(2.5B-2.6B) Cell Differentiation and Stem Cells

What is cell differentiation?

The process by which a cell changes to become specialised to carry out a specific function.

What is a specialised cell?

Cells that have developed certain characteristics to perform specific functions.

Why do animal cells mostly lose their ability to differentiate early on?

Most animal cells differentiate early on.

But, adult stem cells retain the ability to differentiate.

They’re mainly involved in replacing and repairing cells.

How do plants differ from animals in terms of their differentiation ability?

Plants retain the ability to fully differentiate throughout its life.

How and why are ciliated epithelial cells specialised?

• They move mucus in the trachea and bronchi

• have cilia which transport mucus towards throat

  • cilia are extensions of the cell membrane

How and why are red blood cells specialised?

• transport oxygen around the body

• biconcave shape- maximised SA

• contain haemoglobin to bind to oxygen

  • lack a nucleus- maximise space

What is a stem cell?

an undifferentiated cell that is capable of dividing an unlimited number of times

What is an embryonic stem cell?

A cell on the inside layer of an embryo that can become any specialised cell

What is an adult stem cell?

Depending on where is is found, it has the capacity to change into different cells.

e.g. bone marrow- blood, skin- layers of skin/hair follicles, organs- cells in those organs

What are meristem cells?

Cells on the tips of roots and shoots that have the ability to divide to produce a whole new plant.

How can stem cells be used in medicine?

human embryos can be grown in the lab, stem cells extracted and encouraged to differentiate into different specialised cells.

doctors can use these to repair damaged organs

Why are embryonic stem cells more useful that adult stem cells?

• They have a wider range of possible outcomes; adult stem cells can only specialise into certain cells.

• They can be grown and maintained in cultures for longer

Outline some benefits of using stem cells:

• potential to treat a variety of diseases

• reduced doner wait + risk of organ rejection if they’re developed from patient’s own stem cells

  • proof of benefits found in use of adult stem cells

Outline some risks of using stem cells:

• cells cultured in a lab could become infected and transmit a virus to the patient

• risk of mutation accumulation leading to cancer cells

• low donors

  • embryonic stem cells can be collected before and after birth and stored but is expensive

Outline some ethical issues of using stem cells:

• may be sourced from unused IVF embryos- controversial

• religious views- potential for human life

• consent- commodity or human rights? ownership over embryo?