CELL TECHNOLOGYStem 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 cellsImportance Development Repair of Adult Tissue Cancer

CELL TECHNOLOGYStem 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 CellsCan develop into cells of a few types

Types Zygote: Totipotent Embryonic: Pluripotent Adult: Multipotent

EMBRYONIC STEM CELLS

Definition Inner cell mass within fertilized cells.

Stage of DevelopmentBlastocyst Hollow ball of ~64 cells containing an inner mass and trophoblast.

ImportanceAble to be directed to any type of cell. “Pluripotent”

BLASTOCYST

EMBRYONIC STEM CELLS

ADULT (Somatic) STEM CELLS

Definition Tissue specific stem cells (Multipotent)

PurposeReplacement Damaged and injured tissue Continually-replenished cells

TypesBone 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 CellsMuscle Cells

Brain CellsBlood and Skeletal Muscle

PLASTICITY (TRANSDIFFERENTIATION)

CANCER STEM CELLS

Teratocarcinomas (Teratomas)Definition

Germ cell tumor with mixed differentiated tissue and undifferentiated tissue

ExampleLeukemia 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

CloningDefinition Duplicating biological materialTypes Reproductive Therapeutic DNA (Recombinant Technology)

REPRODUCTIVE CLONING

DefinitionProduction of an organism that is genetically identical to an original donor.

Pseudo-cloneClone has genetic material from mitochondria.

ProblemsIncompleteness of genomic imprinting

Process Somatic cell nuclear transfer (SCNT)

SOMATIC CELL NUCLEAR TRANSFER

Process1) 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

DefinitionProducing a blastocyst from a patient’s somatic cells to be used for therapy.

ProcessSomatic Cell Nuclear TransferExtract inner cell mass at blastocystic stageUse cells to grow tissue or organs

ImportanceCells will not be rejected

RECOMBINANT DNA TECHNOLOGY

DefinitionExcising DNA of interest from one genome and inserting it into a foreign genome.

ProcessGenetic Engineering

Biotechnology: Using genetic engineering to create biological systems that produce a

desired product.Importance

Drugs and medicationsGenome 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 ProductionBacteria can be put into a desired environment

to produce desired protein.