Inherited conditions in humans and stem cell research (AQA GCSE)

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  • Created by: MRS T
  • Created on: 02-04-13 14:13
How many dominant alleles must someone inherit to have a genetic disorder?
Only one. e.g. Polydactyly, only one dominant gene is inherited to mean a person suffers from this disorder.
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How many recessive alleles must someone inherit to have a genetic disorder?
A person must inherit two recessive genes. EG cystic fibrosis is caused by a recessive gene. The allele affects cell membranes and causes the production of thick sticky mucus, which can affect the lungs, pancreas and other organs.
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What is a 'carrier' of an allele?
A person who carries an allele but who does not have the disorder themselves as they do not have two recessive alleles.
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Name a genetic disorder which is controlled by a dominant allele.
Polydactyly
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Can disorders such as cystic fibrosis be detected before birth?
Yes, by genetic screening.
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What do we mean by a 'heterozygous' individual?
The individual has one dominant and one recessive allele for a condition.
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Why does sexual reproduction result in variation?
The genetic material from two parents is brought together when the sperm and the egg nuclei fuse.
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What are the chances of a child having polydactyly if one parent is heterozygous and the other parent is homozygous recessive?
50% as the dominant gene controls the condition; a child has a 50:50 chance of inheriting the allele from the heterozygous parent.
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What alternatives are there to using embryonic stem cells?
Adult stem cells can be used that are made in the bone marrow. e.g. leukaemia may be treated in this way.
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What is the advantage of using embryonic stem cells?
They have the potential to differentiate into a wide range of cells.
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Where are embryonic stem cells taken from?
Spare embryos from IVF or the umbilical cord of newborn babies, or they can be made from adult stem cells.
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Why us embryonic stem cell research controversial?
Embryos have the potential to become babies, they cannot give permission and the research is very expensive.
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Why is embryo screening potentially unethical?
As once a disorder is discovered, the parent may abort the child, which some think unethical.
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Other cards in this set

Card 2

Front

How many recessive alleles must someone inherit to have a genetic disorder?

Back

A person must inherit two recessive genes. EG cystic fibrosis is caused by a recessive gene. The allele affects cell membranes and causes the production of thick sticky mucus, which can affect the lungs, pancreas and other organs.

Card 3

Front

What is a 'carrier' of an allele?

Back

Preview of the front of card 3

Card 4

Front

Name a genetic disorder which is controlled by a dominant allele.

Back

Preview of the front of card 4

Card 5

Front

Can disorders such as cystic fibrosis be detected before birth?

Back

Preview of the front of card 5
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