Karteikarten
Protein Synthesis: Transcription and Translation
Karten in diesem Stapel (12)
- 1What are the 3 stages of transcription?Initiation
Elongation
Termination - 2Describe the initiation process of DNA transcription.Promoter regions (TATA box) is detected by transcription factors. Following, RNA polymerase binds to and separate the DNA strands.
- 3Describe the elongation process of DNA transcription.Once RNA polymerase opens the double helix, ONE mRNA strand begins to synthesize accordingly. **the mRNA begins to transcribe at the start sequence/codon ONLY. One DNA strand acts as the template strand, to transcribe the mRNA strand, while the other becomes the coding strand.
- 4True or false: The promoter region is upstream from the initiation site and gets transcribed.False, the promoter region does NOT get transcribed
- 5Describe the termination process of DNA transcription.When RNA polymerase reaches a termination sequence on the template strand (complementary to), trancription stops. (UGA, UAA, UAG --> ACT, ATT, ATC)
- 6A complementary RNA strand is synthesized in the direction of? 5'-3'/3'5'? 5'-3'
- 7Describe what modifications the mRNA strand undergoes before leaving the nucleus, to serve what purpose?1. 5' cap (guanine nucleoside trphosphate, short GTP) is added to the start of primary transcript. This protects the mRNA from digestion.
2. A "poly A tail" (50-250 adenine nucleotides) is added to the 3' end of the RNA. Also prevents degradation of mRNA
3. Splicing: INTRONS are nonfunctional segments of nucleotides that are snipped out of the chain. EXONS code for functional polypeptides and are rejoined by ligase - 8Describe the structure of tRNA.- clover-leaf shape
- single stranded molecule with attachment site at one end of an amino acid, and the opposite end contains an anticodon (3 nucleotide bases complementary to mRNA codon) - 9If the mRNA codon is UUU, how will the corresponding tRNA look like?- 3' end holds amino acid (phe) according to chart
- anticodon has the code AAA - 10Which enzyme joins the amino acid to tRNA?aminoacyl-tRNA synthetase
- 11Explain the different sites on a ribosome unit.Ribosomes are made of large and small subunits that clamp on to the mRNA strand.
P site (P for polypeptide) - holds tRNA carrying the growing pp chain
A site (A for amino acid) - holds tRNA carrying the next aa to be added to the pp chain
E site (E for exit) - discharges tRNA from ribosome
- 12Describe translation process- start codon AUG attaches to the small ribosomal subunit, large and small subunit clamps onto strand
- ribosome moves along mRNA, reading codons
- translation only begins at AUG (start) codon, which corresponds to the a. acid met
- the process of elongation continues until a stop codon is read in the A site.
- release factors recognizes that the ribosome has stalled
and causes the ribosome subunits to disassemble
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- grade 12 bio tdsb version sources - nelson 12 textbook
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