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Genomic Repetitive Elements (Human Focus)

Genomic Repetitive Elements (Human Focus). TYPES OF ELEMENTS. Tandem repeats: a) satellite DNA 1) centromeric and heterochromatic 2) minisatellite 3) microsatellite b) telomers Interspersed repetitive elements: a) transposons 1) Class I – copy and paste (RNA intermediate)

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Genomic Repetitive Elements (Human Focus)

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  1. Genomic Repetitive Elements (Human Focus)

  2. TYPES OF ELEMENTS Tandem repeats: a) satellite DNA 1) centromeric and heterochromatic 2) minisatellite 3) microsatellite b) telomers Interspersed repetitive elements: a) transposons 1) Class I – copy and paste (RNA intermediate) a) retrotransposons (no envelope protein) b) Long Interspersed Nuclear Elements (LINES) c) Short Interspersed Nuclear Elements (SINES; example: Alu) 2) Class II – cut and paste (DNA element) b) Endogenous Retroviruses (ERVs) (contain Envelope Proteins)

  3. Relationship of retroelements Retroelements Retroviruses loss of env Class I retrotransposonsTHE1, copia, Ty loss of LTR Class II retro-transposons loss of pol (RT)

  4. gag LTR pol env LTR Retrovirus Reverse Transcriptase Matrix Capsid Integrase Protein Nucleocapsid Viral RNA genome Viral Envelope Protein 10 KB in size

  5. Retrovirus Replication Cycle Virus Entry Uncoating & Reverse Transcription Release & Maturation Nuclear Translocation Integration into host genome Assembly Transcription Translation

  6. FOR RETROVIRUSES REVERSE TRANSCRIPTION . . . A) OCCURS IN THE CYTOSOL B) USES A t-RNA PRIMER TO INITIATE REVERSE TRANSCRIPTION

  7. Retroviruses Germline Cells Somatic Cells Infection leads to integration of retrovirus genome into the host genome Ovum Sperm e.g., liver cells virus passed on to progeny virus NOT passed on to progeny Endogenous Retrovirus (ERV) Exogenous Retrovirus

  8. Repeated infections in the germline are referred to as “expansions” Germline Cells

  9. LINES AND SINES LINE Proteins: Orf 1 – RNA binding protein Orf2 – Reverse transcriptase Endonuclease activity

  10. FOR LINES AND SINES REVERSE TRANSCRIPTION . . . A) OCCURS IN THE NUCLEUS B) USES THE NICKED DNA TO INITIATE REVERSE TRANSCRIPTION

  11. WHAT ARE THE GENOMIC AND EVOLUTIONARY CONSEQUENCES OF THESE MOBILE ELEMENTS?

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