DNA and Gene Expression

Vocabulary practice flashcards covering DNA structure, replication, transcription, RNA processing, translation, genetic mutations, and eukaryotic gene regulation.

Nucleotide

The subunit of DNA consisting of a sugar, a phosphate group, and a nitrogenous base.

$5'$ End

The end of a DNA strand that has a phosphate group attached to carbon $5$ of the sugar.

$3'$ End

The end of a DNA strand that has an $-\text{OH}$ group attached to carbon $3$ of the sugar.

Antiparallel

The structural arrangement in which two complementary DNA strands run in opposite directions.

Semiconservative DNA Replication

The mode of replication where each newly formed DNA molecule consists of one original (parent) strand and one newly synthesized strand.

Nucleosome

A structural unit formed when DNA wraps around histone proteins in the nucleus.

Chromatin

A complex of DNA and histone proteins formed by nucleosomes that condenses into chromosomes.

Gene Expression

The process of using information stored in a gene to synthesize a functional product, typically a protein or functional RNA.

Promoter

A specific region of DNA where the transcription machinery assembles and RNA polymerase binds.

Template Strand

The DNA strand that is read by RNA polymerase in the $3' \rightarrow 5'$ direction to synthesize RNA $5' \rightarrow 3'$.

Coding Strand

The non-template DNA strand whose base sequence matches the synthesized RNA transcript, except thymine (T) is replaced by uracil (U).

Primary Transcript (pre-mRNA)

The initial RNA copy synthesized directly from DNA before undergoing processing in eukaryotes.

RNA Processing

The eukaryotic modification of pre-mRNA that includes adding a $5'$ cap and a poly-A tail, as well as removing introns via splicing.

Introns

Non-coding segments of pre-mRNA that are removed by RNA splicing.

Exons

Coding sequences of pre-mRNA that remain after splicing and are spliced together to form mature mRNA.

Codon

A sequence of $3$ RNA bases that specifies a particular amino acid or an instruction such as start or stop.

AUG

The start codon that initiates translation and specifies the amino acid methionine.

Stop Codons

The codons UAA, UAG, and UGA that signal the termination of translation and cause the release of the polypeptide.

Transfer RNA (tRNA)

An RNA molecule that transports a specific amino acid to the ribosome during translation.

Anticodon

A $3$-base sequence on a tRNA molecule that base-pairs complementarily with a codon on mRNA.

Ribosomal RNA (rRNA)

RNA that forms the structural and catalytic components of the ribosome.

Silent Mutation

A mutation that changes a codon sequence without altering the amino acid specified.

Missense Mutation

A mutation that alters a codon to code for a different amino acid.

Nonsense Mutation

A mutation that changes an amino acid codon into a premature stop codon.

Frameshift Mutation

An insertion or deletion of nucleotides not in multiples of $3$, which alters the translational reading frame of all subsequent codons.

Differential Gene Expression

The activation of different sets of genes in cells with identical DNA, enabling cellular specialization and distinct functions.

Epigenetics

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

DNA Methylation

An epigenetic modification that typically reduces or silences transcription.

Histone Acetylation

An epigenetic modification that loosens DNA packaging around histones, making chromatin more accessible for transcription.