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(3) Gene Expression

(3) Gene Expression

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(3) Gene Expression

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  1. (3) Gene Expression (E) Splicing and post-translational modification (A) What is Gene Expression? Gene Expression (B) Structure and Functions of RNA (D) Translation (C) Transcription

  2. Gene Expression (a) • State what is meant by ‘phenotype’ • State what ‘phenotype’ is determined by • Name 2 factors that influence gene expression • Name the 2 stages involved in Protein Synthesis • State how gene expression is controlled

  3. What is Gene Expression? • Humans like all organisms are ‘built’ from proteins. • So the proteins each person produces determines their phenotype (physical appearance). • The instructions or code to make these proteins are found in short sections of DNA called genes. • Humans contain 25,000 genes but only a fraction of the genes in a cell are expressed (only a fraction of genes are copied and used to make proteins)

  4. Influencing Gene Expression • Signals from the outside world can work through the genome to change a cell's gene expression. • Click on the link below to access the animation. • In the activity, you act as the signal. As you turn the control knob, epigenetic tags come and go to change the shape of the gene. • http://learn.genetics.utah.edu/content/epigenetics/control/

  5. Green Fluorescent Protein

  6. Influencing Gene Expression • Not all genes are expressed. This is because gene expression is influenced by: • Intra-cellularenvironmental factors (a variety of molecules found inside the cell) • Extra-cellularenvironmental factors. • Regulation of gene transcription is known as epigenetics and is the mechanism by which the activity of any gene is ‘turned’ up or down. • To live, cells must be able to respond and adapt to changes in their environment. • Regulation of the two main steps of protein production is critical to this adaptability.

  7. Controlling Gene Expression • There are 2 main steps in Protein Synthesis: • Step 1 – Transcription • The DNA code is copied into a messenger molecule known as mRNA • Step 2 - Translation • The mRNA code is used to assemble amino acids into the correct order to make the protein inside structures known as ribosomes • Gene expression is controlled by the regulation of both transcription and translation

  8. Gene Expression (a) • State what is meant by ‘phenotype’ • State what ‘phenotype’ is determined by • Name 2 factors that influence gene expression • Name the 2 stages involved in Protein Synthesis • State how gene expression is controlled