Genetics, Heritability, and Transcription Lecture

Vocabulary flashcards covering drug pharmacogenetics, heritability, artificial selection equations, and molecular transcription and RNA processing mechanisms.

Warfarin (Coumadin)

An anticoagulant drug administered in an inactive form that reduces blood clotting by preventing the activation of vitamin K.

CYP2C9

A gene that encodes a cytochrome P450 protein located in the endoplasmic reticulum (ER), which acts as the enzyme that activates warfarin.

Vitamin K

An essential dietary substance required for biological function and the activation of blood clotting factors, whose activation is blocked by active warfarin.

Multifactorial Phenotype

A phenotypic trait whose expression is influenced by multiple factors, including multiple genetic loci and environmental factors such as age, BMI, sex, and diet.

Heritability

The fraction or degree of variation in a phenotype within a population that is attributable to variation in genotype, estimated by the slope of a regression line plotting mean offspring phenotype against mean parental phenotype.

Selection Differential ($S$)

The difference between the mean phenotype of selected parents chosen for breeding and the mean phenotype of the entire parental population.

Response to Selection ($R$)

The shift in the mean phenotype of the offspring generation resulting from selective breeding, which depends directly on the trait's heritability.

Breeder's Equation

The relationship $R = h \times S$, which predicts the response to selection ($R$) by multiplying heritability ($h$) by the selection differential ($S$).

Central Dogma of Molecular Biology

The principle that genetic information is archived in DNA, transcribed into messenger RNA, and then translated into proteins.

Transcription

The cellular process occurring in the nucleus where genetic information in a DNA template is copied into a complementary single strand of RNA.

Translation

The process by which ribosomes in the cytoplasm use the sequence encoded within messenger RNA to synthesize proteins.

RNA Polymerase

The enzyme responsible for separating DNA strands and synthesizing an RNA transcript in a $5'$ to $3'$ direction from a DNA template strand.

Template Strand

The strand of DNA that RNA polymerase binds to and reads to synthesize a complementary RNA transcript.

Coding Strand

The non-template DNA strand that has the same sequence as the newly synthesized RNA transcript, substituting thymine in place of uracil.

Primary Transcript

The initial, unprocessed single-stranded pre-messenger RNA synthesized directly from DNA by RNA polymerase before modifications occur.

$5'$ Cap

A modified nucleotide added to the $5'$ end of the primary transcript to protect the messenger RNA from enzymatic degradation.

Poly-A Tail

A string of adenine nucleotides added to the $3'$ end of an RNA transcript to protect the messenger RNA from degradation.

Introns

Intervening sequences present in the primary transcript that are removed during RNA splicing before the messenger RNA is exported to the cytoplasm.

Exons

The functional segments of a primary transcript that are retained and spliced together to form the mature messenger RNA.

Spliceosome

A complex composed of specialized RNA molecules and proteins that excises introns and ligates exons together during RNA processing.

Alternative Splicing

A regulated process in which exons from a single primary transcript can be spliced in different combinations, allowing a single gene to produce multiple distinct protein products.