Molecular Biology

Step 1: Understanding the Concept:
This question requires matching various components and steps related to the technique of agarose gel electrophoresis with their definitions or associated items.
Step 2: Detailed Explanation:
A. Sea weeds: Agarose, the polysaccharide that forms the gel matrix for electrophoresis, is extracted from certain types of red III. sea weeds (e.g., from the genera Gelidium and Gracilaria).
B. Staining of DNA: To visualize the DNA fragments in the gel after electrophoresis, a fluorescent dye is used. The most classic and common staining agent is IV. Ethidium bromide, which intercalates between the DNA base pairs and fluoresces under UV light.
C. Elution: This is the process of extracting and purifying a specific DNA band from the agarose gel after it has been separated and visualized. It is the I. Isolation of DNA from gel.
D. Separation of DNA fragments: The core purpose of II. Gel electrophoresis is to separate macromolecules like DNA, RNA, or proteins. In the case of DNA, it separates fragments based on their size.
Step 3: Final Answer:
The correct matches are A-III, B-IV, C-I, D-II.

Step 1: Understanding the Concept:
The question asks for the specific term used to describe the DNA products of a Polymerase Chain Reaction (PCR).
Step 2: Detailed Explanation:
Polymerase Chain Reaction (PCR) is a technique used to amplify a specific segment of DNA, creating millions to billions of copies. The target DNA sequence that is amplified is known as the template. The resulting DNA copies produced by this amplification process are called amplicons.
The other terms (Multicons, Polycons, Monocons) are not standard terminology in molecular biology for PCR products and are used as distractors.
Step 3: Final Answer:
The DNA copies generated by PCR are called amplicons.

Step 1: Understanding the Concept:
The question asks for the correct chronological sequence of the major steps in a Western blot, a technique used to detect a specific protein in a complex mixture.
Step 2: Detailed Explanation:
The logical workflow of a Western blot is as follows:
D. Protein denaturation in loading dye. First, the protein sample is prepared by boiling it in a loading buffer containing a detergent like SDS (sodium dodecyl sulfate). This denatures the proteins (unfolds them) and gives them a uniform negative charge.
A. Protein resolution by PAGE. The denatured protein mixture is loaded onto a polyacrylamide gel, and an electric current is applied. The proteins migrate through the gel and are separated based on their size. This is PolyAcrylamide Gel Electrophoresis (PAGE).
C. Transfer onto nitrocellulose membrane. After separation, the proteins are transferred (blotted) from the fragile gel onto a solid support, typically a nitrocellulose or PVDF membrane. This makes the proteins accessible for antibody binding.
B. Primary antibody binding. The membrane is then incubated with a primary antibody that is specific to the protein of interest. This antibody binds only to the target protein on the membrane. (This is followed by washing, secondary antibody binding, and detection, but primary antibody binding is the next key step listed).
Therefore, the correct sequence is D A C B.
Step 3: Final Answer:
The correct order of events is D, A, C, B.

Step 1: Understanding the Concept:
This question tests the knowledge of different blotting techniques used in molecular biology to detect specific macromolecules.
Step 2: Detailed Explanation:
B. Southern blotting: Named after its inventor, Edwin Southern, this technique is used IV. To detect specific DNA in a sample.
A. Northern blotting: This technique is analogous to Southern blotting but is used III. To detect specific RNA molecules, typically to study gene expression.
C. Western blotting: This technique uses antibodies to I. To detect specific proteins in a sample.
D. Eastern blotting: This is a less common technique used for the II. Detection of specific post-translational modification of proteins, such as glycosylation or phosphorylation.
Step 3: Final Answer:
The correct matches are A-III, B-IV, C-I, and D-II.

Step 1: Understanding the Concept:
The question asks about the primary application of the antisense RNA technique. This technique involves an RNA molecule that is complementary to a specific messenger RNA (mRNA).
Step 2: Detailed Explanation:
The central dogma of molecular biology states that a gene (DNA) is transcribed into mRNA, which is then translated into a protein.
An "antisense" RNA molecule is designed to have a sequence that is the reverse complement of the "sense" mRNA molecule.
When the antisense RNA is introduced into a cell, it binds to its target mRNA molecule, forming a double-stranded RNA duplex.
This duplex cannot be translated by the ribosome, and it is often rapidly degraded by cellular enzymes like RNase H.
By preventing the translation of the mRNA into a protein, the antisense RNA effectively stops or "silences" the expression of the target gene. A famous example of its application is the Flavr Savr tomato, where it was used to slow down the ripening process.
Step 3: Final Answer:
The antisense RNA technique is used to bind to and prevent the translation of mRNA, thereby silencing gene expression.

Step 1: Understanding the Concept:
This is a factual recall question asking for the correct expansion of the acronym CRISPR, which is a powerful gene-editing technology.
Step 2: Detailed Explanation:
The acronym CRISPR stands for Clustered Regularly Interspaced Short Palindromic Repeats.
This name describes a specific region in the DNA of bacteria and archaea.
Clustered: The repeat sequences are found grouped together.
Regularly Interspaced: These repeats are separated by unique sequences called "spacers."
Short: The repeat sequences are brief.
Palindromic: The repeat sequences read the same forwards and backwards on opposite DNA strands.
The other options use similar-sounding but incorrect words like "Cumulative," "routinely," and "slight" to serve as distractors.
Step 3: Final Answer:
The correct full form is Clustered regularly inter spaced short palindromic repeats.

Step 1: Understanding the Concept:
This question requires matching different gene therapy strategies (LIST-I) with their corresponding descriptions or mechanisms (LIST-II).
Step 2: Detailed Explanation:
A. Gene inhibition: This strategy is used for diseases caused by a faulty gene that produces a harmful product (gain-of-function mutation). The goal is to stop or 'inhibit' the gene from working. This can be done by blocking transcription or translation. This matches with II. Disarm the product of faulty gene.
B. Gene editing: This refers to the technology that allows scientists to make precise changes to the DNA sequence of an organism. The most well-known and versatile tool for this is III. CRISPR/Cas9.
C. Gene targeting: This is a specific technique that uses homologous recombination to modify an endogenous gene. It can be used to create specific mutations, correct a faulty gene, or replace a gene. This matches well with IV. Replacement of non functional gene with normal gene.
D. Gene Augmentation therapy: This is the most common form of gene therapy, used for diseases caused by the loss of a gene's function (e.g., cystic fibrosis). The strategy is to introduce a healthy, functional copy of the gene into the cells to compensate for the faulty one. This matches perfectly with I. Addition of functional gene to their genome to replace missing product.
Step 3: Final Answer:
The correct matching is: A-II, B-III, C-IV, D-I.

Step 1: Understanding the Concept:
The question provides a definition and asks for the corresponding biological term. The key features are: autonomously replicating, circular, and extrachromosomal DNA.
Step 2: Detailed Explanation:
Recombinant DNA: A molecule of DNA created by joining together DNA segments from different sources. It is not a naturally occurring entity with a specific name.
Cybrid: A cytoplasmic hybrid cell produced by fusing a whole cell with an enucleated cell. It is a cell, not a DNA molecule.
Plasmid: A small, circular, double-stranded DNA molecule that is distinct from a cell's chromosomal DNA. Plasmids are found in bacteria and some eukaryotes, and they replicate independently of the main chromosome. This perfectly matches the definition.
Yeast artificial chromosome (YAC): An engineered DNA molecule used to clone DNA sequences in yeast cells. YACs are linear, not circular.
Step 3: Final Answer:
The term for an autonomously replicating, circular, extrachromosomal DNA molecule is a plasmid.