AP Biology Unit 6 Gene Expression

What kind of chemical bond is found between paired bases of the DNA double helix?

• hydrogen

• ionic

• covalent

Which enzyme catalyzes the elongation of a DNA strand in the 5ʹ → 3ʹ direction?

• primase

• DNA ligase

• DNA Polymerase

• helicase

In which of the following actions does RNA polymerase differ from DNA polymerase?

• RNA polymerase can initiate RNA synthesis, but DNA polymerase requires a primer to initiate DNA synthesis.

• RNA polymerase binds to single-stranded DNA, and DNA polymerase binds to double-stranded DNA.

RNA polymerase moves in which direction along the DNA?

• 3ʹ → 5ʹ along the template strand

• 3ʹ → 5ʹ along the coding (sense) strand

What is the purpose of transcription?

• to create mRNA so that a specific protein can be coded for

• to aide the cell in creating cellular energy (ATP)

• to bind amino acids together to form a polypeptide

• to ensure that daughter cells have the same DNA as the mother cell

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The initial steps in gene expression are modeled. Double-stranded DNA first unwinds into two strands. Which process and product are represented in the diagrams?

• Process: transcription; product: mRNA

• Process: translation; product: protein

• Process: replication; product: tRNA

• Process: recombination; product: polymerase

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Alternative RNA splicing

• is a mechanism for increasing the rate of transcription.

• can allow the production of proteins of different sizes from a single mRNA

A particular triplet of bases in the coding sequence of DNA is AAA. The anticodon on the tRNA that binds the mRNA codon is

• TTT

• UUU

When does translation begin in prokaryotic cells?

• as soon as transcription has begun

• once the pre-mRNA has been converted to mRNA

Why might a point mutation in DNA make a difference in the level of proteinʹs activity?

• It might substitute an amino acid in the active site.

• It might exchange one stop codon for another stop codon.

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