Nutritional biochemsitry Flashcards
What substance is most likely deficient following excess consumption of raw eggs?
biotin
The use of ___ and ingestion of ___ may cause a deficiency in biotin.
antibiotics
raw eggs
What are the major biochemical functions of potassium?
maintains fluid and electrolyte balance across membranes, maintains pH, maintains excitability of nerves
Name three clinical consequences of taking too much vitamin D.
hypercalcemia, loss of appetite, stupor
Symptoms: hemolysis, neurologic problems, retinitis pigmentosa. Vitamin deficiency?
Vitamin E
Where is the body is calcium distributed?
99% bone
1% in blood/tissues
Vitamin C facilitates absorption of ___.
iron
Name two symptoms caused by a deficiency of vitamin A.
night blindness and dry skin
What are the three main causes of vitamin B12 deficiency?
malabsorption, lack of IF, absence of terminal ileum
What is the precursor of coenzyme A?
panthothenate (B5)
Where in the body is phosphorus distributed?
85% bone
15% as esters (lipids, proteins, anhydrides) and inorganic phosphate
Where in the body is selenium distributed?
kidney, heart, liver, pancreas, muscle
Name three key enzymes that require ascorbate as a cofactor. Identify the related pathways.
prolyl and lysyl hydroxylases (collagen synthesis)
dopamine hydroxylase (catecholamine synthesis)
Symptoms: metaplasia of corneal epithelium, dry eyes, bronchitis, pneumonia, follicular hyperkeratosis. What vitamin deficiency?
vitamin A
Name the crucial vitamin that must be included in the treatment of an alcoholic with hypoglycemia.
thiamine
What does a deficiency of vitamin B1 cause?
Beriberi dz and Wernicke-Korsakoff syndrome
Where is vitamin K synthesized?
in the intestines by normal flora
When vitamin B6 is converted to ___, it is a cofactor in what three processes?
pyridoxal phosphate
cofactor in transamination, decarboxylation, trans-sulfuration
Name the enzyme type that requires niacin (B3) as a cofactor.
dehydrogenases
Name the vitamin that is a cofactor for oxidative decarboxylation of alpha-keto acids and is involved with the enzyme transketolase in the HMP shunt.
B1 (thiamine)
Vitamin C is necessary for the ___ of proline and lysine in ___ synthesis.
hydroxylation
collagen
Vitamin C is necessary as a cofactor for the conversion of dopamine to ___.
norepinephrine
What are the major biochemical functions of selenium?
a component of glutathione peroxidase, which helps to destroy free radicals, protection against heavy metal toxicity
Vitamin E functions as an ___ to protect RBCs from ___.
antioxidant
hemolysis
Where in the body is potassium distributed?
major intracellular cation
What are the major biochemical functions of chromium?
forms glucose tolerance factor (w/ nicotinic acid)
GTF promotes formation of disulfide bridges between insulin and its receptor, improving uptake of glucose into cells
Why does thiamine deficiency have such strong neural symptoms?
B1 is a cofactor of pyruvate dehydrogenase
Deficiency of vitamin E causes?
increased fragility of erythrocytes
Name four enzymes that require pantothenic acid as a cofactor. Identify the related pathways.
fatty acid synthase (fatty acid metabolism), fatty acyl CoA synthase (fatty acid metabolism), pyruvate dehydrogenase (PDH), alpha-ketoglutarate dehydrogenase (TCA)
Name the two key enzymes that require cyanocobalamin (B12) as a cofactor. Identify the related pathways.
homocysteine methyl transferase (Met, SAM), methylmalonyl-CoA mutase (odd chain FAs, valine, met, ile, thr)
What substance is most likely deficient? Sxs: megaloblastic macrocytic anemia, neural tube defects, homocysteinemia, DVT
folate
What are the major biochemical functions of calcium?
mineralization of bone, contraction of muscles, membrane permeability, propagation of nerve signals, coagulation and enzyme regulation
Where in the body is copper distributed?
muscle, bone, liver, kidney, brain
Name the enzyme class that requires riboflavin (B2) as a cofactor.
dehydrogenase
The absorption of fat-soluble vitamins depends largely on what two organs?
small intestine, pancreas
Name the enzymes that require thiamine as a cofactor. Identify the related pathways.
pyruvate dehydrogenase (PDH), alpha-ketoglutarate dehydrogenase (TCA), transketolase (HMP shunt)
What vitamin does NAD come from?
Niacin (B3)
What are the clinical findings of scurvy?
swollen gums, bruising, anemia, poor wound healing
Name the enzyme required for the final conversion of Vitamin D to 1,25-vitamin D.
1-alpha-hydroxylase
What substance is most likely deficient? Symptoms: alcoholism, ataxia, nystagmus, ophthalmoplegia, high output cardiac failure, confabulation psychoses
thiamine (B1)
Name three symptoms of beriberi.
polyneuritis, cardiac pathology, edema
Name three enzymes that require biotin as a cofactor. Identify the related pathways.
pyruvate carboxylase (gluconeogenesis), acetyl-CoA carboxylase (FA synthesis), propionyl-CoA carboxylase (odd chain FA, valine, met, ile, thr)
In which population is a thiamine deficiency most often observed?
alcoholics
What is the major activated carrier of CO2 in the body?
biotin
What is the storage form of Vitamin D?
25-OH D3
What coagulation factors require Vitamin K?
factors II, VII, IX, X
proteins C, S
Prolonged exposure to broad spectrum antibiotics causes a deficiency of which vitamin? Why?
vitamin K
destruction of intestinal bacteria that supply vitamin K
What are the major biochemical functions of manganese?
collagen formation, cholesterol synthesis, mitochondrial superoxide dismustase, maintain normal brain chemistry.
Name the enzymes(s) that require pyridoxine (B6) as a cofactor. Identify the related pathway(s).
aminotransferases (protein catabolism), AST, ALT (heme synthesis)
Where in the body is magnesium distributed?
50% bone
25% muscle
25% extracellular tissues
Folic acid is important in the synthesis of ___.
nitrogenous bases in DNA and RNA
A patient has cirrhosis of the liver. Which enzyme action may be altered in the synthesis of Vitamin D?
25-hydroxylase
Folic acid is important in the synthesis of ___.
Nitrogenous bases in DNA and RNA
Biotin is a cofactor for which three carboxylations?
pyruvate to oxaloacetate, acetyl-CoA to malonyl CoA, and propionyl-CoA to methylmalonyl-CoA
What substance is most likely deficient? Symptoms: poor wound healing, easy bruising, perifolicular hemorrhage, bleeding gums, increased bleeding time, painful glossitis, anemia
ascorbate
Name the enzyme defect in rickets. Where is the defect located?
1-alpha hydroxylase
proximal renal tubules
What substance is most likely deficient? Symptoms: diarrhea, dementia, dermatitis
niacin (B3)
Vitamin D increases the intestinal absorption of ___ and ___.
calcium and phosphate
Where in the body is sodium distributed?
major extracellular cation
What substance is most likely deficient? Symptoms: megaloblastic macrocytic anemia, progressive peripheral neuropathy
B12
What are the major biochemical functions of iron?
oxygen transport (hemoglobin), oxygen storage (myoglobin), cofactor in ETC to generate ATP, activates O2 in WBCs to kill bacteria
What are the major biochemical functions of sodium?
maintains fluid and electrolyte balance across membranes, maintains pH, maintains excitability of nerves
Name the vitamin deficiency. Sxs: increased bruising and increased prothrombin time.
vitamin K (not C - there is normal PT in deficiency)
Name the vitamin that is deficient in breast milk and is often postnatally injected.
vitamin K
A deficiency in vitamin B5 causes what four problems?
dermatitis, enteritis, alopecia, adrenal insufficiency
Bone pain and muscle weakness is most clearly associated with a deficiency of which fat soluble vitamin?
vitamin D
Where in the body is manganese distributed?
throughout body, but concentrated in bone, liver, pancreas, and kidney
Vitamin B12 is involved in which two conversions?
homocysteine to methionine and metholmalonyl-CoA to succinyl-CoA
What is the major biochemical function of magnesium?
cofactor for many ATP involving reactions
What are the major biochemical functions of copper?
cytochrome oxidase in the ETC, estrogen degradation, cytosolic SOD (defense against free radicals)
The conversion of 7-dehydrocholesterol to cholecalciferol occurs where?
skin
Cholecalciferol, also called ___, is formed where?
D3
sun-exposed skin
What is the MC vitamin deficiency in North America?
folic acid
Maintenance of healthy epithelium and vision are major functions of which vitamin?
vitamin A
What are the major biochemical functions of phosphorus?
mineralization of bone; DNA, RNA, and ATP synthesis; enzyme regulation (phosphorylation), acid-base balance
What substance is most likely deficient? Sxs: sideroblastic anemia, cheilosis, stomatitis, convulsions
pyridoxine (B6)
Where is vitamin B12 stored?
liver
Where in the body is iron distributed?
hemoglobin, myoglobin, transferrin in blood, ferritin in liver, spleen, bone marrow
Excess endogenous vitamin D is seen in what disease state?
sarcoidosis, where epithelial macrophages convert vitamin D into its active form
Where in the body is chromium distributed?
iron in kidney, liver, muscle, spleen, heart, pancreas, bone
Is toxicity more common for fat or water soluble vitamins?
fat-soluble
What substance is most likely deficient? Sxs: corneal neovascularization, cheilosis (stomatitis), magenta-colored tongue
riboflavin (B2)
Deficiency of vitamin D in children causes ___. In adults it causes ___.
rickets
osteomalacia
Name the enzyme that requires folate as a cofactor. Identify the related pathway.
thymidylate synthase (thymidine synthesis)
What is vitamin B5 a constituent of?
CoA
Which form of vitamin A (cis or trans) acts as a cofactor for the conversion of opsin to rhodopsin?
Cis
What test is used to determine a deficiency of vitamin B12?
Schilling test
Where does 1-alpha hydroxylase activate the final bioactive form of vitamin D?
kidney
What are the symptoms of pellagra?
diarrhea, dermatitis, dementia
Name four clinical manifestations as a result of B2 deficiency.
angular stomatitis, cheilosis, corneal vascularization
What is the general function of vitamin B2?
cofactor in oxidation and reduction
What is vitamin B3 a constituent of?
NAD+, NADP+
