DNA Structure and Function Review

During transcription, this type of ribonucleic acid is responsible for copying the DNA and bringing it out of the nucleus.

• mRNA

• tRNA

• rRNA

• snRNA

What happens to the double helix during the first step of DNA replication?

• The double helix unwinds and the two strands separate.

• The double helix remains intact and does not change.

• The double helix is replaced by a single strand.

• The double helix forms additional bonds with other molecules.

Answer explanation

During the first step of DNA replication, the double helix unwinds and “unzips.”

Here’s what happens:

• - The twisted ladder shape (double helix) untwists

• - The two strands separate from each other

• - The bonds between the base pairs (A–T and C–G) are broken

How does the information from the DNA inside the nucleus get outside to the ribosomes?

• mRNA

• tRNA

• rRNA

• DNA polymerase

What does the ribosome read in groups of three bases during translation?

• Codons

• Anticodons

• Amino acids

• Nucleotides

Which type of mutation involves the rearrangement of chromosome segments?

• Translocation

• Duplication

• Inversion

• Deletion

When these bond together, they form a protein

• Nucleotides

• Fatty Acids

• Amino Acids

• Monosaccharides

Which statement best defines a mutation?

• a change in the order, number, or type of bases in the genetic code

• a process that leads to the formation of new species

• a type of genetic engineering technique

• a method of DNA replication

Which nitrogenous base pairs with adenine in DNA?

• Cytosine

• Guanine

• Thymine

• Uracil

Answer explanation

In DNA, adenine (A) pairs with thymine (T).

Remember that this is different for RNA.

What is the key structural difference between RNA and DNA?

• RNA contains Thymine (T) instead of Uracil (U).

• RNA contains Uracil (U) instead of Thymine (T).

• RNA is double-stranded while DNA is single-stranded.

• RNA has deoxyribose sugar while DNA has ribose sugar.

Answer explanation

The key structural difference between DNA and RNA is:

👉 DNA is double-stranded, while RNA is single-stranded.

👉 They also have different nitrogen bases:

• DNA bases: A, T, C, G

• RNA bases: A, U, C, G

What is the complementary mRNA sequence to this DNA strand: AACTGAA?

• UUGACUU

• AACUGAA

• UUGACAA

• AACTGUU