Biochem - Genetics Flashcards
What happens to DNA upon exposure to UV light?
Pyrimidine dimers are formed
They are then recognized by an endonuclease complex that intiates repair by nicking the damaged strand
What is Pleiotropy?
The occurrence of multiple, seemingly unrelated phenotypic manifestations, often in different organ systems, as a result of a single genetic defect is termed pleiotropy.
What is the most likely inheritace pattern seen here?
Autosomal Recessive
Note: Autosomal recessive disorders affect 25% of offspring of asymptomatic heterozygous carrier parent
A child presents with intellectual disability, gait abnormality, eczema, and a musty body odor.
What is the most likely diagnosis?
What is the inheritance pattern?
What is the likelihood of the next child having the same disease?
PKU
Autosomal Recessive
1/4
(The probability that heterozygous carrier parents will transmit an autosomal recessive disease such as PKU to a child is 1/4)
A patient is undergoing ionizing radiation therapy for testicular cancer.
How does this therapy work?
Ionizinig radiation causes:
- double stranded DNA breaks
- formation of free radicals
What are the promoters of transcription in eukaryotic cells?
TATA and CAAT
What mutation(s) result in duchenne muscular dystrophy?
1. Frameshift mutation
2. Nonsense (premature stop codon)
Which of the following mutations is the most likely to have caused Duchenne Muscular Dystophy:
D. UCA –> UGA
Nonsense mutation (regular codon to stop codon)
Which letter corresponds to the location where ribosomes are formed?
B - The nucleolus
A patient presents with a disease that occurs as a result of dysfunctional protein.
What is the most likely cause of this?
Impaired Splicing
Splicing is performed by spliceosomes, which remove introns. Splice site mutations may result in inappropriate removal of exons and retention of introns, leading to the formation of dysfunctional proteins.
Which DNA/RNA enzyme only functions within the nucleolus?
RNA Polymerase I
The nucleolus is the site of ribosomal subunit maturation and assembly. RNA polymerase I functions exclusively within the nucleolus
What 3 mutations can result in down syndrome?
- Meiotic Nondisjunction (more likely in older mother)
- Unbalaced Translocation
- Mosaicism
Nucleosomes are composed of DNA wrapped around a core of 8 histone proteins.
What protein is located outside of this histone core and helps package nucleosomes into more compact structures by binding and linking the DNA between adjacent nucleosomes?
Histone H1
How does mitochondrial dysfunction present?
- myopathy
- nervous system dysfunction
- lactic acidosis
- red fibers on muscle biopsy
What causes genomic imprinting?
DNA Methylation
