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 1. What does the phrase “gene regulation” mean?  2. If the lac operon cannot bind to the repressor.. What would be the outcome? (Assume E. Coli)  3.

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Presentation on theme: " 1. What does the phrase “gene regulation” mean?  2. If the lac operon cannot bind to the repressor.. What would be the outcome? (Assume E. Coli)  3."— Presentation transcript:

1  1. What does the phrase “gene regulation” mean?  2. If the lac operon cannot bind to the repressor.. What would be the outcome? (Assume E. Coli)  3. What is a..  A. Promoter?  B. Operator?  C. Operon?  D. Repressor?

2  Using this DNA sequence: TACTATCGGCAATTGATC 1. Complete transcription 2. Complete translation 3. Now rewrite the sequence and change one base (add or delete a base, or switch one base to something different) 4. Find product of transcription 5. Find product of translation

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4  Gene regulation allows for control over production of proteins..  Energetic and resource conservation  Drives cellular differentiation, allowing for multiple types of cells with multiple functions

5  DNA segments (genes) code for amino acid sequence (ultimately protein)  Control of expression of other genes  regulatory proteins

6  Group of genes that are regulated together.  Region of DNA where multiple genes are being regulated at the same time.  Ex. lac operon in E.Coli includes genes lacZ, lacY, lacA, promoter, and operator

7  Promoter: Sequence that signals to RNA polymerase, site where RNA polymerase will bind to the DNA sequence to begin transcription.  Operator: Site/Location on DNA sequence where protein can bond to regulate expression. (Transcription factor), “switch” for the operon.  Repressor: Protein that binds to the operator to prevent RNA polymerase from transcribing.

8 Lactose is absent Lactose is present

9  Controls the expression of genes LacZ, lacY, lacA. Expression of genes is in response to the presence or absence of lactose in the environment. (Induced) When lactose is present, lactose binds to repressor (protein), it becomes inactive. No repressor means RNA polymerase CAN bind to promoter and can create necessary enzymes to break down lactose. (lac genes are expressed). When lactose is absent, repressor proteins bind to operator, blocking RNA polymerase from binding to promoter. Transcription cannot occur and no lac genes are expressed.

10  Genes can express or repress proteins to signal a cascade effect of expression:  Multiple genes across multiple chromosomes.  Ex. Homeotic genes

11  Homeotic genes regulate other genes by controlling body anatomy formation during the development of an embryo.  Genes “turn on/off” to regulate when specific body parts should be formed and when they should not be formed.  Eukaryotic organisms contain homeoboxes, regions of DNA nucleotide sequences that are conserved across multiple species.  Ex. Hox genes

12  HOX genes regulate when development of body parts will occur.  Hox genes control the body plan layout for an organism. HOX genes

13  Notice how the area of development corresponds to the location on the Hox genes.  Hox genes are conserved across species. Hox genes are critically important to appropriate body part development.  Similar HOX genes play similar roles in body plan layout in different organisms.


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