Unit 1 - AOS 1 - Stem cells

Question 1

Define Stem cell

Answer 1

• Unlike specialized cells, which have a specific form and function, stem cells are not specialized.
• Meaning they have the potential to become any kind of cell.

Question 2

Key points on cell specialisation

Answer 2

• Cells must be structured to perform specific functions in context of the organism
• If there was no cellular specialization, every cell in your body would be the same

Question 3

Examples of specialised cells and their functions and structure

Answer 3

Red blood cells
- Contain hemoglobin to carry oxygen to cells
- Shape increases surface area to allow more oxygen to be absorbed efficiently

Nerve cells
- All neurons have a cell body and one or more fibres
- These fibres vary in length from microscopic to over 1 meter long.

Question 4

Define cell differentiation

Answer 4

The specialization of cells during an organism’s development

Question 5

Blastocyst

Answer 5

4-5 day old fetus - containing only stem cells

Question 6

Pluripotent

Answer 6

Many potentials - capable of giving rise to several different cell types (stem cells)

Question 7

Unipotent

Answer 7

One potential - capable of giving rise to only one cell type. (red blood cell)

Question 8

Define Gene regulation

Answer 8

What part of the DNA is activated
- The turning on and off of genes within a cell in response to environmental stimuli or other factors (development stage)

Question 9

Defne gene expression

Answer 9

What type of protein is expressed
- What proteins (therefore trait) are expressed from the selected genes

Question 10

Summarise all key points

Answer 10

• All cells contain a complete set of DNA
• Specialized cells only have certain genes that are expressed
• Specialized cells are unipotent: meaning they can only give s=rise to that cell type
• Stem cells have no gene regulation, and are therefore unspecialised
• Stem cells and pluripotent: meaning they can give rise to any cell type
• The difference between cell types is de to the selected gene being expressed.

Question 11

What is therapeutic cloning?

Answer 11

• Involves the creation of an embryo that is genetically identical to patient

The patients cell is taken and fused with a enucleated egg cell, developing into a blastocyst. The stem cells are taken and used to treat the patient.

Question 12

Ethical issue of therapeutic cloning

Answer 12

Because to establish an embryonic stem cell line you must destroy the embryo.