Lecture Handout 6 - BIOT 101 Lecture Handout 6 Central...

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BIOT 101 Lecture Handout 6 Central Dogma of Biology: Control of Gene Expression and Protein Function Vocabulary acetylation attenuation catabolite activator protein (CAP) constitutive expression constitutive genes cyclic AMP (cAMP) deactylation dephosphorylase dephosphorylation DNA methylase euchromatin expressed helix-turn-helix heterochromatin histone histone acetyltransferase (HAT) histone deacetylase (HDAC) histone demethylase histone methyltransferase (HMT) I protein inducible induction kinase Lac operon leucine zipper methylases methylation monocistronic operator site operon phosphorylation polycistronic post-transcriptional control protease proteasome regulon repression repressor protein small nuclear RNA (snRNA) transcriptional control transcriptional factors translational control ubiquitin upstream promoter elements zinc-finger Objectives Understand the difference between constitutive and inducible genes. Understand how protein activity within the prokaryotic and eukaryotic cell can be controlled. Understand the functioning of the Lac operon. Understand how transcription is controlled in eukaryotic cells. Be aware of the various DNA binding motifs that are known to exist. Understand how translation of mRNA can be controlled. Understand how the activity of proteins that have been synthesized can be affected. 1
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BIOT 101 Lecture Handout 6 Central Dogma of Biology: Control of Gene Expression and Protein Function I. The control of metabolic activity in an organism can occur at several levels. The presence of absence of a particular enzyme will obviously affect whether or not the reaction catalyzed by that enzyme occurs or not. If an enzyme is present, the level of activity of that enzyme can be controlled in several ways. Today we are going to concentrate on mechanisms that organisms use to either increase or decrease the amount of a protein that is synthesized. In a particular cell at particular time, certain genes were expressed , this means that the DNA was used to make the RNA and the RNA was used to make protein. In that same cell other genes were “silent”, this means that the DNA was not used to make RNA or the RNA, once synthesized, was not used to make protein. Under different conditions that same cell would “turn-on” the silent gene and produce the protein for which it codes. It was obvious that some form of regulation controls the transcription of DNA into RNA and then the subsequent translation of RNA into protein. A. In both the eukaryotic and prokaryotic cell, some proteins are always needed. These proteins are constantly made. This is referred to as constitutive expression and such genes are said to be constitutive genes . Other proteins are only made if the cell needs that protein. The genes that code for these proteins are said to be inducible . If the protein is an enzyme, the gene for that enzyme will be expressed only when the substrate for that enzyme is present and the product of the reaction is needed. This keeps the cell from making enzymes that either have nothing to work on or will make a
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Lecture Handout 6 - BIOT 101 Lecture Handout 6 Central...

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