Chemistry & Biochemistry II

Question 1

Proteins

Answer 1

• Amino acids are the building blocks for proteins.
• They are formed from the elements
Carbon, Hydrogen, Oxygen and Nitrogen. The nitrogen component distinguishes proteins from fats and carbohydrates.
• The body needs 20 different amino acids to create the proteins needed to function.
• Every amino acid has a carboxyl group/acid (-COOH) and an amino group (-NH3).
Each individual amino acid has a side chain (labelled R) that determines its characteristics.

Question 2

Peptides

Answer 2

• Amino acids join together using dehydration synthesis (by removing water), to create ‘peptide bonds’.
• When 2 amino acids are joined together by a peptide bond, it is called a dipeptide. When 3 join together, it is a tripeptide.
• Aspartame is an example of a harmful dipeptide. It does not occur in nature & is a neurotoxin. It is manufactured to become an artificial sweetener.
• The powerful antioxidant ‘Glutathione’ is a tripeptide containing the amino acids L-cysteine, L-glutamate and glycine. Cysteine is the amino acid most commonly limiting glutathione production. So by ensuring a good intake of cysteine (from foods such as legumes, sunflower seeds & eggs), you will optimise glutathione production

Question 3

Amino Acid Types

Answer 3

• Amino acids with acidic side chains can release hydrogen ions; whether they do or not depends on the pH of the surrounding fluid.
• Amino acids with basic side chains can bind to hydrogen ions; whether they do or not depends on the pH of the surrounding fluid.
• This means the pH of the fluid the protein is in will affect its 3D structure and, therefore, its function, eg. ceviche & squeezed lemon juice (citric acid).

Question 4

Amino Acid Types

Answer 4

• Non-polar amino acids are hydrophobic.
When a protein folds up in a watery environment they like to be on the inside of the protein structure, away from any water. These include Tryptophan (used to produce serotonin-which stimulates gut motility and digestive juices).

• Polar amino acids are hydrophilic.
When a protein folds up in a watery environment they like to be on the outside of the protein structure, interacting with the polar water molecules. These include Tyrosine (which is also used to create adrenaline and thyroxine!).

Question 5

Function of Proteins:

Answer 5

• Structure of body tissues, e.g. Collagen.
• Movement e.g. Actin and myosin fibres (in muscles).
• Carrier molecules, e.g. Haemoglobin.
• Storage molecule, e.g. Ferritin (iron).
• Fluid balance in the blood, e.g. Albumin.
• Enzymes (for reactions in the body).
• Hormones, e.g. Insulin.
• Immune function, e.g. Antibodies.
• Clotting mechanisms, e.g. clotting factors.
• Alternative energy source – Much less efficient than carbohydrate or fat so only used during dietary deficiency.
• Cell membrane proteins, e.g. receptors

Question 6

Denaturation:

Answer 6

• The 3D structure of a protein is key to its function. Proteins work like a “lock and key”. If a protein’s 3D structure changes or ‘unfolds’, we say it has ‘denatured’. Denatured proteins no longer function correctly, e.g. protein fibres in muscle cells.

• Proteins can be denatured by:
– Heat, e.g. cooking (i.e. egg whites become denatured during cooking) and pH changes. Note that this is not necessarily bad.
– Heavy metals, e.g. lead and mercury (these can damage proteins such as hormones, antibodies and enzymes). Exposure must be minimised. Natural chelating agents such as Coriander and Chlorella remove heavy metals from the body.

Question 7

Protein Digestion:

Answer 7

• To digest proteins, the body uses enzymes to help break the peptide bonds between the amino acids.
• These bonds can be broken in a hydrolysis reaction – using water.
• Proteins are mechanically broken down in the mouth, increasing the surface area for the enzymes to work on.
• However, the chemical digestion of proteins begins in the stomach where the enzyme pepsin breaks down long protein chains.
• Pepsin is released by gastric chief cells in the inactive form ‘pepsinogen’. It is the presence of HCl that converts this into pepsin. Pepsin needs to be at pH 2 in order to function correctly, so adequate stomach acid is critical for good protein digestion.

Question 8

Protein Digestion & Absorption:

Answer 8

• As protein rich-chyme enters the small intestine, the hormone CCK is released, which triggers the pancreas to release pancreatic juices.
• Pancreatic juices contain proteases called trypsin and chymotrypsin.
• In the small intestine, these shorter protein chains, that have entered the small intestine from the stomach, are further broken down into tripeptides, dipeptides and single amino acids by pancreatic proteases and brush border enzymes.
• Amino acids and small peptides are then absorbed into the blood.

Question 9

Nucleic Acids:

Answer 9

• Nucleic acids are the largest molecules in the body and are used to store our genetic information.
• The most common nucleic acids are deoxyribonucleic acid (DNA) and ribonucleic acid (RNA).
• The building blocks of nucleic acids are called ‘nucleotides’.
• Nucleotides consist of a phosphate group, sugar and a nitrogenous base.

Question 10

Functions of Nucleic Acids:

Answer 10

• DNA stores genetic information and acts like a recipe book.
• Every living cell contains at least one DNA molecule to carry genetic information from one generation to the next.
• Human DNA molecules are huge. If a DNA molecule could be extracted from a human cell, it would be 2m long.
• DNA acts as a template for protein synthesis (a recipe for producing proteins). RNA is used to copy specific sub-sections
of DNA called ‘genes’, and translate it into proteins. There are 20,000-25,000 genes in the human genome (complete set of DNA).

Question 11

DNA

Answer 11

• The nucleotides in DNA contain the 5-carbon sugar ‘deoxyribose’.
• DNA has four possible nucleotide bases (amino acids):
– Adenine (A) - a ‘purine’
– Cytosine (C)
– Guanine (G) - a ‘purine’
– Thymine (T)

• Purine-rich foods (e.g. shellfish, red meats) contain lots of adenine and guanine bases. These are metabolised to form uric acid and, when in excess, can crystallise in joints and cause gout.

Question 12

Structure of DNA

Answer 12

• DNA has two strands that are wound together like a twisted ladder. This is called the ‘double helix’.
• The two strands are held together by hydrogen bonds (review Biochem. I) between the bases (i.e. in the middle of the ladder), whilst the sugar-phosphate bonds (i.e. at the sides of the ladder) form
covalent bonds. The hydrogen bonds are much weaker, which is how DNA is able to “unzip” during protein synthesis.
• Adenine always pairs with Thymine always pairs with Cytosine. This is important because the sequences of these pairs will ultimately code for the production of a certain protein (i.e. a hormone, such as insulin).

Question 13

RNA

Answer 13

• RNA (Ribonucleic acid) is a strand of nucleotides which contains the sugar ‘ribose’. Whereas DNA is a double stranded structure and instead has the sugar ‘deoxyribose’.
• A molecule of mRNA (messenger RNA) copies the ‘recipe’ in DNA (a ‘gene’). This is known as transcription. The mRNA then travels to a ribosome where it is ‘read’. The ribosome then produces the protein coded for, e.g. a hormone. This is called translation.

Question 14

Genetics

Answer 14

• DNA is also used as a manual for making all the proteins in the body, everything from muscle tissue to enzymes.
• DNA is condensed to form ‘Chromosomes’. The end sections of DNA are called ‘telomeres’.
– The length of telomeres shortens as cells and tissues age. It has been shown that this process of ageing can accelerate from causes such as stress, poor nutrition, poor sleep, chemical agents, a lack of exercise and even negative thoughts.
– The herb Centella asiatica (Gotu kola) has been shown to reduce telomere shortening and hence support healthy aging.

Question 15

Mutation

Answer 15

• A mutation is a change in the DNA sequence.
• Since the DNA sequence provides the code for making proteins, a mutation can cause a change in the sequence of amino acids in the protein.
• This is turn can cause the protein to be a slightly different shape. The shape change may affect the functionality of the protein, eg. Sickle-cell anaemia involves a mutation of the gene that codes for the production of haemoglobin proteins. When this mutation occurs, the proteins in haemoglobin become abnormally shaped and hence the red blood cells are defective.

Question 16

Mutations

Answer 16

• A ‘Mutation’ describes an abnormal change to the genetic sequence. It can be something someone is born with, but most commonly occurs during a person’s lifespan.
• Haeomphilia is a disease linked to mutations of the genes associated with the production of clotting factor 8 (Haemophilia A) or clotting factor 9 (Haemophilia B). As a result, these individuals cannot adequately synthesise key clotting factors and will have problems clotting and stopping bleeding.
• In cancer, mutations occur due to factors such as radiation, poor nutrition, chronic inflammation, medications, chronic stress and carcinogenic chemicals. These mutations affect the genes that code for proteins involved in regulating cell division.

Question 17

Mutations: Folate

Answer 17

• Gene mutations can affect enzyme activity.
• ‘MTHFR’ is an enzyme necessary for converting folate (B9) into a form used for methylation.
• This active form of folate (‘methylfolate’) is
involved in the metabolism of the amino acid homocysteine – a metabolite associated with heart disease and dementia.
• The mutation causes the enzyme to fold up into an abnormal shape.
• People with MTHFR mutations may have higher homocysteine levels and may benefit from taking methylfolate (already activated).
• Harm can come from excessive fortified folic acid foods, e.g. cereals.
• It is worth noting that methylation is a process also required to remove toxic metals such as mercury from the body.

Question 18

Enzymes

Answer 18

• Enzymes are biological catalysts made from protein.
• They speed up reactions, but are not themselves changed in the process, so they can be used over and over again.
• Enzymes generally end in the suffix –ase. E.g. lipase digests fats, proteases digest proteins.
• In enzymatic reactions, the molecules at the beginning of the process are called ‘substrates’,
and the enzyme converts them into different molecules known as the ‘products’, e.g. pepsin is the enzyme, a protein is the substrate, and shorter protein chains are the products.
• When the substrate binds to the enzyme, the enzyme ‘stresses’ the bond in the substrate, which weakens it and allows your body to more easily break the bond, so that the products can be released.

Question 19

Enzyme Cofactors

Answer 19

• Some enzymes require co-factors for activity. These are usually minerals or vitamins. Without these, the enzyme is inactive.
• For example:
– Zinc is required for the enzyme ‘alcohol dehydrogenase’, that breaks down alcohol as part of the alcohol detoxification process.
– Selenium is required for the antioxidant enzyme ‘glutathione peroxidase’.

• A lack of cofactor can lead to a reduction in enzyme activity. This is relevant in clinic, in that deficiencies in these co-factors would effect enzyme reactions all over the body. E.g. a lack of selenium impairs the liver’s ability to produce Glutathione peroxidase.

Question 20

Enzyme- Substrate Concentrations:

Question 21

Enzymes: pH

Answer 21

• Changes in pH can affect the properties of amino acid side chains.
• In acidic conditions, amino acid side chains can bind to H+. In basic (alkaline) conditions, the side chains can lose H+.
• These changes can affect whether or not these side chains can form the bonds and interactions which are essential for the 3D structure of the enzyme.
• Enzymes can be denatured by conditions that are too acidic or too basic.
• This is why the body works so hard to control pH.
• Enzymes have an optimum pH at which they function best.
This is the pH where the protein is the correct shape. For human enzymes the pH range of optimal function is often very narrow, eg. salivary amylase: pH 7, pepsin (stomach): pH 2

Question 22

Enzymes: Temperature

Answer 22

• At high temperatures, molecules move much faster. This leads to more collisions and, therefore, a faster reaction rate.
• However, if the atoms in an enzyme vibrate too much, the weak bonds holding the 3D structure together can break and the enzyme becomes denatured (the structure “unravels”).
• Once the 3D structure is lost, the enzyme no longer works.
• Enzymes usually have an optimum temperature at which they work best. For human enzymes, this is body temperature (~37°C).
• A fever works effectively by speeding up the immune reactions in the body. It is important this does not go beyond 40°C, because then enzymes will denature and metabolic processes will break down.

Question 23

Digestive enzymes:

Answer 23

• Modern dietary habits mean that many people often struggle to produce enough digestive enzymes, eg. overeating, drinking whilst eating, prolonged stress and/or nutritional deficiencies.

• Herbal bitters can be used to stimulate the production of digestive enzymes.
They should be taken 15-20 minutes before meals. Bitters are thought to work by stimulating the Vagus nerve and also trigger the release of Cholecystokinin (CCK).
– These include Gentian (in Swedish Bitters), Barberry bark, Andrographis and Dandelion. Also include bitter greens.

Question 24

Enzymes in Food:

Answer 24

• Plants, like humans, also contain enzymes.
• Some of these have similar functions to human enzymes – for example the *bromelain in pineapples and the *papain in papayas are both proteases – enzymes that help digest proteins.
• Unlike human enzymes, plant enzymes tolerate a wider range of pH❗️

Other examples:
• Sprouts contain up to 100 times more enzymes than and vegetables.
• Kiwi contains the proteolytic enzyme ‘actinidin’. This is the predominant enzyme in kiwi fruit and aids protein digestion.
• Avocado contains the enzyme lipase, which helps digest the fats in avocado.
fruit
• Garlic contains the Sulphur-rich phytonutrient ‘alliin’
and the enzyme which digests it, called ‘alliinase’. When a garlic clove is chopped or crushed, the usually separated compounds mix and the enzyme activity converts alliin into ‘allicin’.
– Allicin has anti-microbial, anti-oxidant, cardio-protective and anti-cancer properties.

Question 25

Enzymes in Food:

Answer 25

• Cooking can be damaging to enzymes naturally present in food. The longer the exposure and the higher the heat, the greater the loss.
• Enzymes start to be destroyed when food is heated above 40°C. This emphasises the potential benefit of eating raw foods. Most people consider the upper raw food limit
to be 46-48°C as there are still some active enzymes after cooking at this temperature.
• The enzymes that remain undamaged in these foods can support digestion, assisting with the breakdown of macronutrients and reducing the digestive burden

Question 26

Raw Foods:

Answer 26

• Raw foods contain more micronutrients than cooked food, i.e. vitamins, minerals, probiotics, anti-oxidants, reduce free radicals and the need for digestive enzymes.
• Cooking often decreases the antioxidant value of food.
• Water-soluble compounds can be lost with boiling, e.g. vitamin C, which leaches into water.

However:
• some compounds in plant-based foods such as lycopene and beta carotene become more available when heated, as they are released from plant cell walls❗️
• It may not be advisable for some individuals to eat raw.
In some digestive disorders such as Small Intestinal Bacterial Overgrowth (SIBO), eating raw can cause immediate bloating.
• Brassica (goitrogenic) foods (e.g. turnips, cabbage, radishes) disrupt the uptake of iodine in the thyroid gland. However, goitrogens are inactivated by the cooking process, so may or may not need to be cooked depending on the thyroid disorder.
• As covered earlier, ‘Yin conditions’ may be caused by excessive raw foods. This can cause lethargy, anaemia, a feeling of being “cold”, through a lack of ‘warming foods’.

Question 27

Enzymes: Inflammation

Answer 27

• Cyclooxygenase-1 and -2 (COX) and Lipoxygenase-5 (LOX) are enzymes involved in the creation of key inflammatory mediators called prostaglandins and leukotrienes.
• Boswellia, curcumin and ginger help to reduce inflammation by inhibiting these enzymes.

Therapeutic Uses:
• Turmeric – easily incorporated into meals. This should be used with black pepper, which
significantly enhances absorption of the compound ‘curcumin’. Turmeric is also fat-soluble, so its absorption is further supported by the presence of fats, e.g. coconut oil.
• Ginger – for maximum medicinal effect use inCpowder form. Try mixing 1⁄4 tsp to some water. Alternatively grate into boiling water and drink once it has steeped for 10 minutes (grated and in hot water). Also add to meals.
• Boswellia – also effective as a powder. Alternatively supplement with pure Boswellia or use Frankincense topically.

Question 28

Enzyme Inhibitors as Drugs:

Answer 28

Enzyme inhibitors are quite often used as drugs, to decrease the rate of biological reactions. For example:

• Antibiotics (such as penicillin) work by inactivating an enzyme necessary for the connections of amino acids in bacterial cell walls (both pathogenic and healthy bacteria) which is important for their structure.
• Statins work by inhibiting HMG-CoA reductase – the enzyme the liver uses to make cholesterol and CoQ10. This explains why statins also deplete CoQ10.

Question 29

Enzyme Therapies:

Answer 29

Systemic enzyme therapy involves taking a large dose of proteolytic enzymes on an empty stomach so that some of the enzymes are able to reach the bloodstream intact.

• The proteases are thought to reduce inflammatory processes and aid in the more efficient clearance of damaged tissue.
• Commonly used enzymes include bromelain (found in pineapple), serrapeptase and pancreatic enzymes.
• The proteolytic enzyme ‘Bromelain’ has been shown to have:
– Anti-inflammatory effects (reduces inflammatory mediators such as ‘bradykinin’) and anti-cancer properties. – Anti-clotting (acts on fibrinogen); may also have positive effects on atherosclerotic plaques.

Question 30

Enzyme Therapies: Serrapeptase

Answer 30

• It is thought to reduce inflammation by:
– Thinning the fluids formed from injury; facilitating fluid drainage.
– Inhibiting the release of pain-mediating chemicals.
– Enhances cardiovascular health by breaking down the protein by-product of blood coagulation called ‘fibrin’. It can, therefore, help dissolve blood clots and atherosclerotic plaques.

• Serrapeptase reduces pain and swelling without inhibiting prostaglandins and has no gastrointestinal adverse effects (like NSAIDs).
• Serrapeptase alleviates pain by inhibiting the release of bradykinin from inflamed tissues. Serrapeptase hydrolyses bradykinin and histamine, thereby reducing swelling, improving microcirculation, aiding healing, as well as the breakdown of sputum.
• Therapeutic uses: Inflammatory-mediated pain (arthritis, spinal disc injuries), scar tissue, fibrocystic breast disease, endometriosis, autoimmunity, excess mucus, resistant bacterial infections (digests biofilm).

Question 31

Energy Production: ATP & Magnesium

Answer 31

• ATP is always present as a magnesium-ATP complex❗️
• Magnesium binds to phosphate groups in ATP, holding the molecule in a slightly curved / strained shape that aids the loss of phosphate, facilitating energy release.
• Without magnesium, ATP isn’t biologically active as it is difficult to release the energy from between the phosphate groups.
• Hence low energy is a symptom of magnesium insufficiency.
• Magnesium is a central component of chlorophyll (like how iron is at the core of haemoglobin). So increase intake of green vegetables.

Question 32

Turning Food into Energy:

Answer 32

• The process of turning glucose, fat or even proteins into energy isn’t straightforward. The energy isn’t always released in handy ATP-sized packages.
• So at certain points during the process, the body has to use ‘energy carriers’ to temporarily capture the energy released.
• And then we can convert the trapped energy into ATP molecules later.
• The main intermediate energy carriers are derived from B vitamins.

Question 33

Energy from Carbohydrates:

Question 34

1. Glycolysis:

Answer 34

• first stage of aerobic (38 molecules of ATP made) and anaerobic (only 2 molecules of ATP made) respiration and occurs in the cytosol.
• glucose is transformed into two molecules of a substance called pyruvate. Through this “splitting” of glucose, some energy is released, but 2 ATP is used up.
• Glucose contains 6-carbon atoms, whilst pyruvate contains 3 (so goes from a 6-carbon structure to 2 x 3 carbon structures).
• Energy is directly released and trapped as 4 ATP and 2 NADH. There is, therefore, a net
gain of 2 ATP and the 2 NADH (trapped energy).
• Glycolysis requires Magnesium and B3.

Question 35

2. Acetyl CoA formation:

Answer 35

• If oxygen is plentiful, pyruvate will enter the mitochondria and be converted to ‘Acetyl CoA’, ready to enter the Krebs cycle. This process allows us to get more energy out of glucose.
• Pyruvate will react with a Vitamin B5 carrier molecule, which then allows it to enter the mitochondria.
• This process requires Vitamin B1, Lipoic acid and Vitamin B5.
• • CoenzymeAisnaturallysynthesised from pantothenate (vitamin B5), which is found in food such as meat, vegetables, cereal grains, legumes and eggs.
  • It is a vital carrier molecule to transport the acetyl group into the mitochondria so that it can participate in the Krebs Cycle.

Question 36

3. Kreb’s Cycle:

Answer 36

• a series of reactions, where Acetyl CoA is modified by enzymes. Through this process, energy is released or trapped.
• The Krebs Cycle is also known as the Citric Acid Cycle.
• Acetyl CoA enters the Krebs cycle. For each glucose, enough energy is released to make:
– 2 ATP
– 6 NADH
– 2 FADH
• The Krebs Cycle requires– Magnesium, Manganese, Iron, B1, B2, B3.

• many of these enzymes can be easily blocked by heavy metals such as aluminium and mercury❗️

Question 37

4. The Electron Transport Chain:

Answer 37

• allows the energy trapped in the NADH and FADH2 to be turned into ATP with the help of 4 enzyme complexes, which are embedded in the inner folds of the mitochondria.
• Oxygen is very much essential for this step to occur❗️ (Without oxygen, NAD and FAD cannot be recycled).

Co-factors:
– Complex I: requires Iron & Sulphur.
– Complex II: requires CoQ10.
– Complex III: requires Iron.
– Complex IV: requires Copper ions.

Question 38

Summary:

Answer 38

Question 39

CoQ10

Answer 39

• Coenzyme Q10 is a key component of the electron transport chain and is stored in the mitochondria.
• CoQ10 levels are depleted by statin use, which act on the pathway shared for cholesterol and CoQ10 synthesis. This explains adverse effects such as muscle aching and fatigue.
• CoQ10 has antioxidant properties and helps recycle other antioxidants such as vitamin C and E.
It, therefore, reduces free radical damage, which is a common cause of mitochondrial damage. In addition, CoQ10 slows down aging changes and also inhibits arterial LDL oxidation.

• Sources: Meat, poultry, fish (especially sardines and anchovies), nuts, sesame seeds, broccoli, cauliflower, oranges, strawberries.

Question 40

Mitochondrial damage:

Answer 40

• Mitochondrial damage can occur due to:
– Free radicals.
– Medical drugs and alcohol- these increase free radicals, decrease antioxidants (i.e. glutathione) and deplete key nutrients.
– Environmental toxins: pollution, heavy metals, BPA (in plastic). • This damage may compromise the electron transport chain, without generating energy.

• Poor mitochondrial functioning is linked to:
– Fibromyalgia, type 2 diabetes, chronic fatigue syndrome, the pathogenesis of cancer.

Question 41

Supporting Mitochondria:

Answer 41

– Reduce toxic load (i.e. heavy metals, free radicals, chemicals ingested, inhaled, injected, absorbed through the skin, etc.).
– Increase nutrient cofactors (previous slides).
– Increase production of glutathione and glutathione peroxidase (by increasing Sulphur & Selenium-rich foods) and mitochondrial antioxidants including CoQ10.
– Support detoxification (liver) and elimination (bowel, kidneys, skin, lungs) processes.

Herbal medicines can also be used to support mitochondrial function in the following ways:
• Supporting mitochondrial functions. These include adaptogenic herbs (especially Ginseng, Astragalus, Rhodiola), as well as Gingko Biloba, Rosemary and Curcumin (turmeric).

• “Cleansing the blood” and removing encumbering elements. These include Burdock, and Dandelion

Question 42

Energy from fats:

Answer 42

• In the absence of sufficient carbohydrates, fats can also be used for energy production.
• Lipases split triglycerides from adipose tissue into fatty acids and glycerol.
• The fatty acids are transported to the liver, where the body uses a process called beta-oxidation to convert them into molecules of Acetyl CoA.
• The acetyl CoA can then enter the Krebs cycle, just like carbohydrates.

*Fats yield a lot more energy than carbohydrates. So whilst burning carbohydrates is easier, burning fats is more efficient❗️

Question 43

Getting Into The Mitochondria

Answer 43

• In order to get into the mitochondria and be used for energy, fatty acids must first combine with coenzyme A (from vitamin B5).
• This process requires ATP and, therefore, magnesium. • A carnitine-dependent enzyme is then needed to ferry the fatty acid into the mitochondria.
• L-carnitine is, therefore, required to transport fatty acids into the mitochondria. This explains why
L-carnitine is often found in weight loss formulas, to help the fatty acids enter the mitochondria and be “burned“ for energy.

Question 44

Beta Oxidation:

Answer 44

• The aim of beta-oxidation is to gradually chop the fatty acid chain into acetyl CoAs, ready to go into the Krebs cycle. This process occurs in the mitochondria.
• Beta-oxidation requires Vitamin B2, Vitamin B3 and Sulphur. This produces energy.
• The process repeats until the entire fatty acid chain is broken down into acetyl CoA units, which can then enter the Krebs cycle. The amount of energy produced depends on the length of the fatty acid chain.

Question 45

Ketone bodies:

Answer 45

• Most body tissues can use fatty acids for energy directly when carbohydrates are in short supply, but the brain cannot!
• The brain gets its energy from ketone bodies when sufficient glucose is not available, e.g. fasting.
• The mitochondria of liver cells can convert acetyl CoA into ketone bodies – acetone, acetoacetic acid and β-hydroxybutyrate.
Acetoacetic acid
• These can cross the blood brain barrier and be used as a source of energy.
• Ketone bodies can also be formed when protein is used for energy.

Question 46

Ketosis 🆚 Ketoacidosis:

Answer 46

• The production of ketones is called ‘ketogenesis’. The body state of forming ketones is known as ‘ketosis’.
• Ketosis can occur during high fat (and low carbohydrate) diets and whilst fasting. This state is highly beneficial for the body.
• Ketosis is never harmful from diet alone. Although, in some pathological states, ketone bodies form in excessively high quantities; this creates a state known as ‘ketoacidosis’. This dangerous state can occur in diabetes mellitus and alcoholism.
• Both acetoacetic acid and beta-hydroxybutyrate are acidic, so if levels of these ketone bodies are extremely high, the pH of the blood drops. This is dangerous in that it affects the blood pH.
• Ketoacidosis can be smelled on a person’s breath. This is due to acetone (smells like nail varnish remover).

Question 47

Energy from Protein (eg. chia/quinoa):

Answer 47

• The carbon parts of amino acids can be broken down to generate ATP, or they can be used
for gluconeogenesis – making glucose.
• One key point in the degradation of all amino acids is the loss of nitrogen. Vitamins B3 and B6 are important cofactors – both of which help remove nitrogen.
• For amino acids to enter the Krebs cycle, or to be used to make other molecules, they must first lose their amine (NH2) group.
• This results in the creation of ammonia (NH3). Most ammonia is converted to urea in the ‘urea cycle

Question 48

Gluconeogenesis:

Answer 48

• Gluconeogenesis describes the formation of new glucose from other non-carbohydrate sources. Key examples include:
– Pyruvate
– Lactic acid (the heart does this)
– Glycerol
– Some amino acids (e.g. glutamine)
• Takes place in the liver and, to a lesser extent, the kidneys (during periods of fasting, starvation or intense exercise). The process requires energy (ATP).
• Biotin is an important cofactor❗️

Question 49

Energy from Food:

Answer 49

• Adults in their fed state will obtain their energy:

• 47% from carbohydrate
• 38% fat
• 15% protein
• In fasting states, the body will source its energy from glycogen, then fat, then available protein.
• The major source of energy for the body are:
• Glucose - from carbohydrates.
• Fatty acids - from fat metabolism.
• Ketone bodies - from fat or amino acid metabolism.
• Amino acids - from protein (or body if starving).