The synthesis of RNA unde the direction of DNA 

Produces messenger RNA (mRNA)

Occurs in three stages:

-Initiation 

-Elongation

-Termination 

(Messenger RNA) 

A type of RNA produced during transcription that creates a blueprint of the protein that is to be synthesized

 In prokaryotes, mRNA produced by transcription is immediately translated without more processing 

In eukaryotic cells, the nucleur envelope seperates transcription from translation 

In eukaryotic cell, RNA transcripts are modified through RNA processing to yield finished mRNA 

The syntheis of polypeptides which occurs under the direction of mRNA 

Occurs in ribosomes 

The initial RNA transcript from any gene 

The central dogma is the concept that cells are governed by a cellular chain of command: DNA ->RNA->Protein 

A series of nonoverlapping, three-nucleotide words

Provide the flow of information from gene to protein

These triplets are the smallest units of unifrom length that can encode for all the amino acids 

There are 20 amino acids, but only four nucleotide bases in DNA 

Ex: AGT at a particular position on a DNA strand results in the placement of the amino acid serine at the corresponding position of the polypeptide that is to be produced 

mRNA base triplets 

Each one specifies the amino acid to be placed at the corresponding position along the polypeptide 

Are read in the 5' to 3' direction during translation 

All 64 codons were deciphered by the mid-19-60's

Of the 64, 61 are for amino acids; 3 are "stop" signals to end translation 

No codon specifies more than one amino acid 

Must be read in the correct reading frame (correct grouping) in order for the specified polypeptide to be produced 

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A cayalyzing enzyme in transcription that cayalyzes RNA synthesis 

Pries the DNA strands apart and hooks together the RNA nucleotides 

RNA synthesis follows the same base-pairing rules as DNA, except uracil substitutes for thymine 

Transcription Factors 

As RNA polymerase moves along the DNA, it untwists the double helix 10-20 bases at a time 

Transcription progresses at a rate of 40 nucleotides per second in eukaryotes 

A gene can be transcribed simultaneously by several RNA polymerases 

Differ among bacteria and eukaryotes In bacteria, the polymerase stops transcription at the end of the terminator 

In eukaryotes, the polymerase continues transcription after the pre-mRNA is cleaved from the growing RNA chain; the polymerases eventually fall off the DNA 

Enzymes in the eukaryotic nucleus modify pre-mRNA before the genetic messages are dispatched to the cytoplasm 

During RNA processing, both ends of the primary transcript are usually altered 

Also, usually some interior parts of the molecule are cut out, and other parts are spliced together 

Each end of a pre-mRNA molecule is modified in a particular way:

-The 5' end recieves a modified nucleotide 5' cap

-The 3' end gets a poly-A tail

These modifications shar several functions:

-They seem to facilitate the export of mRNA

-They protect mRNA from hydrolytic enzyes 

-They help ribosomes attach to the 5' end 

The stretches of RNA that are eventually expressed into amino acid sequences 

(As opposed to introns)

Catalytic RNA molecules that function as enzymes and can splice RNA 

Their discovery of ribozymes rendered obsolete the belief that lal biological catalysts were proteins 

Three properties of RNA enable it to function as an enzyme 

-It can form a three-dimensional structure because of its ability to base pair with itself 

-Some bases in RNA contain functional groups 

-RNA may hydrogen-bond with other nucleic acid molecules 

The modular architecture consisting of discrete regions known as ______

In many cases, different exons code for the different domains in a protein 

Exon shuffling may result in the evolution of new proteins 

(transfer RNA) 

The form of RNA that helps to transfer an mRNA message into a protein 

Molecules of tRNA are not identical:

-Each carries a specific amono acid of one end 

-Each has an anticodon on the other end; the anticodon base-pairs with a complementary codon on mRNA