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Genetics/Gene Regulation

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Question
Dear Dr. Robichaud
I want to know if I remove a houskeeping gene that is essential for general cell metabolism,from euchromatin to a region of hetrochromatin, what would be the likely effect on the cell?

2- we have fewer gene regulators than genes in the cell. so how specific gene activate or regulate? could one regulatory gene activates more than on gene? so how it can discriminate between them? would you please explain about this?
Regards
Alhan

Answer
Hello Alhan!

Heterochromatin is typically not read as often as euchromatin. In the best of cases, the cell would be 'sick' and grow slowly. Worst case, the cell would die from lack of a housekeeping gene.

How do we know we have fewer gene regulators than genes?  At last count, it takes only a maximum of 25,000 genes to make a human. There is much more DNA in the cell than is required to produce that many genes. Perhaps you need to check your assumptions?

An example which may interest you is human pigmentation; it's something everyone wonders about. If we imagine a person as a factory, there is a whole department in the factory dedicated to producing the two known pigment genes for skin and hair, eumelanin (brownish) and pheomelanin (reddish). There are also support staff that indicate when the pigment is produced, how it is delivered, and where it goes, as well as how much the workers make. All of these factors are also controlled by DNA variations, separate genes, and a secondary code on the histones that pack and unpack the genomic DNA. What color we see at the end is a summation of the entire department's efforts, which could be ten or more genes total for skin or hair color. Also, the instructions on what to make varies over time given how old the person is. For example, most often people's hair darkens at maturity, then grays at seniority, but this is not a hard and fast rule.

Regulating some genes is simple - one gene, one regulator binds, gene on. Regulator leaves, gene off. (or vice versa) Other proteins and genes have differing roles throughout the body and wear many hats. Scientists are still working on figuring out all the roles - that's what the 'annotated' human genome means.

Does this help?  

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Trista Robichaud, PhD

Expertise

No homework questions, especially ones copied and pasted from textbooks. I will answer questions about principles or give hints, but I do not do other's homework. I'm comfortable answering basic biochemistry, chemistry, genetics, and biology questions up to and including an undergraduate level of understanding. This includes molecular biology, protein purification, and genetics. My training/inclination is primarily in structural biology, or how the shapes of things affect their function. Other interests include protein design, protein engineering, enzyme kinetics, and metabolic diseases such as cancer, atherosclerosis, and diabetes. Regrettably, I cannot diagnose any disease. I can tell you how we currently understand the basic science behind a disease state, but I cannot recommend treatment in any way. Please direct such questions to your medical professional.

Experience

I hold a PhD in Biomedical Science from the University of Massachusetts Medical School in Worcester. I specialize in Biochemistry, with a focus on protein chemistry. My thesis work involved the structure and functions of the human glucose transporter 1. (hGLUT1) Currently I am a postdoc working in peptide (mini-protein) design and enzymology at the University of Texas Health Science Center in San Antonio, Texas. I am in Bjorn Steffensen's lab, researching inhibitors of gelatinase A, a matrix metalloproteinase. I have also been answering Chemistry/Biochemistry questions on this site since summer 2010.

Organizations
2001 American Association for the Advancement of Science, 2007 American Chemical Society 2007 Protein Society 2011 UTHSCSA Women’s Faculty Association

Publications
Publications Levine KB, Robichaud TK, Hamill S, Sultzman LA, Carruthers A. Properties of the human erythrocyte glucose transport protein are determined by cellular context. Biochemistry 44(15):5606-16, 2005. (PMID 15823019) Robichaud TK, Appleyard AN, Herbert RB, Henderson PJ, Carruthers A “Determinants of ligand binding affinity and cooperativity at the GLUT1 endofacial site” Biochemistry 50(15):3137-48, 2011. (PMID 21384913) Xu X, Mikhailova M, Chen Z, Pal S, Robichaud TK, Lafer EM, Baber S, Steffensen B. “Peptide from the C-terminal domain of tissue inhibitor of matrix metalloproteinases-2 (TIMP-2) inhibits membrane activation of matrix metalloproteinase-2 (MMP-2)” Matrix Biol. 2011 Sep;30(7-8):404-12. (PMID: 21839835) Robichaud TK, Steffensen B, Fields GB. Exosite interactions impact matrix metalloproteinase collagen specificities. J Biol Chem. 2011 Oct 28;286(43):37535-42 (PMID: 21896477) Poster Abstracts: Robichaud TK, Carruthers. A Mutagenesis of the Human type 1 glucose transporter exit site: A functional study. ACS 234th Meeting, Boston MA. Division of Biological Chemistry, 2007 Robichaud TK, Bhowmick M, Tokmina-Roszyk D, Fields GB “Synthesis and Analysis of MT1-MMP Peptide Inhibitors” Biological Chemistry Division of the Protein Society Meeting, San Diego CA 2010 Robichaud TK; Tokmina-Roszyk D; Steffensen B and Fields GB “Exosite Interactions Determine Matrix Metalloproteinase Specificities” Gordon Research Conference on Matrix Metalloproteinase Biology, Bristol RI 2011

Education/Credentials
INSTITUTION AND LOCATION DEGREE (if applicable) YEAR(s) FIELD OF STUDY Oakland University, Auburn Hills MI BS 1993-1998 Biochemistry University of Massachusetts Medical School, Worcester MA PhD 2001-2008 Biochemistry & Molecular Pharmacology University of Texas Health Science Center, San Antonio TX Postdoc 2009-Present Biochemistry

Awards and Honors
1998 Honors College Graduate, Oakland University 2009 Institutional National Research Service Award, Pathobiology of Occlusive Vascular Disease T32 HL07446 2011 1st Place, Best Postdoctoral Poster, Dental Science Symposium, UTHSCSA, April 2011

Past/Present Clients
Invited Seminars: Robichaud TK, Fields GB. “Synthesis and Analysis of MTI-MMP Triple Helical Peptide Inhibitors” Pathology Research Conference, University of Texas Health Science Center San Antonio Pathology Department (June 18th, 2010) Robichaud TK & Hill, B “How To Give A Great Scientific Talk” Invited Lecture, Pathobiology of Occlusive Vascular Disease Seminars, UTHSCSA (Nov 11th 2010), Cardiology Seminar Series, Texas Research Park (Feb 21st, 2011) Robichaud TK; Tokmina-Roszyk D; Steffensen B and Fields GB “Exosite Interactions Determine Matrix Metalloproteinase Specificities” Gordon-Keenan Research Seminar “Everything You Wanted to Know About Matrix Metalloproteinases But Were Afraid to Ask” Bristol, RI (Aug 6th, 2011)

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