2 - MZH - Stem cells

Question 1

Define stem cells

Answer 1

Undifferentiated cells with the potential to differentiate into a variety of the specialised cell types of the organism

Question 2

List 3 properties of stem cells:

Answer 2

• They’re unspecialised
• Can divide repeatedly to make new cells
• Can differentiate into many kinds of specialised cells

Question 3

What is a blastocyst

Answer 3

Human body has cells which all developed from a single cell - the zygote that was formed by the fusion of an egg cell and a sperm cell.

The zygote divides to form a tiny ball of cells called a blastocyst.

Question 4

Another word for singled-celled organisms?

Answer 4

Unicellular organisms

Question 5

What does the stem cell potency decribe?

Give the different potencies + their properties.

Answer 5

Stem cell potency = describes a stem cell’s ability to differentiate into different cell types.

Totipotent - (Early stem cells). Can differentiate into any type of cell.* A fertilised egg or zygote up to 8 or 16 cell stage from its first few mitotic divisions are totipotent. *Produces a whole organism.

Pluripotent - Can form all tissue types but not whole organisms. Present in early embryos and are the origin of the different types of tissue within an organism.

Multipotent - Can only form a range of cells within a type of tissue. Adult stem cells are multipotent.

Question 6

Example of a multipotent stem cell?

Answer 6

Haematopoetic stem cells in the bone marrow can give rise to the various types of blood cells.

Question 7

Another name for:

Red blood cell

White blood cell

Where arer they and other blood cells made?

Answer 7

Red blood cell = Erythrocyte

White blood cell = Neutrophil

Bone marrow via differentiation of hematopoietic stem cells.

Question 8

Use of stem cell transplantation?

1. Heart disease
2. Alzheimer’s disease
3. Another use?

Answer 8

1. Muscle tissue can be permanently damaged as a result of a heart attack. Use stem cells to replace these damaged muscle cells (repair of damaged tissues).
2. Brain cells are destroyed as a result of the build up of abnormal proteins. At present drugs cna only alleviate symptoms. Stem cells may result in the production of new brain cells (treatment of a neurological condition)
3. Understand why things go wrong.

Question 9

Name and explain the source of plant stem cells

Answer 9

Meristematic tissue - Plants where growth is taking place in plants

E.g.

Tips of roots

Stems

Vascular cambium tissue.

Question 10

2 ways stem cells are used in research and medicine?

Answer 10

• Spares left over from IVF
• Using multipotent cells andculturing them in the lab (e.g. via a skin scraping)

Question 11

Sources of animal stem cells?

Answer 11

Embryonic stem cells - Present in the very early stages of embryo developemnt (totipotent).

Tissue (adult) stem cells - Present throughout life from birth and are found in specific areas e.g. bone marrow. Multipotent but research shows that they can be artificially stimulated to become pluripotent.

Induced pluripotent stem cells (iPS cells) - Developed in laboratories by reprogramming differentiated stem cells to switch on certain genes and become undifferentiated.

Regenerative medicine? - Using iPS cells to build organs for transplant.

Stem cells in umbilical-cord blood

Question 12

Forms of cell specialisation? + example?

Answer 12

Changes of cell shape - Red blood cell, sperm cells…

Changes in number of particular organelles - Palisade cells (contains lots of chloroplasts)

Production of particular molecules - White blood cells (produces antibodies)