Cell Bio-Engineering Project

Lore & Background

Natural cloning occurs without genetic engineering or human intervention, allowing life forms to spread for hundreds of millions of years. It is utilized by plants like blueberry and Hazel trees, fungi, bacteria, and clonal colonies such as Pando trees. Mechanisms include binary fission, budding, fragmentation, and parthenogenesis. Accidental natural cloning happens when a fertilized egg splits to form identical twins carrying identical DNA. Artificial cloning encompasses reproductive cloning and molecular cloning. Reproductive cloning uses SCNT to create cloned organisms, while molecular cloning amplifies DNA fragments containing whole genes or other sequences for applications ranging from genetic fingerprinting to large-scale protein production. The term 'clone' was coined by Herbert J. Webber in 1903 from the Ancient Greek word κλών (klōn), meaning twig. In horticulture, the spelling 'clon' was used until the early twentieth century before the final 'e' indicated a long 'o'.

In Their Own Story

The process of cloning any DNA fragment essentially involves four steps: fragmentation to break apart a strand of DNA; ligation to glue pieces together in a desired sequence; transformation to insert new DNA into cells; and screening or selection to identify successfully transfected cells. While these steps are standard, alternative routes like Gibson assembly or Golden Gate Cloning rely on recombination rather than restriction enzymes. To amplify DNA, the sequence must link to an origin of replication. Specialized cloning vectors allow for recombinant protein production and other tools. Modern vectors include selectable antibiotic resistance markers, permitting only successfully transformed cells to grow. Additionally, color selection markers provide blue/white screening on X-gal medium. Despite these measures, further investigation via PCR or DNA sequencing is required to confirm successful cloning.

Reader's Guide

Cell cloning derives a population from a single cell. For unicellular organisms like bacteria and yeast, this simply requires inoculating the appropriate medium. However, cloning cells from multicellular organisms is arduous as they do not readily grow in standard media. A useful technique involves using cloning rings: a single-cell suspension plated at high dilution creates isolated colonies. When colonies consist of only a few cells, sterile polystyrene rings are placed over them, trypsin is added, and the cloned cells are collected for further growth. Somatic-cell nuclear transfer (SCNT) can create embryos for research or therapeutic purposes, also known as 'research cloning' or 'therapeutic cloning'. The goal is to harvest stem cells to study human development or treat diseases like diabetes and Alzheimer's. This involves removing the nucleus from an egg cell and inserting a somatic cell nucleus, such as one from a patient's skin. The reprogrammed cell develops into a blastocyst genetically identical to the donor. While clonal human blastocysts have been created, stem cell lines are yet to be isolated from a clonal source.

Did You Know?

• The term 'clone' derives from the Ancient Greek word κλών (klōn), meaning twig.
• Identical twins are an accidental form of natural cloning that occurs when a fertilized egg splits.
• Dolly the sheep was the first mammal cloned from an adult somatic cell in 1996.
• Modern cloning vectors often use blue/white screening on X-gal medium to identify successful transformations.
• While clonal human blastocysts have been created, stem cell lines are yet to be isolated from a clonal source.