B2.3 Cell specialisation

Define what a stem cell is.

A stem cell is a cell that can divide (by mitosis) an unlimited number of times and has the potential to remain a stem cell or to develop into a specialised cell.

What are the properties of stem cells?

Stem cells have the capacity to divide endlessly and differentiate along different pathways.

What is cell differentiation?

Cell differentiation is the development of unspecialised cells (following fertilisation) into specialised cells.

What is the importance of the stem cell niche?

The stem cell niche can maintain cells or promote their proliferation and differentiation.

Give two examples of the location of stem cell niches in adult humans.

Two examples of the location of stem cell niches in adult humans are bone marrow and hair follicles.

What is meant by totipotency in stem cells?

Totipotent stem cells are stem cells that can differentiate into any cell type found in an embryo and can become cells that make the placenta.

What are pluripotent stem cells?

Pluripotent stem cells are embryonic stem cells that can differentiate into any cell type found in an embryo but are not able to differentiate into the cells of the placenta.

True or False? Multipotent stem cells are adult stem cells that can differentiate into any cell type.

False. Multipotent stem cells are adult stem cells that can differentiate into closely related cell types, for example, stem cells in bone marrow.

What type of stem cells are those found in cells in early-stage animal embryos?

Cells in early-stage animal embryos are totipotent.

Compare cell surface area with cell volume in relation to the exchange of materials.

The exchange of materials across a cell surface depends on its surface area whereas the need for exchange depends on cell volume.

As cells increase in size their surface area to volume ratio (SA:V) decreases.

As cells increase in size their surface area to volume ratio (SA:V) decreases.

How is the size of male gametes (sperm cells) adapted to their function?

Male gametes are long and narrow to allow for streamlined movement/swimming toward the egg.

How is the size of red blood cells adapted to carry out their function?

Red blood cells are small to allow movement through narrow capillaries.

How is the size of muscle cells adapted for their function?

Muscle cells are larger than normal cells, and their longer length and diameter are designed to exert force during muscle contraction.