B5 Micronutrients and Macronutrients

B.5.1 Outline the differences between micronutrients and macronutrients
Micronutrients
- needed in small amounts
- measured in mg or μg per day (recommended daily intake)

- enables body to produce enzymes, hormones, and other health essential substances
- even though in small amounts, deficiency consequences are severe
- includes vitamins and trace minerals (Fe, Cu, Zn, I, Se, Mn, Mo, Cr, Co, B)

Macronutrients
- needed in large amounts
- provides energy in body to build and maintain structure
- includes carbohydrates, proteins and lipids
- and some minerals needed on larger scales (Na, Mg, K, Ca, P, S, Cl)

B.5.2 Compare the structures of retinol (Vitamin A), calciferol (Vitamin D) and ascorbic acid (Vitamin C).
B.5.3 Deduce whether a vitamin is water-soluble or fat-soluble from its structure
Examples
Water-soluble: Vitamins B and C
Fat-soluble: Vitamins A, D, K

Vitamins
- needed in small amounts
- not synthesized in body, hence need in diet
- broken down
- some fat-soluble (slower absorption, excess stored in fat tissue - can have some serious side effects; mostly non-polar, with long hydrocarbon chains or rings)
- some water-soluble (directly transported in blood, excess filtered by kidneys and excreted; has polar bonds and forms h-bonds with water)
- difference in structure determines their solubility

Source: IB Chemistry Textbook

B.5.4 Discuss the causes and effects of nutrient deficiencies in different countries and suggest solutions.

Malnutrition: unbalanced/ irregular supply of nutrients
- especially in underdeveloped countries, but also high consumption of processed, energy-dense but micronutrient poor food
- resulting chronic diseases e.g. obesity, diabetes (so also prevalent in industrial countries)

Iodine
- needed for synthesis of hormone thyroxine (regulates metabolic rate)
- in most seafood/ some vegetables
- lack of: swelling thyroid gland (goitre); in children, largest cause of preventable mental retardation
- solution: add to salt (low cost)

Vitamin A (retinol)
- needed for healthy skin (acne treatment), good eyesight, protection against some damaging effects of toxins (anti-oxidants)
- orange and yellow fruits/vegetables, spinach, egg yolks
- lack of: xerophthalmia (dry eyes and night blindness)
- solution: fat-soluble, so its added to margarine (Vitamin A fortification); inexpensive, has reduced levels of xero. in many parts of the world; possibly rice for Vitamin A fortification

Iron
- most prevalent micronutrient deficiency
- essential for hemoglobin (which is responsible for blood transporting oxygen around the body)
- lack of: anemia, symptoms include fatigue, brittle nails, poor endurance and lowered immunity
- source: red meat, green leafy veg, nuts and seeds
- solution: iron supplementation may increase susceptibility to malaria (also widespread)
- iron fortification best when added with vitamin C to cereal flour and milk products.

Other micronutrient deficiencies and diseases
Niacin (Vitamin B3)
- Pellagra: dermatitis, diarrhea, dementia

Thiamin (Vitamin B1)
- Beriberi: weight loss, fatigue, swelling

Vitamin C
- Scurvy: bleeding gums, lowered resistance to infection and dark spots on skin

Vitamin D
- Rickets: softened, deformed bones

Selenium 
- Kashin-Beak disease: atrophy and degeneration of cartilage (happens esp. in northern Russia and China, where the soil is Se deficient)


Macronutrient deficient
Protein
- when prolonged is life threatening
- Marasmus: mainly in infants from developing countries at the time of weaning; failure to gain weight, then weight loss and emaciation (weak and thin)
- Kwahiorkor: similar to Marasmus, affects young children whose diet is high in starch and low in protein 

SUMMARY

Micronutrient deficiencies include:

• iron—anemia

• iodine—goitre

• retinol (vitamin A)—xerophthalmia, night

blindness

• niacin (vitamin B3)—pellagra

• thiamin (vitamin B1)—beriberi

• ascorbic acid (vitamin C)—scurvy

• calciferol (vitamin D)—rickets.

Macronutrient deficiencies include:

• protein—marasmus and kwashiorkor.

Some causes of malnutrition may be discussed

here.

Solutions include:

• providing food rations that are composed of

fresh and vitamin- and mineral-rich foods

• adding nutrients missing in commonly

consumed foods

• genetic modification of food

• providing nutritional supplements

• providing selenium supplements to people

eating foods grown in selenium-poor soil.

B4 Lipids

B.4.1 Compare the composition of the three types of lipids found in the human body
Triglycerides (fats and oils), phospholipid (lecithin) and steriods (cholesterol)

Triglycerides (fats and oils)
- glycerol and 3 fatty acids
- Glycerol has 3 carbon atoms, each having an -OH group
- Fatty acids are long chains with carboxylic acid terminal group. (R-COOH)

Source: IB Chemistry textbook

Phospholipids
- similar to triglyceride
- glycerol and 2 fatty acids
- third -OH has a phosphate group
- different phospholipids vary fatty acids and phosphate groups attached
- have polar/ hydrophilic heads (phosphate group) and 2 non-polar tails (the hydrocarbon chains)
- hence, spontaneous form is a phospholipid bilayer, which creates the basis of membrane structures
- maximum interaction with polar head and water, creating a non-polar/ hydrophobic interior
Most common phospholipid: Lecithin 

Phospholipid bilayer
Source: IB Chemistry Textbook

The structure of phospholipids
Source: IB Chemistry Textbook

Steriods
- 4 fused rings
Most important: Cholesterol
- used in synthesis of many other steroids e.g. sex hormones

Structure of cholesterol
Source: IB Chemistry Textbook

B.4.2 Outline the differences between HDL and LDL cholesterol and outline its importance
Cholesterol is insoluble in blood
HDL
- high density lipoprotein
- good cholesterol
- tends to carry away cholesterol from the arteries thus slowing the build up
- high levels of HDL seems to protect against heart attack
- poly-unsaturated fats e.g. in fish, nuts and corn oil seem beneficial in lowering LDL

LDL
- low density lipoprotein
- bad cholesterol
- main source: saturated fat/oil and trans fat
- high levels of LDL are associated with increased deposition in the walls of arteries

Omega-3-polyunsaturated fatty acid
- in flaxseeds and fish oil
- help reduce risk of heart disease and optimum neurological development
- cannot be made by the body and must be included in diet, hence called "essential fatty acids"


B.4.3 Describe the difference in structure between saturated and unsaturated fatty acids.
Most naturally occurring fats contain a mixture of saturated, mono-saturated and poly-saturated fatty acids and are classified according to the predominant type of unsaturation present.

Saturated 
- all C-C single bonds
- tetrahedral 109.5 bond angles between atoms
- so molecules pack closely together, significant VDW forces.
- hence created saturated triglycerides with relatively high mpt that are solid at room temp.
- called 'fats' e.g. butter and lard

A saturated triglyceride

 Source: IB Chemistry Textbook

Unsaturated
- one or more C=C double bond
- 120 bond angles with kinks in the chain (made by the double bond) making it more difficult for them to pack closely
- unsaturated triglycerides with weaker IMF, lower mpt
- liquids at room temp.
- called 'oils', mostly in plants and fish e.g. corn oil and cod liver oil

An unsaturated triglyceride

Source: IB Chemistry Textbook

**Strong correlation between saturated fat rich diets and elevated levels of LDL cholesterol, associated increase in the cause heart disease.**


B.4.4 Compare the structures of the two essential fatty acids linoleic (omega-6-fatty acid) and linolenic (omega-3-fatty acid) and state their importance.
Body is unable to produce either fatty acid
Both are "essential fatty acids"
- from plants and fish e.g. shellfish, leafy vegetables, canola oil, flaxseed oil
- aids metabolic processes e.g. synthesis of lipids: prostaglandins (which helps lower blood pressure)

'Omega-3' 'Omega-6' represents the position of the first double bond in the molecule relative to terminal -CH3 group. Referred to as 'Omega' (the last letter in Greek alphabet) to represent its distance from -COOH group (the 1st carbon). 'Omega-3' essentially means third carbon counting backwards.

Comparing structures: (from markscheme)
- both have 18 carbon atoms;
- both have -COOH;
- linoleic acid has 2 double carbon bonds AND linolenic acid has 3 double carbon bonds/ linoleic acid has less double bonds;
- both have first double carbon bond on C9/ first double bond of linoleic is after the 6th C atom and first of linolenic is after the 3rd C atom counting from -CH3 terminal group;

Source: American Heart Association

B.4.5 Define the term iodine number and calculate the number of C=C double bonds in an unsaturated fat/oil using addition reactions
Iodine number - number of grams of iodine which will react with 100g of fat
1 mole of iodine will react with 1 mole of double bonds in fat. Higher no. double bonds per molecule = large iodine number
Used to determine the degree of unsaturation in fat
- addition reaction, breaks C=C (alkene) and adds I

- reacting known amount of fat with known amount of iodine
- after reaction completes, excess iodine is calculated by titration with Na2S2O3 (Sodium Thiosulphate), and reacted iodine is found.

- Find Mr > Find moles > Find mole ratio of iodine to fat/oil > iodine number


B.4.6 Describe the condensation of glycerol and three fatty acid molecules to make a triglyceride
Esterification is a condensation reaction. Condensation means the reaction has a side product, but not necessarily water.

Ester linkages between the glycerol and fatty acids are created during the reaction.
Each fatty acid chain is different. (R1, R2, R3) They differ in these two ways:
Hydrocarbon chain length
- most abundant fatty acids have even number of carbon atoms between 14-22 Cs.

Number and position of C-C bonds in chain
Fatty acids with:
no double bonds = saturated
just 1 double bond = mono-saturated
several double bonds = poly-saturated

Their natures affects their melting points and other important properties.

Source: IB Chemistry Textbook

B.4.7 Describe the enzyme-catalysed hydrolysis of triglycerides during digestion
Fats and oils cannot be transported in blood
- broken into fatty acids and glycerol in the gut (digestion)
- hydrolysis reaction (water used), under control of lipase enzyme

Lipase
- secreted in different parts of the gut
- act sequentially to digest lipids
- usually slowest molecules to digest, may take hours before they are soluble and are absorbed into the blood
- enzyme is made of protein, hence sensitive to pH change; control pH in different area of the guts is one way the body controls lipid digestion.


B.4.8 Explain the higher energy value of fats compared to carbohydrates
Lipids
- stored energy, released when broken down (respiration, oxidation produces carbon dioxide and water)
- less oxidised than carbs, hence undergoes more oxidation and releases more energy per unit mass when used as respiratory substrate.

**energy from a gram of lipid = x2 energy from a gram of carbohydrate

- but because of its insolubility, lipid energy is not as readily available as carbohydrates (so it's not good for immediate energy source e.g. for a marathon)
- but makes ideal storage molecules (e.g. a trip to the Arctic), called adipose tissue

Adipose tissue 
- in different parts of the body
- reservoirs of energy
- helps protect some body organs e.g. kidneys and layer of fat under the skin helps insulate the body


B.4.9 Describe the importance roles of lipids in the body and the negative effects that they can have on health.
Important roles include:
- energy storage
- insulation and protection of organs
- helps synthesis of steroid hormones
- structural component of cell membrane (phospholipids)
- helps determine selective transport of metabolites across cell boundaries
- in nerves the myelin sheath (special layer of phospholipids) gives electrical insulation to the nerves and speeds up nervous transmission.
- omega-3 poly-unsaturated fatty acids reduce the risk of heart disease
- poly-unsaturated fats may lower levels of LDL cholesterol
- cholesterol also important in plasma membrane structure
- lipids help absorb fat-soluble vitamins (A, D, E, K)

Negative effects include:
- increased risk of heart disease from elevated levels of LDL cholesterol and trans fatty acids; the major source of LDL cholesterol is saturated fats, in particular lauric (C12), myristic (C14) and palmitic (C16) acids
- obesity
- excess lipids, because of their low solubility causes them to deposit on the walls of the main blood vessels (restricts blood flow - atherosclerosis, associated with high blood pressure and leads to heart disease)

B9 Respiration

B.9.1 Compare aerobic and anaerobic respiration of glucose in terms of oxidation/reduction and energy released.
Redox equations should be used as appropriate.

Aerobic - uses oxygen as the terminal electron acceptor
Anaerobic - uses terminal electron acceptors other than oxygen

Aerobic respiration
- glucose is converted into pyruvate, which, in presence of oxygen, changes to carbon dioxide and water. Overall, glucose undergoes oxidation and oxygen undergoes reduction.
- breaks down glucose, amino acids and fatty acids to release energy
- oxygen is the terminal electron acceptor

Glucose + Oxygen à  Carbon dioxide + Water + Energy

- high energy yielding process
- up to 38 ATP molecules produced for every glucose
- occurs in almost all living organisms
- excess carbon dioxide and water is excreted (the removal of the toxic waste products of metabolism) and maximum energy is released from the glucose

Anaerobic respiration
- happens in the absence of air
- pyruvate is converted to lactate in human beings, whereas yeast converts pyruvate into ethanol and carbon dioxide.
- not so much energy and more toxic waste produced.
- If oxygen is unavailable this process also occurs in humans.
E.g. intense exercise - lactic acid in muscle tissue is built up, resulting in muscle pain and cramping.
E.g. bacteria in milk also produces lactic acid (the optical isomer of the one produced in muscle cramping)
E.g. yeast produces alcohol (also toxic). In the end there is too much alcohol that the yeast cannot survive.
- Respiration that occurs without oxygen to produce ATP

Glucose à Energy (ATP) + Ethanol + Carbon dioxide

or

Glucose à Energy (ATP) + Lactic acid

- relatively less energy yield than aerobic
- in alcoholic fermentation 2 molecules of ATP are produced for every glucose in the reaction. The same for lactate fermentation
- Hence, in anaerobic respiration one glucose is broken down into 2 ATP.




B.9.2 Outline the role of copper ions in electron transport and iron ions in oxygen transport.
(Cytochromes and hemoglobin are suitable examples)

HEMOGLOBIN AND OXYGEN
- iron is essential in this process, because of its ability to form complexes.

Hemoglobin
- a complex protein
- has porphyrin rings at certain sites.
- A Fe2+ ion at the center of the ring attracts and transports oxygen.
- At high oxygen concentrations (like the lungs) the hemoglobin binds to the oxygen which is then carried around through the bloodstream to cells for respiration.
- At high carbon dioxide concentrations (like in cells) the hemoglobin binds to the carbon dioxide which are then transported back to the lungs where the carbon dioxide is exhaled.
- Carbon monoxide and cyanide are poisonous for hemoglobin. They attach rather permanently to the Fe2+ ion so it is unable to bind to any oxygen molecules rendering it useless.

In the mitochondria food is oxidised at the cellular level involving redox reactions and electron transport.
Cytochromes - enzymes that catalyse the oxidation processes; it incorporates porphyrin rings with either a Cu2+ or Fe2+at the center,
- contain Cu2+ or Fe3+ ions
- porphyrin ligand contains 4 nitrogen atoms, each dontaes 2 electrons
For each step of the oxidation of glucose:

Fe3+à Fe2+ + e-

or 

Cu2+à Cu+ + e-

Cytochrome structure heme group is from cytochrome oxidase.

Oxidation stage of glucose:

C6H12O6 + 6H2O à 6CO2+ 24H+ +24e-

Fe3+ + e- à  Fe2+   (Metal ion is reduced)

Reduction stage:

O2 + 4H+ +4e- à  2H2O

Fe2+ à  Fe3+ + e-   (Metal ion is oxidized)

Cu+  à Cu2+  + e-

8.1 Theories of acids and bases

8.1.1 Define acids and bases according to the BrØnsted-Lowry and Lewis theories
BrØnsted - Lowry acid              H+/proton donor
BrØnsted - Lowry base              H+/ proton acceptor
Lewis acid                                 electron pair acceptor (dative bond)
Lewis base                                 electron pair donor (dative bond)

8.1.2 Deduce whether or not a species could act as a BrØnsted-Lowry and/or a Lewis acid or base.

All BrØnsted-Lowry acids are Lewis acids, but not all Lewis acids are BrØnsted-Lowry acids.

Some species can act as acids/bases (amphoteric/ amphiprotic substances)
Amphoteric:
- B-L acid must be able to disscociate + release H+
- B-L base must be able to accept H+, therefore must have a lone electron pair
According to B-L theory they must possess both a lone e- pair and hydrogen that can be released as H+.

8.1.3 Deduce the formula of the conjugate acid (or base) of any BrØnsted-Lowry base (or acid).
Conjugate pairs - there is always a donor and acceptor
B-L theory - if an acid donates a H+ there is also a base present to accept the proton

Conjugate base pairs

Acids react to form bases (vice versa), therefore it is easy to predict the formula, the conjugate acid-base pairs differs by ONE proton.

e.g. H2O and H3O+ (found in all acid-base reactions in aqueous solutions)

B1 Energy

B.1.1 Calculate the energy value of a food from enthalpy of combustion data.
Energy
Heat produced = mCΔT
Energy comes from respiration.
Calorific value - the amount of energy available
Carbohydrates are the most readily available source of energy
Fats that are non-oxidised provide the the most energy per mass.
Food is (not burned but) converted into carbon dioxide and water through oxidation.


The bomb calorimeter
Used to measure the energy content of food.
The sample of food is heated and ignited electrically. The heat given out from the combustion is transferred to a water system and the energy is calculated by the change in temperature and mass of water.

Heat produced = heat absorbed by water + heat absorbed by calorimeter
= (m x C x ΔT)water + (m x C x ΔT)calorimeter

Stirrer: to keep the water at a uniform temperature
Bomb: sealed unit where the combustion reaction occurs
Thermometer: measures the rise in temperature of water
Water: absorbs the heat of the reaction
Electric coil: heats the device to start the reaction



Cellular respiration
A set of metabolic processes that occur in the cell to convert biochemical energy from nutrients into adenosine triphosphate (ATP)
Involves catabolic redox reactions, one molecule is reduced the other is oxidised.

Adenosine Triphosphate (ATP)
- adenine group
- ribose sugar
- 3 phosphate groups
Energy that is released from combustion of carbon molecules is stored in ATP.

ATP to ADP (Adenosine Diphosphate)
- Energy released when phosphate group is released (to form ADP)
- Reversible reaction, the cell can store or release energy.
- ATP to ADP releases ~30.5 kj/mol

A1 Analytical Techniques

A.1.1 State the reasons for using analytical techniques.
Qualitative analysis - detects the presence not quantity of a substance in a mixture. e.g substances in an athlete's blood
Quantitative analysis - measure the quantity of a substance in a mixture. e.g. alcohol in a driver's breath
Structural analysis - how the atoms are arranged in molecular structures. e.g. to determine the structure of a naturally occurring or artificial product.

A1.2 State that the structure of a compound can be determined by using information from a variety of analytical techniques singularly or in combination.
The techniques analyses the effect of different forms of energy on the substance.
Infrared spectroscopy - identifies the bonds in a molecule.
Mass spectroscopy - determines relative atomic and molecular masses. The fragmentation pattern is like a fingerprint, it identifies unknown substances or evidence for the arrangement of atoms in a molecule.
Nuclear magnetic resonance spectroscopy - shows the chemical environment of certain isotopes (hydrogen, carbon, phosphorus and fluorine) in a molecule, giving vital structural information.

**However, information from only one technique is usually insufficient to determine or confirm a structure.**

7.1 Dynamic equilibrium & 7.2 The position of equilibrium

7.1.1 Outline the characteristics of chemical and physical systems in a state of equilibrium.
Chemical systems e.g. Dissociation

Characteristics of an equilibrium
1. Dynamic equilibrium: reactions have not stopped, they're still occurring (see right)
2. Closed systems: This prevents exchange of matter with the surroundings
3. Concentrations remain constant: the products and reactants are produced and destroyed at an equal rate
4. No macroscopic properties change (no observable change): colour, density depends on concentration of the equilibrium mixture
5. Eqm can be reached from either direction: the same eqm mixture will be established under the same conditions, regardless of the starting product/reactant mixture.

Usually in an eqm mixture either products/reactants will have a higher concentration

If the eqm lies to the right = more products are being formed

If the eqm lies to the left = more reactants being formed

7.2.1 Deduce the equilibrium constant expression (Kc) from the equation for a homogeneous reaction.

7.2.2 Deduce the extent of a reaction from the magnitude of the equilibrium constant.
The magnitude of Kc determines the EXTENT of the reaction, not how fast it will achieve eqm.

If Kc >> 1, the reaction is almost to completion

If Kc << 1, the reaction hardly proceeds

7.2.3 Apply Le Chatelier’s principle to predict the qualitative effects of changes of temperature, pressure and concentration on the position of equilibrium and on the value of the equilibrium constant.

"A system at equilibrium when subjected to a change will respond in such a way as to minimize the effect of the change." 

- Le Chatelier's Principle on distrupting the equilibrium

CONCENTRATION

Adding reactants: eqm shifts right (in favour of the products), and a new mixture is established

Adding products: eqm shifts left (in favour of the reactants), and a new mixture is established

Removing reactants: eqm shifts left (in favour of the reactants), and a new mixture is established
Removing products: eqm shifts right (in favour of the products), and a new mixture is established


PRESSURE
Increase: favours the side with less gas molecules/moles
Decrease: favours the side with more gas molecules/moles
This changes the equilibrium, but not Kc. Kc stays the same.

TEMPERATURE
Kc is temperature dependent, a change in temperature will cause a change in Kc.

7.2.4 State and explain the effect of a catalyst on an equilibrium reaction.
A catalyst will speed up both forward AND backward reactions, therefore the eqm will not shift.

7.2.5 Apply the concepts of kinetics and equilibrium to industrial processes.