Problem 5 - Biology of Humans: Concepts, Applications, and Issues

Question

Choose the incorrect statement about restriction enzymes. a. They are used to create recombinant plasmids. b. They are necessary for translation. c. They are used to produce DNA fingerprints. d. They cut DNA at specific sequences.

Step-by-Step Solution

Answer

b. They are necessary for translation.

Step 1: Understand the function of restriction enzymes

Restriction enzymes are proteins that cut DNA at specific sequences. These sequences are known as recognition sites, and each restriction enzyme has a specific site that it identifies and cuts.

Step 2: Evaluate statement a

Statement a says that restriction enzymes are used to create recombinant plasmids. This is true because restriction enzymes can cut DNA at specific sites, allowing DNA fragments from different sources to be combined and inserted into plasmids.

Step 3: Evaluate statement b

Statement b says that restriction enzymes are necessary for translation. This is false because translation is the process of protein synthesis from mRNA, which does not involve restriction enzymes.

Step 4: Evaluate statement c

Statement c says that restriction enzymes are used to produce DNA fingerprints. This is true because restriction enzymes can cut DNA into fragments at specific sequences, and these fragments can be separated by gel electrophoresis to produce a DNA fingerprint.

Step 5: Evaluate statement d

Statement d says that restriction enzymes cut DNA at specific sequences. This is true as it directly describes the main function of restriction enzymes.

Key Concepts

DNA Fingerprinting

DNA fingerprinting is a technique used to identify individuals based on unique patterns in their DNA.

This method utilizes the fact that each person's DNA has distinctive sequences.

Here's how it works:

• Restriction enzymes cut the DNA at specific sequences, creating fragments.
• These fragments are then separated using a method called gel electrophoresis.
• The resulting pattern of bands is unique to each individual and can be compared to other samples.

This technique is widely used in forensic science to link suspects to crime scenes.
It's also used in paternity testing and in genetic studies to understand hereditary traits.

Recombinant Plasmids

Recombinant plasmids are DNA molecules engineered by combining DNA from different sources.

Here’s a simplified explanation:

• First, restriction enzymes cut the DNA at specific sequences.
• Then, DNA fragments from another source are inserted into these cuts.
• The newly combined DNA is inserted into plasmids – small, circular DNA molecules.

This process allows scientists to study specific genes or produce proteins, such as insulin, by inserting the recombinant plasmid into bacteria.
Bacteria can replicate quickly, creating multiple copies of the gene or producing large amounts of proteins.

Protein Synthesis

Protein synthesis is the process in which cells build proteins.

It occurs in two main stages: transcription and translation.

During transcription:

• DNA is copied into mRNA (messenger RNA) inside the nucleus.
• This mRNA carries genetic information from the DNA to the ribosome, the cell's protein-making machinery.

In translation, the mRNA is read and used to assemble amino acids into a protein chain:

• tRNA (transfer RNA) matches amino acids to the codons in mRNA.
• The ribosome links the amino acids together to form a protein.

It's essential to note that restriction enzymes are not involved in protein synthesis.
Their role is in manipulating DNA, not in making proteins.