Biochemistry Flashcards
What cell CANNOT utilize ketones as an energy source? Why?
RBCs because they lack mitochondria to convert it into acetyl CoA
Fabry’s disease
What is it? how is it inherited What are characteristics?
lysosomal storage disease
X-linked recessive deficeincy in alpha-galactosidase
accumulation of globotriaosylceramide
kidney disease, angiokeratoma, cardiac disease, peripheral neuropathy
what enzyme is defective in Lesch-Nyhan? If this enzyme is defective, what enzyme activity is increased?
Hypoxanthine-Guanine Phosphoribosyltransferase (defective)
phosphoribosyl pyrophosphate aminotransferase (increased purine de novo synthesis)
What is a silent mutation? What are its consequences?
change in nucleotide (often wobble base aka 3rd) but amino acid stays the same
What is a missense mutation? what are its consequences?
nucleotide substitution resulting in a changed amino acid
e.g. sickle cell (glutamic acid –> valine)
What is a nonsense mutation? What are its consequences?
nucleotide substitution resulting in an early stop codon
Usually results in a nonfunctional protein
What is a frameshift mutation? what are its consequences?
deletion OR insertion of a number of nucleotides NOT divisible by 3
Protein may be shorter OR longer and its function may be disrupted or altered
What type of connections allow osteocytes to communicate?
gap juncitons
What is the most common cause for down syndrome? (default in what process)
meiotic nondisjucntion
Through what mechanism does ionizing radiation kill cells?
1) double stranded DNA breaks
2) free radical formation
What is the inheritance of CF?
autosomal recessive
What is the most common mutation in CF? What does this mutation do?
3-base pair deletion at phenylalanine at amino acid position 508 (delta-F508)
causes misfolding of the CFTR channel which results in proteasomal degradation, preventing it from reaching the cell surface
What are the steps of elestin sythesis
mRNA – tropoelastin –> microfibrillar scaffold –> desmosine cross-links via lysyl oxidase
True or False: The lagging strand in DNA synthesis is unique because it must synthesize mutliple, short DNA fragments
true
What is the mnemonic for the familial dyslipidemias?
1 LP, 2 LD, 3 with E, 4 gets more
What is deficient in type I familial dyslipidemia? What is elevated? what are the clinical findings?
LPL
TGs (chylomicrons)
can present with: acute pancreatitis, eruptive xanthomas, creamy layer in supernatant
What is deficient in type II familial dyslipidemia? What is elevated? what are the clinical findings?
LDL receptor
cholesterol (LDL)
tendon xanthoma (achilles)
What is deficient in type III familial dyslipidemia? What is elevated? what are the clinical findings?
apoE
chylomicron and VLDL remnants (products after LDL and VLDLs get hydrolized via LPL)
palmar xanthomas
What is deficient in type IV familial dyslipidemia? What is elevated? what are the clinical findings?
ApoA-V
VLDL
increased risk for pancreatitis
What is the role of DNA polymerase III?
5’ to 3’ DNA synthesis and 3’ to 5’ exonuclease activity (this means it also proofreads the growing DNA strand and can fix an error should it occur)
What is the role of DNA polymerase I?
5’ to 3’ DNA synthesis and 3’ to 5’ exonuclease activity
degrades RNA primer and replaces it with DNA
What is the role of ligase?
joining of okazaki fragments in the lagging strand
What is the function of primase?
synthesis of an RNA primer
What is the MELAS syndrome of mitochondrial myopathies? What does muscle biopsy show?
MELAS = mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes
biospy shows ragged red fibers (due to accumulation of diseased mitochondria)
