᴇ-sᴛʀᴀɴᴅᴇᴅ ᴅɴᴀ ᴍᴏʟᴇᴄᴜʟᴇs ғᴏᴜɴᴅ ɪɴ ʙᴀᴄᴛᴇʀɪᴀ ᴀɴᴅ ɪɴ sᴏᴍᴇ ʏᴇᴀsᴛ.

(ɪɪ) ᴀᴅᴀ ɪs ᴀᴅᴇɴᴏsɪɴᴇ ᴅᴇᴀᴍɪɴᴀsᴇ ᴅᴇғɪᴄɪᴇɴᴄʏ, ᴛʜɪs ᴇɴᴢʏᴍᴇ ɪs ᴄʀᴜᴄɪᴀʟ ғᴏʀ ᴛʜᴇ ɪᴍᴍᴜɴᴇ sʏsᴛᴇᴍ ᴛᴏ ғᴜɴᴄᴛɪᴏɴ. ᴛʜᴇ ᴘᴀᴛɪᴇɴᴛ ʟᴀᴄᴋs ғᴜɴᴄᴛɪᴏɴᴀʟ ᴛ-ʟʏᴍᴘʜᴏᴄʏᴛᴇs ᴀɴᴅ ғᴀɪʟs ᴛᴏ ғɪɢʜᴛ ᴛʜᴇ ɪɴғᴇᴄᴛɪɴɢ ᴘᴀᴛʜᴏɢᴇɴs. ᴄʜɪʟᴅʀᴇɴ ᴡɪᴛʜ ᴀᴅᴀ ᴅᴇғɪᴄɪᴇɴᴄʏ ᴀʀᴇ ᴄᴜʀᴇᴅ ʙʏ ʙᴏɴᴇ ᴍᴀʀʀᴏᴡ ᴛʀᴀɴsᴘʟᴀɴᴛᴀᴛɪᴏɴ ᴏʀ ᴇɴᴢʏᴍᴇ ʀᴇᴘʟᴀᴄᴇᴍᴇɴᴛ ᴛʜᴇʀᴀᴘʏ, ᴡʜᴇʀᴇ ᴀᴅᴀ ɪs ɢɪᴠᴇɴ ʙʏ ɪɴᴊᴇᴄᴛɪᴏɴ. ʙʏ ᴜsɪɴɢ ɢᴇɴᴇ ᴛʜᴇʀᴀᴘʏ ᴛᴇᴄʜɴɪǫᴜᴇs, ʟʏᴍᴘʜᴏᴄʏᴛᴇs ᴀʀᴇ ᴛᴀᴋᴇɴ ғʀᴏᴍ ᴛʜᴇ ᴘᴀᴛɪᴇɴᴛ’s ʙᴏɴᴇ ᴍᴀʀʀᴏᴡ ᴀɴᴅ ᴛʜᴇ ɴᴏʀᴍᴀʟ ɢᴇɴᴇ ғᴏʀ ᴀᴅᴀ ɪs ɪɴᴛʀᴏᴅᴜᴄᴇᴅ ɪɴᴛᴏ ᴛʜᴇ ʟʏᴍᴘʜᴏᴄʏᴛᴇs ᴜsɪɴɢ ʀᴇᴛʀᴏᴠɪʀᴜs. ᴛʜᴇsᴇ ᴄᴇʟʟs ᴀʀᴇ ʀᴇ-ɪɴᴛʀᴏᴅᴜᴄᴇᴅ ɪɴ ᴛʜᴇ ᴘᴀᴛɪᴇɴᴛ’s ɪᴍᴍᴜɴᴇ sʏsᴛᴇᴍ.ᴀs ᴛʜᴇsᴇ ᴄᴇʟʟs ᴀʀᴇ ɴᴏᴛ ɪᴍᴍᴏʀᴛᴀʟ, ᴛʜᴇ ᴘᴀᴛɪᴇɴᴛ ʀᴇǫᴜɪʀᴇs ᴘᴇʀɪᴏᴅɪᴄ ɪɴғᴜsɪᴏɴ ᴏғ sᴜᴄʜ ɢᴇɴᴇᴛɪᴄᴀʟʟʏ ᴇɴɢɪɴᴇᴇʀᴇᴅ ʟʏᴍᴘʜᴏᴄʏᴛᴇs. ʜᴇɴᴄᴇ, ɪᴛ ɪs ɴᴏᴛ ᴀ ᴘᴇʀᴍᴀɴᴇɴᴛ ᴄᴜʀᴇ.ɪғ ᴛʜᴇ ғᴜɴᴄᴛɪᴏɴᴀʟ ɢᴇɴᴇ ɪs ɪɴᴛʀᴏᴅᴜᴄᴇᴅ ɪɴᴛᴏ ᴛʜᴇ ʙᴏɴᴇ ᴍᴀʀʀᴏᴡ ᴄᴇʟʟs ᴀᴛ ᴇᴀʀʟʏ ᴇᴍʙʀʏᴏɴɪᴄ sᴛᴀɢᴇ, ɪᴛ ᴡᴏᴜʟᴅ ʙᴇ ᴀ ᴘᴇʀᴍᴀɴᴇɴᴛ ᴄᴜʀᴇ.