Cell Differentiation

Q: What is cell differentiation?

It’s the process where unspecialized stem cells become specialized cells with specific structures and functions.

Q: What does a zygote become through mitosis?

An embryo made of genetically identical, unspecialized stem cells.

Q: What allows specialized cells to do their specific jobs?

Their specific shapes, sizes, and proteins (like enzymes or hemoglobin).

Q: How many specialized cell types do humans have?

220

Q: What is a totipotent stem cell?

A stem cell that can become all cell types, including the placenta. Found in the zygote.

Q: What is a pluripotent stem cell?

Can become any body cell, but not the placenta. Found in the inner cell mass of the blastocyst.

Q: What is a multipotent stem cell?

Can become a few related cell types. Found in adult tissues like bone marrow or skin.

Q: What is a unipotent stem cell?

Can only become one type of cell. Found in specialized tissues.

Q: Example of a multipotent stem cell?

Blood stem cells in bone marrow → can become red cells, white cells, and platelets.

Q: Do all cells have the same DNA?

Yes, but they express different genes depending on what type of cell they become.

Q: What determines the structure and function of a differentiated cell?

The proteins it makes from gene expression.

Q: What is gene expression?

When specific genes are turned on to make proteins. Process: DNA → RNA → Protein.

Q: What are morphogens?

Chemical signals that tell cells what to become by creating concentration gradients

Q: How do morphogen gradients affect cells?

• High concentration = Cell A

• Medium = Cell B

• Low = Cell C

Q: Example of a morphogen?

Retinoic acid in zebrafish embryos – helps decide what a cell becomes.

Q: What is a stem cell niche?

A special area in tissues where adult stem cells are stored and controlled.

Q: What do stem cell niches do?

• Protect stem cells

• Send signals

• Keep them dormant or trigger them to divide

Q: Where are adult stem cells found?

Brain, bone marrow, skin, liver, intestines, muscles, and more.

Q: What does the bone marrow niche produce?

Red blood cells, white blood cells, and platelets from multipotent stem cells.

Q: What does the hair follicle niche produce?

Skin cells like keratinocytes and melanocytes, used in skin renewal and repair.

Q: What are induced pluripotent stem cells (iPSC)?

Adult cells reprogrammed to act like pluripotent embryonic cells.

Q: Who created iPSC and when?

Shinya Yamanaka in 2006.

Q: What can iPSC be used for?

• Treating diseases like diabetes and leukemia

• Modeling diseases in labs

• Creating patient-specific cells for therapy

Q: What is the pathway from fertilization to specialized cells?

Fertilization → Zygote → Embryo → Specialized Cells

Q: What controls differentiation?

Gene expression and morphogen gradients.

Q: What are the 3 main types of stem cells by potential?

Totipotent, Pluripotent, Multipotent.

Q: Why are iPSCs important in medicine?

They offer new ways to study and treat diseases using the patient’s own cells.