One Gene One Enzyme. There is redundancy in the code but not ambiguity!

One Gene One Enzyme

There is redundancy in the code but not ambiguity!

In prokaryotes, RNA is directly translated into the polypeptide

RNA in eukaryotes is processed before translation

Genes

• The DNA provides the instructions to make the protein

• RNA is the link between gene and protein

• DNA codes for RNA and RNA codes for the protein

Transcription/Translation• The DNA and RNA molecules are

composed of nucleotide monomers.

• When converting from DNA to RNA you are simply transcribing the code from the language of DNA nucleotides to RNA nucleotides

• Proteins are “written” in the language of amino acids.

• When converting from RNA to protein we are translating from the nucleotide language to amino acid language

RNA

• In what ways are RNA molecules different from DNA?

• RNA is single stranded

• In RNA, uracil replaces thymine

• Nucleotides have ribose instead of deoxyribose

• In eukaryotes, RNA leaves the nucleus

The Genetic Code is Universal

• The code (A,U,C,G) is shared by all organisms

• CCG codes for what amino acid?• This holds true for all species of living

organisms.• Bacteria, therefore can be programmed

to synthesize human proteins by inserting human DNA

RNA splicing• Removes noncoding regions called introns

• snRNP (short nuclear ribonucleoproteins) recognize the splicing signals that are at the ends of introns

• The RNA in the snRNP is called snRNA (small nuclear RNA)

• spliceosome is the larger protein assemby that surrounds the snRNP

• The spliceosome cuts and releases the introns, and then joins exons together

Evolutionary role of introns

• Introns may play regulatory role

• Different intron removal may lead to different proteins

• Introns may enhance crossing over between homologous regions by increasing the distance between exons

Messenger RNA consists of leader, reading frame, and

trailer sequences.

tRNAs bring amino acids to the ribosomes during translation to be

assembled into polypeptide chains.

Peptide Bonds Join Amino Acids

What are the functions of the 4 different types of RNA?

tRNA Assembly

Ribosomes, consist of two subunits, each of which contains rRNA and

ribosomal proteins.

Initiation of Translation

Elongation

Termination

Review

Polyribosomes