Chapter 19 - Genetic Engineering, Stem Cell Research & Cloning

wake up!

What are stem cells?

Cells found in the early embryo and in other parts of the human body that are not fully differentiated.

What are the general properties of stem cells?

Capable of dividing and renewing themselves for long times

Undifferentiated, but has the capacity to develop into differentiated cells

Where can stem cells come from?

Embryonic Stem Cell

Stem Cells from Umbilical Cord

Adult Stem Cells

What is an Embryonic Stem Cell?

They make up the inner mass of cells of the blastocyst that exists in the 1st week of development.

How many stem cells from umbilical cord blood is collected?

100 mL collected with 1.5x10^5 CD34+ cells from placenta during 3rd stage of delivery/post-delivery.

What are Adult Stem Cells?

Cells from bone marrow and peripheral blood

How many stem cell types are there?

Four.

• Totipotent

• Pluripotent

• Multipotent

• Adult

What are some characteristics of Totipotent stem cells?

• Most versatile

• Totipotent = one-celled

• Can be any and all human cells

• Can rise to functional organisms

How many days does it take for Totipotent stem cells to specialize into Pluripotent stem cells?

Four days.

What are some characteristics of Pluripotent stem cells?

• Can give rise to all tissue types

• Cannot make an entire organisms

What are Induced Pluripotent Stem Cells? (iPSCs)

Adult cells genetically converted to an embryonic stem cell-like state.

When were iPSCs introduced?

2007, for human cells.

In animal studies, what have iPSCs shown?

Shown to possess pluripotent stem cell characteristics

What are Multipotent stem cells?

• Less plastic, more differentiated

• Can give rise to a limited range of cells within a tissue type

What are Adult Stem Cells?

• Multipotent stem cell in adult humans used to replace dead cells.

What are some Adult stem cell characteristics?

• Undifferentiated cell present in differentiated tissue

• Self-renewing

• Can yield all cell types present in its origin tissue

What are some tissue types that Adult Stem Cells been identified for?

• hematopoietic (blood)

• endothelial

• muscle

• mesenchymal

• epidermal cells

• neural

• gastrointestinal

What are some clinical applications of Stem Cells?

• Diabetes

• Leukemia

• Nervous System Diseases

• Primary Immunodeficiency Diseases

• Diseases of Bone and Cartilage

• Cancer

What is a clone?

An exact genetic copy of a molecule, cell plant or animal.

What are the three cloning methods?

DNA

Therapeutic/embryo

Reproductive

What is involved in DNA cloning?

• Only the DNA of a cell is replicated

• It is the transfer of a DNA fragment from one organism to a self-replication genetic element (such as a bacterial plasmid)

• DNA of interest can be spread in a foreign host cell.

What is the possible applications of DNA cloning?

Gene Therapy

Gene Sequencing

What is involved in Gene Therapy?

• Experimental

• Introduces cells that compensate for abnormalities

  • or give benefits

• This may be used to treat disorder instead of drugs or surgery

What are some approaches to Gene Therapy?

• Replacing mutated gene with healthy copy

• Inactivating a mutated and improperly functioning gene

• Introducing a new gene to fight disease

What is Gene Sequencing?

Technique for determining the exact sequence of nucleotides, or bases, in a DNA molecule.

What is Therapeutic/Embryo Cloning?

• Production of human embryos for treatment/research

• Nucleus of bodily cell is inserted into an unfertilized, no-nucleus egg

• Egg is stimulated to become embryo

• Stem cells in the blastocyst would be identical to the person whose cell it was

What is Reproductive Cloning?

Technology used to generate an animal with the same nuclear DNA as another animal.

In reproductive cloning, what is Somatic cell nuclear transfer? (it’s a three-step process)

• Transfer of genetic material from donor adult cell nucleus to an egg with a removed nucleus

• Egg treated with chemicals/electric current for cell division

• Once egg reaches suitable stage, it is transferred to female host uterus

What are some possible applications for Reproductive Cloning?

• Repopulating endangered animals

• Production of genetically altered animals that would serve as models for studying human disease.