Stem Cells

Question 1

How do cells become specialised?

Answer 1

Some genes are expressed while others are silenced due to cell differentiation mediated by transcription factors. Cells produce proteins that determine their structure & function.

Question 2

What is a transcription factor?

Answer 2

A protein that controls the transcription of gene so that only certain parts of the DNA are expressed e.g in order to allow a cell to specialise

Question 3

How do transcription factors work?

Answer 3

1) move from the cytoplasm into the nucleus
2)bind to promoter region upstream of target gene
3)make it easier or more difficult for RNA polymerase to bind to gene. This increases or decreases rate of transcription

Question 4

What is a stem cell?

Answer 4

Undifferentiated cells that can divide indefinitely and turn into other specific cell types

Question 5

Name and define the 4 types of stem cell?

Answer 5

-Totipotent: can develop into any cell type including placenta and embryo
-Pluripotent: can develop into any cell type excluding placenta and embryo
-Multipotent: can only develop into any cell few different types of cell
-unipotent: can only develop into one type of cell

Question 6

Suggest some uses of stem cells

Answer 6

-repair of damaged tissue
-drug testing on artificially grown tissue
-treating neurological diseases
-researching developmental biology

Question 7

2 groups of specialised cells in blood

Answer 7

Red blood cell: biconcave, no nucleus, lots of haemoglobin to carry oxygen
White blood cells: lymphocytes, eosinophils, neutrophils to engulf foreign material.