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level: 20.3 Regulation of transcription and translation

Questions and Answers List

level questions: 20.3 Regulation of transcription and translation

QuestionAnswer
KW!Active site/binding site has a specific 3o structure therefore is complementry
Gene Expression- Every cell in your body has the same DNA, although there are lots of different cells with different functions - Genes are turned on and off in cells this process is called GENE EXPRESSION. - “every cell has the same orchestra, but they play different tunes”
Transcription Factors- These are molecules that bind to the DNA PROMOTOR and are required to begin transcription - Transcription factors will bind to a specific sequence of DNA, because the 3o structure is specific thus complementary to the seq. of DNA - RNA polymerase will only bind once transcription factors have binded
Oestrogen- Oestrogen is a steroid hormone - It is lipid soluble so can diffuse through the cell membrane - Oestrogen binds to a complementary shaped receptor on a transcription factor - The change in tertiary structure removes the inhibitor - The transcription factor diffuses into the nucleus and binds to DNA promotor region - Transcription begins (because RNA polymerase binds)
Explain why oestrogen only leads to a gene expression in target cells?- Transcription factors will only be complementary to target cells
siRNA- Small Interfering RNA - These are short pieces of double stranded RNA that can prevent gene expression by interfering with mRNA (breaking it down) - They work by combining with an enzyme, then attach the enzyme to the complementary mRNA - The enzyme then Digests mRNA
How does siRNA regulate gene expression ? (1)- A mature mRNA leaves a nuclear pore - This is converted into a double stranded RNA by an enzyme - This is the broken into smaller sections, it is now siRNA
How does siRNA regulate gene expression ? (2)- The siRNA joins to a RISC complex (enzyme) - The original mRNA is removed - This leaves a strand which is complementary to the original RNA strand
How does siRNA regulate gene expression ? (3)- The RISC enzyme is guided to mRNA strand + hydrolyses it into shorter sections - The mRNA can no longer be translated so the gene is silenced
What is the potential of siRNA- Enables us to find the functioning of genes by switching them off - Treating genetic disease by switching off faulty genes