Genetics Flashcards
mostly defintions
What is Aneuploidy?
having an abnormal number of chromosomes
What is Autosomal Dominance?
manifests in the heterozygous state - affects both sexes equally
What is Autosomal Recessive?
manifests only in the homozygous state - affects both sexes equally
What is Allelic Homogeneity?
When all individuals with a disease have the same mutation (Huntington’s)
What is Allelic Polymorphism?
When more than one allele can be found for a given gene within the normal population
What is Allelic Heterogeneity?
When different mutations on the same gene result in the same condition forming (cystic fibrosis)
What is an Allele?
one of several alternative forms of a gene at a specific locus
What is Autozygosity?
Homozygous by inheritance - person has inherited the same mutant allele through two branches of the same family.
What is Compound Heterozygosity?
where there are 2 different mutations on the same allele.
What is Consanguinity?
the reproductive union between 2 relatives.
What is Hemizygous?
Describes a gene carried on an unpaired chromosome, such as located on the X chromosome in a male.
What is imprinting?
for some genes only 1 out of 2 is active. for particular genes it’s always the paternal or maternal. (prader-willi syndrome and Angelmans)
What is locus Heterogeneity?
mutations in a different gene causing the same clinical condition.
What is Lyonisation?
The process of X chromosome inactivation. is a random process, the paternal or maternal X could be turned off - can be skewed. Prevents females having twice as many X products as men)
What is mosaicism?
a population of mutated cells that aren’t found in your normal germline DNA.
What does mitochondrial DNA contain?
22 tRNA-encoding genes, 13 protein-encoding regions.
What is microtubule nucleation?
the process by which several tubulin molecules interact to form a microtubule seed.
What is penetrance?
the proportion of people with a genotype that show the expected phenotype. can be complete (expressed by all) or incomplete (expressed by some)
What is polymorphism?
frequent hereditary variations at a locus
What is the Transcriptome?
the set of genes which are transcribed. all the mRNA within a cell
What is Varibale Expression?
Variation in clinical features in people with a genetic disorder with the same gene alteration
What is the wild type?
the normal version of an allele
What is Anticipation?
where genetic disorders affect successive generations earlier than their parents or more severly. Usually caused by triplet expansions.
What is a triplet expansion?
the triplet in a gene is repeated more than it’s needed. when repeated beyond the normal level can cause a disease.
What is Homoplasmy?
when all copies of mitochondrail DNA are identical
What is heteroplasmy?
multiple copies of mtDNA in each cell, the level of heteroplasmy can vary between cells, tissues and relatives.
What is Expressivity?
the range of phenotypes expressed by a specific genotype.
