tailieunhanh - Ebook USMLE road map - Genetics: Part 2

(BQ) Part 2 book "USMLE road map - Genetics" presents the following contents: Mitochondrial dysfunction, congenital changes, congenital changes, genetics and cancer, genetics and common diseases, pharmacogenetics, genetics and medical practice. | 6 MITOCHONDRIAL DYSFUN ION I. General Principles A. The mitochondrial chromosome is a double-stranded circular DNA 16 569 bp encoding 22 transfer RNAs tRNAs 2 ribosomal RNAs and 13 proteins essential for oxidative phosphorylation Figure 6-1 . B. Each mitochondrion of the hundreds in any cell contains at least one copy of the DNA. 1. When all mitochondrial DNAs in the same the cell are the same the cell is said to be homoplasmic when they differ the cell is heteroplasmic. 2. The distribution of mitochondrial DNA s may vary among cells and may change with aging. C. Mitochondria in the egg outnumber those in sperm by 1000-fold and sperm mitochondria likely are destroyed in the egg cytoplasm. Thus traits referable to mitochondrial DNA are always transmitted from the mother giving a characteristic pedigree structure sometimes called cytoplasmic inheritance Figure 6-2 . 1. Either sex can be affected. 2. Males cannot or very rarely transmit the trait. II. Mitochondrial Physiology A. Defective mitochondrial function often affects the energy supply of the cell and thus nerves and muscles often show problems first because of their high energy requirements Table 6-1 . B. Mutations in mitochondrial DNA develop up to 10-fold faster than those in nuclear DNA likely due to local accumulation of reactive oxygen species during oxidative phosphorylation. C. Integrity of oxidative phosphorylation declines with aging in somatic cells presumably due to accumulated mutations in mitochondrial DNA eg a 5-kilobase kb deletion often accumulates in hearts with aging but rarely is seen before age 40 . D. Most mitochondrial proteins are encoded by nuclear genes. 1. Mutations affecting mitochondria can thus arise in two genomes. 2. The site of mutations usually can be distinguished by pedigree pattern s . 68 Copyright 2008 by The McGraw-Hill Companies Inc. Click here for terms of use. Chapter 6 Mitochondrial Dysfunction 69 Origin MERRF 8344 G 5 Kb deletion Complex I genes OTO 1555G MELAS 3243 G

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• USMLE road map Genetics
• Mitochondrial dysfunction
• Congenital changes
• Congenital changes
• Genetics and cancer
• Genetics and common diseases
• Chromosomal disorders
• Autosomal dominant inheritance
• Autosomal recessive inheritance
• X linked inheritance
• Vascular pathology
• Fundamentals of angiography
• Noninvasive vascular imaging
• Vascular interventions
• Carotid and vertebral arteries
• Inferior vena cava
• Portal and hepatic veins
• Image guided percutaneous biopsy
• Gastrointestinal tract intervention
• Percutaneous abscess
• Musculoskeletal intervention
• Image guided breast intervention