Chapter 10.4

How many cells does life begin as?

Life begins as one cell.

What is a zygote?

It is a fusion of an egg and a sperm cell.

What is an embryo?

It is an early development stage.

During development, what do cells become?

They become specialized (differentiated).

What is differentiation?

It is the process in which embryonic cells become specialized.

Specialized cells perform?

They perform the more complex functions of the body.

What are some examples of specialized cells?

Some examples are nerve cells and muscle cells.

Describe differentiation in mammals.

In mammal differentiation, adult cells reach a point when differentiation is complete and can no longer become other cell types.

How does one cell create all of the specialized cell types in the human body?

One cell can create all of this because the first cell is totipotent. In particular, only the fertilized egg and the cells from the first few divisions are this way.

Define totipotent.

The ability for a cell to develop into any cell type.

What does the embryo become four days after fertilization?

It becomes a blastocyst.

What is a blastocyst?

It is a ball of cells with a cluster of cells inside (the inner cell mass).

Cells of the inner cell mass are called?

They are called embryonic stem cells and are pluripotent.

What does it mean when a cell is pluripotent?

It means that a cell can develop into most (not all) cell types.

What are embryonic stem cells (ESC)?

They are unspecialized cells from which differentiated cells develop.

What are adult stem cells (ASC)?

They are cells that replace cells in the adult body.

What are some examples of adult stem cells?

Some examples are skin and blood cells.

What does it mean when a cell is multipotent?

It means that a cell can develop into many types of cells, but its potential is limited compared to the pluripotent embryonic stem cells. Stem cells in certain tissues will produce cells of that type.

What are some examples of multipotent cells?

Some examples are blood stem cells (red and white blood cells).

True or false: One of the benefits of stem cell research is that it can show scientists how different cell types develop.

True.

True or false: One of the benefits of stem cell research is that it can show when and how certain diseases arise during development.

True.

True or false: One of the benefits of stem cell research is that it allows scientists to grow new healthy cells to replaced diseased cells in humans.

True.

Why do we use stem cells to cure heart attacks?

Heart attacks destroy heart muscle cells. Therefore, injecting ASCs or pluripotent ESCs may allow new, healthy heart cells to replace the damaged cells.

True or false: Adult stem cell research does NOT raise ethical questions.

True.

True or false: Embryonic stem cell research DOES raise ethical questions.

True.

What is the argument against ESC research?

The argument for this is that taking the embryonic cells from the blastocyst destroys a human life.

What is the argument supporting ESC research?

The argument for this is that ESC research pursues cures for diseases.

What is the solution that scientists are working toward regarding the ethics of ESC research?

Scientists are working to use ESCs without destroying embryos in ESC research to make it more ethical.

What are the ways that scientists are working to use ESCs without destroying embryos?

Taking just a few cells from the blastocyst and leaving the rest intact; taking adult stem cells and changing their genes to turn them back into pluripotent stem cells.