Chapter 10 Gene expression, Transcription and Translation

Gene Expression

The process by which information from a gene is used to synthesize a functional gene product, typically proteins.

Transcription

The process of copying a segment of DNA into RNA.

Translation

The process of converting the sequence of nucleotides in mRNA into a sequence of amino acids in a polypeptide.

Central Dogma

The framework explaining the transfer of genetic information from DNA to RNA to protein.

mRNA (messenger RNA)

RNA that carries the genetic information from DNA to the ribosome for protein synthesis.

RNA Polymerase

An enzyme that synthesizes RNA from a DNA template during transcription.

Promoter

A region of DNA that initiates transcription of a specific gene.

Template Strand

The strand of DNA that serves as a template for RNA synthesis during transcription.

Coding Strand

The DNA strand that is not used as a template during transcription, has the same sequence as the transcribed RNA (with T replaced by U).

Introns

Non-coding segments of RNA that are removed during RNA splicing.

Exons

Coding segments of RNA that are spliced together to form mature mRNA.

5' Cap

A modified guanine nucleotide added to the 5' end of eukaryotic mRNA to protect it and facilitate translation.

3' Poly A Tail

A sequence of adenine nucleotides added to the 3' end of eukaryotic mRNA that enhances stability and regulates translation.

Spliceosome

A complex of proteins and RNA that removes introns from pre-mRNA.

Codon

A sequence of three nucleotides on mRNA that specifies an amino acid.

Amino Acid

The building blocks of proteins, coded by codons in mRNA.

Aminoacyl-tRNA Synthetase

An enzyme that attaches the appropriate amino acid to its corresponding tRNA.

tRNA (transfer RNA)

RNA molecules that carry amino acids to the ribosome during protein synthesis.

Ribosome

The cellular machinery made of rRNA and proteins that assembles amino acids into polypeptides.

Release Factor

A protein that recognizes stop codons during translation, prompting termination.

Start Codon

The first codon in mRNA that signals the beginning of translation; typically AUG (which codes for methionine).

Stop Codon

Codons that signal the end of translation; UAA, UAG, UGA.

Peptide Bond

The bond that links amino acids together in a protein.

Ribozyme

An RNA molecule with enzymatic activity, such as catalyzing splicing reactions.

Retroviruses

Viruses that transcribe their RNA into DNA in a host cell.

Structural Genes

Genes that code for proteins, which determine an organism's traits.

RNA Modifications

Processes that prepare pre-mRNA for translation, including capping, polyadenylation, and splicing.

Functional Product

The final product of gene expression, often a protein or an active RNA molecule.

Elongation Phase

The stage of translation where tRNA delivers amino acids to the ribosome to build the polypeptide chain.

Termination Phase

The stage of translation where the ribosome reaches a stop codon, releasing the newly synthesized polypeptide.

snRNPs (small nuclear ribonucleoproteins)

Components of the spliceosome that play a key role in RNA splicing.

Reading Frame

The way nucleotides in mRNA are grouped into codons during translation.

Eukaryotic Transcription

More complex than prokaryotic transcription, involving multiple RNA polymerases and additional proteins.

Prokaryotic Translation

Translation that occurs in the cytoplasm, often occurring simultaneously with transcription.

Genetic Code

The set of rules by which information encoded in mRNA is translated into proteins.

Energy Input in Translation

GTP hydrolysis provides the energy necessary for the assembly of ribosomal subunits and tRNA during initiation.

Alternative Splicing

A process that allows a single gene to produce multiple proteins by rearranging exons during RNA splicing.

Transcription Factors

Proteins that bind to specific DNA sequences to regulate gene transcription.

A, P, E Sites

The three sites in a ribosome where tRNA binds during translation: the aminoacyl site (A), peptidyl site (P), and exit site (E).

Functional Diversity of Proteins

Variety of functions that proteins can have based on their structure and the specific amino acids they contain.