Transcription and Translation PPT

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Transcript Transcription and Translation PPT

One Gene One Enzyme
Genes
• The DNA provides the instructions to
make the protein
• Every three bases on DNA create a
triplet code
• RNA is the link between gene and
protein
• DNA codes for RNA and RNA codes for
the protein
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
Transcription
• The DNA and RNA molecules that 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
The Code is Universal
• The code is shared by almost all
organisms
• CCG codes for what amino acid?
• Proline. This holds true for all species
of living organisms.
• Bacteria, therefore can be programmed
to synthesize human proteins by
inserting human DNA
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
The 5’ Cap and Poly-A Tail protect the mRNA from
hydrolytic enzymes as the mRNA leaves the nucleus
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
Translation
• 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
tRNAs bring amino acids to the
ribosomes during translation to be
assembled into polypeptide chains.
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
Peptide Bonds Join Amino
Acids
Termination
Review