Study BMB 400 Chapter 14 Flash Cards

 
Pile Management Card
BMB 400 Chapter 14

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poly A tail
-enhances translation by promoting efficient recycling of ribosomes
-poly= many uses of ribosomes to come!
Kozak sequences
-purine bases 3 bases upstream of AUG and G immediately after
-"A/G" NN AUG G
to improve euk translation...
-Kozak sequences
-poly A tail
scanning
-ribosome moves in a 5’->3’ direction until it encounters the first 5’-AUG-3’ start codon
-ribosome attaches to 5' end, scans until sees start codon
-does its 'thang'
How do euks recruit ribosomes?
-5' cap!
-required, actually
-scanning
leaderless mRNA
-no RBS
:-(
where are RBSs?
-Usually 3-9 base pairs upstream of 5’ start codon
-complementarity/space affects translational effiency
can an ORF w/o a RBS still get translated?
-Yes!
-coupled translation
-only if polycistronic
-start codon of downstream ORF overlaps stop codon of upstream ORF
-5’-AUGA-3 contains stop and start sequence
16S rRNA
-what mRNA is complementary to in SD sequence
-small ribosomal subunit
Shine-Degarno
-RBS in prokaryotes
-mRNA complementary to small ribosomal subunit (16S rRNA)
-to position start codon correctly
-
monocistronic mRNA
-eukaryotic
-1 ORF per mRNA
polycistronic mRNAs
-prokaryotic
-2 or more ORFs on 1 mRNA
-encode proteins for similar functions
operon
-A group of distinct genes that are expressed and regulated as a unit
-operator, a promoter, and one or more structural genes that are transcribed together
stop codon
-nearly universal (pros and euks)
-UAA (ochre), UAG (amber), UGA (opal)
-UAA most common
Met
-AUG
-start codon in euks
start codons in prokaryotes
-multiple ones used in bacteria and archae
-AUG most common
-regardless of start codon, always codes for formyl-Met
-AUG
-GUG
-UUG
-AUU
-CUG
formyl-Met
-ALWAYS start aa in bacteria
ORF
-continuous, non-overlapping codons
how much energy taken up by protein synthesis?
-rapidly growing bacteria, 80% of cell's energy for protein synthesis
-50% of cell's weight
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