2011 biochem Flashcards
Which of the following shows a variation in the level of its stores throughout the day and overnight and is responsible for supplying blood with glucose?
Liver
Which amino acid deletion is responsible for cystic fibrosis?
Phenylalanine
What is the most common sequence in the human genome?
Alu sequence
Which of the following is the precursor for the amino acids aspartate and aspargine?
Oxaloacetate
Which of the following processes will be inhibited if a drug that blocks sprecher’s shunt is administered?
Converting C24,6 to C22,6
What is the product of the rate limiting step of cholesterol synthesis catalyzed by HMG-CoA reductase?
Mevalonate
What is a consequence of a diet rich in trans fats?
Low LDL receptor function
What stimulates gluconeogenesis?
Low levels of fructose-2,6-bisphosphate
Which enzyme is responsible for extracting ammonia from glutamate in the liver?
Glutamate dehydrogenase
What is an effect of the superoxide free radical?
Degrading the iron-sulfur centers
Which enzyme catalyzes the rate limiting step of fatty acid synthesis?
Acetyl-CoA carboxylase
A lysosomal enzyme lost its leader sequence as a result of a mutation that altered the sequence of its gene. Where will you find this enzyme after it is synthesized?
Cytoplasm
What will contribute fluidity to the cytoplasmic membrane?
unsaturated fatty acids
Which substrate’s usage for gluconeogenesis increases at first and then decreases during intermediate starvation?
Amino acids
Which of the following vitamins is most likely to result in toxicity?
Vitamin A (any fat soluble vitamin)
What is broken down in the intestine and then resynthesized following absorption?
Triglycerides
Which of the following is essential for β-oxidation of odd-chain fatty acids?
Vitamin B12
In which sub-cellular location are ketone bodies synthesized?
Mitochondria
What molecule mediates the transfer of electrons from a 2 electron carrier to a 1 electron carrier?
FAD
What are transcription factors?
Regulatory proteins
A person has triacylglyceridemia but his apo-CII was normal. What should be investigated next?
Lipoprotein lipase
What happens to the Ras protein in cancer?
It is permanently activated
What is the objective of the non-oxidative stages of pentose phosphate pathway in rapidly proliferating cells?
The generation of ribose-5-phosphate
What are enhancers and supressors?
DNA elements
Which carbons in ddNTP don’t have hydroxyl groups?
2’,3’ deoxyribose
What is the cause in HbS that leads to the sickle cell morphology in sickle-cell anemia?
Aggregation at Low oxygen tension
Which amino acid is phosphorylated on proteins?
Serine
Which of the following is inhibited upon administration of aa-tRNA analogs?
Elongation
What leads to the formation of pyramidine dimers?
UV radiation
Which amino acid is responsible for beta-turn in the structure of a protein?
Proline
What is similar regarding isoenzymes?
They catalyze the same reaction
Why does the liver express glucokinase?
To ensure rapid glucose uptake after a meal
