Review 6: RNA & Gene Expression

Describe the role of messenger RNA (mRNA) in the process of protein synthesis.

• It carries amino acids to the ribosome.

• It serves as a template for assembling amino acids into a protein.

• It forms the structure of the ribosome.

• It catalyzes the formation of peptide bonds.

Answer explanation

Messenger RNA (mRNA) serves as a template for assembling amino acids into a protein during protein synthesis, guiding the ribosome in the correct sequence to form the polypeptide chain.

Which of the following best describes a mutation in DNA?

• A permanent change in the sequence of nucleotides.

• A temporary change in the protein structure.

• A reversible change in the cell membrane.

• A change in the number of chromosomes.

Answer explanation

A mutation in DNA refers to a permanent change in the sequence of nucleotides, which can affect how genes function. This distinguishes it from temporary changes or alterations in protein structure or chromosome number.

Tags

NGSS.HS-LS3-2

Explain how enzymes speed up chemical reactions in cells.

• By increasing the temperature of the reaction.

• By lowering the activation energy required for the reaction.

• By changing the pH of the environment.

• By providing energy to the reactants.

Answer explanation

Enzymes speed up chemical reactions by lowering the activation energy required for the reaction. This allows the reaction to occur more easily and quickly, without changing the temperature or pH.

Tags

NGSS.HS-PS1-2

What is the significance of gene expression in cells?

• It determines the cell's ability to divide.

• It controls the production of proteins that determine cell function.

• It regulates the cell's energy production.

• It maintains the cell's structural integrity.

Answer explanation

Gene expression is crucial as it controls the production of proteins, which are essential for determining cell function. Without proper gene expression, cells cannot produce the proteins needed for their specific roles.

Tags

NGSS.HS-LS1-1

Evaluate the potential impact of a point mutation in a gene.

• It always results in a nonfunctional protein.

• It may have no effect, or it may alter the protein function.

• It always causes a frameshift mutation.

• It results in the deletion of the gene.

Answer explanation

A point mutation can be silent, meaning it has no effect, or it can change the amino acid sequence, potentially altering protein function. Thus, the correct choice is that it may have no effect, or it may alter the protein function.

Tags

NGSS.HS-LS3-2

Illustrate the process of transcription in protein synthesis.

• DNA is replicated to form two identical strands.

• mRNA is synthesized from a DNA template.

• Proteins are assembled from amino acids.

• tRNA brings amino acids to the ribosome.

Answer explanation

Transcription is the process where mRNA is synthesized from a DNA template. This step is crucial in protein synthesis, as it converts the genetic information in DNA into a format that can be translated into proteins.

Identify the role of ribosomal RNA (rRNA) in protein synthesis.

• It carries genetic information from DNA to the ribosome.

• It forms the core of the ribosome's structure and catalyzes protein synthesis.

• It transports amino acids to the ribosome.

• It modifies proteins after synthesis.

Answer explanation

Ribosomal RNA (rRNA) is essential in protein synthesis as it forms the structural core of ribosomes and has catalytic properties that facilitate the assembly of amino acids into proteins.

Investigate how a change in enzyme structure can affect its function.

• It will always increase the enzyme's activity.

• It may alter the enzyme's ability to bind to its substrate.

• It will have no effect on the enzyme's function.

• It will cause the enzyme to become a different type of protein.

Answer explanation

A change in enzyme structure can affect its active site, potentially altering its ability to bind to the substrate. This can lead to decreased or increased activity, but it does not guarantee an increase in activity.

Explain the process of translation in protein synthesis.

• DNA is copied into mRNA.

• mRNA is decoded to produce a specific polypeptide.

• Proteins are broken down into amino acids.

• DNA is repaired after damage.

Answer explanation

Translation is the process where mRNA is decoded by ribosomes to synthesize a specific polypeptide chain, which then folds into a functional protein. This step is crucial in protein synthesis.

What is the role of transfer RNA (tRNA) in protein synthesis?

• It carries genetic information from the nucleus to the ribosome.

• It brings amino acids to the ribosome for protein assembly.

• It forms the structure of the ribosome.

• It catalyzes the formation of peptide bonds.

Answer explanation

Transfer RNA (tRNA) plays a crucial role in protein synthesis by bringing amino acids to the ribosome, where they are assembled into proteins. This function is essential for translating the genetic code into functional proteins.