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Gene regulation

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All cells contain a complete set of DNA, but only a subset is expressed, generating diverse cell types like nerve, cardiac, and muscle cells. Gene regulation involves promoters and repressors that determine gene expression. For example, lactose binding to a repressor activates the breakdown of lactose. Eukaryotic genes often have a TATA box to aid RNA polymerase positioning. As cells differentiate from a fertilized egg, Hox genes play a crucial role in this process. Mutations can impact gene function, with small changes sometimes leading to significant effects on an organism.

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Gene regulation

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Presentation Transcript

  1. Gene regulation

  2. How does DNA make different cells? • All cells have a full set of DNA • Not all the DNA is expressed in each one • Promoters and repressors allow only certain genes to be expressed (make protein) Nerve, cardiac, muscle, white blood cells

  3. The gene that breaks down lactose is repressed

  4. How it works • When lactose is added, it binds to the repressor protein.

  5. Activation Left side: why do you think this process is called a “positive” feedback loop? When lactose binds to the repressor, it moves away, allowing the protein to be made

  6. Eukaryotic Gene Regulation • Many eukaryotic genes have a sequence called the TATA box that helps to position RNA polymerase. Direction of transcription

  7. Differentiation • From a fertilized egg to an adult, cells grow and divide. • They also differentiate into many different types of cells • Hox genes control that differentiation • They are inherited from the genes of our common ancestors

  8. Gene mutation • Point mutation: the subtraction, addition or substitution of a single nucleotide • Changing a nucleotide will change the codon • Can change the amino acid • Subtraction and addition can cause a “Frame shift” making all amino acids downstream change • This can completely change a protein • Most mutations are harmful Left side: why don’t all mutations causes changes to the amino acids?

  9. Not all mutations are equal • If you put a hox gene for “eye” from a fruit fly into a mouse embryo, it will develop into an mouse eye. • If you move a hox gene for an eye from the head to the back of a fruit fly embryo the eye will develop on the back • Small genetic changes can make large changes to an organism.

  10. Summaryreview • What do hox genes do? • What are repressors and promoters? • What causes a frame shift?

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