more organisms born than can survive, organisms vary in characteristics, variation is inherited, differences in reproduction and survival due to variation
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Two sources introduce variation
mutation and recombination
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Mendel: Wrinkled x Round
F1 all round, F2 round:wrinkled = 3:1
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DNA transmits genetic info. by...
digital code, duplication using old strands as templates, variation introduced during DNA replication
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Mutation
heritable change in the genetic information of an organism, caused by errors in DNA replication, external factors
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Mutagens
chemicals/ionising radiation which cause mutations
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Missense mutation
base replaced with another
7 of 19
Nonsense mutation
triplet removed
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Insertion (frameshift)
base added in, extra
9 of 19
Deletion (frameshift)
base removed
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Sickle-cell anaemia
harmful, but beneficial in malarial zones
11 of 19
Diploid
two copies of each gene
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Genotype
complement of alleles found in an organism
13 of 19
Phenotype
physical effects produced by a genotype
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Dominant
one copy of the allele causes the phenotype
15 of 19
Recessive
two copies needed for the organism to display the phenotype
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Autosomal recessive disorders
two affected parents will always have affected children, close relatives who reproduce more likely to have affected children
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Autosomal dominant disorders
affected children usually have affected parent, heterozygotes (Aa) affected, two affected parents can have unaffected child
18 of 19
Polygenic inheritance
height determined by many genes, can be due to environment
19 of 19
Other cards in this set
Card 2
Front
mutation and recombination
Back
Two sources introduce variation
Card 3
Front
F1 all round, F2 round:wrinkled = 3:1
Back
Card 4
Front
digital code, duplication using old strands as templates, variation introduced during DNA replication
Back
Card 5
Front
heritable change in the genetic information of an organism, caused by errors in DNA replication, external factors
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