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B io Factsheet
September 2001 Number 94

Gene Mutations
By studying this Factsheet you should gain a knowledge of:
Remember : ­ DNA and RNA are polymers of nucleotides, designated by
· the nature and causes of gene mutation;
· the effects of gene mutations; the letters of their nitrogenous…

Page 2

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Gene Mutations Bio Factsheet

A `nonsense' mutation changes an amino-acid-specifying codon into a Natural selection plays a part when heterozygous sickle cell trait individuals
chain-terminating codon. For instance, if UCA, which codes for serine, is live in areas where malaria is prevalent. The malarial parasite lives in normal
substituted, making…

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Gene Mutations Bio Factsheet

Other examples in nature of gene mutations which have produced beneficial 2. The drawings below show the appearance of normal human red cells
variations to the mutated organism are: and red cells from an individual suffering from sickle cell anaemia. The
· the development of antibiotic…

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Gene Mutations Bio Factsheet

Answers 3. (a) (i) recessive;
1. (a) (i) nucleotides could be omitted during replication of DNA (in because obvious heterozygotes/carriers don't show the
meiosis/gamete formation); condition/the alleles in 6/8/13 must have come from the parents
thus mRNA does not include the omitted nucleotides (during who do…


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