基因与基因组学2.ppt

3、单核苷酸多态性(single-nucleotide polymorphism, SNP) replacement of single nucleotide acid appears in the specific position of genome DNA molecule Define a SNP position must suffice the frequency of the variation of this position appearing more than 1% in public 1996年由麻省理工学院 Lande ES提出。 According to the nucleus acid replacement type, SNP contains: G/A, C/T, G/T, A/C, A/T和 G/C. It is the most widespread hereditary variation in the human genome, occupies 90% of DNA polymorphism SNP of gene and regulation area, SNP may affect the gene function. At the same time, SNP is also the important genetic marker uses in seeking for disease susceptibility gene at present example of gene detection RFLP： * * * * 鸡卵清蛋白成熟mRNA与DNA杂交电镜图 DNA mRNA 法国科学家Chambon的遗憾 7. alternative splicing Introns existing in all sorts of gene don’t encode protein generally. they were removed by alternative cleaving, one inrton can be act as exon in another condition------alternative splicing 8. there is genefamily Genefamily refers to a group of genes that the sequence of nucleotide acid is same or similar, or the function of encoded products are similar Stability: Different nations, folks and individuals have the same number of chromosome and gene, the same distribution of gene, and basically the same nucleotide acid sequence There are approximately 3×109bp in complete sequence, about 3.5000 coding genes 三、human genome the gene coding protein only account for two--three percent in genome and exist in single copy form. rest of DNA sequence mostly are inserts and repeats lied in interior and interspace of gene （一）Many repetitive sequences exist in human genome Highly Repetitive Sequence: Repetitive frequency106, not encode for protein or RNA a.　inverted repeats An?inverted repeat?(or?IR) is a sequence of?nucleotides?followed downstream by its?reverse complement.[1]?The intervening sequence of nucleotides between the initial sequence and the reverse