Spliceosome attachs to hnRNA and begins to snip out non-coding introns mRNA strand composed of exons...

Spliceosome attachs to hnRNA and begins to snip out

non-coding introns

mRNA strand composed of exons is free to leave the nucleus

TRANSLATION: turning mRNA into a protein.

Group of three nucleotides on mRNA is called a CODON. 4 types of nucleotides arranged in multiples of 3 means 43 = 64 possible combinations

Each codon ultimately stands for an amino acid.Slight variations for the same a.a. are called “synonyms.”

There are START and STOP codons:AUG = start; UAA, UAG, UGA = stop

A hairpin loop is produced when single-stranded RNA doubles back on itself and

complementary base pairing occurs.

A tRNA molecule. The amino acid attachment site is at the open end of the cloverleaf (the 39 end), and the anticodon is located in the loop

opposite the open end.

An aminoacyl - tRNA synthetase has an active site for tRNA and a binding site for the particular amino acid that is to be attached to that tRNA.

tRNA= smallest RNA Interprets genetic info in DNA & brings specific

amino acids to ribosome for protein synthesis.

Only tRNA can translate genetic info into amino

acids for proteins. One or more different

tRNAs for each of 20 A.A. tRNAs are all similar, made

of 70-90 nucleotides. H bonds between some

bases make loops

The interaction between anticodon (tRNA) and codon

(mRNA), which involves

complementary base pairing, governs the proper placement of

amino acids in a protein.

The Universal Genetic Code.

A transfer RNA molecule (tRNA for short) brings correct amino acid to ribosome & drops it off. e.g.: AUG (codes for methionine) tRNA brings methionine to ribosome.

Ribosomes, which contain both rRNA and protein, have structures that contain two

subunits. One subunit is much larger than the other.

Initiation of protein synthesis begins with the formation of an initiation complex.

The process of translation that occurs during protein synthesis

The process of translation that occurs during protein synthesis (cont’d)

The process of translation that occurs during protein synthesis. (cont’d)

Several ribosomes can simultaneously proceed along a single strand of mRNA one after another. Such a complex of mRNA and

ribosomes is called a polysome.

Chemistry at a

Glance:Protein

Synthesis

•Errors do occur•Repair enzymes always making repairs•Mutations usually are harmful•Sometimes milder ones lead to genetic variety

Recombinant DNA is made by inserting a gene obtained from a cell of one kind of organism into

the DNA of another kind of organism.

Cleavage pattern resulting from a restriction enzyme that cleaves DNA between G and A

bases in the 5’-to-3’ direction in the sequence G - A - A - T - T - C.

The double helix structure is not cut straight across.

The “sticky ends” of the cut plasmid and the cut gene are complementary and combine to form

recombinant DNA.