Welcome Guest Search | Active Topics |

Tag as favorite
Altius FL 7 BB Section question 57
Options
Previous Topic Next Topic
Moon_5252
#1 Posted : Wednesday, September 01, 2021 5:43:44 PM
Rank: Newbie

Groups: Registered
Joined: 4/25/2020
Posts: 1

Thanks: 0 times
Was thanked: 0 time(s) in 0 post(s)
Hello! I was hoping to clarify a question from our Altius practice exam #7. For the BB Section Question 57:

If the triplet codon on a coding DNA strand is CTG, the complementary tRNA codon must be which of the following?

a) GUC
b) GAC (my answer)
c) CTG
d) CUG (correct answer according to Altius?)

I am wondering why is the answer to the question is CUG instead of GAC? Is it not that the mRNA transcribed be the same sequence as the coding DNA, meaning that the complementary tRNA is GAC (DNA: CTG -> mRNA: CUG -> tRNA GAC)?
Back to top
Report?
INSTR_Taylor_140
#2 Posted : Friday, September 03, 2021 2:00:33 AM
Rank: Member

Groups: Registered
Joined: 6/11/2021
Posts: 27

Thanks: 0 times
Was thanked: 0 time(s) in 0 post(s)
Hi Moon!

According to Altius, the correct answer is D but is actually CAG (not CUG as written below). The reasoning is because the triplet codon from the coding strand of the DNA is carried to the cytoplasm by mRNA. The mRNA will be composed of complementary sequences to the DNA strand (with U replacing T). This mRNA is then read by tRNA in the cytoplasm which carries an anticodon for each triplet sequence. If CTG is the original codon in the coding strand of DNA; the mRNA complementary sequence will be CUG; the complementary anticodon in tRNA must therefore be CAG because, by convention, nucleotide sequences are always written from 5' to 3'.

Hope that helps!
Taylor
Back to top
Report?
Users browsing this topic
Guest
Tag as favorite
You cannot post new topics in this forum.
You cannot reply to topics in this forum.
You cannot delete your posts in this forum.
You cannot edit your posts in this forum.
You cannot create polls in this forum.
You cannot vote in polls in this forum.

Clean Slate theme by Jaben Cargman (Tiny Gecko)
Powered by YAF | YAF © 2003-2009, Yet Another Forum.NET
This page was generated in 0.083 seconds.