Most of a cells DNA is not translated

Question 1

What are stem cells?

Answer 1

Multicellular organisms that are made up from many different cell types that are specialised for function
Stem cells are unspecialised cells that can develop into other types of cell

Question 2

What are totipotent cells?

Answer 2

• Stem cells that can mature and develop into any type of body cell in an organism
• An example of totipotent cells are in embryos and fertilised egg cells
• These totipotent stem cells are only avaliable in the first few cell divisions of an embryo
• These embryonic cells later become pluripotent. These can still diferentiate into any cells in the body but lose the ability to become cells in the placenta
• The stem cells in mammals are either multipotent or unipotent

Question 3

How do stem cells become specialised?

Answer 3

• Stem cells become specialised as during their development they only transcribe and translate parts of DNA
• Stem cells all contain the same genes but during their development, not all of them are transcribed and translated
• under one set of conditions, certain genes are expressed and others are switched off
• The genes that are expressed get transcribed into MRNA and are translated into proteins
• These proteins modify the cell and cause it to be specialised

Question 4

Where do stem cells originate from?

Answer 4

• embryonic stem cells
• umbilical cords
• placental stem cells
• adult stem cells

Question 5

What are totipotent stem cells?

Answer 5

• found in early emvryos and can differentiate into any type of cell for a limited time
• For example, a zygote can develop into specialised cells such as pluripotent stem cells

Question 6

What are multipotent stem cells?

Answer 6

• found in adults and can differentiate into a limited number of specialised cells
• they usually develop into cells of a particular type.
• For example, bone marrow can develop into any type of blood cells

Question 7

What are unipotent stem cells?

Answer 7

• can only differentiate into a single type of cell
• derived from multipotent stem cells and are made in adult tissue
• An example are cardiomyocytes, these are heart muscles and can divide into new tissue

Question 8

What are pluripotent stem cells?

Answer 8

• found in embryos and can differentiate into almost any cell

Question 9

What are induced pluripotent stem cells?

Answer 9

• IPS cells are a type of pluripotent stem cells that are produced from unipotent stem cells
• The adult stem cells are genetically altered by inducing genes and transcription factors whithin the cell to express themselves
• The process switches on genes that were otherwised turned off and allows the adult stem cells to express genes associated with pluripotency
• IPS cells can divide into a limitless supply of cells

Question 10

What can stem cells be used for?

Answer 10

• heart muscle cells
• skeletal muscle cells
• B cells of the pancreas
• Nerve cells
• Blood cells
• Skin cells
• Bone cells
• Cartillage cells
• Retina cells of the eye