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David Sadava H. Craig Heller Gordon H. Orians William K. Purves David M. Hillis Biologia.blu B – Le basi molecolari della vita e dell’evoluzione The Eukaryotic.

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Presentation on theme: "David Sadava H. Craig Heller Gordon H. Orians William K. Purves David M. Hillis Biologia.blu B – Le basi molecolari della vita e dell’evoluzione The Eukaryotic."— Presentation transcript:

1 David Sadava H. Craig Heller Gordon H. Orians William K. Purves David M. Hillis Biologia.blu B – Le basi molecolari della vita e dell’evoluzione The Eukaryotic Genome and Its Expression

2 What are the characteristics of the eukaryotic genome? How are eukaryotic gene transcripts processed? How is eukaryotic gene transcription regulated? The Eukaryotic Genome and Its Expression

3 Key differences between eukaryotic and prokaryotic genomes: eukaryotic genomes are larger; eukaryotic genomes have more regulatory sequences; much of eukaryotic DNA is non-coding. The Eukaryotic Genome and Its Expression - What are the characteristics of the eukaryotic genome? ?

4 The Eukaryotic Genome and Its Expression - What are the characteristics of the eukaryotic genome? ?

5 Eukaryotes have multiple chromosomes. In eukaryotes, translation and transcription are physically separated which allows many points of regulation before translation begins. The Eukaryotic Genome and Its Expression - What are the characteristics of the eukaryotic genome? ?

6 Eukaryote model organisms: yeast, Saccharomyces cerevisiae; nematode (roundworm), Caenorhabditis elegans; fruit fly, Drosophila melanogaster; thale cress, Arabidopsis thaliana. The Eukaryotic Genome and Its Expression - What are the characteristics of the eukaryotic genome? ?

7 Eukaryotic mRNA is transcribed in the nucleus but translated in the cytoplasm The Eukaryotic Genome and Its Expression - What are the characteristics of the eukaryotic genome?

8 Eukaryote genomes have two types of highly repetitive sequences that do not code for proteins: minisatellites: 10–40 bp, repeated several thousand times. Number of copies varies among individuals— provides molecular markers; microsatellites: 1–3 bp, 15–100 copies. The Eukaryotic Genome and Its Expression - What are the characteristics of the eukaryotic genome? ?

9 Other moderately repetitive sequences can move from place to place in the genome - transposons. Transposons make up 40 percent of human genome, only 3–10 percent in other sequenced eukaryotes. The Eukaryotic Genome and Its Expression - What are the characteristics of the eukaryotic genome? ?

10 DNA transposons and transposition The Eukaryotic Genome and Its Expression - What are the characteristics of the eukaryotic genome?

11 The function of the transposons is unclear. They may be cellular parasites. If a transposon is inserted into a coding region, a mutation results. If it’s in a somatic cell, cancer can result. Transposons can carry genes to new locations—adding to genetic variation. Transposons may have played a role in endosymbiosis: genes from the once- independent prokaryotes may have moved to the nucleus by DNA transposons. The Eukaryotic Genome and Its Expression - What are the characteristics of the eukaryotic genome? ?

12 Transcription of an eukaryotic gene (part 1) The Eukaryotic Genome and Its Expression - What are the characteristics of the eukaryotic genome?

13 Transcription of an eukaryotic gene (part 2) The Eukaryotic Genome and Its Expression - What are the characteristics of the eukaryotic genome?

14 Protein-coding genes have noncoding sequences—introns. The coding sequences are extrons. Transcripts of introns appear in the pre- mRNA, they are removed from the final mRNA. The Eukaryotic Genome and Its Expression - What are the characteristics of the eukaryotic genome? ?

15 RNA splicing removes introns and splices exons together. Pre-mRNA is bound by small nuclear ribonucleoprotein particles (snRNPs). Consensus sequences are short sequences between exons and introns. snRNP binds here, and also near the 3′ end of the intron. The Eukaryotic Genome and Its Expression - How are eukaryotic gene transcripts processed?

16 With energy from ATP, proteins are added to form an RNA-protein complex, the spliceosome. The complex cuts pre-mRNA, releases introns, and splices exons together. The Eukaryotic Genome and Its Expression - How are eukaryotic gene transcripts processed?

17 The spliceosome The Eukaryotic Genome and Its Expression - How are eukaryotic gene transcripts processed?

18 During development, different globin genes are expressed at different times: differential gene expression. γ-globin is in hemoglobin of human fetus—it binds oxygen more tightly than adult hemoglobin. The Eukaryotic Genome and Its Expression - How are eukaryotic gene transcripts processed?

19 Differential expression in the globin gene family The Eukaryotic Genome and Its Expression - How are eukaryotic gene transcripts processed?

20 Some gene families have pseudogenes—from a mutation that results in loss of function. Pseudogenes may lack a promoter, or recognition sites for removal of introns. They are designated by ψ (psi). Expression of genes must be precisely regulated during development. Gene expression can be regulated at several points in the transcription and translation processes. The Eukaryotic Genome and Its Expression - How are eukaryotic gene transcripts processed?

21 The Eukaryotic Genome and Its Expression – How is the eukaryotic gene transcription regulated? ? Potential points for the regulation of gene expression (part 1)

22 Potential points for the regulation of gene expression (part 2) The Eukaryotic Genome and Its Expression – How is the eukaryotic gene transcription regulated?

23 Potential points for the regulation of gene expression (part 3) The Eukaryotic Genome and Its Expression – How is the eukaryotic gene transcription regulated?

24 Proteasome Breaks Down Proteins Local remodeling of chromatin for transcription (part 1) The Eukaryotic Genome and Its Expression – How is the eukaryotic gene transcription regulated?

25 Local remodeling of chromatin for transcription (part 2) The Eukaryotic Genome and Its Expression – How is the eukaryotic gene transcription regulated?

26 Transcription factors, regulators, and activators (part 1) The Eukaryotic Genome and Its Expression – How is the eukaryotic gene transcription regulated?

27 Transcription factors, regulators, and activators (part 2) The Eukaryotic Genome and Its Expression – How is the eukaryotic gene transcription regulated?

28 Coordinating gene expression (part 1) The Eukaryotic Genome and Its Expression – How is the eukaryotic gene transcription regulated?

29 Coordinating gene expression (part 2) The Eukaryotic Genome and Its Expression – How is the eukaryotic gene transcription regulated?

30 Transcription from multiple genes for rRNA The Eukaryotic Genome and Its Expression – How is the eukaryotic gene transcription regulated?

31 Alternative splicing results in different mature mRNAs and proteins The Eukaryotic Genome and Its Expression – How is the eukaryotic gene transcription regulated?

32 Proteasome breaks down proteins The Eukaryotic Genome and Its Expression – How is the eukaryotic gene transcription regulated?


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