Vitamins Flashcards
Water soluble vitamins (2)
Vitamin C
B vitamins
Fat soluble vitamins (4)
Vitamin D
Vitamin A
Vitamin K
Vitamin E
Vitamin definition (3)
Organic compounds required for maintenance of health
They cannot be synthesised in the body (must be provided in the diet)
They are required in very small amounts
Water soluble vitamin characteristics (6)
Absorbed in blood Freely transported Excreted readily in urine Possible toxicity from supplements Required in frequent doses Mainly co enzymes for energy metabolism
Lipid soluble vitamin characteristics (6)
Absorbed in lymph before entering blood Often protein bound Stored in cells associated with fat Less readily excreted Toxicity is likely from supplements Requires periodic doses
Name b vitamins 1-6
Thiamin Riboflavin Niacin Adenine Pantothenic acid B6- pyridoxine, pyridoxal, pyridoxamine
Name b vitamins 7 to 12
Biotin Adenosine mono phosphate Folate PABA PHGA Cobalamin
Which b vitamin is non-essential and which AA is it derived from?
Niacin
Tryptophan
Similar features of the b vitamins (4)
Co factors in different enzyme systems
Found in the same foods
Water soluble so not stored in body for long
Frequently lost
What are b vitamins co enzymes involved in?(4)
Release of energy from foods
Metabolism regulation
Cell division of red blood cells
Cell division of GI tract
What are co enzymes (3)
Organic molecules required by certain enzymes to carry out catalysis
Bind to active site of enzyme
Often function as intermediate carriers of electrons or functional groups
Sources of thiamin (3)
Animal products
Wheat in bread (although must be fortied as it is lost in milling)
Germinating seeds
What is TTP involved in?(2)
Pyruvate dehydrogenase entering TCA cycle
a-ketogluterate dehydrogenase (TCA cycle)
Effects of thiamin deficiency
Beri beri
Beri beri symptoms (4)
Fatigue
Loss appetite
Nervous system dysfunction
Heart failure
Sources of riboflavin (b2)
Animal products
What are riboflavin co enzymes (FMN/FAD) involved in?(2)
Oxidation reduction reactions including :
Electron transport
Fatty acid synthesis and oxidation
Name of riboflavin deficiency
Ariboflavinosis
Symptoms of ariboflavinosis (4)
Cracks around mouth
Blood shot eyes
Skin rash
Magnets tongue
Best source of niacin (B3)
Meats (also found in some cereals)
What is the issue with niacin from cereals (2)
Low bioavailability
Due to it being bound to compounds in cereal
How much tryptophan is needed to make a gram of niacin
60g
Functions of niacin (3)
Co enzymes forms of niacin (NAD/NADP) involved in hydrogen transfer in body
Also needed by more than 200 enzymes
Involved in carbs, lipid and protein metabolism
What type of reactions is NADH involved in?
What type is NADPH involved in?
Energy production reactions
Anabolic reactions
What is a consequence of tryptophan and niacin deficiency
Pellagra
85% of pantothenic acid in food is as _______
CoA
Key functions of CoA (3)
First step of TCA cycle
Beta oxidation of FAs
Fatty acid synthesis
PA deficiency symptoms (4)
Skin sensations - burning feet
Fatigue
Muscle weakness
Depression
What is folic acid?(3)
Synthetic form of folate
Used in dietary supplements
Absorbed better than folate
Which type of foods are higher in folate
Raw
2 forms of folate
Monoglutamte
Polyglutamate
Which is the main form of folate in food?
Polyglutamate
Roles of folate (4)
Amino acid metabolism
DNA synthesis
Cell division
Red blood cell formation
Effects of folate deficiency (3)
Decreased metabolism of methionine which increase homocysteine
This is a risk factor for heart disease
3 stages of folate deficiency
Low folate plasma due to low intake
Red blood cell folate diminishes (after 4 months)
Megaloblastic anaemia occurs
Megaloblastic anaemia (5)
Release of large immature erythrocytes into blood
Large cells due to decreased DNA synthesis
Failure of cells to divide properly
Leads to excess Haemoglobin
However they are ineffective at delivering oxygen
Benefits of folate supplementation during pregnancy
Decrease incidence of neural tube defect
What is neural tube defect?
Opening in spinal cord or brain
Sources of vitamin B12
Animal foods only
What prevent vegans from becoming severely B12 deficient?
Bacterial contamination in food and water we consuming produces B12
What can also cause B12 deficiency?
Lack of intrinsic factor in gastric juice
What happens to B12 after use(3)
Returns to liver
Secreted in bile
Can be used again
Roles of B12 (2)
Co enzyme involved in:
Folate methionine cycle
Synthesis of succinyl CoA
Main cause of B12 deficiency
Inadequate absorption (not intake)
B12 deficiency outcomes (3)
Megaloblastic anaemia
Demethylation of nerves
May induce folate deficiency (increasing homocysteine)
Name the B6 vitamers
Pyridoxine - alcohol form
Pyridoxamine - amine form
Pyridoxal - aldehyde form
Name the metabolically active form of vitamin B6
Pyridoxal phosphate (PLP)
Functions of B6 (2)
Co enzyme for glycogen phosphorylase
AA transamination reaction
Secondary causes of B6 deficiency (4)
Malabsorption
Coeliac disease
Dialysis for renal failure
Chronic alcoholism
Which b vitamin has higher storage than usual and why?
B12
Can be bound to a protein
Which lipid soluble vitamin can be a co enzyme
Vitamin K
What can affect b vitamins?(3)
Heat during cooking
Exposure to light
Exposure to air
Ultimate role of co enzymes
Helps transfer functional groups from one compound to another
Symptoms of pellagra - the 4 Ds
Dermatitis
Dementia
Diarrhoea
Death
Vitamin B6 deficiency symptoms (4)
Inflammation of tongue
Lesions around lips and mouth
Peripheral neuropathy
Anaemia
What is vitamin D3 known as?
Cholecalciferol
What is vitamin D2 known as?
Ergocalciforel
What is involved in vitamin A transport?(3)
Transthyretin
Lipoproteins
Retinol binding protein
What enzyme in vitamin C synthesis is not produced by humans
L-gulono-gamma-lactose oxidase
What proportion of vitamin E is excreted?
70%
What kind of side chain does vitamin E contain?
Isoprenoid
Retinol is _____ to retinyl palmitate
Esterified
Retinoic acid is _______ to retinal
Reduced
Retinol is _____ to retinal
Oxidised
Which organ responses to a drop in phosphorus
Kidney
What percentage of vitamin A is absorbed?
80
What is 1, 25(OH)2 also know as?
Calcitrol
What vitamin converts homocysteine to methionine?
B12
What vitamin converts homocysteine to cystathionine and then to cysteine
B6
Which vitamin is key for the synthesis of purines and pyrimidines?
Folate
