Gene Expression Flashcards

Flashcards covering key vocabulary and concepts from the Gene Expression: DNA Transcription and Translation lecture notes.

Central Dogma of Life

Information flow in all organisms from DNA to RNA to protein

Transcription

DNA is transcribed to RNA via complementary base pairing rules (U instead of T)

Translation

mRNA is translated to an amino acid polypeptide by ribosomes in the cytoplasm

Gene Expression

The process of turning a gene “ON” to produce RNA and protein

Gene Regulation

How a cell controls which genes, out of the many genes in its genome, are expressed (“turned on”)

Transcription

Takes place in the nucleus using DNA as a template to make an RNA (mRNA) molecule

RNA Polymerase

Enzyme that uses one strand of DNA as a template to produce an mRNA molecule with complementary base pairs

Codons

Triplets of mRNA that are read by ribosomes, informing them which amino acids to bind to each other

Promoter

A region of a gene where RNA polymerase binds to initiate transcription

Transcription Factors

Proteins that bind to the promoter region and help recruit the appropriate polymerase in eukaryotes

Elongation

The addition of nucleotides to the mRNA strand during transcription, using complementary base pairs

Termination (Transcription)

The ending of transcription, occurring when RNA polymerase crosses a termination sequence in the gene

RNA processing

Eukaryotic pre-mRNAs undergo extensive processing before translation, including splicing out introns and adding a 5′ cap and 3′ poly-A tail.

Spliceosomes

Protein complexes that catalyze pre-mRNA splicing, composed of proteins and snRNAs.

RNA Polymerase I

Located in the nucleolus, transcribes, processes, and assembles ribosomal RNA (rRNA) into ribosomes.

RNA Polymerase III

Located in the nucleus, transcribes structural RNAs including 5S pre-rRNA, transfer pre-RNAs (pre-tRNAs), and small nuclear pre-RNAs.

Translation (Protein Synthesis)

he decoding of an mRNA message into a polypeptide product.

Ribosome

A complex macromolecule composed of structural and catalytic rRNAs and many distinct polypeptides.

Initiation (Translation)

Translation begins when an initiator tRNA anticodon recognizes a codon on mRNA. The large ribosomal subunit joins the small subunit, and a second tRNA is recruited.

Elongation (Translation)

As the mRNA moves relative to the ribosome, the polypeptide chain is formed.

Termination (Translation)

Entry of a protein release factor into the A site terminates translation and the components dissociate.

Codon

A nucleotide triplet that specifies a particular amino acid or stop codon.

Genetic Code Degeneracy

A given amino acid can be encoded by more than one nucleotide triplet.

Signal Sequence

A short tail of amino acids that directs a protein to a specific cellular compartment.

Chaperones

Helper molecules that prevent proteins from aggregating during the folding process.

Mutation

A change that occurs in our DNA sequence, either due to mistakes when the DNA is copied or as the result of environmental factors such as UV light and cigarette smoke.

Hereditary Mutations

Mutations inherited from a parent, present throughout a person’s life in virtually every cell.

Acquired (Somatic) Mutations

Mutations that occur at some time during a person’s life and are present only in certain cells.

Mosaicism

Somatic mutations that happen in a single cell early in embryonic development.

Polymorphisms

Genetic alterations that occur in more than 1 percent of the population, considered a normal variation in the DNA.