How Genes Work: The Genetic Code and Transcription

These flashcards cover key vocabulary terms and definitions relevant to the genetic code and transcription as outlined in the lecture notes.

Gene

A segment of DNA that codes for a protein.

RNA polymerase

Enzymes that synthesize RNA from DNA and make RNA polymers by bonding ribonucleotides together.

Promoter

A special DNA sequence near a gene that serves as a binding site for RNA polymerase to initiate transcription.

Transcription factors/sigma factor

Regulatory factors that help RNA polymerase bind to the promoter in prokaryotes and eukaryotes.

Transcription bubble

The region where the DNA strands are unwound during transcription.

Exon

Segments of eukaryotic genes that code for proteins.

Intron

Noncoding segments of eukaryotic genes that are removed during splicing.

Triplet code

A three-letter combination of genetic letters that allows for the translation of all 20 amino acids.

Codon

A nucleotide 'word' that codes for a specific amino acid.

Genetic code table

A table that relates nucleotide sequences to the amino acids they code for.

Start codon

The codon that signals the start of protein synthesis, specifically AUG, which codes for methionine.

Stop codon (nonsense codon)

Signal where protein synthesis should stop, such as UAA, UAG, or UGA.

Unambiguous

Each codon codes for only one amino acid, ensuring specific translation.

Redundant

The genetic code is redundant, with most amino acids being coded for by more than one codon.

(Nearly) universal

Codons specify the same amino acids in nearly all organisms.

Aminoacyl tRNA-synthetase

An enzyme that attaches amino acids to their respective tRNA molecules.

Point mutation

A mutation that changes one or a few nucleotides in the DNA sequence.

Chromosomal mutation

A mutation that affects entire chromosomes or large portions of them.

Missense mutation

A mutation that results in a change in at least one amino acid in a protein.

Nonsense mutation

A mutation that introduces a stop codon, resulting in a shortened, usually nonfunctional protein.

Silent mutation

A mutation that does not change the amino acid sequence of a protein.

Frameshift mutation

A mutation due to the insertion or deletion of bases that shifts the reading frame.

Deletion

A chromosomal mutation where a portion of a chromosome is missing.

Duplication

A chromosomal mutation where a portion of a chromosome is repeated.

Inversion

A chromosomal mutation where a section of a chromosome is reversed.

Translocation (of a chromosome segment)

A chromosomal mutation where a piece of one chromosome breaks off and joins another chromosome.