Terms Flashcards
(39 cards)
What is Mendelian inheritance?
Simple patterns of inheritance in which genes and traits are passed from parents to their children.
The five modes of Mendelian inheritance are autosomal dominant, autosomal recessive, X-linked dominant, X-linked recessive, and Y-linked.
Define a gene.
A discrete segment of DNA or RNA that functions as a template to synthesize a functional RNA molecule or a functional DNA unit.
Also defined as a unit of heredity or a heritable factor that controls a phenotype.
What are alleles?
Identifiable variants or versions of a gene.
The popular press often refers to alleles as ‘the gene for X’ (e.g., the gene for obesity).
What is a locus?
A position or region on a DNA sequence, chromosome, or genetic map.
The plural form is loci.
What is a phenotype?
What we observe in an individual, including clinical or biochemical tests.
What is a genotype?
A description of the alleles at a particular locus in an individual.
True or False: Heterozygotes manifest the disease in recessive disorders.
False.
What is the founder effect?
High frequency of a particular allele in a small population due to inheritance from a single founder.
List the features of autosomal recessive inheritance.
- Affected individuals usually do not have affected parents
- Parents are often asymptomatic carriers
- Both males and females are affected and transmit
- Consanguinity may be apparent in the parents of an affected child.
What is the Hardy-Weinberg Distribution formula?
p² + 2pq + q² = 1.
Fill in the blank: In Hardy-Weinberg Distribution, p represents the _______.
frequency of one allele.
What are the features of autosomal dominant inheritance?
- An affected person usually has an affected parent
- Both males and females are affected and transmit.
What are the features of X-linked recessive inheritance?
- Formally restricted to males
- Unaffected carrier females
- No male to male transmission
- All daughters of an affected male will be carriers.
What is mitochondrial inheritance?
A distinct and simple pattern of non-Mendelian inheritance where mitochondria are inherited maternally.
What is pleiotropism?
Situations in which genes appear to have multiple and often apparently unrelated effects.
Define variable expressivity.
Variation in the severity or age of onset of a disease.
What is penetrance?
The probability that a particular genetic variant will result in the phenotype.
Fill in the blank: Incomplete penetrance results in occasional ‘______’ generations with dominantly inherited phenotypes.
skipped.
What is anticipation in genetics?
A tendency for symptoms of a genetic disorder to become apparent at an earlier age in successive generations.
What is genetic heterogeneity?
The phenomenon where a single phenotype can be caused by different genes or mutations.
Define allelic heterogeneity.
One gene, more than one different mutation.
What is locus heterogeneity?
One apparent phenotype resulting from mutations in more than one gene or locus.
What does the notation ‘46, XY, t(5;10)(p13;q25)’ signify?
It describes a specific chromosomal abnormality including translocation.
What does the LDLR gene do?
Provides instructions for making a protein that binds to low-density lipoproteins (LDLs) to regulate cholesterol levels.
