Translation and RNA Splicing

Flashcards related to RNA Splicing, Translation, and related concepts.

Introns

Sequences found in pre-mRNA that may regulate gene expression.

Alternative RNA splicing

The process where some genes encode more than one kind of polypeptide, depending on which segments are treated as exons during splicing.

Modular architecture consisting of domains

Discrete regions that proteins often have, with different exons coding for the different domains of a protein.

Exon shuffling

A process that may result in the evolution of new proteins.

Translation

The conversion of coded information (after transcription and processing) into a sequence of amino acids.

Translation

The synthesis of a polypeptide under the direction of mRNA.

Adaptors

Connect amino acids to mRNA.

Complimentary base pairing

Copying or transferring information from nucleic acid to nucleic acid.

Genetic Code Problem

Both DNA and RNA use 4 'letters' each, while proteins have 20 'letters'.

Nucleotide triplets

The smallest possible unit to cover all 20 amino acids, each triplet is called a codon.

Degenerate code

Each amino acid is represented by multiple codons.

Reading the Code

Each 3 nucleotides represents an amino acid and the code is nonoverlapping.

Reading the Code

Extracting correct information requires the correct start site and Reading Frame.

Extraordinary conservation of the genetic code

Indication of commonality in all living organisms

Francis Crick proposed the presence of an Adaptor

Connect the two polymers(RNA template and amino acids)

Crick’s Adaptor Hypothesis - 20 Adaptors

One for each of the 20 amino acids, with one site for binding to an amino acid and one site for binding to the codon on the mRNA template.

Attachment of Amino Acid to tRNA

Uses tRNA Synthetase enzyme.

Ribosomes

Very large macromolecular machines that contain both RNA and protein (RNPs).

Initiation, Elongation (and Translocation), Termination

Translation is divided into these 3 phases.

Forming the Initiation Complex

Sets the reading frame.

Translocation:

Ribosome moves in 3' direction.

Elongation and Translocation Repeat

Protein built in N-term to C-term Direction Continues until Stop Codon.

Making Lots of Protein from a Single Gene

A gene can be transcribed repeatedly resulting in many copies of the mRNA.

Polyribosome

One mRNA can be simultaneously translated by many ribosomes.

Posttranslational Modifications

Folding, Covalent Attachments, S-S Bridge, Proteolytic Cleavage, Multi-subunit Association

Protein Targeting

Proteins have amino acid signals that direct the proteins to the right place.

Nuclear Localization Sequence (NLS)

Small sequence of C-terminal amino acids common on some nuclear proteins.

Protein Targeting II

Proteins destined for the Endomembrane System or for secretion begin on free ribosomes and then move to the RER membrane.

Mutation

Change in genetic sequence.