Transcription Flashcards

Flashcards about Transcription

Genetic Code Combinations

The use of three nucleotides results in 64 different possible combinations, coding for the 20 amino acids that exist.

Redundancy in the Genetic Code

More than one codon can code for a single amino acid.

Redundancy Minimizes Errors

Minimize errors that may lead to serious mutations.

Start Codon

Signals initiation of the mRNA strand.

Stop Codon

Signals termination of the mRNA strand.

Primary Transcript

The mRNA before any changes are made.

5' Cap

Protects the mRNA from digestion and plays a role in the initiation of translation.

Poly-A Tail

A string of approximately 200 adenine ribonucleotides is added to the 3' end by the enzyme poly-A polymerase.

Exons

Coding regions of a eukaryotic gene.

Introns

Noncoding regions of a eukaryotic gene.

Spliceosomes

Cut out the introns and join the remaining exons together.

RNA Polymerase

Binds to the promoter and opens the double helix, it starts building the single-stranded mRNA in the 5' to 3' direction

Template Strand

The strand of DNA that RNA polymerase uses to create the mRNA transcript.

Coding Strand

The strand of DNA that is not used for transcription.

mRNA Sequence

The mRNA sequence is complementary to the template strand and identical to the coding strand, except that the mRNA sequence contains uracil(U) instead of thymine(T).

Elongation

The mRNA strand is elongated until the end of the gene is reached.

RNA Polymerase

An enzyme that must bind to the segment of DNA that is to be transcribed.

Upstream Region

Indicates where the RNA polymerase should start transcribing and which DNA strand should be transcribed.

Promoter

A sequence on one of the DNA strands that is adjacent (beside) the start of a gene.