Question

A _______ is a molecule that can be used to carry a fragment of DNA into a host organism. a. cloning vector c. GMO b. chromosome d. \(\mathrm{CDNA}\)

Short answer

The correct answer is a. cloning vector.

Step-by-step solution

Understanding the Question

We need to identify which term refers to a molecule that carries a DNA fragment into a host organism. This term is typically associated with molecular biology and genetic engineering.

Analyzing Each Option

- **Cloning vector:** A cloning vector is a DNA molecule used to carry a gene of interest into a host cell. It is specifically designed for easy insertion of DNA fragments. - **GMO (Genetically Modified Organism):** This is an organism that has had its DNA altered or modified. It does not describe the molecule used to carry DNA. - **Chromosome:** Chromosomes are structures within cells that contain DNA. They are not used to carry fragments of DNA into other organisms. - **cDNA (complementary DNA):** cDNA is synthesized from a mature mRNA template and used in gene cloning. However, it is not a carrier molecule itself.

Conclusion

Based on the analysis, a cloning vector is the molecule that carries a fragment of DNA into a host organism. Therefore, the correct answer is option **a. cloning vector**.

Key concepts

DNA Fragment

In the realm of molecular biology and genetic engineering, a **DNA fragment** is a piece of DNA that has been extracted from an organism. This fragment is often used to analyze or manipulate genes. A DNA fragment can be single or double-stranded, and its length can vary greatly, depending on its intended use. DNA fragments often play a crucial role in cloning as they contain the gene sequences that scientists wish to study or replicate. The process begins with cutting or "digesting" the DNA at specific sequences using enzymes called restriction endonucleases. This results in fragments that can be separated and isolated for various applications. Once isolated, a DNA fragment can be introduced into a host organism using a cloning vector. This enables scientists to investigate the function of specific genes, produce protein products, or engineer organisms with desirable traits.

Host Organism

In genetic engineering, a **host organism** is a living cell or microorganism where DNA fragments are introduced and propagated. It serves as the environment where the DNA of interest can replicate and express the genetic material it carries. Host organisms are typically chosen based on their ability to support the cloning vector and DNA fragment introduction, as well as their ease of cultivation. Common host organisms include:

• Bacteria like *Escherichia coli* (E. coli) - popular due to rapid growth and simplicity.
• Yeast - useful for expressing eukaryotic proteins.
• Mammalian cells - used for complex proteins that require specific conditions present in animals.

Choosing the appropriate host is essential for successful gene expression and function analysis. It allows researchers to study the effects of inserted genes in a controlled setting.

Genetic Engineering

**Genetic Engineering** is the process of altering or manipulating an organism's genome using biotechnology. It involves directly manipulating one or more genes to produce desired traits or outcomes. This field has led to revolutionary advancements in medicine, agriculture, and environmental science. Some key techniques in genetic engineering include:

• Recombinant DNA technology - combining DNA from different organisms.
• Gene cloning - making copies of a particular gene.
• CRISPR-Cas9 - a precise gene-editing tool that can change specific DNA sequences.

Applications of genetic engineering are vast: from creating crops resistant to pests and diseases to developing treatments for genetic disorders. It also allows for mass production of insulin and other important pharmaceuticals through genetically modified bacteria.

Molecular Biology

Molecular biology is the branch of science that studies the molecular basis of biological activity. It focuses on understanding the interactions within cells, particularly how DNA, RNA, and proteins are synthesized and regulated. Core aspects of molecular biology include:

• DNA Replication - how DNA is copied before cell division.
• Transcription - converting DNA sequences into RNA.
• Translation - using RNA to synthesize proteins.

Understanding these processes gives insights into how genes are controlled and expressed, which is crucial in diagnosing diseases, developing therapies, and advancing genetic engineering techniques. Molecular biology has laid the groundwork for innovations in biotechnology and genomics, making it a cornerstone of modern science.