医学遗传学 04基变的分子机制eng v

1、medical geneticsmedical genetics the most common gene change involves a single base mismatch-a misspelling-placing the wrong base in the dna. at other times, a single base may be dropped or added. and sometimes large pieces of dna are mistakenly repeated or deleted. medical geneticsmedical genetics

2、when a gene contains a mutation, the protein encoded by that gene is likely to be abnormal. medical geneticsmedical geneticsmedical genetics gene mutations can be either inherited from a parent or acquired. medical geneticsmedical genetics hereditary mutations are carried in the dna of the reproduct

3、ive cells. when reproductive cells containing mutations combine to produce offspring, the mutation will be in all of the offsprings body cells. medical genetics the fact that every cell contains the gene change makes it possible to use cheek cells or a blood sample for gene testing. medical genetics

4、medical genetics acquired mutations are changes in dna that develop throughout a persons lifetime. medical genetics although mistakes occur in dna all the time, especially during cell division, a cell has the remarkable ability to fix them. but if dna repair mechanisms fail, mutations can be passed

5、along to future copies of the altered cell. medical geneticsmedical genetics(1) morphological mutations give rise to altered forms. medical geneticsmedical geneticsmedical genetics(2) lethal mutations result in nonviable organisms. medical genetics(3) conditional mutations gives a mutant phenotype u

6、nder restrictive conditions (environmental) and causes a wild type phenotype under permissive conditions. medical genetics(4) biochemical mutations result in the inability to carry out a specific biochemical pathway (inborn errors of metabolism). medical genetics(5) loss-of-function (null) mutations (lof) result in no gene function are usually recessive although some haploinsufficient dominant lof mutations exist. medical geneticsmedical genetics a common lof mutation is the partial loss-of-function or leaky mutation. medical geneticsmedical genetics(6) gain-of-function mutation (gof)