Term
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Definition
| strand being transcribed (anti-sense, 3’-5’) |
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Term
| non-template strand or coding strand |
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Definition
| other strand matches mRNA (5’-3’, sense strand) |
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Term
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Definition
| carries specific information from DNA to site of protein synthesis |
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Term
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Definition
| RNAs that carry specific amino acids and complementary sequences (anticodons) that interpret messenger RNA |
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Term
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Definition
RNA molecules that are structural and catalytic (ribozyme) components, along with some proteins, of ribosomes
participate in matching tRNA to mRNA at ribosome |
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Term
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Definition
•enzyme that catalyzes synthesis of an RNA molecule
•requires a detachable, regulatory protein subunit to function = sigma
•two portions together form a holoenzyme
• RNA polymerase is the core enzyme = portion that has the ‘active site’ |
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Term
| 3 stages of transcription |
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Definition
| initiation, elongation, termination |
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Term
TRANSCRIPTION
step 1: initiation (in bacteria) |
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Definition
• sigma binds to a site on DNA on the promoter (upstream from gene, 40-50 base pairs)
• double-helix opens
-template strand is channeled to active site
-mRNA synthesis begins
• sigma is released – transcription proceeds |
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Term
TRANSCRIPTION
step 2: elongation (in bacteria) |
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Definition
• RNA polymerase adds nucleotides in 5” to 3” direction along DNA template in 3’ to 5’ direction - mRNA is complementary, hence, antiparallel to DNA (guided by zipper and rudder)
-hydrolysis of tri- nucleotide is EXERGONIC providing energy to condensation reaction |
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Term
TRANSCRIPTION
step 3: termination (in bacteria) |
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Definition
transcription termination signal
-final bases fold back in a “hairpin’
-results in release of mRNA from polymerase |
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Term
| basal transcription factors |
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Definition
| in eukaryotic transcription, (no sigma) bind to promoter and initiate transcription |
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Term
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Definition
transcribes genes that code for large RNA molecules of ribosomes
snrps |
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Term
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Definition
transcribes protein coding genes to make mRNA
snrps |
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Term
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Definition
| transcribes genes that code for tRNA and small ribosomal RNA molecules |
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Term
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Definition
| small nuclear ribonucleoproteins = small nuclear RNA and protein that bind to consensus sequences at boundaries of exons and introns |
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Term
| cap added to 5' after transcription |
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Definition
• specialized nucleotide, 7-methylguanylate = modified GTP
• protects RNA from degradation by hydrolytic enzymes
• provides recognition site for ribosomal binding |
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Term
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Definition
added at the end of transcription
• facilitates export of mRNA from nucleus
• stabilizes RNA |
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Term
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Definition
| are 3' to 5' = to fit with codons of mRNA |
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Term
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Definition
can pick up and carry a specific amino acid
carries the anticodon = complementary sequence to codon on mRNA
•many tRNAs have a generic base called an inosine, a modified adenine that can pair with A, U or C |
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Term
| aminoacyl-tRNA synthetases |
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Definition
enzymes that catalyze the attachment of a specific amino acid to its tRNA
uses ATP |
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Term
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Definition
| tRNAs covalently linked to amino acid |
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Term
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Definition
| in bacteria, more than one gene coded into a single mRNA – with multiple start codons and stop codons |
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Term
TRANSLATION
1. initiation (bacteria) |
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Definition
1. mRNA binds to a small ribosomal subunit with help from protein initiation factors
2. initiator aminoacyl tRNA binds to start codon along with f-met
3.the large ribosomal subunit binds, completing the complex. first enters A site but immediately moves to P |
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Term
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Definition
-uses GTP and elongation factors to put next tRNA into vacant A slot
-amino group of new amino acid bonds to carboxyl group of last amino acid on chain = peptide bond
-tRNA is released from A-site - requires a special non-protein enzyme (ribozyme) = peptidyl transferase
-tRNA moves to P-site as ribosome moves along mRNA = translocation - uses GTP energy |
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Term
TRANSLATION
3. Termination |
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Definition
•when mRNA presents a stop codon (UAA, UGA or UAG)
•release factors recognize stop codons
•causes ribosome to disassociate into the two subunits |
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Term
| post-translational events |
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Definition
•spontaneous formation of secondary, tertiary and quaternary structure – facilitated by molecular chaperones
•proteolysis = cleavage of chains into segments, reattachment of some
•glycosylation = addition of carbohydrates |
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