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20 Cards in this Set
- Front
- Back
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What are the 4 main ways that transcription differs from replication?
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1. RNA is single stranded (although base pairing occurs)
2. Only a portion of DNA is transcribed at a given time 3. Transcription occurs throughout the cell cycle, (not just prior to cell division) 4. Because transcription is used to direct protein synthesis(and cell function/responses), regulation of transcription (GENE EXPRESSION) is complex |
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What contains coding for protein synthesis?
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Messenger RNA
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What transfers the amino acid onto the emerging poly peptide during translation?
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Transfer RNA
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What are the 2 main components in ribosomes?
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Ribosome = rRNA + protein
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What is the most abundant form of cytosolic RNA?
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ribosomal RNA 80%
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What type of RNA is the most diverse?
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messenger RNA
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What type of RNA is the least diverse?
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ribosomal RNA
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How are RNA's produced?
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Transcription, a process where double-stranded DNA is read by RNA polymerase, which writes a sequence of RNA that is a precursor of mRNA tRNA or rRNA
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What is required for transcription to occur?
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1. double-stranded DNA as a TEMPLATE (not single stranded DNA, nor RNA)
2. activated precursors:ATP, GTP, CTP, UTP 3. RNA polymerase 4. Signal to allow transcription to begin |
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Is a primer required for transcription to occur?
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NO primer is required
(primers are required for DNA replication [RNA is the primer for DNA replication]) |
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How is each new base added to RNA (in both replication & transcription)
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Bases are added by forming a phosphodiester bond on the free 3' end of RNA
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What is the template for synthesis of RNA?
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DNA
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Where does transcription start?
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Transcription starts at the promoter
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What constitutes the promoter in transcription?
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A location where RNA polymerase initiates RNA synthesis
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What are the 3 modifications made to mRNA before leaving the nucleus?
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1. A methyl guanosine cap on the 5'end
2. A tail of up to 200 adenosine ribonucleotides 3. Removal of introns, regions which have no role in protein synthesis |
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Where does the initiator tRNA, usually carrying methionine, attach to?
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The P site of the ribosome
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On the ribosome, what does the P site refer to?
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P refers to the site holding the peptide chain
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What does the A site refer to on the ribosome?
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A refers to the tRNA accepting site
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Why is UAA a stop codon?
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UAA does not have an anticodon
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What is the tRNA protein "look-alike" that releases tRNA and stops polypeptide synthesis
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The releasing factor
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