Transcriptomics

1. What is transcriptomics?

• study of transcriptome--> the complete set of RNA transcripts produced by DNA 
• The transcriptome is the set of all messenger RNA (mRNA) molecules in one cell or a population of cells. It differs from the exome in that it includes only those RNA molecules found in a specified cell population, and usually includes the amount or concentration of each RNA molecule in addition to the molecular identities.

  - measuring : micro array and RNA-seq are used for measure about transcriptome in organisms.

 

2. Relationship between genomics and transcriptomics

• comparison of transcriptomes allow the identification of what kinds of genes are used in certain cell

 

 

3. What are mRNAs? 

• large family of RNA that convey genetic information from DNA to the ribosome
• related to transcription in which RNA polymerase makes mRNA transcripts from template DNA
• processing 
• • 5' cap addition : critical for recognition by the ribosome  / protection from RNases
  • Editing : change nucleotide composition of the mRNA
  • polyadenylation : protecting mRNA from degrading by exonucleases
• structure
• • coding region : composed of codons, containing genetic information
                           coding region begin with start codon and end with stop codon
  • untranslated region ( 5' UTR / 3' UTR )
  • • location : before the start codon  / after the stop codon
    • feature : locus which are not translated
    • advantage : mRNA stability, mRNA localization , translational efficiency
  • poly(A) tail 
  • • composition : lone repetitive sequences of adenine nucleotides
    • function : promote export from the nucleus / stimulate translation / protect the mRNA from degradation (by exonucleases)

     

 

 

4. How to measure RNA expression?

• high-throughput methods >> microarray

 

 

5. Relationship between Transcriptome and Proteome.

• transcriptome is related to the mRNA transcript while Proteome is related to protein product. Because mRNA is intermediate of protein production, there relative amount of expression can indicate the expression degrees of others.

 

 

6. What is a UTR?

• untranslated region ( 5' UTR / 3' UTR )
• • location : before the start codon  / after the stop codon
  • feature : locus which are not translated
  • advantage : mRNA stability, mRNA localization , translational efficiency

 

 

7. What is ncRNA ?

• non-coding RNA : RNA molecule that is not translated into a protein
• function
• • gene-regulation
  • • trans-acting ncRNAs : microRNAs
    • cis-acting ncRNAs : riboswitch (5'-UTR)

 

 

8. What is poly A ?

• composition : lone repetitive sequences of adenine nucleotides
• function : promote export from the nucleus / stimulate translation / protect the mRNA from degradation (by exonucleases)