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I. Control of Gene Expression

I. Control of Gene Expression. Fig.1-1. (A) A diagramatic representation of mesophyll leaf cell. (B) Thin section TEM through a meristematic root tip cell. The nucleus. Contains most of the cell ’ s genetic information Serves as the center of regulatory activity.

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I. Control of Gene Expression

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  1. I. Control of Gene Expression

  2. Fig.1-1. (A) A diagramatic representation of mesophyll leaf cell. (B) Thin section TEM through a meristematic root tip cell.

  3. The nucleus • Contains most of the cell’s genetic information • Serves as the center of regulatory activity

  4. Nucleus of root tip cell

  5. 1) The nuclear envelope is a dynamic structure with many functions NE: nuclear envelopes NP: nuclear pores

  6. 2) Nuclear pore complexes function both as molecular sieves and as active transporters n Protein & r Protein RNA

  7. Basic process of transport in Nuclear Pore Complex 1. Permit free diffusion of small molecules through 9 nm diameter channel 2. A larger regulated central channel functions in the active transport of proteins and RNA molecules

  8. 3) The nucleolus, a prominent organelle in the interphase nucleus, is the ribosome factory of the cell • - Not membrane bounded • - Specialized regions of the nucleous • - A product of active ribosomal genes • - >100 different proteins and nucleic acids • - Transcibing rDNA • Processing rRNA transcript • assembling rRNA • import rProteins into ribonucleoprotein

  9. 4) During mitosis, the nuclear envelope disassembles into vesicles that participate in the formation of new envelopes around the daughter nuclei.

  10. Central dogma of molecular biology

  11. Chapter 7. Control of Gene Expression

  12. An Overview of Gene Expression Arethey from samegenomes ?? Fig. 7-1. A mammalian neuron and a lymphocyte

  13. The different cell types of a multicellular organism • contains the same DNA • They synthesize and accumulate • different sets of RNA and protein molecules. • They do this • without altering the sequence of their DNA.

  14. Fig. 7-2. Evidence that a different cell contains all the genetic instructions necessary to direct the formation of a complete organism.

  15. Different cell types synthesized different sets of proteins 1. Many process are common to all cells, and therefore cells in a single organism have many protein in common. 2. Some proteins are abundant in the specialized cells. 3. A typical human cell expresses 10,000- 20,000 of mRNAs of its 30,000 genes (The pattern of mRNA abundance could be the characteristics of cell types) 4. There are many steps after transcription at which gene expression can be regulated .(post-transcriptional and post translational regulation)

  16. Fig. 7-3 Differences in mRNA expression patterns among different types of human cancer cells

  17. There are many steps after transcription at which gene expression can be regulated .(post-translational regulation) P Fig. 7-4 Differences in the proteins expressed by two human tissues

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