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29.3 - Homework - Translation and Transcription

Last updated 11 months ago
4 questions

Transcription

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Eukaryotic RNA modifications

In bacteria, RNA transcripts can act as messenger RNAs (mRNAs) right away. In eukaryotes, the transcript of a protein-coding gene is called a pre-mRNA and must go through extra processing before it can direct translation.
  • Eukaryotic pre-mRNAs must have their ends modified, by addition of a 5' cap (at the beginning) and 3' poly-A tail (at the end).
  • Many eukaryotic pre-mRNAs undergo splicing. In this process, parts of the pre-mRNA (called introns) are chopped out, and the remaining pieces (called exons) are stuck back together.
End modifications increase the stability of the mRNA, while splicing gives the mRNA its correct sequence. (If the introns are not removed, they'll be translated along with the exons, producing a "gibberish" polypeptide.)


Transcription happens for individual genes

Not all genes are transcribed all the time. Instead, transcription is controlled individually for each gene (or, in bacteria, for small groups of genes that are transcribed together). Cells carefully regulate transcription, transcribing just the genes whose products are needed at a particular moment.
For example, the diagram below shows a "snapshot" of an imaginary cell's RNAs at a given moment in time. In this cell, genes 1, 2 and 3, are transcribed, while gene 4 is not. Also, genes 1, 2, and 3 are transcribed at different levels, meaning that different numbers of RNA molecules are made for each.

Translation

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DO NOT JUST SKIP THIS QUESTION OR DO IT HALF WAY OR YOU WILL RECEIVE A ZERO ON THE ENITRE ASSIGNMENT!!!

Create an infographic that shows:

A) Transcription
  • DNA being transcribed by RNA polymerase in the nucleus into mRNA
  • Label the DNA, RNA polymerase, and single stranded mRNA (Link to Helpful Graphic )

B) Exiting the Nucleus
  • mRNA leaving the nucleus to go the ribosomes
  • Label the single stranded mRNA, the cytoplasm, and the ribosome (Link to Helpful Graphic )

C) Translation
  • mRNA codons being translated by tRNA anticodons
  • create the codons in red font, you can create the codon yourself. A, C, U, and G are the possible letters in the codon.
  • Label the mRNA, the tRNA, and amino acid. (Link to Helpful Graphic )