Exploring DNA and Gene Expression

What is the primary enzyme responsible for adding nucleotides during DNA replication?

• DNA helicase

• DNA polymerase

• RNA polymerase

• Ligase

Answer explanation

DNA polymerase is the primary enzyme that adds nucleotides to the growing DNA strand during replication, ensuring accurate copying of the genetic material.

Which process involves the synthesis of mRNA from a DNA template?

• Translation

• Replication

• Transcription

• Splicing

Answer explanation

Transcription is the process where mRNA is synthesized from a DNA template. It involves the enzyme RNA polymerase, which reads the DNA sequence and creates a complementary RNA strand.

What is the role of restriction enzymes in genetic engineering?

• To synthesize DNA

• To cut DNA at specific sequences

• To replicate DNA

• To transcribe RNA

Answer explanation

Restriction enzymes are crucial in genetic engineering as they cut DNA at specific sequences, allowing scientists to manipulate and insert genes effectively. This precise cutting is essential for cloning and gene editing.

Which of the following is an application of PCR (Polymerase Chain Reaction)?

• DNA sequencing

• Protein synthesis

• RNA splicing

• Cell division

Answer explanation

PCR is primarily used to amplify DNA, making it a crucial step in DNA sequencing. The other options, such as protein synthesis and RNA splicing, do not involve PCR.

How does a mutation in a DNA sequence affect protein synthesis?

• It always results in a nonfunctional protein

• It may change the amino acid sequence of the protein

• It has no effect on the protein

• It always stops protein synthesis

Answer explanation

A mutation in a DNA sequence can lead to changes in the amino acid sequence of the resulting protein, potentially altering its function. Therefore, the correct answer is that it may change the amino acid sequence of the protein.

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NGSS.HS-LS1-1

NGSS.HS-LS3-2

Describe the semi-conservative nature of DNA replication.

• Each new DNA molecule consists of two new strands

• Each new DNA molecule consists of one old and one new strand

• Each new DNA molecule is identical to the original

• Each new DNA molecule is completely new

Answer explanation

DNA replication is semi-conservative, meaning each new DNA molecule contains one original (old) strand and one newly synthesized strand. This ensures genetic continuity and accuracy in the replication process.

Which organelle is primarily involved in the translation process of protein synthesis?

• Nucleus

• Ribosome

• Golgi apparatus

• Mitochondria

Answer explanation

The ribosome is the organelle responsible for translating mRNA into proteins during protein synthesis. It reads the sequence of nucleotides and assembles the corresponding amino acids, making it essential for this process.

What is the impact of a frameshift mutation on a gene?

• It changes one amino acid in the protein

• It does not affect the protein

• It shifts the reading frame, potentially altering the entire protein

• It only affects the start codon

Answer explanation

A frameshift mutation alters the reading frame of the gene, which can change all subsequent amino acids in the protein, potentially leading to a nonfunctional protein. This is why the correct answer is that it shifts the reading frame.

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NGSS.HS-LS3-2

How does gel electrophoresis separate DNA fragments?

• By size, with smaller fragments moving faster

• By charge, with positively charged fragments moving faster

• By shape, with circular fragments moving faster

• By sequence, with AT-rich fragments moving faster

Answer explanation

Gel electrophoresis separates DNA fragments primarily by size. Smaller fragments move faster through the gel matrix than larger ones, allowing for effective separation based on their lengths.

What is the significance of the central dogma of molecular biology?

• It describes the flow of genetic information from RNA to DNA to protein

• It describes the flow of genetic information from DNA to RNA to protein

• It describes the flow of genetic information from protein to RNA to DNA

• It describes the flow of genetic information from DNA to protein to RNA

Answer explanation

The central dogma of molecular biology describes the flow of genetic information from DNA to RNA to protein, highlighting how genetic instructions are transcribed and translated to produce proteins, which are essential for cellular functions.