We’ve updated our privacy policy so that we are compliant with changing global privacy regulations and to provide you with insight into the limited ways in which we use your data. Show You can read the details below. By accepting, you agree to the updated privacy policy. Thank you! View updated privacy policy We've encountered a problem, please try again. Gene regulation in eukaryotes in a nutshell covering all the important stages of gene regulation in eukaryotes at transcriptional level, translation level and post-translational level. Gene regulation in eukaryotes in a nutshell covering all the important stages of gene regulation in eukaryotes at transcriptional level, translation level and post-translational level. Presentation on theme: "Chapter 19 Regulation of Gene Expression in Eukaryotes"— Presentation transcript: 1 Chapter 19 Regulation of Gene Expression in Eukaryotes
2 Chapter Outline Ways of Regulating Eukaryotic Gene Expression: An Overview Induction of Transcriptional Activity by Environmental and Biological Factors Molecular Control of Transcription in
Eukaryotes Posttranscriptional Regulation of Gene Expression by RNA Interference Gene Expression and Chromatin Organization Activation and Inactivation of Whole Chromosomes © John Wiley & Sons, Inc. 3
Ways of Regulating Eukaryotic Gene Expression: An Overview 4 Eukaryotic Gene Expression 5 Controlled Transcription of DNA
6 Alternate Splicing of RNA
7 Alternate Splicing of the Rat Troponin T Gene 8
Cytoplasmic Control of mRNA Stability
9 Induction of Transcriptional Activity by Environmental and Biological Factors 10 The Heat-Shock Genes (Proteins)
11 Induction of the Drosophila hsp70 Gene by Heat Shock 12 Regulation of Gene Expression by Steroid Hormones 13 Regulation of Gene Expression by Peptide Hormones
14 Hormone Response Elements
15 Activation of Transcription by Hormones 16 Molecular Control of Transcription in Eukaryotes 17 DNA Sequences that Control Transcription 18 Properties of
Enhancers
19 Tissue-Specific Enhancers of the Drosophila yellow Gene
20 There Are Several Types of Transcription Factors 21 Regulation of Transcription by Enhancers 22 Proteins That Control
Transcription 23 Structural Motifs (smaller fragment) of Transcription Factors
24 -----control elements
25 Model for Enhancer Action
26 Combinatorial Model for Gene Expression 27
Post-transcriptional Regulation of Gene Expression by RNA Interference
28 RNA Interference Small, noncoding RNAs base pair with target sequences in mRNA.
The small RNAs interfere with expression of the target mRNAs. RNAi has been documented in C. elegans, Drosophila, Arabidopsis, and in mammals, including humans. © John Wiley & Sons, Inc. 29 © John Wiley & Sons, Inc.
30 © John Wiley & Sons, Inc. 31
MicroRNAs Some molecules that induce RNAi are derived from microRNA (mir) genes. The mir transcript forms a stem-loop structure that is processed by the enzymes Drosha and Dicer to form an miRNA © John Wiley & Sons, Inc. 32 Sources of siRNA and
miRNA
33 Gene Expression and Chromatin Organization
34 Chromatin packaging: Eu- or hetero-chromatin 35 Molecular Organization of Transcriptionally Active DNA 36 The -Globin Gene Cluster
37 Chromatin Remodeling In preparation for transcription, nucleosomes are altered
by multiprotein complexes in a process called chromatin remodeling. © John Wiley & Sons, Inc. 38 Types of Chromatin Remodeling Complexes
39 Reverse Remodeling Active chromatin can be made inactive by biochemical modifications to histones. Histone deacetylases (HDACs) remove acetyl groups from histone
proteins. Histone methyl transferases (HMTs) add methyl groups to histone proteins. DNA methyl transferases (DNMTs) add methyl groups to nucleotides to inactivate transcription. © John Wiley & Sons, Inc. 40 Euchromatin and
Heterochromatin 41 Chromatin Is Divided
into Euchromatin and Heterochromatin 42 Types of Heterochromatin 43 DNA Methylation Most methylated cytosines are found in the dinucleotide sequence CG, denoted mCpG. The restriction
enzyme HpaII recognizes and cleaves the sequence CCGG, but cannot cleave the sequence when the second cytosine is methylated. © John Wiley & Sons, Inc. 44 CpG Islands CpG dinucleotides occur less often that expected in mammalian genomes, probably due to mutation into TpG dinucleotides over the course of
evolution. The distribution of CpG dinucleotides is uneven. Most CpG islands are located near transcription start sites; cytosines in these regions are rarely methylated. © John Wiley & Sons, Inc. 45 Gene
Expression Is Associated with DNA De-methylation 46 Methylated DNA is Associated with Transcriptional Repression 47 What is eukaryotic gene regulation?In Summary: Eukaryotic Epigenetic Gene Regulation
Epigenetic mechanisms control access to the chromosomal region to allow genes to be turned on or off. These mechanisms control how DNA is packed into the nucleus by regulating how tightly the DNA is wound around histone proteins.
What are the 5 levels of eukaryotic gene regulation?Gene expression in prokaryotes is regulated only at the transcriptional level, whereas in eukaryotic cells, gene expression is regulated at the epigenetic, transcriptional, post-transcriptional, translational, and post-translational levels.
How are genes regulated in eukaryotic cells?Gene expression in eukaryotic cells is regulated by repressors as well as by transcriptional activators. Like their prokaryotic counterparts, eukaryotic repressors bind to specific DNA sequences and inhibit transcription.
Why is gene regulation important in eukaryotes?Gene regulation is essential for viruses, prokaryotes and eukaryotes as it increases the versatility and adaptability of an organism by allowing the cell to express protein when needed.
|