真核生物基因组的结构和功能

Structure and Function of Eukaryotic genome英文版分子生物学简述

Structure and Function of Eukaryotic genome

• Unique structure
  • The proportion of coding sequences of genes in the eukaryotic genome is much smaller than the non-coding sequences
  • Higher eukaryotic genes contain a large number of multigene families and pseudogenes in repetitive eukaryotic genomes
  • About 60% of human genes are posttranscribed with alternative splicing, and 80% of them will change the sequence of the protein
  • Eukaryotic genomic DNA binds to proteins to form chromosomes, which are stored in the nucleus. In addition to gametocytes, the genome of somatic cells is diploid, that is, there are two copies of the homologous genome
  • Even on the chromosome with the highest gene density, there are geneticless "desert regions' , namely, without any gene coding sequence within the 500-kb region
• Repetitive sequence
  • Highly repetitive sequence (20%)
    • design feature
      • inverted repeats
      • inverted repeats
    • function
      • Participate in the regulation of replication levels Participate in the regulation of gene expression
      • Participate in chromosome pairing
  • Moderately repetitive sequence
    • Short scattered in the nuclear element
    • Long scattered in nuclear elements
  • Lowly repetitive sequence
    • Most genes encoding proteins fall into this category
    • The proteins encoded by single-copy sequences largely embody the various functions of living organisms
    • Special significance for medical practice (localization mutation therapy)
• Multigene family
  • Gene families are distributed in clusters on a single chromosome, and they can act simultaneously to synthesize certain proteins
  • The distribution of clusters of different members of a gene family is found on different chromosomes that encode a set of functionally closely related proteins
  • Several DNA families of several single-copy genes or several groups of genes with similar sequence, but function not necessarily related can be assigned to gene superfamilies
• Pseudogene
  • Pseudogenes are a stretch of DNA sequence present in the genome that is very similar to normal genes but generally cannot be expressed
    • Unprocessed pseudogenes originate from mutations in multiple or single-copy genes or from incomplete duplication of genes
    • Processed pseudogenes often lack the regulatory sequences required for normal gene expression, have no introns, and may have a ploy (A) tail
• Mitochondrial DNA structure
  • Ring molecule
  • Diseases caused by mitochondrial DNA mutations should be maternally inherited