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Biochemistry - Nutrition

Terms in this set (120)

Fat soluble vitamins (4)
A, D, E, K
Water soluble vitamins (9)
B1 - Thiamine
B2 - Riboflavin
B3 - Niacin
B5 - Pantothenic acid
B6 - Pyroxidine
B7 - Biotin
B9 - Folate
B12 - Cobalamin
C - Ascorbic acid
Steatorrhoea can interfere with absorption of ... soluble vitamins?
Steatorrhoea can interfere with absorption of fat soluble vitamins
Mineral oil intake can interfere with absorption of ... soluble vitamins?
Mineral oil intake can interfere with absorption of fat soluble vitamins
Which water soluble vitamins are stored by the body?
B9, B12
(a) Where is B9 stored?
(b) How long is B9 stored?
(a) Liver
(b) 3 - 4 months
(a) Where is B12 stored?
(b) How long is B12 stored?
(a) Liver
(b) 3 - 4 years
Symptoms of B-complex deficiencies (3)
Dermatitis
Glossitis
Diarrhoea
Vitamin A/ retinol function (4)
Antioxidant
Visual pigment
Differentiation factor
Prevents squamous metaplasia
What can be used to treat measles?
Vitamin A/retinol
What can be used to treat acute myeloid leukaemia (AML) subtype M3?
Vitamin A/retinol
What can be used to treat severe cystic acne?
Oral isotretinoin/13- cos retinoid acid
What can be used to treat acute promyelocytic leukaemia?
Tretinoin/all-trans retinoid acid
Vitamin A/retinol deficiency symptoms (5)
Night blindness
Scaly skin
Corneal degeneration
Bitot spots on conjunctiva
Immunosuppression
Acute vitamin A/retinol excess symptoms (4)
Nausea
Vomitting
Vertigo
Blurred vision
Chronic vitamin A/retinol excess symptoms (4)
Alopecia
Hepatomegaly
Arthralgia
Pseudotumor cerebri
In excess which fat soluble vitamin is teratogenic?
Vitamin A/retinol
Before prescribing isotretinoin, what is required?
Negative pregnancy test
Two forms of contraception
Which vitamin contains a sulphur group?
Vitamin B1/thiamine
Dehydrogenase enzymes thiamine pyrophosphate is a coenzyme of (4)
Pyruvate dehydrogenase
a-ketoglutarate dehydrogenase
Transketolase
Branched-chain ketoacid dehydrogenase
How does vitamins B1/thiamine deficiency impair glucose breakdown?
Thiamine pyrophosphate is a coenzyme of pyruvate dehydrogenase (PD). PD links glycolysis with the TCA cycle.
In what conditions does vitamin B1/thiamine deficiency present generally?
Malnutrition and alcoholism, deficiency generally secondary to malabsorption and malnutrition respectively
How is vitamin B1 deficiency diagnosed?
Increased RBC transketolase activity following vitamin B1 administration
Which two conditions present as vitamin B1/thiamine deficiency?
Wernicke-Korsakoff syndrome and beriberi
Classic triad of symptoms in Wernicke-Korsakoff syndrome
Confusion, ophthalmoplegia, ataxia
Neural structures are damaged in Wernicke-Korsakoff syndrome (2)
Thalamus
Mammillary bodies
Two types of beriberi
Dry beriberi
Wet beriberi
Symptoms of dry beriberi (2)
Polyneuritis
Symmetrical muscle wasting
Symptoms of wet beriberi (2)
High output cardiac failure
Edema
Vitamin A/Retinol derived medication that is teratogenic
Isotretinoin
Vitamin B1/thiamine function
Cofactor of dehydrogenase enzymes
Vitamin B2/riboflavin function
Component of the flavins FAD and FMN - cofactors in redox reactions, such as succinate dehydrogenase
Vitamin B2/riboflavin deficiency (2)
Cheilosis
Corneal vascularisation
Vitamin B3/niacin function
Component of NAD+, NADP+
Vitamin B3/niacin synthesis requires (3)
Tryptophan
Vitamin B2/riboflavin
Vitamin B6/pyroxidine
What water soluble vitamin can vitamin B3/niacin treat?
Dyslipidaemia
What is Hartnup's disease?
Autosomal recessive condition
Deficiency of neutral amino acid transporters
Reduced tryptophan absorption
Vitamin B3/niacin deficiency
Pellagra-like symptoms
Mild vitamin B3/niacin deficiency causes
Glossitis
Severe vitamin B3/niacin deficiency causes
Pellagra
Pellagra symptoms (3)
Diarrhoea
Dementia
Dermatitis
Causes of pellagra (3)
Hartnup's disease (reduced tryptophan absorption)
Malignant carcinoid syndrome (increased tryptophan metabolism)
Isoniazid (increased vitamin B6/pyroxidine excretion)
Vitamin B3/niacin excess symptoms (3)
Facial flushing
Hyperglycaemia
Hyperuricaemia
Vitamin B5/pantothenic acid function (2)
Component of coenzyme A
Fatty acid synthase
Vitamin B5/pantothenic deficiency symptoms (4)
Dermatitis
Enteritis
Alopecia
Adrenal insufficiency
Vitamin B6/pyroxidine function (4)
Amino acid metabolism
Glucose metabolism
Lipid metabolism
Haemoglobin synthesis and function
Neurotransmitters requiring vitamin B6/pyridoxine (5)
Serotonin
Epinephrine
Norepinephrine
Dopamine
GABA
Three forms of catalysis requiring vitamin B6/pyridoxine cofactor
Transamination
Decarboxylation
Glycogen phosphorylase
Vitamin B6/pyridoxine deficiency symptoms (4)
Convulsions
Hyperirritability
Peripheral neuropathy
Sideroblastic anaemia
How does vitamin B6/pyridoxine cause sideroblastic anaemia?
Impaired haemoglobin synthesis and iron excess
What molecules is vitamin B6/pyridoxine involved in synthesising? (9)
Cystathione
Heme
Niacin
Histamine
Serotonin
Epinephrine
Norepinephrine
Dopamine
GABA
What is the biologically active form of vitamin B6/pyridoxine?
Pyroxidal phosphate
Vitamin B7/biotin function
Cofactor for carboxylation enzymes
Vitamin B7/biotin a cofactor for what enzymes (3)
Pyruvate carboxylase
Acetyl-CoA carboxylase
Propionyl-CoA carboxylase
Vitamin B7/biotin deficiency symptoms (3)
Dermatitis
Alopecia
Enteritis
Causes of vitamin B7/biotin deficiency
Antibiotics
Avidin from egg whites, binding vitamin B7/biotin - preventing absorption
What is vitamin B9/folate converted to?
Tetrahydrofolic acid (THF)
Function of THF
Coenzyme for 1 carbon transfer/methylation reactions
Function of vitamin B9/folate
Involved in synthesis of nitrogenous bases in DNA and RNA
Which part of the digestive tract absorbs vitamin B9/folate
Jejunum
Does vitamin B9/folate deficiency have neurologic symptoms?
No; B6, B12 and vitamin E have neurologic symptoms on deficit
Vitamin B9 deficiency symptoms (4)
Macrocytic anaemia
Megaloblastic anaemia
Hyper segmented polymorphonuclear cells (PMNs)
Glossitis
How is vitamin B9/folate deficiency diagnosed?
Raised homocysteine
Normal methylmalonic acid
What is the most common vitamin deficiency in the US?
Vitamin B9/folate deficiency
Lifestyles that may cause vitamin B9/folate deficiency (2)
Alcoholism
Pregnancy
Drugs causing vitamin B9/folate deficiency
Phenytoin
Sulphonamides
Methotrexate
Which vitamin administered during early pregnancy reduces risk of neural tube defects?
Vitamin B9/folate
Vitamin B12/cobalamin function
Cofactor for methionine synthase and methylmalonyl-CoA mutase
Causes of vitamin B12/cobalamin deficiency (4)
Malabsorption (coeliac disease,enteritis)
Lack of intrinsic factor (pernicious anaemia, gastric bypass surgery)
Absence of terminal ileum (surgical resection e.g. Crohns)
Insufficient intake (veganism)
Anti-intrinsic factor antibodies are diagnostic of?
Pernicious anaemia
Vitamin B12/cobalamin deficiency symptoms (5)
Macrocytic anaemia
Megaloblastic anaemia
Hyper segmented polymorphonuclear cells (PMNs)
Parasthesia
Degeneration of dorsal columns, lateral corticospinal tracts and spinocerebellar tracts
How is vitamin B12/cobalamin deficiency diagnosed?
Raised homocysteine
Raised methylmalonic acid
Does prolonged vitamin B12/cobalamin deficiency cause permanent damage
Yes, prolonged vitamin B12/cobalamin deficiency causes permanent nerve damage
Draw the pathway resulting in the formation of cysteine, include vitamin B6/pyridoxine and vitamin B12/cobalamin
Vitamin C/ascorbic acid function (4)
Antioxidant
Reduce iron from Fe3+ to Fe2+ for absorption
Hydroxylation of proline and lysine in collagen synthesis
Conversion of dopamine to NE, via dopamine B-hydroxylase
Scurvy is a deficiency of which vitamin?
Vitamin C/ascorbic acid
Symptoms of scurvy (6)
Swollen gums and knees
Bruising
Petechiae
Anaemia
Perifollicular haemorrhage
Subperiosteal haemorrhage
Vitamin C/ascorbic acid excess symptoms (3)
Nausea
Diarrhoea
Calcium oxalate nephrolithiasis
What additional approach, involving vitamins, could be used to treat methaemoglobinaemia?
Vitamin C/ascorbic acid
In scurvy, synthesis of what molecule is compromised?
Collagen
Vitamin D2 alternative name
Ergocalciferol
Vitamin D3 alternative name
Cholecalciferol
What is the storage form of vitamin D
Vitamin 25-OH D3
Vitamin 1,25-(OH)2 D3 alternative name
Calcitriol, active form of vitamin D3
What is the active form of vitamin D?
Calcitriol, 1,25-(OH)2 D3
Vitamin D function (3)
Intestinal absorption of calcium
Intestinal absorption of phosphate
Bone mineralisation and resorption
(a) How do high levels of calcitriol affect bone?
(a) How do low levels of calcitriol affect bone?
(a) Bone resorption
(b) Bone mineralisation
Who should be receiving vitamin D supplements?
Breastfed infants should receive oral vitamin D
Vitamin D deficiency symptoms (3)
Rickets in children
Osteomalacia in adults
Hypocalcaemic tetany
What vitamin is seen in excess during granulomatous disease?
Vitamin D, activation by epithelioid macrophages
Vitamin D excess symptoms (4)
Hypercalcaemia
Hypercalciuria
Loss of appetite
Stupor
Vitamin E alternative names (2)
Tocopherol
Tocotrienol
Vitamin E function
Antioxidant
Which vitamin can enhance the anticoagulant effect of warfarin?
Vitamin E
Vitamin E deficiency symptoms (4)
Haemolytic anaemia
Acanthocytosis
Muscle weakness
Posterior column and spinocerebellar tract demyelination
Difference between presentations of vitamin B12/cobalamin deficiency and vitamin E deficiency
Vitamin E does not present with:

Megaloblastic anaemia
Hyper segmented neutrophils
Raised methylmalonic acid
Vitamin K function
Cofactor for the gamma-carboxylation of glutamic acid residues on various proteins required for blood clotting
How is vitamin K synthesised?
Synthesised by intestinal flora
Vitamin K alternative names (3)
Phytomenadione
Phylloquinone
Phytonadione
In the clotting cascade what clotting factors and proteins require vitamin K for maturation?
Clotting factor II
Clotting factor VII
Clotting factor IX
Clotting factor X

Protein C
Protein S
Vitamin K deficiency in neonates causes?
Neonatal haemorrhage with:

Raised PT
Raised aPTT
Normal bleeding time
PT stands for
Prothrombin time
aPTT stands for
Activated partial thromboplastin time
Why may neonates have vitamin K deficiency?
Neonates have sterile intestines and thus cannot synthesise vitamin K
Why may prolonged broad spectrum antibiotics cause vitamin K deficiency?
Vitamin K is synthesised by intestinal flora
What is given to neonates to prevent hemorrhagic disease of the newborn?
Vitamin K
Which class of molecules is zinc essential for?
Enzymes, over 100 enzymes require zinc to function
What is a zinc finger?
Transcription factor motif
Zinc deficiency symptoms (5)
Hypogonadism
Reduced adult hair
Dysgeusia
Anosmia
Acrodermatitis enteropathica
Protein malnutrition
Kwashiorkor
Total calorie malnutrition
Marasmus
Protein malnutrition symptoms (2)
Edema, reduced plasma oncotic pressure
Liver malfunction, fat deposition due to reduced apolipoprotein synthesis
Presentation of total calorie restriction
Emaciation: Tissue and muscle wasting, loss of subcutaneous fat, +/- edema
Draw the pathway of ethanol metabolism
Drug that inhibits alcohol dehydrogenase
Fomepizole
Antidote to methanol glycol and ethanol glycol poisoning
Fomepizole
Drug that inhibits acetaldehyde dehydrogenase
Disulfiram
What order of kinetics does alcohol dehydrogenase have?
Zero order kinetics
Ethanol metabolism affects the NADH/NAD+ ratio how?
Ethanol metabolism increases NADH/NAD+ ratio
Three consequences of raised NADH/NAD+ ratio in ethanol metabolism
Pyruvate => Lactate (lactic acidosis)
Oxaloacetate => Malate (fasting hypoglycaemia)
Dihydroxyacetone phosphate => glycerol 3-phosphate (combines with fatty acids to form triglycerides => hepatosteatosis)
How does raised NADH/NAD+ ratio affect the TCA?
Raised NADH/NAD+ ratio affects TCA production of NADH resulting in:

Increased acetyl-CoA for ketogenesis: ketoacidosis
Increased acetyl-CoA for lipogenesis: hepatosteatosis
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