Describe the double helix structure of dna
Answers
DNA is made up of molecules called nucleotides. Each nucleotide contains a phosphate group, a sugar group and a nitrogen base. The four types of nitrogen bases are adenine (A), thymine (T), guanine (G) and cytosine (C). The order of these bases is what determines DNA's instructions, or genetic code.
Explanation:
ᴛʜᴇ sᴀʟɪᴇɴᴛ ғᴇᴀᴛᴜʀᴇs ᴏғ ᴛʜᴇ ᴅᴏᴜʙʟᴇ-ʜᴇʟɪx sᴛʀᴜᴄᴛᴜʀᴇ ᴏғ ᴅɴᴀ ᴀʀᴇ ᴀs ғᴏʟʟᴏᴡs:
(ɪ) ɪᴛ ɪs ᴍᴀᴅᴇ ᴏғ ᴛᴡᴏ ᴘᴏʟʏɴᴜᴄʟᴇᴏᴛɪᴅᴇ ᴄʜᴀɪɴs, ᴡʜᴇʀᴇ ᴛʜᴇ ʙᴀᴄᴋʙᴏɴᴇ ɪs
ᴄᴏɴsᴛɪᴛᴜᴛᴇᴅ ʙʏ sᴜɢᴀʀ-ᴘʜᴏsᴘʜᴀᴛᴇ, ᴀɴᴅ ᴛʜᴇ ʙᴀsᴇs ᴘʀᴏᴊᴇᴄᴛ ɪɴsɪᴅᴇ.
(ɪɪ) ᴛʜᴇ ᴛᴡᴏ ᴄʜᴀɪɴs ʜᴀᴠᴇ ᴀɴᴛɪ-ᴘᴀʀᴀʟʟᴇʟ ᴘᴏʟᴀʀɪᴛʏ. ɪᴛ ᴍᴇᴀɴs, ɪғ ᴏɴᴇ
ᴄʜᴀɪɴ ʜᴀs ᴛʜᴇ ᴘᴏʟᴀʀɪᴛʏ 5'→3', ᴛʜᴇ ᴏᴛʜᴇʀ ʜᴀs 3'→5'.
(ɪɪɪ) ᴛʜᴇ ʙᴀsᴇs ɪɴ ᴛᴡᴏ sᴛʀᴀɴᴅs ᴀʀᴇ ᴘᴀɪʀᴇᴅ ᴛʜʀᴏᴜɢʜ ʜʏᴅʀᴏɢᴇɴ ʙᴏɴᴅ
(ʜ-ʙᴏɴᴅs) ғᴏʀᴍɪɴɢ ʙᴀsᴇ ᴘᴀɪʀs (ʙᴘ). ᴀᴅᴇɴɪɴᴇ ғᴏʀᴍs ᴛᴡᴏ ʜʏᴅʀᴏɢᴇɴ
ʙᴏɴᴅs ᴡɪᴛʜ ᴛʜʏᴍɪɴᴇ ғʀᴏᴍ ᴏᴘᴘᴏsɪᴛᴇ sᴛʀᴀɴᴅ ᴀɴᴅ ᴠɪᴄᴇ-ᴠᴇʀsᴀ.
sɪᴍɪʟᴀʀʟʏ, ɢᴜᴀɴɪɴᴇ ɪs ʙᴏɴᴅᴇᴅ ᴡɪᴛʜ ᴄʏᴛᴏsɪɴᴇ ᴡɪᴛʜ ᴛʜʀᴇᴇ ʜ-ʙᴏɴᴅs.
ᴀs ᴀ ʀᴇsᴜʟᴛ, ᴀʟᴡᴀʏs ᴀ ᴘᴜʀɪɴᴇ ᴄᴏᴍᴇs ᴏᴘᴘᴏsɪᴛᴇ ᴛᴏ ᴀ ᴘʏʀɪᴍɪᴅɪɴᴇ. ᴛʜɪs
ɢᴇɴᴇʀᴀᴛᴇs ᴀᴘᴘʀᴏxɪᴍᴀᴛᴇʟʏ ᴜɴɪғᴏʀᴍ ᴅɪsᴛᴀɴᴄᴇ ʙᴇᴛᴡᴇᴇɴ ᴛʜᴇ ᴛᴡᴏ
sᴛʀᴀɴᴅs ᴏғ ᴛʜᴇ ʜᴇʟɪx .
(ɪᴠ) ᴛʜᴇ ᴛᴡᴏ ᴄʜᴀɪɴs ᴀʀᴇ ᴄᴏɪʟᴇᴅ ɪɴ ᴀ ʀɪɢʜᴛ-ʜᴀɴᴅᴇᴅ ғᴀsʜɪᴏɴ. ᴛʜᴇ ᴘɪᴛᴄʜ
ᴏғ ᴛʜᴇ ʜᴇʟɪx ɪs 3.4 ɴᴍ (ᴀ ɴᴀɴᴏᴍᴇᴛʀᴇ ɪs ᴏɴᴇ ʙɪʟʟɪᴏɴᴛʜ ᴏғ ᴀ
ᴍᴇᴛʀᴇ, ᴛʜᴀᴛ ɪs 10-9 ᴍ) ᴀɴᴅ ᴛʜᴇʀᴇ ᴀʀᴇ ʀᴏᴜɢʜʟʏ 10 ʙᴘ ɪɴ ᴇᴀᴄʜ ᴛᴜʀɴ.
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