Chapter 12: Gene Expression at the Molecular Level I: mRNAs and Proteins

A comprehensive set of vocabulary flashcards based on key concepts from gene expression and its molecular mechanisms.

Gene

Segments of DNA that code for an RNA or protein product.

Human genome

Contains 3.2 billion base pairs of DNA.

Nuclear DNA

Spread across 46 chromosomes in humans.

mtDNA

Mitochondrial DNA, ~16,500 base pairs in one circular chromosome.

Protein coding genes

Approximately 20,000 genes that produce over 100,000 proteins.

ncRNA

Non-coding RNAs, important for regulation of gene expression.

Transcription

Process of converting DNA into RNA.

Translation

Process of synthesizing proteins based on mRNA sequence.

Central dogma

The flow of genetic information: DNA > RNA > Protein.

mRNA

Messenger RNA that carries the genetic code to ribosomes.

Promoter

Region of DNA that initiates transcription of a specific gene.

Transcription factors

Proteins that assist in the initiation of transcription.

Alternative splicing

A process by which different combinations of exons are joined together.

Spliceosome

A complex that removes introns from pre-mRNA.

Introns

Non-coding sequences removed during RNA splicing.

Exons

Coding sequences that are retained in mature mRNA.

5' cap

A modified guanine nucleotide added to the beginning of mRNA.

Poly-A tail

A sequence of adenine nucleotides added to the 3' end of mRNA.

Ribosome

Molecular machine where translation occurs.

tRNA

Transfer RNA that brings amino acids to the ribosome during translation.

Aminoacyl-tRNA synthetases

Enzymes that attach the correct amino acid to tRNA.

Peptide bond

Chemical bond formed between amino acids during protein synthesis.

Start codon

Codon that signifies the start of protein synthesis (AUG for methionine).

Stop codon

Codon that signals the termination of protein synthesis.

Reading frame

The way nucleotides are grouped into codons.

Ribosomal-binding site

The site on mRNA where the ribosome attaches for translation.

Post-translational modification

Chemical modifications affecting protein functionality after translation.

Chaperone proteins

Proteins that assist in the folding of other proteins.

Translation initiation

The assembly of mRNA, tRNA, and ribosomal subunits.

Polypeptide chain

A sequence of amino acids linked by peptide bonds.

Genetic code

The relationship between DNA code and amino acid sequence.

Elongation (in translation)

The process where ribosomes synthesize polypeptides.

Termination (in translation)

The process that ends translation when a stop codon is reached.

mRNA modification

Changes made to pre-mRNA to create mature mRNA.

Transcribed region

Part of the gene that is copied to produce RNA.

3' untranslated region

Region at the end of mRNA that does not code for proteins.

C-terminus

The end of a protein or polypeptide with a free carboxyl group.

N-terminus

The start of a protein or polypeptide with a free amino group.

Transcription bubble

The region where DNA is unwound during transcription.

Sigma factor

Protein that aids the binding of RNA polymerase to the promoter.

Regulatory sequence

A DNA sequence that regulates gene expression.

Functional product

The final active form of a gene product, either RNA or protein.

Base pairing rules

Rules that dictate how nucleotides pair in DNA and RNA.

E. coli

A type of prokaryote often used in genetic studies.

Eukaryotic transcription

More complex transcription process involving RNA polymerases I-III.

Termination region

Region in DNA that signals the end of transcription.

dNTPs

Deoxyribonucleotide triphosphates, the building blocks for DNA synthesis.

RNA polymerase II

Specifically synthesizes mRNAs in eukaryotes.

Translation machinery

The complex of tRNA, mRNA, and ribosomes that synthesizes proteins.

Degenerate code

Characterization of the genetic code where multiple codons can code for the same amino acid.

Chloroplasts

Organelles in plant cells where photosynthesis occurs and also possess ribosomes.

Polysomes

Clusters of ribosomes translating the same mRNA simultaneously.

Ribosomal subunits

The large and small components of the ribosome that facilitate translation.

Release factor

A protein that recognizes stop codon and triggers termination of translation.

Endomembrane system

Set of membranes that interact and function in compartmentalizing cell processes.

Start codon sequence in RNA

The RNA sequence that corresponds to the start codon (AUG).

Mutation

A change in the DNA sequence that can affect amino acid coding.

Genetic regulation

The mechanisms that control gene expression levels.

RNA degradation

The breakdown of RNA molecules in the cell.