Lesson 11 - Gene Expression Quizizz

One major difference between DNA and RNA structure is that in RNA adenine binds with _____.

• guanine

• cytosine

• uracil

• thymine

Answer explanation

Both nucleic acids include the nitrogenous bases cytosine, guanine, and adenine. In RNA, adenine binds with uracil, while in DNA adenine binds to thymine.

DNA and RNA polymers differ in that RNA polymers tend to be _____.

• shorter and single-stranded

• longer and single-stranded

• shorter and double-stranded

• longer and double-stranded

Answer explanation

Most RNA is short and single-stranded because RNA transcription produces a single RNA sequence complementary to a section of DNA. Because DNA stores information required for survival, DNA tends to be longer than RNA and double-stranded, providing a copy of the stored information.

DNA functions to _____ information, whereas RNA _____ information.

• store; transfers

• transfer; stores

• catalyze; transcribes

• translate; catalyzes

Answer explanation

DNA contains information required for life (the genetic code) whereas RNA copies and transports the information to ribosomes for protein synthesis.

The process of forming mRNA from a DNA template is _____.

• transcription

• translation

• replication

• ribosomal processing

Answer explanation

The production of an RNA transcript involves the copying of DNA code into RNA code.

The process of converting a nucleotide sequence to an amino acid sequence is _____.

• transcription

• translation

• replication

• ribosomal processing

Answer explanation

Ribosomal RNA reads the mRNA codons and assists the attachment of the corresponding tRNA that carries the specified amino acid.

The three-dimensional structure of a tRNA molecule supports its ability to _____.

• synthesize a protein by catalyzing peptide bond formation

• recognize and bind to a mRNA codon during translation

• splice mRNA by associating with proteins to form a spliceosome

• carry information from the DNA to a ribosome for translation

Answer explanation

Transfer RNA folds into a three-dimensional structure that binds to a specific amino acid in one region and complementary mRNA codon in another.

The enzyme that unwinds DNA during transcription is _____.

• RNA polymerase

• DNA polymerase

• promoter enzyme

• helicase

Answer explanation

RNA polymerase opens the DNA strand and catalyzes formation of bonds between RNA nucleotides, building a strand of mRNA that is complementary to the DNA bases.

Expression of a gene is regulated by _____.

• transcription factors binding to the promoter

• RNA polymerase binding to introns

• a ribosome binding to the start of the gene

• the position of the first AUG

Answer explanation

A group of proteins called transcription factors regulate gene expression by binding to the promoter region upstream of a gene. Transcription-factor binding is activated by cellular signals such as low enzyme concentration or changes in the environment.

One difference between prokaryotic and eukaryotic transcription is that _____.

• prokaryotic mRNA is modified before translation

• eukaryotic translation begins while mRNA is still being transcribed

• prokaryotic transcription occurs in the cytoplasm

• eukaryotic translation occurs in the cytoplasm

Answer explanation

Prokaryotes lack membrane-bound organelles, including a nucleus, so transcription occurs in the cytoplasm. Prokaryotic and eukaryotic translation is similar in that the process occurs in the cytoplasm.

The 3’ end of eukaryotic mRNA is modified with nucleotides thought to assist in nuclear exit and stability of the mRNA. The structure of this 3’ tail is best described as:

• a long, repetitive series of adenine nucleotides.

• a unique sequence of nucleotides containing some adenines.

• a short, repetitive sequence composed of modified “cap” nucleotides.

• a unique sequence of nucleotides ending with a 5’ cap.

Answer explanation

A poly-A tail is added to eukaryotic mRNA during post-transcriptional processing. Although its exact purpose is unknown, experimental data indicate that this long string of adenine nucleotides assists with transport of mature mRNA into the cytoplasm for translation and/or determines how long an mRNA remains in the cytoplasm before degradation.