Yeast Artificial Chromosomes (YACs)


Yeast is a type of single-celled fungus that can grow and reproduce by budding. Yeast is widely used in baking, brewing, and biotechnology. Yeast cells have a nucleus that contains their genetic material, which is organized into linear structures called chromosomes. Chromosomes are made of DNA, the molecule that stores and transmits genetic information.

DNA stands for deoxyribonucleic acid. It is composed of four types of nucleotides: adenine (A), thymine (T), cytosine (C), and guanine (G). These nucleotides form complementary base pairs: A with T and C with G. The nucleotides are arranged in a double helix structure, where two strands of DNA are held together by hydrogen bonds between the base pairs. The sequence of nucleotides in a DNA strand determines the genetic code, which instructs the cell on how to make proteins.

Proteins are the molecules that perform most of the functions in living organisms. They are made of amino acids, which are linked together by peptide bonds. The order of amino acids in a protein is determined by the order of nucleotides in the DNA that encodes it. Each group of three nucleotides called a codon, specifies one amino acid. For example, the codon ATG codes for the amino acid methionine.

The process of making proteins from DNA is called gene expression. It involves two main steps: transcription and translation. Transcription is the synthesis of a messenger RNA (mRNA) molecule from a DNA template. mRNA is a single-stranded molecule that carries genetic information from the nucleus to the cytoplasm, where translation occurs. The translation is the synthesis of a protein from an mRNA template. It involves the use of ribosomes, which are complexes of RNA and protein that read the mRNA and assemble the amino acids into a polypeptide chain.

Yeast cells have about 16 chromosomes that contain about 12,000 genes. Genes are segments of DNA that encode specific proteins or functional RNAs. Some genes are essential for the survival and growth of yeast cells, while others are involved in specialized functions such as metabolism, stress response, or mating. Yeast cells can also exchange genetic material with other yeast cells through sexual reproduction or horizontal gene transfer.

Yeast artificial chromosomes (YACs) are synthetic chromosomes that can be constructed and manipulated in yeast cells. They can carry large segments of foreign DNA from other organisms, such as humans or plants. YACs are useful tools for studying gene function, genome organization, and chromosome behavior in eukaryotes. In this article, we will explore the structure, working principle, process, advantages, uses, and limitations of YACs.