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15 Cards in this Set
- Front
- Back
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What was Gregor Mendel's famous publication? |
"Experiments in Plant Hybridisation" -1866. |
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What are genes? |
Hereditary factors responsible for traits.
Unit of function that controls the synthesis of at least one polypeptide chain or RNA molecule. |
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What are alleles? |
Alleles are different forms of genes. |
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What are Mendel's three laws? |
1. The Principle of Dominance 2. The Principle of Segregation 3. The Principle of Independent Assortment |
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What is Klinefelter Syndrome? |
-1/1000 affected. -XXY or XXXY or XXYY -Male -Reduced facial and pubic hair, small testis, taller than normal, sterile, normal intelligence. |
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What is Turner Syndrome? |
-1/3000 affected. -XO -Female -Underdeveloped secondary sex characteristics, short, low hairline, broad chest, folds on skin on neck, normal intelligence. |
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What is Colour Blindness? |
-X-linked recessive trait. -Two gene encoding receptors for red and green light are x-linked. |
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How is the Y chromosome dominant? |
-Sex-determining Region Y (SRY) encodes for a DNA binding protein (TDF) that works as a transcription factor for testis development. -An XX male carries TDF on an X chromosome. -An XY female has the SRY region of the Y chromosome deleted. |
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What is Androgen Insensitivity Syndrome? |
-If the testosterone signalling system fails, the individual develops like a female (with XY) -No ovaries, Tfm gene on X. Transmitted from mother to son. |
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What are the steps in X-chromosome inactivation? |
1- Repressor of inactivation binds to one X chromosome. 2- X-inactivation Centre (XIC) activates in the other. 3- X chromosome inactivated. 4- Forms a Barr Body |
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What is Haemophilia? |
-A blood clotting disorder. -1/7000 males are affected. -X-linked Recessive. |
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What is Fragile X Syndrome? |
-One of the main causes of mental retardation. -1/3600 males. |
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What is Down Syndrome? |
-A trisomy of chromosome 21. -1/700 affected. -Short, broad hands, palmar crease, mental retardation, large tongue, epicardial fold. |
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What is non-disjunction? |
-Non-disjunction occurs where in meiosis, DNA does not divide between cells, rather, all moving into one. -It is more likely to occur the longer a cell is arrested in prophase 1, i.e. the older the woman is. |
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Vaardenburg Syndrome |
-Deafness, visual problems, white forelock. -X-linked dominant. -Equal frequency in both sexes. -Does not usually skip generations. -Unaffected individuals do not transmit the trait. |
