The Flow of Genetic Information
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Transcript of The Flow of Genetic Information
The Flow of Genetic Information
From Gene to Protein
It All Begins with DNA• DNA: in the
nucleus• Polymer of
nucleotides– Deoxyribose sugar– Phosphate group
(negative charge)– Nitrogen base (A,T,
C,G)
Importance of Nucleotide Sequences
• Different organisms : different order of nucleotides in DNA strands
• Closely related organisms: order of nucleotides in their DNA is more alike
Central Dogma
Codons• Sequence of 3
bases needed to code for an amino acid
• Amino acids are monomers for proteins
Transcription
• Transcription: DNA to mRNA
• Occurs in the nucleus
Important Aspects of Transcription
• RNA Polymerase : pries DNA strands apart, adds RNA nucleotides (only in a 5’ to 3’ direction)
• Promoter: DNA sequence where RNA polymerase attaches and begins transcription
• Transcription unit: stretch of DNA that is transcribed
For each gene only one DNA Strand is Transcribed
Process of Transcription
Eukaryotic Cells Modify RNA
• 5’ end is capped off with a 5’ cap• 3’ end contains a poly-A tail• Introns (noncoding sequences are
removed)/RNA splicing• Exons are joined together
From Pre-mRNA to mRNA
Transcription Overview
• Transcription occurs in the nucleus, mRNA is transported to cytoplasm
• Transcription results in pre-mRNA and RNA processing yields finished mRNA
Translation
• mRNA brings its message to the ribosome and the message is interpreted by tRNA
Ribosomes• Found in the cytoplasm• Facilitate the coupling of mRNA
codons and tRNA anticodons• Made of 2 subunits: large and small
subunits• Constructed of proteins and rRNA
Ribosome Structure
Translation Overview
Protein Synthesis Overview