Untitled Quiz

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Which of the following statements about phenylalanine degradation are TRUE?

phenylalanine hydroxylase uses tetrahydrobiopterin as a cofactor (correct)
a deficiency of phenylalanine hydroxylase results in higher concentration of phenylpyruvate, phenyllactate and phenylacetate (correct)
phenylalanine hydroxylase uses ascorbic acid as a cofactor
a deficiency of homogentisate oxidase causes tyrosinemia type II
phenylalanine hydroxylase uses NADPH as a cofactor

Which statements concerning the anabolic processes are CORRECT?

they are processes of oxidation of substrate molecules
they are processes of synthesis of cell-specific proteins and nucleic acids (correct)
they are processes of energy accumulation in microergic compounds
they are reductive processes that “store” energy in the bonds of organic molecules (correct)
they are processes of synthesis of ATP

Which of the following hormones have a membrane receptor?

retinoic acid
calcitriol
triiodothyronine
ACTH (correct)
glucagon (correct)

Glycogen synthase is:

active in its dephosphorylated form (D) Signup and view all the answers

Which processes do NOT take place in the liver?

synthesis of chylomicrons (C), ammoniagenesis (E) Signup and view all the answers

What type of bond connects the nucleotides in DNA?

3', 5'-phosphodiester (E) Signup and view all the answers

Which of the following statements about Krebs cycle is TRUE?

the cycle represents the final steps of oxidation of C-atoms that come from different substrates of biological oxidation (B), the regulatory enzymes are less active when the levels of NADH are high (C), some of the intermediates of the cycle could be used for the synthesis of carbohydrates, lipids and proteins (D) Signup and view all the answers

“Jaundice” is a condition of hyperbilirubinemia, the reasons for which could be:

defects in the enzyme UDP-glucuronyl transferase in the liver or other liver diseases (A), abnormal breakdown of red blood cells (accelerated hemolysis) (B), obstruction of the biliary paths (C) Signup and view all the answers

Which of the following statements about the regulation of the synthesis of fatty acids is TRUE?

citrate activates the main regulatory enzyme (E) Signup and view all the answers

How many ATP molecules are synthesized in the microsomal electron-transport chains?

three ATP molecules (E) Signup and view all the answers

Which of the following compounds does NOT derive from arginine:

ethanolamine (B) Signup and view all the answers

The N-atom in carbamoyl phosphate, used for the pyrimidine ring synthesis, derives from:

ammonia (NH3) (A) Signup and view all the answers

Which of the following statements about glycogen degradation in the liver is TRUE?

it is the first mechanism for maintenance of the blood glucose level during fasting periods (C) Signup and view all the answers

Cholesterol:

is synthesized in the cytoplasm and the endoplasmic reticulum (A), is synthesized from Acetyl-CoA (C), the main regulatory enzyme of the synthesis is HMG-CoA synthase (E) Signup and view all the answers

Indicate the protein involved in the storage of iron in cells?

ferritin (D) Signup and view all the answers

Which of the following phospholipids contain sphingosine, one fatty acid, a phosphate group and choline?

sphingomyelins (B) Signup and view all the answers

Which of the following mechanisms play role in ammonia detoxification?

urea biosynthesis in the kidneys (A), glutamine biosynthesis in the brain (B), reductive amination of alpha-ketoglutarate (C) Signup and view all the answers

Which of the following statements regarding the oxidation of fatty acids are CORRECT?

oxidation of short-chain fatty acids occurs in peroxisomes (B), FADH2 and NADH are obtained in each of the cycles of β-oxidation in the mitochondria (C), β-oxidation of fatty acids with an even number of carbon atoms, below 18 occurs in the mitochondria of the cells (D) Signup and view all the answers

Which of the following lipoprotein complexes transports exogenous (dietary) lipids, mainly TAG?

chylomicrons (C) Signup and view all the answers

Which are thе regulatory enzymes of pyrimidine biosynthesis?

aspartate transcarbamoylase (B), carbamoyl phosphate synthetase II (E) Signup and view all the answers

Which of the following enzymes release arachidonic acid from the membrane glycerophospholipids?

phospholipase A2 (B) Signup and view all the answers

Which of the following reactions require S-adenosyl methionine (SAM) as a donor of methyl groups?

norepinephrine to epinephrine (A), dUMP to dTMP (B), ethanolamine to choline (E) Signup and view all the answers

Which of the following statements about insulin and glucagon are TRUE?

glucagon is an activator of gluconeogenesis and glycogen degradation in liver (A), insulin is secreted in response to hyperglycemia (B), insulin inhibits the pentose phosphate pathway (E) Signup and view all the answers

Complex I of the mitochondrial respiratory chains:

receives electrons from the reduced cofactors of the oxidative processes in the mitochondrial matrix (A), co-works with cytochromes as its cofactors (C), transports electrons towards ubiquinone (D) Signup and view all the answers

Which of the following compounds are considered as “the key molecules” for the cell metabolism?

glyceraldehyde-3-phosphate (A), glucose-6-phosphate (C), acetyl-CoA (E) Signup and view all the answers

Porphyrias belong to a heterogenic group of diseases where:

there are deficiencies of enzymes included in heme synthesis pathway (B), the regulatory enzymes of heme synthesis “escape” their allosteric regulation (C), there is a lack of heme and development of anemia (D) Signup and view all the answers

Phenylalanine Degradation

The metabolic process of breaking down phenylalanine, requiring certain cofactors.

Krebs Cycle

A series of chemical reactions used by all aerobic organisms to generate energy through the oxidation of acetate derived from carbohydrates and fats.