Modern Genetics: Stem Cells

Question 1

Sources of stem cells

Answer 1

Embryonic
Umbilical cord
Somatic eg brain

Question 2

What is cell determination

Answer 2

Unspecialised cells switch genes on and off to become specialised

Question 3

What are homebox genes

Answer 3

Family of similar genes that direct the formation of many body structures during early embryonic development

Question 4

Evidence for cell determination

Answer 4

Tadpole switching position of genes a few days apart

Question 5

Epigenetic control of haemoglobin

Answer 5

Activation of gamma globin in foetus by histone acetylation
Silence gamma globin gene at birth
Transcription factors switching on beta globin gene in spleen and bone marrow near birth

Question 6

Benefits of human therapeutic cloning

Answer 6

Low risk of rejection
Doesn’t use embryos
Useful to treat diseases caused by faulty cells

Question 7

Drawbacks of human therapeutic cloning

Answer 7

Creates early embryo which is destroyed
If testing genetic disease DNA needs modifying first so cultured cells don’t carry the mutation
Increases risk of cancer

Question 8

Induced pluripotent stem cells: procedure

Answer 8

Biopsy- reprogramming factors Oct 4 and Oct 3

Induction of pluripotentcy- iPS cells

Question 9

Exam structure for cell differentiation

Answer 9

Stimulus chemical
Causes some genes to be switched on and off
Only active genes are transcribed
Because mRNA is made only at active genes
Protein made
Which determines cell structure and function