Genetics, Transcription, Translation, and Gene Regulation

Practice vocabulary flashcards defining core concepts across genetics, transcription, RNA processing, translation, operons, and eukaryotic gene regulation.

True-Breeding Lines

Strains of organisms that consistently produce offspring displaying the exact same phenotype as the parent generation.

$F_1$ Generation

The first filial generation produced from a parental cross.

Autosomal Dominant Phenotype

A trait that appears in every generation of a pedigree, affecting males and females with equal likelihood.

Autosomal Recessive Phenotype

A trait affecting males and females equally, where affected individuals must carry two copies of the recessive allele (homozygous).

X-Linked Recessive Phenotype

A rare trait that frequently skips generations and appears far more commonly in males because they inherit only one $X$ chromosome.

Autosomes

The $22$ non-sex chromosomes present in human haploid sets that are not directly involved in determining sex.

Haploid Gamete

A reproductive cell containing exactly $1$ copy of each gene, which combines with another gamete at fertilization to form a diploid offspring.

Pedigree Symbols

Standard genealogical notations where a circle represents a female, a square represents a male, a filled shape denotes an affected individual, and a diagonal slash indicates a deceased individual.

Codominant Alleles

A condition in which both alleles in a heterozygous individual are simultaneously expressed and contribute to the observable phenotype.

Incomplete Dominance

A genetic interaction in which the dominant allele does not completely mask the recessive allele, resulting in an intermediate phenotype (such as red and white flowers yielding purple).

CFTR Gene

A gene responsible for producing a protein that acts as a chloride channel to regulate the movement of chloride ions across cell membranes.

Wild Type

The standard, most commonly occurring version of an allele or phenotype in a natural population, often designated as $X^{+}$.

Polygenic Traits

Characteristics exhibiting continuous variation that are influenced by the combined additive effects of multiple genes rather than a single gene locus.

Loss-of-Function Alleles

Mutated alleles that cause the resulting RNA or protein product to malfunction or be completely absent from the cell.

Genome

The complete, entire collection of genetic material and genes present within an organism.

Locus

The specific physical position or site of a gene on a chromosome.

Multiple Alleles

A genetic system with $3$ or more alternative forms of a gene within a population, although any individual diploid organism inherits only $2$ of them.

Epistasis

A gene interaction where the phenotypic expression of one gene is masked or altered by the presence of an entirely different gene.

Fitness

The ability of an individual organism to survive, produce viable offspring, and pass its alleles on to the next generation.

Transcription

The biological process occurring in the nucleus of eukaryotic cells where RNA polymerase copies genetic information from a DNA template into complementary messenger RNA (mRNA).

Promoter

The specific regulatory DNA sequence where RNA polymerase makes initial contact and collaborates with other proteins to initiate transcription before moving down the gene.

Template Strand

The single strand of DNA that is directly read by RNA polymerase to synthesize a complementary strand of RNA.

Coding Strand

The DNA strand complementary to the template strand whose sequence matches the newly synthesized RNA, except that it contains thymine ($T$) instead of uracil ($U$).

Poly-A Tail

A long chain of adenine nucleotides appended to the $3'$ end of a eukaryotic pre-mRNA transcript prior to nuclear export.

$5'$ Cap

A chemically modified nucleotide added to the $5'$ terminus of eukaryotic pre-mRNA that protects the transcript and facilitates ribosome attachment during translation.

Rho-Dependent Termination

A mechanism of transcriptional termination in which a Rho protein attaches to the nascent RNA, travels along it, catches up with RNA polymerase, and knocks it off the template.

Rho-Independent Termination

A termination mechanism driven by a self-complementary sequence at the end of a gene that causes the synthesized mRNA to fold back on itself into a hairpin structure, dislodging RNA polymerase.

Translation

The ribosomal process that converts the language of nucleic acids into proteins by reading mRNA codons and assembling a specific chain of amino acids.

tRNA

Transfer RNA; specialized RNA molecules that ferry specific amino acids to the ribosome; if uncharged (empty), translation cannot proceed.

Codon

A contiguous sequence of $3$ nucleotide bases in mRNA that specifies a particular amino acid or serves as a translational start or stop command.

Anticodon

A sequence of $3$ nucleotides situated on one loop of a tRNA molecule that base-pairs complementarily with an mRNA codon during translation.

Release Factor

A specialized protein that binds directly to a stop codon in the ribosomal A site, prompting the termination of translation and peptide release.

Ribozyme

An RNA molecule capable of catalyzing specific biochemical reactions analogous to protein enzymes.

Reading Frame

One of three possible non-overlapping ways to read a sequence of nucleotide triplets (codons) in DNA or RNA to specify an amino acid sequence.

Genetic Code

The universal dictionary defining the functional correspondences between all $64$ possible mRNA codons and the specific amino acids incorporated into proteins.

Introns

Intervening non-coding segments within a eukaryotic pre-mRNA that are excised during RNA splicing before the transcript is translated.

Exons

Expressed regions of pre-mRNA transcripts that are spliced together and preserved in the mature mRNA to code for protein products.

Open Reading Frames (ORFs)

Long continuous stretches of DNA that lack termination codons, used by researchers to identify protein-coding sequences in uncharacterized genomes.

Operon

A functional genetic unit found in prokaryotes consisting of a cluster of genes regulated by a single shared promoter and transcribed into a single polycistronic mRNA.

lacZ

A structural gene in the lac operon that encodes beta-galactosidase, an enzyme that hydrolyzes lactose into glucose and galactose.

lacY

A structural gene in the lac operon that codes for lactose permease, a membrane protein facilitating the transport of lactose into the bacterial cell.

lacA

A structural gene in the lac operon encoding transacetylase, the enzyme responsible for converting lactose into allolactose.

Conditional Gene Expression

The activation of specific genes only under particular environmental circumstances, such as nutrient uptake, DNA repair, or motility requirements.

Constitutive Gene Expression

The continuous, uninterrupted transcription and expression of essential genes under all cellular conditions.

Activators

Transcription factor proteins that exert positive control by binding DNA regulatory sites (such as enhancers) to upregulate gene expression.

Repressors

Transcription factor proteins that exert negative control by binding regulatory sites (such as silencers) to suppress or block gene transcription.

Chromatin

The nuclear complex composed of eukaryotic DNA wrapped around and associated with structural histone proteins.

Nucleosome

The basic repeating structural subunit of chromatin, consisting of a segment of DNA coiled around a core of histone proteins.

Epigenetics

Heritable molecular modifications made to DNA or chromatin that alter gene expression profiles without changing the primary nucleotide sequence.

Circadian Rhythms

Endogenous physical, behavioral, and mental cycles repeating roughly every $24\text{ hrs}$, whose disruption can trigger insomnia, weight loss difficulty, and depressive episodes.

Pladienolide

A pharmacologic agent that inhibits RNA splicing, thereby reducing the cellular concentrations of mature mRNA and functional protein.