CELL TECHNOLOGY Stem Cells Definition Unspecialized cells that have two defining properties: 1) the ability to differentiate into other cells 2) the ability to self-regenerate to form more stem cells Importance Development Repair of Adult Tissue Cancer

CELL TECHNOLOGY Stem Cells Differentiation Potential Totipotent Cells Can develop into all cell types Pluripotent Cells Can develop into cells of the three germ layers (ectoderm, mesoderm, endoderm) Multipotent Cells Can develop into cells of a few types Types Zygote: Totipotent Embryonic: Pluripotent Adult: Multipotent

EMBRYONIC STEM CELLS Definition Stage of Development Importance Inner cell mass within fertilized cells. Stage of Development Blastocyst Hollow ball of ~64 cells containing an inner mass and trophoblast. Importance Able to be directed to any type of cell. “Pluripotent”

BLASTOCYST

EMBRYONIC STEM CELLS

ADULT (Somatic) STEM CELLS Definition Tissue specific stem cells (Multipotent) Purpose Replacement Damaged and injured tissue Continually-replenished cells Types Bone Bone Marrow Stromal Cells :Bone, Cartilage,Fibers Hematopoietic Stem Cells : Blood Cells Brain Neural Stem Cells: Neurons, Astrocytes, Oligodendrocytes

ADULT STEM CELLS

ADULT (Somatic) STEM CELLS Plasticity (Transdifferentiation) Definition Ability to differentiate into multiple cell types. Examples Hematopoietic Stem Cells Brain, Muscle (Cardiac and Skeletal), and Liver Cells Stromal Cells Muscle Cells Brain Cells Blood and Skeletal Muscle

PLASTICITY (TRANSDIFFERENTIATION)

CANCER STEM CELLS Teratocarcinomas (Teratomas) Definition Germ cell tumor with mixed differentiated tissue and undifferentiated tissue Example Leukemia Acute Increased growth in an early stem cell Chronic Decreased response to death or differentiation in a stem cell

Fundamental Remaining Questions 1) Does one common type of stem cell migrate to different organs and repair tissue or are there multiple types of stem cells? 2) Does every organ have stem cells (some of which have not yet been discovered)? 3) Are the stem cells programmed to divide a finite number of times or do they have unlimited cell proliferation capacity?

CELL TECHNOLOGY Cloning Definition Duplicating biological material Types Reproductive Therapeutic DNA (Recombinant Technology)

REPRODUCTIVE CLONING Definition Production of an organism that is genetically identical to an original donor. Pseudo-clone Clone has genetic material from mitochondria. Problems Incompleteness of genomic imprinting Process Somatic cell nuclear transfer (SCNT)

SOMATIC CELL NUCLEAR TRANSFER Process 1) Remove mammary cell from donor and starve. 2) Remove egg cell from a different donor and enucleate. 3) Place mammary cell into egg cell. 4) Apply a brief shock to cause mammary cell contents to mix with egg cell contents. 5) Allow cell to go through mitosis. 6) Implant into a surrogate sheep.  

REPRODUCTIVE CLONING

THERAPEUTIC CLONING Definition Producing a blastocyst from a patient’s somatic cells to be used for therapy. Process Somatic Cell Nuclear Transfer Extract inner cell mass at blastocystic stage Use cells to grow tissue or organs Importance Cells will not be rejected

RECOMBINANT DNA TECHNOLOGY Definition Excising DNA of interest from one genome and inserting it into a foreign genome. Process Genetic Engineering Biotechnology: Using genetic engineering to create biological systems that produce a desired product. Importance Drugs and medications Genome enhancement

Fig. 24.15

RECOMBINANT DNA TECHNOLOGY Steps (1) DNA Isolation a) Isolate foreign DNA from desired cell.   b) Isolate DNA plasmid vector from bacteria.   (2) DNA Fragmentation a)Cut desired gene from foreign DNA using “Restriction enzymes”.   b) Open plasmid using “Restriction enzymes” to form a gap for DNA insertion.

RESTRICTION ENZYMES

RECOMBINANT DNA TECHNOLOGY Steps (3) Plasmid Recombination Insert the foreign gene into the gap of the plasmid by complementary base pairing of the sticky ends and sealing with DNA ligase. (4) Recombinant Plasmid Uptake Plasmid is taken up by bacteria through transformation.

RESTRICTION ENZYMES

RECOMBINANT DNA TECHNOLOGY Steps (5) Plasmid Replication Bacterial cell is replicated producing desired DNA clones.   (6) Gene Isolation DNA sequences can be cut from Plasmids and added to other genomes. Protein Production Bacteria can be put into a desired environment to produce desired protein.