19 Questions
What is the primary cause of a genetic disease according to the given text?
Mutation in the DNA of an essential gene
Which type of mutations causes a genetic disease by decreasing the amounts and functions of gene products?
Mutations at the structural genes
What is the result of mutations at the control genes according to the given text?
Decreased synthesis velocity of proteins
In which type of genetic disorder do gain function mutations alter the biochemical phenotype?
Single gene disorders
What is the biochemical lesion in Tay-Sachs disease?
Deficiency of hexoaminidase A
What is the genetic basis of almost all lysosomal storage diseases?
Autosomal recessive inheritance
What is the main cause of death in patients with Duchenne muscular dystrophy?
Respiratory failure
Which gene is affected in both Duchenne and Becker muscular dystrophy?
Dystrophin gene
What is the estimated mutation rate for the DMD gene in normal males?
(10)-4
What is the size of the DMD gene?
2300 kb
What is the mechanism of mutation in Duchenne or Becker muscular dystrophy?
Gene deletion
What is the phenotype associated with Becker muscular dystrophy if the patient is still walking at the age of 16?
BMD
Which protein is responsible for carrying oxygen in red blood cells?
Hemoglobin A
What is the characteristic of red blood cells in thalassemia minor?
Microcytic
Which type of CFTR mutations results in an improperly functioning Cl⁻ channel?
Class III
What is the common cause of cystic fibrosis?
CFTR gene mutation
Which gene mutation leads to the inability to break down the amino acid phenylalanine?
Phenylalanine hydroxylase gene mutation
What is the severe form of thalassemia characterized by little or no production of beta globin?
Thalassemia major
Which type of CFTR mutations results in defective conduction through the Cl⁻ channel?
Class IV
Study Notes
- Thalassemia: a blood disorder caused by decreased production of beta globin, a subunit of hemoglobin
- Hemoglobin: a protein in red blood cells responsible for carrying oxygen
- Thalassemia: results from mutations in the beta globin gene, leading to impaired synthesis or function of the protein
- β-thalassemias: subtypes of thalassemia characterized by reduced beta globin production, leading to anemia and red blood cell damage
- Single base pair mutations are common causes of β-thalassemia
- Thalassemia minor: a mild form of the disorder characterized by hypochromic, microcytic red blood cells and possible mild anemia
- Thalassemia major: a severe form of the disorder characterized by little or no production of beta globin and the absence of normal hemoglobin A
- CFTR gene mutations: a common cause of cystic fibrosis, a genetic disorder affecting the respiratory and digestive systems, characterized by the production of thick, sticky mucus
- Class I CFTR mutations: result in a defect in protein production, leading to premature stop codons or mutations that generate truncated proteins
- Class II CFTR mutations: result in defective protein processing, leading to misfolded proteins that are not transported to the cell membrane
- Class III CFTR mutations: result in defective regulation of protein, leading to an improperly functioning Cl¯ channel
- Class IV CFTR mutations: result in defective conduction through the Cl¯ channel, leading to an inability to transport chloride ions properly
- Thalassemia: can be diagnosed through DNA mutation analysis and prenatal testing
- Phenylketonuria (PKU): a genetic disorder caused by mutations in the phenylalanine hydroxylase gene, leading to an inability to break down the amino acid phenylalanine
- PKU: can be detected through newborn screening and treated with a phenylalanine-restricted diet
- Cystic fibrosis: can be detected through DNA mutation analysis and treated with medications to help thin the mucus in the lungs and improve respiratory function.
Test your knowledge of the molecular and biochemical principles underlying genetic disorders. Explore the role of DNA mutations, gene products, mRNA, and proteins in causing single gene disorders.
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