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20 Cards in this Set

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What are the 4 main ways that transcription differs from replication?
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
What contains coding for protein synthesis?
Messenger RNA
What transfers the amino acid onto the emerging poly peptide during translation?
Transfer RNA
What are the 2 main components in ribosomes?
Ribosome = rRNA + protein
What is the most abundant form of cytosolic RNA?
ribosomal RNA 80%
What type of RNA is the most diverse?
messenger RNA
What type of RNA is the least diverse?
ribosomal RNA
How are RNA's produced?
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
What is required for transcription to occur?
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
Is a primer required for transcription to occur?
NO primer is required
(primers are required for DNA replication [RNA is the primer for DNA replication])
How is each new base added to RNA (in both replication & transcription)
Bases are added by forming a phosphodiester bond on the free 3' end of RNA
What is the template for synthesis of RNA?
DNA
Where does transcription start?
Transcription starts at the promoter
What constitutes the promoter in transcription?
A location where RNA polymerase initiates RNA synthesis
What are the 3 modifications made to mRNA before leaving the nucleus?
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
Where does the initiator tRNA, usually carrying methionine, attach to?
The P site of the ribosome
On the ribosome, what does the P site refer to?
P refers to the site holding the peptide chain
What does the A site refer to on the ribosome?
A refers to the tRNA accepting site
Why is UAA a stop codon?
UAA does not have an anticodon
What is the tRNA protein "look-alike" that releases tRNA and stops polypeptide synthesis
The releasing factor