Genetics Review: Chromosomal Abnormalities, Microbial Genetics, and Recombinant DNA Technology

Comprehensive vocabulary flashcards covering chromosomal abnormalities, ploidy alterations, extranuclear inheritance, bacterial and viral genetics, recombinant DNA techniques, and modern genetic engineering applications.

Deletion

A chromosomal aberration involving the loss of a DNA segment and its associated genetic material from a chromosome.

Cri-du-chat syndrome

A human genetic disorder caused by a terminal or interstitial deletion on the short arm ($p$ arm) of chromosome 5.

Wolf-Hirschhorn syndrome

A chromosomal deletion syndrome caused by a partial loss of genetic material from the short arm ($p$ arm) of chromosome 4.

Duplication

A chromosomal aberration characterized by the presence of an extra copy of a specific chromosome segment.

Paracentric inversion

A chromosomal rearrangement where a segment within one chromosome arm rotates 180 degrees without spanning or including the centromere.

Pericentric inversion

A chromosomal rearrangement where a chromosome segment rotates 180 degrees and includes the centromere, with breakpoints occurring on both arms.

Cross-over suppressor

A chromosome structural variation (such as an inversion) that appears to suppress crossing over because recombinant gametes contain fatal duplications and deletions.

Balanced chromosome complement

A genomic state in which a complete set of genetic information is present without any net loss or gain of chromosomal material.

Reciprocal translocation

A structural chromosomal alteration in which segments from two non-homologous chromosomes break and are reciprocally exchanged.

Robertsonian translocation

A chromosomal rearrangement formed by the fusion of the long arms ($q$ arms) of two acrocentric chromosomes near their centromeres, typically accompanied by the loss of the short arms.

Endopolyploidy

The occurrence of polyploid nuclei within specific cells or tissues of an otherwise diploid organism.

Euploidy

The condition of having one or more complete, exact multiples of the basic chromosome set characteristic of a species.

Monoploidy

The condition in which a cell or organism possesses only a single basic set of chromosomes ($1n$).

Autopolyploid

A polyploid organism whose extra sets of chromosomes are derived entirely from a single ancestral species.

Allopolyploid

A polyploid individual or species resulting from hybridization between two or more distinct species, combining their complete chromosome complements.

Endoreduplication

The process of chromosome replication occurring in the absence of subsequent nuclear or cell division, resulting in elevated ploidy.

Aneuploidy

A numerical chromosome abnormality wherein a cell has one or a few chromosomes above or below the normal euploid number (such as $2n + 1$ or $2n - 1$).

Polysomy

An aneuploid condition in which a specific individual chromosome is represented more than the normal diploid number of times.

Trisomy

A specific form of aneuploidy in which an otherwise diploid cell contains three copies of a particular chromosome ($2n + 1$).

Monosomy

A form of aneuploidy characterized by the absence of a single chromosome from a diploid genome ($2n - 1$).

Maternal effect

An inheritance pattern in which the offspring's phenotype is determined strictly by the maternal nuclear genotype via substances deposited into the oocyte cytoplasm.

Extranuclear inheritance

The transmission of traits governed by genetic material situated outside the nucleus, specifically within organellar genomes.

Mitochondria

Membrane-bound eukaryotic organelles containing their own non-nuclear circular genome that produce ATP and are typically inherited uniparentally.

Chloroplasts

Photosynthetic organelles in plants and algae containing their own extranuclear circular DNA, transmitted through cytoplasmic inheritance.

Endosymbiont

An organism that lives within the body or cells of another organism in a mutualistic relationship, representing the evolutionary origin of mitochondria and chloroplasts.

Heteroplasmy

The presence of two or more genetically distinct populations of organellar DNA within a single cell or individual.

Homoplasmy

A cellular state where all copies of an organellar genome (mitochondrial or plastid DNA) are genetically identical.

Wolbachia

A genus of maternally inherited, intracellular endosymbiotic bacteria widespread among arthropods that manipulates host reproductive mechanisms.

Nucleoid

The central, non-membrane-enclosed region inside a prokaryotic cell that contains the compacted bacterial chromosome.

Conjugation

The unidirectional transfer of genetic material between bacterial cells through direct physical contact mediated by a pilus.

Episome

A plasmid or circular genetic element that can replicate independently in the cytoplasm or integrate into the host bacterial chromosome.

Merodiploid

A partially diploid bacterial strain that carries two copies of a specific gene region, typically due to the introduction of an $F'$ plasmid.

Transformation

The genetic alteration of a bacterial cell resulting from the direct uptake and genomic incorporation of exogenous naked DNA from the surrounding environment.

Lytic

A viral developmental cycle wherein a bacteriophage replicates within a host cell and subsequently lyses the cell wall to release new viral particles.

Lysogenic

A phage developmental pathway in which viral DNA integrates into the host chromosome as a prophage or persists as an episome, replicating synchronously with the host without causing cell death.

Virulent phage

A bacteriophage that reproduces exclusively via the lytic cycle, inevitably destroying its host bacterium.

Temperate phage

A bacteriophage capable of choosing between entering a destructive lytic cycle or establishing a stable, dormant lysogenic relationship with its host.

Transduction

The bacteriophage-mediated transfer of bacterial DNA sequences from one bacterial host to another.

Specialized transduction

The phage-mediated transfer of only specific bacterial genes immediately flanking the prophage integration site, caused by aberrant prophage excision.

Generalized transduction

The transfer of any arbitrary segment of bacterial donor chromosome via a phage that randomly mispackages host DNA instead of viral DNA during assembly.

Prophage

The latent form of a temperate phage genome integrated into the circular host bacterial chromosome.

Lysogen

A bacterial host cell carrying a dormant prophage integrated within its genome.

Restriction endonuclease

A bacterial enzyme that recognizes specific, short palindromic DNA sequences and cleaves the phosphodiester backbone at defined restriction sites.

Genomic DNA vs. cDNA

Genomic DNA contains the entire unaltered sequence of an organism including exons and non-coding introns, whereas complementary DNA (cDNA) is synthesized in vitro from processed mRNA and lacks introns.

Plasmid

A small, circular, self-replicating extrachromosomal DNA molecule widely used as a vector to clone and manipulate genes in recombinant DNA technology.

Functional complementation

A genetic screening method used to isolate a cloned wild-type gene by its capacity to rescue a mutant phenotype when transformed into a mutant host.

Positional cloning

A strategy for identifying and isolating a gene based strictly on its known chromosomal map position without prior information about its encoded protein.

Southern blot

A molecular biology technique used to detect specific target DNA sequences through gel electrophoresis, membrane transfer, and hybridization with a labeled single-stranded probe.

Northern

An analytical method (Northern blot) used to study gene expression by separating RNA fragments by size via gel electrophoresis, transferring them to a membrane, and identifying targets with labeled probes.

SDS-PAGE

Sodium dodecyl sulfate polyacrylamide gel electrophoresis; a method used to separate denatured proteins primarily on the basis of their molecular weight.

Western

An analytical method (Western blot) used to detect specific proteins within a sample using gel electrophoresis, transfer to a nitrocellulose or PVDF membrane, and detection with targeted antibodies.

PCR

Polymerase chain reaction; an enzymatic method used to exponentially amplify specific target DNA fragments in vitro through repetitive cycles of denaturation, primer annealing, and extension.

Next generation DNA sequencing

High-throughput DNA sequencing methodologies that execute massively parallel reactions to rapidly sequence millions of fragments simultaneously.

Site-directed mutagenesis

A molecular method used to create defined, intentional nucleotide alterations at specific sites within a cloned gene sequence.

Reporter transgene

A recombinant gene construct joining a regulatory promoter sequence to an easily assayable reporter gene (such as GFP or luciferase) to monitor expression pattern and transcriptional activity.

Transgenic organism

An organism whose genome has been stably modified through the artificial introduction of a foreign gene or DNA sequence.

Genetically modified plant

A plant whose nuclear or plastid genome has been altered using recombinant DNA technology to introduce traits such as pest resistance or herbicide tolerance.

Gene therapy

The clinical technique of delivering functional exogenous genetic material into human cells to correct, replace, or supplement a mutated disease-causing gene.

Adult stem cell

An undifferentiated multipotent cell present in differentiated post-natal tissues that can divide to replenish dying cells and regenerate damaged tissues.

Embryonic stem cell

A pluripotent stem cell derived from the inner cell mass of a blastocyst that possesses the developmental capacity to differentiate into all cell lineages of the adult body.

Induced pluripotent stem cell

A differentiated adult somatic cell that has been reprogrammed into an embryonic stem cell-like pluripotent state via the forced expression of defined transcription factors.

Reverse genetics

An experimental approach that determines the biological function of a known DNA sequence by mutating or inactivating it and analyzing the resulting phenotypic consequences.

Gene knock out

A genetic engineering method in which an endogenous gene is permanently disrupted, inactivated, or deleted to investigate its function in vivo.

RNAi

RNA interference; an evolutionary conserved post-transcriptional gene silencing mechanism wherein small double-stranded RNA molecules trigger sequence-specific mRNA degradation or translational repression.

CRISPR-Cas9

A targeted genome editing system derived from bacterial immunity that employs a synthetic guide RNA to direct the Cas9 endonuclease to generate site-specific double-strand breaks in DNA.