stem cells

Question 1

what are stem cells

Answer 1

Stem cells are cells with the potential to develop into many different types of cells in the body.
* a stem cell can self-renew-copying to make more stem cells.
* all cells in the body come from stem cells
* a stem cell is a cell that is not yet specialised
* the process of specialisation is called differentiation
* once the differentiation pathway of a stem cell has ben decided, it can no longer become another type of cell on it’s own

Question 2

what are the different types of stem cells

Answer 2

different kinds of stem cells can be distinguished in terms of their potency. Potency- a measure of how many ranges of specialised cells a stem cell can make.
descriptions of stem cell potencies include;
* totipotent
* multipotent
* unipotent
* pluripotent
* oligopotent

Question 3

stem cells; totipotent cells

Answer 3

• have the potential to give rise to all cell types
• the fertilised egg is said to be totipotent
• other totipotent cells include embryonis cells of a two-, four- or eight cell embryo.

Question 4

stem cells; pluripotent

Answer 4

• can differentiate into many types of cells
• originate from the primary germ cell layer (mesoderm, endoderm, ectoderm)
• Eg. embryonic stem cells from the inner cell mass of the blastocyst

Question 4

stem cells; multipotent cells

Answer 4

• can make multiple types of specialised cells, but not all types
• they can differentiate into closely related cells
• Eg; multipotent blood stem cells can differentiate into red blood cells, platelet, white blood cell
• tissue stem cells are multipotent

Question 5

stem cells; oligopotent cells

Answer 5

• have the ability to differentiate into just a few types of cells
• Eg. adult (somantic) lymphoid or myeloid stem cells

Question 5

stem cells; unipotent cells

Answer 5

• have the ability to produce only stem cells of their own type- because they can self renew, they are termed ‘stem cells’
• Eg: adult (somatic) muscle stem cells.

Question 6

stem cell in regenerative medicine

Answer 6

because stem cells have the unique ability to regenerate damaged tissue, research is being carried out on the potential of their use in the treatment of a large number of human disorders or conditions.
* potential uses fro these purposes are called cell-based theparies, adn the field of research is termed regenerative medicine.
* this research leads to scientists requiring a source of stem cells

Question 6

what are some sources of stem cells

Answer 6

• embryonic stem cells
• parthenotes
• somantic stem cells - adult stem cells (multipotent)
• induced pluripotent stem cells

Question 7

source 1; embryonic stem cells (pluripotent) - (blastocyst)

Answer 7

• embryonic stem cells are taken from inside the blastocyst, a very early stage embryo
• the blastocyst is a ball of 50-100 cells, and it is not yet implanted in the womb
• it is made of an outer layer of cells, a fluid-filled space and a group of cells called the inner cell mass.
• the ES cells are formed in the inner cell mass

Question 8

source 1; embryonic stem cells (pluripotent) - how is found/deprived

Answer 8

• derived from donated IVF embryos
• can be grown indefinitely in the laboratory in an unspecialised state
• retain the ability to specilise into many different tissue types - known as pluripotent
• can restore function in animals models following transplantation
• embryonic stem cells can differentiate into all possible types of specialised cells.

Question 9

what are some challenges with the embryonic stem cells

Answer 9

• scientists have trouble controlling stem cells. if we could force embryonic stem cells to make whatever kind of cells we want, then we would have a powerful tool for developing treatment for disease
• if we could control stem cells, we could be able to grow new insulin - producing cells to transport into a patient with diabetes.

Question 10

source 2 - partenotes (pluripotent)

Answer 10

• unfertilised human eggs that are artificially stimulated to begin development but are not capable of developing into a human
• potential source of embryonic stem cels (ESCs)

Question 11

source 3 - somantic stem cells - adult stem cells (multipotent)

Answer 11

• also include stem cells isolated from foetal and cord blood
• reside in kost tissues of the body where they are involved in repair and replacement
• generally very diffucult to isolate
• already used to treat patients (haematological, malignances, diseases of the immune system)

Question 12

source 4 - induced pluripotent stem cells [iPS’s]

Answer 12

• derived from adult cells in 2007 - very recent discovery!
• can be grown indefinitely in culture in an undifferentiated state
• similar properties to embryonic stem cells as can differentiate into many different tissue types - pluripotent
• can create stem cells directly from a patient for research
  (the steps of induced pluripotent stem; starting cells from donor tissue – induced change in gene expression – pluripotent stem cells)(induced pluipotent stem cells behaves like an embryonis stem cells.)

Question 12

what are some challenges for stem cells thepary and regenerative medicine;

Answer 12

• production or required cell type in sufficient numbers and pure form
• what cells to transplant
• how to deliver the cells
• problems of tissue rejection

Question 13

what makes stem cells so valuable?

Answer 13

no one stem cells type fits all applications.
* research must continue using all types of stem cells

Question 14

what is therapeutic cloning

Answer 14

• used to create stem cells for patients with degenerative disease such as parkinson’s disease or trauma injuries
• a disease-free cell is taken from the patient to povide the nucleus.
  because the genetic material originated from the patient the stem cells are a genetic match, and on immune response doesn’t occur.

Question 15

🧬 Differentiation & Specialisation

Answer 15

• Differentiation is the process where stem cells become specialised.
• During this, certain genes are activated, and others are silenced, leading to:
• Unique structure
• Specific function
• Example: A stem cell differentiating into a nerve cell or muscle cell.

Question 16

🌱 Types of Stem Cells by Potency

Answer 16

• Totipotent Stem Cells:
• Can form all cell types, including embryonic and extra-embryonic tissues (e.g., placenta).
• Found in: Zygote to 8-cell stage of the embryo.
• Pluripotent Stem Cells:
• Can form almost any cell type, but not extra-embryonic tissues.
• Found in: Inner cell mass of the blastocyst (early embryo).
• Can become: Muscle, nerve, skin, etc.
• (Bonus) Multipotent Stem Cells:
• More limited – can form related types of cells.
• Example: Hematopoietic stem cells → blood cells only.