Biotechnology Genetic Engineering Cloning Cloning is the process

Biotechnology Genetic Engineering

Cloning • Cloning is the process in which identical offspring are formed from a single cell or tissue • Many plants have the ability to naturally clone themselves; this is called totipotent (i. e. strawberries, aspen trees) • Most animal cells are not totipotent (except salmanders) but technology has advanced to allow us to clone (i. e. Dolly the sheep) C. C. the cat (carbon copy, or copy cat)

Cloning • There a few ways that cloning can occur 1. Nuclear transfer from blastula 2. Nuclear transfer with electrical or chemical shock 3. Identical twins 4. By budding

Nuclear transfer from blastula The nucleus of a cell from a blastula is removed and transplanted into an enucleated unfertilized egg Enucleated = cells that does not contain a nucleus - This egg begins to divide by mitosis, eventually forming an organism Removing the nucleus from a cell

Nuclear transfer from blastula Mitosis Fertilized Egg Remove Nucleus Blastula Stage Unfertilize Remove d Egg Nucleus Enucleate d Cell with transplanted nucleus begins to divide by mitosis

Why clone from a blastocyst? • Tried at gastrula stage but when they transplanted the nucleus the cell did not divide • Nuclear material must now be fixed and cells would have already started to differentiate

Nuclear transfer with electrical shock

Dolly and Telomeres • If cells divided without telomeres, they would lose the ends of their chromosomes, and the necessary information they contain. • The telomeres are disposable buffers blocking the ends of the chromosomes, are consumed during cell division, and are replenished by an enzyme, telomerase reverse transcriptase.

Identical Twins • After an egg has been fertilized, the newly formed zygote will divide and redivide through successive mitotic cycles to form the multicellular embryo • If a cell should break free from the forming embryo early in this process (prior to differentiation), it will develop into a second embryo having identical genetic information Are they clones?

Abnormal Cell Division: Cancer • The growth, differentiation and replication of cells is highly controlled • Uncontrolled cell division occurs when cells divide and they do not have a mechanism to stop • This results in a tumor

Cancer: Tumors • A benign tumor is a tumor that stays in one place, and often eventually stops dividing • A malignant tumor is a tumor that can metastasize (spread)

Carcinogens • Carcinogenic or cancer-causing agents (x-rays, UV light, chemicals and some viruses) can cause mutations in the chromosomes that affect the replication process • Mutations can also occur on their own

• http: //www. pbs. org/wgbh/nova/cancer/p rogram. html