Genetics Question Bank for Unit 2

Maternal effect

Phenomenon where the genotype of the maternal parent determines the phenotype of the offspring.

Epigenetic inheritance

Transmission of non-genetic information that affects gene expression across generations.

Dosage compensation

Mechanism that equalizes gene expression between sexes despite differing chromosome numbers.

Lyon Hypothesis

Theory explaining X-chromosome inactivation in female mammals.

X-Chromosome Inactivation

Process by which one of the X chromosomes in females is randomly inactivated to balance dosage.

Barr bodies

Inactivated X chromosomes in female somatic cells.

Genomic Imprinting

Differential expression of a gene depending on whether it is inherited from the mother or the father.

Monoallelic expression

Expression of only one allele of a gene while the other allele is silent.

DNA methylation

Addition of methyl groups to DNA, affecting gene expression without altering the DNA sequence.

Extranuclear inheritance

Inheritance of traits determined by genes located outside the nucleus, such as mitochondrial DNA.

Mitochondrial DNA

Circular DNA located in mitochondria, inherited maternally.

Chloroplast DNA

DNA found in chloroplasts, involved in photosynthesis, also inherited maternally.

Heteroplasmy

Presence of multiple types of mitochondrial DNA within a single cell.

Endosymbiosis Theory

Theory explaining the origin of mitochondria and chloroplasts as former free-living prokaryotes.

Synteny

Conservation of blocks of genetic information across species.

Genetic Linkage

Tendency of genes located close together on the same chromosome to be inherited together.

Two-factor cross

Genetic cross examining the inheritance of two different traits.

Three-factor cross

Genetic cross examining the inheritance of three different traits.

Recombinant offspring

Offspring that have a different combination of alleles than either parent.

Nonparental offspring

Offspring that do not resemble either parent due to recombination.

Non-recombinant offspring

Offspring that have the same combination of alleles as the parents.

Positive interference

Phenomenon where one crossover event reduces the likelihood of another crossover event occurring nearby.

Karyotype

Photographic or diagrammatic representation of an individual's complete set of chromosomes.

Deletion

Loss of a chromosome segment.

Duplication

Repeated segment of a chromosome.

Inversion

Rearrangement of a chromosomal segment in reverse order.

Translocation

Movement of a chromosome segment to another chromosome.

Paralogs

Genes that have evolved by duplication and may have different functions.

Cri du chat syndrome

Genetic disorder caused by deletion of a segment on chromosome 5, characterized by a distinctive cry.

Down syndrome

Genetic disorder caused by trisomy of chromosome 21.

Robertsonian translocation

Fusion of two acrocentric chromosomes at their centromeres.

Semisterility

Reduced fertility, often due to chromosomal abnormalities.

G-banding

Technique for staining chromosomes to produce a pattern of bands.

Aneuploidy

Condition of having an abnormal number of chromosomes.

Euploidy

Condition of having a complete set of chromosomes.

Polytene chromosome

Giant chromosome whose structure consists of many identical chromatids lying alongside one another.

Nondisjunction

Failure of homologous chromosomes or sister chromatids to separate properly during cell division.

Haplodiploid

Organisms with two different forms of sex determination based on ploidy.

Autopolyploidy

Polyploidy that arises from a single species.

Alloploidy

Polyploidy that involves the combining of chromosomes from two different species.

Allopolyploidy

Polyploidy resulting from hybridization between two different species.