Cellular & Molecular Bioscience- Micronutrients - Vitamins

Question 1

Macronutrients

Answer 1

LARGE amounts (>grams/day)

Question 2

Micronutrients

Answer 2

SMALL amounts (mg - μg/day)
Do not yield energy

Question 3

MACRO-NUTRIENT - Principal component of the body

How much of daily intake

Answer 3

55-65% of the body weight (25% in bones – 75% in the brain)
It does NOT provide energy

Question 4

What are the roles of water?

Answer 4

Needed for nearly all the cellular reactions
SOLVENT -It moves nutrients and waste within/between cells/tissues/organs

Maintain the body temperature – Thermoregulation
Moisten tissues (in the eyes, nose and mouth) and lubricate joints
Protect your spinal cord and other sensitive tissues
Dispose of through urination, perspiration, and bowel movements

Question 5

Water balance

Answer 5

balance between water intake and output (loss)

Question 6

Water Output

Answer 6

The minimum obligatory water excretion is about 500 mL
Above this amount, excretion adjusts to balance intake

Question 7

Water Balance Disorders
Dehydration(hypohydration) :

Answer 7

Mild (< 5% body weight) - dry skin and mouth, tiredness, lack of concentration
Moderate (5-10%)
Severe (>10%) - seizures, kidney failure and even death

Question 8

Overhydration

Answer 8

Excessive water intake that affects the electrolyte concentrations and could result in electrolyte imbalance. Urine production is significantly increased

Question 9

Water intoxication

Answer 9

In rare cases, usually kidney disorders, drinking excessive amounts of water can lead to intoxication - hyponatraemia (due to low levels of sodium in the blood)

Question 10

Does essential micro- nutrient provide energy?

Answer 10

no

Question 11

What are the roles of electrolytes?

Answer 11

• many serve as electrolytes
• regulate fluid balance, blood pH and are critical for nerve and muscle function (action potential, neuromuscular junction, cell signalling)

Question 12

Classification of minerals

Answer 12

MAJOR minerals
>100mg required per day
Sodium, Potassium, Chloride, Calcium, etc

TRACE minerals
<100mg required per day
iron, copper, zinc, selenium, fluoride etc.

Question 13

What are enzymes?

Answer 13

proteins - act as biological catalysts to speed up specific enzymatic reactions by reducing activation energy

Question 14

Cofactors activate

Answer 14

enzymes

Question 15

Essential ions>

Answer 15

activator ions - loosely bound

metal ions for metalloenzymes - tightly bound

Question 16

Coenzymes >

Answer 16

Cosubstrates - loosely bound
Prosthetic groups - tightly bound

Question 17

HOLOENZYME

Answer 17

A complete catalytically-active enzyme together with its cofactor

Question 18

APOENZYME

Answer 18

The protein part of the enzyme on its own without its cofactor

Question 19

Essential MICRO-NUTRIENT

Answer 19

They must be provided by the diet (small amount)
Some essential vitamins are synthesised from dietary precursors
Do NOT provide energy

Question 20

Roles of vitamins

Answer 20

Essential for metabolic processes
Assist enzymes as coenzymes
Act as individual units

Question 21

What are the 2 classes of vitamins

Answer 21

WATER soluble
Excess excreted via kidney by urine
Increased risk of deficiency
Decreased risk of toxicity (excessive intake)
Vitamins B and vitamin C

LIPID soluble
Excess stored in the body (usually in liver)
Decreased risk of deficiency
Increased risk of toxicity
Vitamins A, D, E & K

Question 22

Water soluble Vitamins – B group vitamins

Answer 22

Serve as coenzymes to Assist enzymes (to release energy)
But they do not directly provide the body with fuel
May have overlapping functions
Named in order of discovery, B4, B8, B10, B11 no longer classified as vitamins as it was found that they are produced by the body
Some can be synthesised by bacteria of the intestinal flora (Mutualism)

Question 23

Vitamin B1 - Thiamine
roles

Answer 23

Part of the coenzyme TPP (thiamin pyrophosphate)
To activate many enzymes (holoenzymes) involved in:
Carbohydrates catabolism (e.g. pyruvate oxidation into acetyl-CoA – lecture 6)
Neuronal action potential conduction & neuro-muscular transmission

sources?
(whole grains, legumes, pork as the richest source, fruits, and yeast)

Question 24

Vitamin B1 – Thiamine – deficiencies

Answer 24

Malnourished – inadequate intake
Prevalent in diets largely based on white rice (low content of B1)
Alcohol impairs thiamine absorption
Athletes and pregnant women with high carbohydrate catabolism

Beriberi - Prolonged thiamine deficiency, affecting different organ systems

Dry beriberi – affects nervous system (paralysis, peripheral neuritis)

Wet beriberi – affect cardiovascular system (cardiac failure, characteristic oedema)
Wernicke–Korsakoff syndrome - severe form of dry beriberi (mental confusion, jerky eye movements, memory loss)

no risk of toxicity

Question 25

Vitamin B2 - Riboflavin roles

Answer 25

part of the coenzymes FMN (flavin mononucleotide) and FAD (Flavin adenine dinucleotide) FAD assists enzymes involved in energy metabolism FAD is an electron carrier/acceptor during the citric acid cycle sources? Dairy products, eggs, green vegetables and almonds

Question 26

Vitamin B2 Deficiency

Answer 26

Only common in developing countries Symptoms - inflammation of the mouth, lips, and GI tract (stomatitis) no risk of toxicity

Question 27

Vitamin B3 – Niacin roles

Answer 27

Part of the coenzyme NAD (Nicotinamide adenine dinucleotide) and NADP (Nicotinamide adenine dinucleotide phosphate) Both act as coenzymes of enzymes involved in oxidorectuctase metabolic reactions (NAD - catabolic and NADP - anabolic) NAD is an electron carrier during glycolysis and citric acid cycle NAD++ H+ + 2e- ⇄ NADH sources? Meat, poultry, fish, and nuts

Question 28

Vitamin B3 – Niacin – deficiencies

Answer 28

body can make this vitamin from the tryptophan (essential a.a) needs are met AFTER protein synthesis

Question 29

Vitamin B3 Deficiency

Answer 29

In diets based on maize (low content of niacin and tryptophan) Chronic alcoholics also at risk

Question 30

Pellagra - characterised (3Ds) - name

Answer 30

Dermatitis Diarrhoea Dementia

Question 31

Vitamin B3 toxicity

Answer 31

large dose of nicotinic acid (supplements / food) Skin flushes, liver damage

Question 32

Vitamin B5 – Pantothenic acid roles

Answer 32

part of the coenzyme A, which acts as a coenzyme of enzymes crucial to many metabolic pathway, such as: Enzyme converting pyruvate into acetyl-CoA Fatty acids activation (in fatty acyl CoA) to enter the β-oxidation cycle sources? widespread in foods

Question 33

What are the three forms of Vitamin B6? ROLES

Answer 33

converted to the coenzyme PLP (pyridoxal phosphate), of many enzymes of numerous reactions (>100), e.g.: In tryptophan metabolism (link to vitamin B3 synthesis) Synthesis of neurotransmitters, haem, nucleic acids Urea metabolism sources? Meats, fish, poultry, potatoes and other starchy vegetables And intestinal normal flora release vitamin B6

Question 34

Rare deficiencies B6 vitamin

Answer 34

Alcohol contributes to the destruction of vitamin B6 Neurological, anaemia, inflammation Toxicity - cause nerve degeneration

Question 35

Vitamin B7 - Biotin roles

Answer 35

It is a coenzyme itself Critical to assist enzymes of the citric acid cycle and other sources? Widespread in natural foods Also, vitamin B7 id produced by bacteria in the GI

Question 36

B7 - Deficiencies rarely occur

Answer 36

Risk for people who eat large amount of raw eggs, as a protein in egg white seizes biotin and reduces its absorption symptoms include skin rash, hair loss, and neurological impairment

Question 37

Vitamin B9 – Folic acid / folate roles

Answer 37

Converted to coenzyme THF (tetrahydrofolate) of enzymes: involved in the biosynthesis of nitrogenous bases (DNA/RNA), amino acids and the embryonic development of spinal cord sources? Dark green and leafy vegetables, legumes, fruits, nuts

Question 38

B9 DEFICIENCY - pregnant women and people with cancer are at risk

Answer 38

Some anti-cancer drugs (e.g. methotrexate) interfere with folic acid synthesis To support baby's development, folic acid supplement in pregnancy (first 12 w) Effects - In pregnancy - low birth weight, premature birth and neural tube defects (spina bifida) Also, megaloblastic anaemia (larger RBCs) due to faulty erythrocyte multiplication and maturation

Question 39

Vitamin B12 – cobalamin Roles

Answer 39

Converted to 2 active forms -coenzymes of enzymes involved: Production of THF coenzyme from folic acid (vitamin B9) Regulation of cell replication and nerve activity sources? Foods of animal origin (meat, fish, poultry, shellfish)

Question 40

Deficiency B12 (some are consequences of reduced Vitamin B9)

Answer 40

Megaloblastic anaemia, gastrointestinal (diarrhoea, loss of bladder control) neurological symptoms (seizures, degeneration of spinal cord)

Question 41

Vitamin C – ascorbic acid roles

Answer 41

coenzyme of enzymes involved in: the synthesis of collagen (connective tissue of bones, teeth, tendons), carnitine (fatty acids transporter), steroids, etc Potent antioxidant to neutralise free radicals sources? Citrus fruits/juices, tomatoes, potatoes, other vegetables

Question 42

Vitamin C Deficiency (rare in developed countries)

Answer 42

Scurvy - swollen gums, bruising, haemorrhage, bone fracture, loose teeth, poor wound healing and anaemia Toxicity - GI distress after very large dose

Question 43

Vitamin A – Retinol / retinal / retinoic acid ROLES

Answer 43

does NOT form a coenzyme Three forms (retinol, retinal, retinoic acid). Stored in the liver Promoting vision (major role in eyesight) Participating in protein synthesis and cell differentiation, Supporting reproduction and regulating growth sources? (Retinol): fortified milk, fish, liver (carotenoids): broccoli, spinach, orange fruits, carrots

Question 44

Vitamin A deficiencies

Answer 44

Night blindness - Blindness after the sun goes down due to corneal damage Failure to adapt vision after changes of lights (flash of bright light at night or after dark) Xerophthalmia - Corneal damage. Total blindness Keratinisation - dry/ hyperkeratotic skin, skin infection

Question 45

Toxicity oF VIT A

Answer 45

large dose of supplements Skin rush, hair loss, liver and bone abnormalities Toxicity in pregnancy can lead to birth defects

Question 46

Vitamin D – calciferol It comes in two major forms. Vitamin D2 and D3 Sunlight UVB induces the synthesis of pre-vitamin D3 > PMP-202 ROLES

Answer 46

Regulate calcium in the blood (mineralization of bones) Regulates the keratinocyte turnover in the skin sources? Synthesized in the uncovered skin with the help of sunlight (UVB) Diet: fortified milk, liver, fatty fish (salmon, sardines)

Question 47

Vit D - deficiency

Answer 47

rickets (children)- distortion of the long bones of the legs, pelvis, spine osteomalacia (adults) - leading to bone softening and osteoporosis

Question 48

Toxicity - Vit D

Answer 48

Hypercalcaemia - calcium deposits in organs (e.g. kidneys, liver, heart), anorexia, insomnia, abnormal bone formation

Question 49

Vitamin E – calciferol Roles

Answer 49

Act as an antioxidant against free radical species Involved in smooth muscle growth and the maintenance of nerves Sources? (degraded by heat) - Vegetable oils, nuts, seeds, whole grains

Question 50

Vit E deficiency

Answer 50

Usually due to malabsorption of fat rather than lack of dietary intake Symptoms include nerve damage and anaemia

Question 51

Toxcicity in vit E

Answer 51

Augments the effects of anticlotting drugs

Question 52

Vitamin K – calciferol

Answer 52

There are three forms of Vitamin K (K1, K2, K3) - Roles Acts as a coenzyme to assist the formation of coagulation factors participates in the metabolism of bone proteins, osteocalcin

Question 53

Sources of Vit K

Answer 53

Green leafy vegetables, broccoli, brussels sprouts, and cabbage Vit. K2 - Produced by bacteria of the gut flora

Question 54

Vt k - deficiency

Answer 54

Rare Liver damage (e.g. alcoholics) or newborns with sterile intestines (no gut flora) anaemia, bruising and bleeding at the mucosal membranes (e.g. gums, nose) no toxicity known. not stored in great quantities in liver.