1. Online Counseling Resource YCMOU ELearning Drive… School of Architecture, Science and Technology Yashwantrao Chavan Maharashtra Open University, Nashik – 422222, India

2. Introduction Programmes and Courses  SEP–SBI082–CP1-01 SEP–SBI082–Unit 01-01

3. School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.3 Credits  Academic Inputs by Sonali Alkari Faculty YCMOU Nagpur Centre, Faculty LAD college P.G. D of Biotechnology Research officer Ankur Seeds Pvt Ltd sonalisa_alkari@yahoo.co.in

4. School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.4 How to Use This Resource  Counselor at each study center should use this presentation to deliver lecture of 40-60 minutes during Face-To-Face counseling.  Discussion about students difficulties or tutorial with assignments should follow the lecture for about 40-60 minutes.  Handouts (with 6 slides on each A4 size page) of this presentation should be provided to each student.  Each student should discuss on the discussion forum all the terms which could not be understood. This will improve his writing skills and enhance knowledge level about topics, which shall be immensely useful for end exam.  Appear several times, for all the Self-Tests, available for this course.  Student can use handouts for last minutes preparation just before end exam.

5. School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.5 Learning Objectives  After studying this module, you should be able to: Define Gene Explain what is gene expression? Explain Expression system and stages of gene expression Explain Gene networks and expression State Gene Regulation and its importance

6. School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.6 What is Gene?  The word gene is derived from the Greek word ‘genesis’ meaning ‘to be born’.  The hereditary determiners, a term used by Mendel for the discrete particles passing characteristics from one generation to the next generation.  The term gene was coined by Johannson.  A gene can be defined as a functional unit of genetic material consisting of nucleotides; determiner of a unit character; a segment of DNA that codes for the synthesis of specific protein.

7. School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.7 What is Gene Expression?  Gene expression is the process by which inheritable information from a gene, such as the DNA sequence, is made into a functional gene product, such as protein or RNA.  Control of gene expression basically occurs at two levels, prior to transcription and post- transcriptionally.  post-transcriptional control of gene expression is not control at the level of the gene.  Gene expression can be control by either acting to increase the rate of transcription of individuals genes or, by contrast, inhibit the rate of transcription of individuals genes

8. School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.8 Gene Expression  Gene expression occurs in two major stages (see Figure).  The first is transcription.  The second stage is protein synthesis

9. School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.9 Transcription  In this process, the gene is copied to produce an RNA molecule (a primary transcript) with essentially the same sequence as the gene.  Most human genes are divided into exons and introns, and only the exons carry information required for protein synthesis (see Gene structure ).Gene structure  Most primary transcripts are therefore processed by splicing to remove intron sequences and generate a mature transcript or messenger RNA (mRNA) that only contains exons.

10. School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.10 Protein Synthesis  This stage is also known as translation and is so called because there is no direct correspondence between the nucleotide sequence in DNA (and RNA) and the sequence of amino acids in the protein.  In fact, three nucleotides are required to specify one amino acid.  The chain of amino acids must fold up to generate the final tertiary structure of the protein.

11. School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.11 Expression System :1  An expression system consists, minimally, of a source of DNA and the molecular machinery required to transcribe the DNA into mRNA and translate the mRNA into protein using the nutrients and fuel provided.  In the broadest sense, this includes every living cell capable of producing protein from DNA. However, an expression system more specifically refers to a laboratory tool, often artificial in some manner, used for assembling the product of a specific gene or genes.

12. School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.12 Expression System :2  It is defined as the "combination of an expression vector, its cloned DNA, and the host for the vector that provide a context to allow foreign gene function in a host cell, that is, produce proteins at a high level".  In addition to these biological tools, certain naturally observed configurations of DNA (genes, promoters, enhancers, repressors) and the associated machinery itself are referred to as an expression system.

13. School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.13 Gene Networks and Expression  Genes have sometimes been regarded as nodes in a network, with inputs being proteins such as transcription factors, and outputs being the level of gene expression.  The node itself performs a function, and the operation of these functions have been interpreted as performing a kind of information processing within cell and determine cellular behaviour.

14. School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.14 Prokaryotes 1.All RNA species are synthesized by a single RNA polymerase 2.mRNA is translated during transcription Eukaryotes 1.Three different RNA polymerases are responsible for the different classes of RNA molecules. 2.mRNA is processed before transport to the cytoplasm where it is translated. Caps and tails are added and internal parts of the transcript are removed. Differences in Gene Expression :1

15. School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.15 Differences in Gene Expression :2 Prokaryotes 3.Genes are contiguous segments of DNA that are colinear with the mRNA that is translated into a protein. 4.mRNAs are often polycistronic. Eukaryotes 3.Genes are often split. They are not contiguous segments of coding sequences; rather, the codng sequences are interrupted by intervening sequences. 4.mRNAs are monocistronic.

16. School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.16 Gene Regulation:1  This differential gene expression is achieved by regulating transcription and translation.  All genes are surrounded by DNA sequences that control their expression. Proteins called transcription factors bind to these sequences and can switch the genes on or off.  Gene expression is therefore controlled by the availability and activity of different transcription factors.

17. School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.17 Gene Regulation:2  Gene Regulation mechanisms invariably involve the sensing of intracellular or extracellular conditions by proteins (metabolic control) which then either bind to DNA, bind to, modify, or cause the modification of proteins which in turn bind to DNA, or which modify or cause the modification of other factors involved in transcription (such as RNA polymerase).  Some of these transcritpion proteins interfere with RNA polymerase action (Repressors; negative control) while others enhance RNA polymerase action (activators).

18. School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.18 Gene Regulation:3  As transcription factors are proteins themselves, they must also be produced by genes, and these genes must be regulated by other transcription factors.  In this way, all genes and proteins can be linked into a regulatory hierarchy starting with the transcription factors present in the egg at the beginning of development.  A number of human diseases are known to result from the absence or malfunction of transcription factors and the disruption of gene expression thus caused.

19. School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.19 Transcriptional Control:1  Minimizing resources devoted to protein synthesis:  It can be wasteful, and sometimes even harmful, to express a gene at an inappropriate time.  Synthesizing proteins, for example, from transcription through translation and beyond, is metabolically expensive.  Consequently, regulation of protein action is both important and most economically achieved as early in protein synthesis as possible.

20. School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.20 Transcriptional Control:2 Transcriptional control is particularly economical:  Most economical is at a point prior to transcription since transcription is the first relatively expensive step in protein syntehsis.  Thus, the activity of specific proteins about cells is very often regulated through either blocks (negative control) on or enhancement (positive control) of RNA polymerase action and thus at the level of transcription.  Regulation is achieved through the action of specific regulatory proteins.

21. School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.21 Negative Control [repression, repressor protein]  The binding of a specific protein (repressor protein) to DNA at a point that interferes with the action of RNA polymerase on a specific gene is a form of negative control of protein synthesis.  This interference with RNA polymerase activity is termed repression (of the action of RNA polymerase) and the consequent to this lack of gene expression a gene is described as repressed.

22. School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.22 Negative Control [repression, repressor protein]  Action results in lack of activity:  This form of control of gene expression is called negative control because the controlling action results in an absence of activity.  Contrast this with positive control.

23. School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.23 Positive Control [activation, activator protein]  Action results in activity:  In contrast to negative control, very often a specific gene requires the binding of a specific This type of control is also termed positive control in the sense that the action of the activating protein results in a positive action: gene expression.  protein (an activating protein) in order to achieve RNA polymerase binding and gene expression.  This type of control of gene expression is termed activation since in its absence the gene is not active (i.e., is not expressed).

24. School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.24 Gene Regulation Is Necessary  By switching genes off when they are not needed, cells can prevent resources from being wasted. There should be natural selection favoring the ability to switch genes on and off.  A typical human cell normally expresses about 3% to 5% of its genes at any given time.  Cancer results from genes that do not turn off properly. Cancer cells have lost their ability to regulate mitosis, resulting in uncontrolled cell division.

25. School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.25 What You Learn… Gene is a functional unit of genetic material Gene expression is the process by which is gene is expressedin functional product. two different process transcription and translation controls gene expression. Expression system is source of DNA and the molecular machinery required to transcription There is differences Prokaryotic and Eukaryotic Gene Expression. Transcriptional control is the Gene Regulation mechanisms. negative control and enhancement positive control are different Type of Transcriptional control Gene Regulation is important for switching genes off

26. School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.26 Critical Thinking Questions 1.What is gene expression and state different stages of gene expression?. 2.What is gene regulation and how it is achieved? 3.State different types of Transcriptional control.

27. School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.27 Hints For Critical Thinking Question 1.Define gene, gene expression and state stages transcription and translation. 2.State what is Gene control & its regulation and transcription factors 3.What is Transcriptional control and different types as positive and negative. © 2007, YCMOU. All Rights Reserved.27

28. School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.28 Study Tips:1  Book1 Title: Genes IX. Author: Benjamin Lewin Publisher: Jones & Bartlett Publishers  Book2 Title: Genetics from Genes to Genomes Author: L. H. Hartwell, L. Hood, M. L. Goldberg Publisher: Tata McGraw-Hill

29. School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.29 Study Tips:2  Book3 Title: Genetics Author: Monore W.Strickberger Publisher: PHI of India  Book4 Title: Genetics Author: C.Serin Publisher: Tata McGraw-Hill

30. School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.30 Study Tips www.en.wikipedia.org Microsoft Encarta Encyclopedia http://en.wikipedia.org/wiki/ Wikipedia the free encyclopedia

31. End of the Presentation Thank You !