Genomics & Epigenetics – Lecture Vocabulary

24 vocabulary flashcards summarizing fundamental terms and definitions from the lecture on genomics and epigenetics.

Genome Size

The total number of nucleotides in an organism’s DNA.

Gene Number

The total count of genes (DNA sequences that code for functional products) in a genome.

Gene Density

The ratio of gene number to genome size; lower in eukaryotes because most of their DNA is non-coding.

Genome Size Paradox

The lack of correlation between genome size and organismal complexity (e.g., a grape’s genome is larger than a human’s).

Junk DNA

Non-coding DNA that does not encode proteins; abundant in eukaryotic genomes.

Introns

Non-coding sequences within genes; present in eukaryotes, largely absent in prokaryotes.

Exons

Coding regions of a gene that remain in mature mRNA; about 2 % of the human genome.

Alternative Splicing

Process by which different combinations of exons are joined to produce multiple proteins from a single gene, explaining humans’ relatively low gene count.

Transposable Elements

Mobile DNA sequences that can change position within the genome; make up ~44 % of human DNA.

Repetitive DNA

Highly repeated nucleotide sequences, comprising ~15 % of the human genome.

Unique Non-coding DNA

Single-copy non-coding sequences (~14 % of the genome).

Regulatory Sequences

DNA regions (about 5 % of the genome) that control when, where, and how much genes are expressed.

Epigenetics

Heritable changes in gene expression that occur without altering the underlying DNA sequence.

DNA Methylation

Addition of methyl groups to DNA that tightens chromatin and represses transcription.

Histone Acetylation

Addition of acetyl groups to histone tails that loosens chromatin and increases gene expression.

Genomic Imprinting

Epigenetic phenomenon where only one parental allele (maternal or paternal) is expressed while the other is silenced.

Prader-Willi Syndrome

Disorder caused when paternally expressed genes on Chromosome 15 are deleted or mutated while maternal alleles are imprinted.

Angelman Syndrome

Disorder resulting when maternally expressed genes on Chromosome 15 are deleted or mutated while paternal alleles are imprinted.

Temperature-Dependent Sex Determination

Process in many reptiles where incubation temperature during a critical period determines sex via epigenetic pathways.

Pattern I Development

TSD pattern in which males form at cooler temperatures and females at warmer ones (e.g., turtles).

Pattern II Development

TSD pattern in which females form at cold or hot extremes and males at intermediate temperatures (e.g., crocodiles).

Royal Jelly

Special diet fed to honey-bee larvae that inhibits DNA methylation, triggering queen development.

Queen Bee Phenotype

Larger, fertile, long-lived female produced from the same genome as workers due to royal-jelly-induced epigenetic changes.

Gene Density (Eukaryote vs. Prokaryote)

Eukaryotes have lower gene density than prokaryotes because they contain many introns and large amounts of non-coding DNA.