Question

question 1 points 1 the complimentary messenger rna strand that would be synthesized from the dna base sequence of ugacu would be ______. \\(\circ\\) agtug \\(\boldsymbol{\circ}\\) acuga \\(\circ\\) tgaca \\(\circ\\) gacgu

Explanation:

Step1: Recall base pairing rules

In transcription, DNA to mRNA: A pairs with U, T (but DNA has T, mRNA has U) – wait, wait, the DNA sequence here? Wait, the problem says DNA base sequence of UGACU? Wait, no, DNA has A, T, C, G. Wait, maybe a typo, but the key is mRNA complementary to DNA (or maybe the given is a DNA or RNA? Wait, the question is about complementary mRNA from DNA sequence UGACU. Wait, no, DNA has T, so maybe the given is a DNA sequence with a typo (using U instead of T? Or maybe it's a RNA template? Wait, no, transcription: DNA (template) to mRNA. The base pairing is A-U, T-A, G-C, C-G. Wait, if the DNA template is (let's correct: maybe the DNA is T G A C T, but written as UGACU? Maybe a typo, but the options have U. Wait, the mRNA is complementary to DNA. So for each base in DNA: A→U, T→A, G→C, C→G. Wait, the given DNA sequence (assuming it's DNA with U as T? No, DNA has T. Wait, maybe the given is a RNA (like a template, but no, transcription is DNA to mRNA). Wait, the options: ACUGA. Let's check the complement. Let's take the DNA sequence as (assuming the given U is T, so DNA: T G A C T? No, the given is UGACU. Wait, maybe the original is a DNA with sequence T G A C T, but written as UGACU (maybe a mistake, using U for T). Then mRNA would be A C U G A (ACUGA), because T (DNA) pairs with A (mRNA), G→C? Wait no, wait: DNA template to mRNA: A (DNA) pairs with U (mRNA), T (DNA) pairs with A (mRNA), G (DNA) pairs with C (mRNA), C (DNA) pairs with G (mRNA). Wait, if the DNA is UGACU (but DNA should have T, so maybe it's a RNA (like a coding strand, but no). Wait, maybe the given is a DNA sequence with U instead of T (a typo), so DNA: T G A C T. Then mRNA: A C U G A (ACUGA), which is option ACUGA. Let's check the options: ACUGA is one of them. So step 1: recall base pairing (DNA to mRNA: A-U, T-A, G-C, C-G). Step 2: take each base in DNA (assuming U is T) and find complement. So U (T) → A, G→C? Wait no, wait: DNA base: T (U in typo) → A (mRNA), G→C? No, wait G (DNA) pairs with C (mRNA)? No, G (DNA) pairs with C (mRNA)? Wait no, G (DNA) and C (mRNA) pair? Wait no, in DNA-DNA, G-C, but DNA to mRNA: G (DNA) pairs with C (mRNA)? No, wait mRNA is complementary to DNA template. So DNA template: 3' to 5', mRNA 5' to 3'. So for each base in DNA template (3' to 5'): A (DNA) → U (mRNA), T (DNA) → A (mRNA), G (DNA) → C (mRNA), C (DNA) → G (mRNA). Wait, let's take the given sequence as DNA: U G A C U (assuming U is T, so DNA: T G A C T). Then mRNA: A C U G A (ACUGA), because T (DNA) → A (mRNA), G→C? No, wait T (DNA) → A (mRNA), G (DNA) → C (mRNA)? No, G (DNA) pairs with C (mRNA)? Wait no, G (DNA) and C (mRNA) would form a pair? Wait, no, G (DNA) and C (mRNA) are complementary? Wait, G and C are complementary in DNA, but in DNA to mRNA, G (DNA) pairs with C (mRNA)? Wait, no: A (DNA) - U (mRNA), T (DNA) - A (mRNA), G (DNA) - C (mRNA), C (DNA) - G (mRNA). Yes. So DNA: T (U) G A C T (U). So T→A, G→C? No, wait G (DNA) → C (mRNA)? No, wait G (DNA) and C (mRNA) pair? Wait, no, G (DNA) and C (mRNA) are complementary? Wait, G and C are complementary (3 H-bonds), so yes. So DNA: T (U) G A C T (U). So first base: T (U) → A (mRNA), second: G → C? No, wait no: G (DNA) → C (mRNA)? Wait, no, in DNA to mRNA, the base pairing is A-U, T-A, G-C, C-G. So G (DNA) pairs with C (mRNA)? No, G (DNA) and C (mRNA) would be a pair? Wait, no, G (DNA) and C (mRNA) are complementary (G-C), yes. So DNA: T (U) G A C T (U). So:

T (U) → A (mRNA)

G → C? No, wait no: G (DNA) pairs with C (mRNA)? Wait, no, G (DNA) and C (mRNA) is a pair? Wait, no, G (DNA) and C (mRNA) are complementary (G-C), yes. Wait, but then the second base G (DNA) would pair with C (mRNA), but the option ACUGA has C as the second base? Wait, ACUGA: A C U G A. Let's check the DNA sequence UGACU (T G A C T). So DNA: T (1), G (2), A (3), C (4), T (5). mRNA: A (1), C (2), U (3), G (4), A (5). Yes! Because T→A, G→C? No, wait G→C? Wait, no, G (DNA) pairs with C (mRNA)? Wait, no, G (DNA) and C (mRNA) is a pair? Wait, no, G (DNA) and C (mRNA) are complementary (G-C), yes. Wait, but T (DNA) → A (mRNA), G (DNA) → C (mRNA), A (DNA) → U (mRNA), C (DNA) → G (mRNA), T (DNA) → A (mRNA). So DNA: T G A C T (UGACU with U as T) → mRNA: A C U G A (ACUGA). Yes, that matches option ACUGA.

Answer:

ACUGA (the option with ACUGA)