Question

the dna double helix is antiparallel. this means that the two strands
a) are parallel and are identical to each other.
b) are parallel and are the mirror images of each other.
c) are parallel and run in opposite directions.
d) cross over each other many times.

question 4 (5 points)
listen
whats the function of the start codon of an mrna sequence?
a) the start codon protects the mrna from being degraded.
b) the start codon signals for the ribosome to release the mrna sequence.
c) the start codon signals for the ribosome to begin assembling amino acids at that point in the mrna sequence.
d) the start codon acts as a checkpoint in the eukarvotic cell cvcle.

Explanation:

First Question (DNA double helix antiparallel)

In DNA's double - helix structure, "antiparallel" means the two strands are parallel in terms of their overall orientation but have opposite 5' - 3' directions (run in opposite directions). Option A is wrong as strands aren't identical. Option B is wrong as they aren't mirror images. Option D is wrong as DNA strands don't cross over many times; they form a double helix with specific base - pairing.

Second Question (Function of start codon)

The start codon (e.g., AUG in most cases) is recognized by the ribosome. It signals the ribosome to start the process of translation, where amino acids are assembled into a polypeptide chain. Option A is wrong as the 5' cap and poly - A tail protect mRNA from degradation. Option B is wrong as stop codons signal ribosome to release mRNA. Option D is wrong as start codon is related to translation, not cell cycle checkpoints.

Answer:

C) are parallel and run in opposite directions.