BABS1201 Lecture Notes - Lecture 11: Luciferase, Intron, Tata Box
Gene Expression I
Gene expression
• To get translate DNA to proteins
• DNA contains the instructions for how a cell will function
o Proteins perform these functions (enzymes)
• Central dogma:
o Information in DNA is translated to produce proteins through RNA
o DNA codes for RNA which codes for protein (in a one-way direction)
Differences between DNA and RNA
DNA
RNA
• Double stranded
• Single stranded
• Deoxyribose sugar
2' C lacks an oxygen molecule
• Ribose sugar
• 2' C has an OH group
• Nucleotides: ATCG
Contains thymine instead of
uracil
• Thymine - has a methyl group
• Nucleotides: AUCG
Uracil - replaces thymine
• Uracil - methyl group is replaced with a hydrogen
atom
• DNA
o Repository of genetic information
o Ideal state - stable (durable for multiple replication)
▪ Contains: double-strands, deoxyribose
• RNA
o Used to be translated into proteins
o Ideal state: less stable for easier translation
•
Protein synthesis
• Gene - parts of DNA that codes for proteins
• Transcription
o DNA to RNA
o DNA is transcribed into messenger RNA (mRNA), using base pairing
▪ RNA - single strand ribose backbone
• Translation
o Nucleotide to amino acid
o mRNA is translated into protein
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o One codon (3 nucleotides) code for each amino acid
•
The genetic code
• It is known that - 4 bases codes for 20 amino acids
o Duplex code (2 nucleotides per amino acid) =
▪ Less amino acid variations produced than exist in real life
o Triplex code (3 nucleotides per amino acid) =
▪ 64 different codes, but only 20 variations of amino acids exists
▪ The code is redundant - multiple combinations produce the same amino acid
• AUG - start sequence (only one combination)
• UGG - Trp
• Stop - UAA, UGA UAG
•
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find more resources at oneclass.com