genetic definitions

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Locus
Point on the chromosome
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Allele
Version of a DNA sequence at a particular locus
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Genotype
The total set of alleles possessed by an individual at a particular locus
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Phenotype
The expression of a specific trait based on genetic and environmental influences
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Polymorphism
The occurrence of two or more alleles at a particular locus such that the least common allele is present at a frequency of at least 1% of alleles
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Single nucleotide polymorphism
A single base change giving rise to a new allele
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Mutation
A permanent change in a DNA sequence which is generally but not always associated with a disease
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Missense mutation
A nucleotide substitution that changes the specified amino acid
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Silent mutation
Substitution of one base for another in an exon or gene coding region, such that the amino acid sequence is not modified
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Frameshift mutation
A mutation caused by an insertion or deletion of a number of nucleotides not divisible by three, thus due to the triplet nature the insertion or deletion disrupts the ORF
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Nonsense mutation
The insertion or deletion or substitution leads to expression of a stop codon, truncated protein
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Haplotype
A variant sequence which comprises of more than one closely linked base changes that are inherited together
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Linkage disequlibrium
The occurrence of observed genotype of allele combinations in greater proportions than expected from the allele/genotype frequencies
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Homozygous
Having two copies of the same allele at a particular locus
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Heterozygous
Having two different alleles at a particular locus
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Hemizygous
Having only one copy of a gene of DNA sequence in diploid cells
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Heteroplasmy
The presence of a mixture of more than one type of mitochondrial DNA within a cell or individual
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Autosomal recessive
A pattern of inheritance in which an affected individual has two copies of a mutant gene
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X-linked recessive
mode of inheritance in which a mutation in a gene on the X-chromosome causes the phenotype to be expressed in males who are hemizygous or in females who are homozygous for the mutation
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Autosomal dominant
A pattern of inheritance in which an affected individual has one copy of a mutant gene and one normal gene on a pair of autosomal chromosomes
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Co-dominance
A form of inheritance in which both alleles are equally expressed
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Incomplete dominance
A heterozygous condition in which both alleles at a gene locus are expressed, often producing an intermediate phenotype
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Polygenic
A trait whose expression is determined by more than one locus (diabetes)
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Cytoplasmic inheritance (maternal)
mutations in mitochondrial DNA
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Expressivity
Degree to which a disease is manifest
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Penetrance
Chance of a person with defective gene developing the disorder
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Anticipation
The process of increasing severity or decreasing age of onset of symptoms from one generation to the next
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Consanguinity
Unions contracted between persons biologically related as second cousins or closer (increased likelihood of rarer recessive disorders
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Heritability
The proportion of phenotypic variance attributable to genetic factors
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Uniparental disomy
Occurs when a person receives two copies of a chromosome one part of a chromosome from one parent and none from the other parent
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Hardy-Weinberg Principle
p squared + 2pq + q squared = 1 and p+q=1
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Other cards in this set

Card 2

Front

Version of a DNA sequence at a particular locus

Back

Allele

Card 3

Front

The total set of alleles possessed by an individual at a particular locus

Back

Preview of the back of card 3

Card 4

Front

The expression of a specific trait based on genetic and environmental influences

Back

Preview of the back of card 4

Card 5

Front

The occurrence of two or more alleles at a particular locus such that the least common allele is present at a frequency of at least 1% of alleles

Back

Preview of the back of card 5
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