Lecture 4 Flashcards
(100 cards)
1
Q
Amino acids are formed from (elements)
A
Carbon, hydrogen, oxygen and nitrogen
2
Q
Amino acids composition, what determines its characteristics
A
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.
3
Q
How are amino acids joined together?
A
Amino acids join together using dehydration synthesis (by removing water) to create ‘peptide bonds’.
4
Q
When two amino acids are joined together
by a peptide bond, what is it called? Give an example.
A
Dipeptide. Aspartame is an example of a harmful dipeptide.
5
Q
What is a tripeptide? Give an example.
A
When three amino acids are joined together by a peptide bond, it is called a tripeptide.
The powerful antioxidant ‘glutathione’ is a tripeptide.
6
Q
Glutathione contains amino acids
A
L-cysteine, L-glutamate and glycine.
7
Q
How does the pH of the fluid affect the protein’s 3D structure and function?
A
Amino acids with acidic side chains can release hydrogen ions.
Amino acids with basic side chains can bind to hydrogen ions.
Whether they do or not depends on the pH of the surrounding fluid.
8
Q
What amino acids are hydrophobic? Give an example.
A
Non-polar amino acids. Tryptophan (used to produce serotonin - stimulates gut motility and digestive juices).
9
Q
What amino acids are hydrophilic? Give an example.
A
Polar amino acids. These include tyrosine (used to create adrenaline and thyroxine).
10
Q
What determines the 3D shape of the protein?
A
The combinations of the polar and non-polar amino acids.
11
Q
Name four functions of proteins.
A
- Structure of body tissues, e.g., collagen.
- Movement e.g., actin and myosin fibres (in muscles).
- Carrier molecules, e.g., haemoglobin.
- Storage molecules, 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.
12
Q
What does ‘denatured’ protein mean?
A
If a protein’s 3D structure changes or ‘unfolds’, we say it has ‘denatured’. Denatured proteins no longer function correctly.
13
Q
How can proteins be denatured?
A
– Heat, e.g., cooking.
– Heavy metals, e.g., lead and mercury (these can damage
proteins such as hormones, antibodies and enzymes).
14
Q
Name two natural chelating agents.
A
Coriander and chlorella remove heavy metals from the body
15
Q
How do enzymes help protein digestion?
A
Enzymes help break the peptide bonds between amino acids in a hydrolysis reaction (using water). E.g. in the stomach, the enzyme pepsin breaks down long protein chains.
16
Q
Protein digestion in the stomach
A
The chemical digestion of proteins begins in the stomach. Pepsin is released by gastric chief cells in the inactive form ‘pepsinogen’. The presence of HCl converts it into pepsin. Pepsin needs to be at pH 2 in order to function correctly, so adequate stomach acid is critical for good protein digestion.
17
Q
Protein digestion in small intestine
A
Protein-rich chyme enters the small intestine. The hormone CCK is released. It triggers the pancreas to release pancreatic juices (contain proteases trypsin and chymotrypsin). Protein chains are further broken down into tripeptides, dipeptides and single amino acids by pancreatic proteases and brush border enzymes. Amino acids and small peptides are absorbed into the blood.
18
Q
What are nucleic acids? Name two most common nucleic acids.
A
Nucleic acids are the largest molecules in the body and are used to store our genetic information.
- Deoxyribonucleic acid (DNA) - sugar with 1 oxygen missing.
- Ribonucleic acid (RNA).
19
Q
What are the building blocks of nucleic
acids called?
A
Nucleotides.
20
Q
Nucleotides consist of
A
A phosphate group, sugar and a nitrogenous base.
21
Q
Functions of Nucleic Acids (DNA and RNA)
A
DNA carries genetic information and acts as a template for protein synthesis.
RNA is used to copy specific sub-sections of DNA called ‘genes’, and translate them into proteins.
22
Q
Describe the difference between DNA and RNA structure.
A
RNA (Ribonucleic acid) is a single strand of nucleotides which contains the sugar ‘ribose’. Whereas DNA is a double-stranded structure and instead has the sugar ‘deoxyribose’.
23
Q
Name four possible nucleotide bases. How are they paired?
A
– Adenine (A) — a ‘purine’
– Cytosine (C)
– Guanine (G) — a ‘purine’
– Thymine (T)
Adenine always pairs with thymine. Guanine always pairs with cytosine.
24
Q
Structure of DNA
A
DNA has two strands that are wound together. This is called the ‘double helix’.
The two strands are held together by hydrogen bonds between the bases, whilst the sugar-phosphate bonds (at the sides) form covalent bonds. The hydrogen bonds are much weaker, which is how DNA is able to ‘unzip’ during protein synthesis.
25
RNA function
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.
26
What are ‘telomeres’?
The end sections of DNA .
27
What herb has been shown to reduce telomere shortening and hence support healthy ageing?
Centella asiatica (Gotu kola).
28
Mutation
An abnormal change to the genetic sequence.
A change in the sequence of amino acids in the protein can cause the protein to be a slightly different shape. This may affect the functionality of the protein, e.g. sickle-cell anaemia, haemophilia, and cancer.
29
What nutrients can influence gene expression?
Metabolites of vitamin A, vitamin D, essential fatty acids and zinc.
30
How fibre can have an effect on gene expression?
By affecting hormone levels and through the metabolites created when intestinal flora feed on the fibre.
31
What is methylfolate?
Active form of folate involved in the metabolism of the amino acid homocysteine - a metabolite associated with heart disease and dementia.
32
What is MTHFR and its functions?
‘MTHFR’ is an enzyme necessary for converting folate (B9) into a form used for methylation.
33
What environment would promote ‘pathological’ gene expression?
Acidic, anaerobic, glucose-rich, chronic stress, radiation, vaccine, drug toxins, junk food.
34
What is methylation? What is it required for?
The process of adding a methyl group (-CH3). Methylation is a process also required to remove toxic metals such as mercury from the body.
35
What are enzymes, and their functions?
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.
- They create a lower energy way for starting materials to meet and react, which allows reactions to happen in mild conditions within the body.
36
Definition of substrates and products in enzymatic reactions.
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’.
37
Enzymes: mode of action.
When the substrate binds to the enzyme, the enzyme ‘stresses’ the bond in the substrate, which weakens it and allows the body to more easily break the bond, so that the products can be released.
38
Name two co-factors for enzyme activity.
– Zinc is required for the enzyme ‘alcohol dehydrogenase’, which breaks down alcohol as part of the alcohol detoxification process.
– Selenium is required for the antioxidant enzyme ‘glutathione peroxidase’.
39
What can affect the speed of enzyme reaction?
Substrate concentration
40
How 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+.
Enzymes can be denatured by conditions that are too acidic or too basic.
41
Optimum pH: salivary amylase and pepsin.
Salivary amylase is in its correct shape when the surrounding pH is about 7. When swallowed, the amylase enters the stomach (a pH of 2–3) and is deactivated.
Pepsin is the correct shape at a pH of 2. If stomach acid production is not sufficient, pepsin will not fold up in the right way to effectively digest proteins.
42
Name five key digestive enzymes.
Saliva
- Salivary amylase
Stomach
- Gastric lipase
- Pepsinogen → pepsin
Pancreas
- Pancreatic amylase
- Pancreatic lipase
- Pancreatic proteases
Villi/brush border
- Sucrase
- Maltase
- Lactase
43
How over-eating can impair the digestion and absorption of nutrients in food?
Constantly eating taxes enzyme production.
By eating more often, more enzymes are produced and used up, so eventually, enzyme production cannot meet the demand.
44
How do bitters stimulate the production of digestive enzymes? Name two.
Bitters stimulate the Vagus nerve and trigger the release of cholecystokinin (CCK).
These include gentian (in Swedish bitters), barberry bark, andrographis, dandelion, and bitter greens.
45
Name three examples of enzymes in food.
* Sprouts contain up to 100 times more enzymes than fruit 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.
* 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’.
46
How does cooking affect the enzymes?
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.
47
What happens to water-soluble compounds during cooking?
Cooking often decreases the antioxidant value of food.
Water-soluble compounds can be lost with boiling, e.g., vitamin C, which leaches into water.
48
Name one digestive disorder when it's not advisable to eat raw foods and why?
Small Intestinal Bacterial Overgrowth (SIBO), eating raw can cause immediate bloating.
49
What compounds in plant-based foods become more available when heated?
Lycopene and beta-carotene.
Brassica (goitrogenic) foods disrupt the uptake of iodine in the thyroid gland. However, goitrogens are inactivated by the cooking process.
50
1. Name two enzymes involved in the creation of key inflammatory mediators called prostaglandins and leukotrienes.
2. What foods can naturally inhibit these enzymes?
1. Cyclooxygenase-1 and -2 (COX) and Lipoxygenase-5 (LOX).
2. Boswellia, curcumin and ginger.
51
Turmeric is best absorbed with
Should be used with black pepper, which significantly enhances absorption of the compound ‘curcumin’.
Fat-soluble, its absorption is further supported by the presence of fats, e.g., coconut oil.
52
Therapeutic uses: Ginger
For maximum medicinal effect use in powder form. Try mixing ¼ tsp with 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.
53
Therapeutic uses: Boswellia
Effective as a powder. Alternatively, supplement with pure boswellia or use frankincense topically.
54
Name two drugs that are used as enzyme inhibitors to decrease the rate of biological reactions.
* Antibiotics work by inactivating an enzyme necessary for the connections of amino acids in bacterial cell walls which is important for their structure.
* Statins work by inhibiting HMG-CoA reductase — the enzyme the liver uses to make cholesterol and CoQ10.
55
Name three proteolytic enzymes.
Bromelain, serrapeptase and pancreatic enzymes.
56
Name two bromelain properties.
– 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.
57
How does Serrapeptase reduce inflammation?
– By thinning the fluids formed from injury;
facilitating fluid drainage.
– Inhibiting the release of pain-mediating chemicals (inhibits the release of bradykinin from inflamed tissue) without inhibiting prostaglandins.
– Enhances cardiovascular health by breaking down ‘fibrin’ (can help dissolve blood clots and atherosclerotic plaques).
- Improves microcirculation, aids healing reduces swelling.
- Breakdown of sputum
58
What is ATP and its functions?
Adenosine Triphosphate is the energy currency of the body.
It is used to capture the energy released by reactions in the body such as ‘burning glucose’.
ATP is how the body ‘traps’ energy from these reactions in a way that the body can use it.
59
ATP structure
ATP is a nucleotide with three phosphate groups. The bonds between the phosphate groups contain lots of energy.
When water is added to ATP, one phosphate group is removed, releasing energy via a hydrolysis reaction.
60
Role of magnesium for ATP
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 (low energy is a symptom of magnesium insufficiency).
Magnesium is a central component of chlorophyll (increase intake of green vegetables).
61
Functions of ATP
* Capture the energy from oxidation reactions (the energy created when we burn fuel like glucose).
* Drive body reactions (building proteins).
* Fuel movement.
* Transport substances across membranes (active transport).
* Cell division.
62
Why an adequate intake of B vitamins is essential for optimal energy levels?
The main intermediate energy carriers are derived from B vits.
63
Name two energy carriers and what vitamins are required to make them.
NAD is made from vitamin B3 (niacin), or from the amino acids tryptophan and aspartic acid.
FAD is made from vitamin B2 (riboflavin).
64
NAD and FAD mode of action.
NAD or FAD sweep in and steal electrons and a hydrogen from the glucose (or fats). They trap the energy temporarily.
65
Oxidised meaning
Chemically ‘burned’ inside the body.
66
Name the four steps of cellular respiration.
1. Glycolysis (or anaerobic cellular respiration)
2. Formation of acetyl CoA
3. Krebs cycle
4. Electron transport chain
67
What nutrients are required for glycolysis?
Magnesium and B3
68
What happens in glycolysis?
Glycolysis occurs in the cytosol.
Through the 10 steps, glucose (6-carbon structure) is transformed into two molecules of pyruvate (2 x 3-carbon structures). Through this ‘splitting’ of glucose, some energy is released, but 2 ATP is used up.
Energy is directly released and trapped as 4 ATP and 2 NADH. There is a net gain of 2 ATP and the 2 NADH (trapped energy).
69
Why anaerobic respiration isn't favourable for the body?
When oxygen isn’t available, NADH cannot be recycled in the electron transport chain and turned into ATP.
The anaerobic body accumulates lactic acid (this can cause muscle pain) and creates an acidic environment.
70
Describe Acetyl CoA formation, including required nutrients.
If oxygen is plentiful, pyruvate will enter the mitochondria and be converted to ‘acetyl CoA’. This process allows us to get more energy out of glucose and requires vitamin B1, lipoic acid and vitamin B5.
- Pyruvate will react with a vitamin B5 carrier molecule, which then allows it to enter the mitochondria.
- Vitamin B1 and lipoic acid enable the pyruvate to lose one of its 3 carbon atoms. Acetyl CoA hence has 2 carbons.
- During the transformation, 2 more packets of energy are trapped as NADH.
71
Coenzyme A role in ATP formation
It is naturally synthesised from pantothenate (vitamin B5),
* It is a vital carrier molecule to transport the acetyl group into the mitochondria so that it can participate in the Krebs Cycle.
* Coenzyme A carries energy in a high-energy bond.
72
The Krebs Cycle
The Krebs Cycle is a series of reactions, where acetyl CoA is modified by enzymes in the mitochondrial matrix. Through this process, energy is released or trapped.
* It is also known as the Citric Acid Cycle (the first molecule that forms during the cycle's reactions ― citrate).
* For each glucose, enough energy is released to make:
– 2 ATP
– 6 NADH
– 2 FADH
Many of the enzymes can be easily blocked by heavy metals such as aluminium and mercury.
73
What nutrients are required for the Krebs Cycle?
Magnesium, manganese, iron, B1, B2, B3.
74
The Electron Transport Chain
The final step in the process allows the energy trapped in the NADH and FADH2 to be turned into ATP with the help of four enzyme complexes which are embedded in the inner folds of the mitochondria.
75
Why oxygen is important in electron transport chain?
A hypoxic environment will reduce their ability to produce ATP. Without oxygen, NAD and FAD cannot be recycled.
76
What nutrients are required for complex 1 in the electron transport chain?
Iron and sulphur.
77
What nutrients are required for complex 2 in the electron transport chain?
CoQ10.
78
What nutrients are required for complex 3 in the electron transport chain?
Iron.
79
What nutrients are required for complex 4 in the electron transport chain?
Copper ions.
80
CoQ10 functions
- It is a key component of the electron transport
chain and is stored in the mitochondria.
- It has antioxidant properties and helps recycle other antioxidants such as vitamin C and E (reduces free radical damage - a common cause of mitochondrial damage).
- Slows down ageing changes.
- Inhibits arterial LDL oxidation.
81
Why CoQ10 levels are depleted by statin use?
Statins act on the pathway shared for cholesterol and CoQ10 synthesis. This explains adverse effects such as muscle aching and fatigue.
82
Food sources of CoQ10 (name four).
Meat, poultry, fish (especially sardines and anchovies), nuts, sesame seeds, broccoli, cauliflower, oranges, strawberries.
83
Name three causes of mitochondrial damage.
– 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.
84
What conditions is poor mitochondrial functioning linked to?
Fibromyalgia, Type 2 diabetes, chronic fatigue syndrome, the pathogenesis of cancer.
85
How can we support mitochondrial health?
* Reduce toxic load (i.e., heavy metals, free radicals, chemicals ingested, inhaled, injected, absorbed through the skin, etc.).
* Increase nutrient co-factors.
* Increase production of glutathione and glutathione peroxidase (by increasing sulphur and selenium-rich foods) and mitochondrial antioxidants including CoQ10.
* Support detoxification (liver) and elimination (bowel, kidneys, skin, lungs) processes.
86
What herbal medicines can be used to support mitochondrial function?
* Adaptogenic herbs: ginseng, astragalus, rhodiola.
* Gingko biloba.
* Rosemary.
* Curcumin (turmeric).
* ‘Cleansing the blood’ and removing encumbering elements: burdock and dandelion.
87
How many ATP one molecule of glucose makes during aerobic and anaerobic respiration?
Aerobic respiration - 38 molecules of ATP.
Anaerobic respiration - 2 ATP.
88
How are fats 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.
89
What is a better source of energy - carbohydrates or fats?
Fats yield a lot more energy than carbohydrates.
So whilst burning carbohydrates is easier, burning fats is more efficient.
90
In order to get into the mitochondria and be used for energy fatty acids must combine with?
Co-enzyme A (from vitamin B5).
* This process requires ATP and, therefore, magnesium.
* A carnitine-dependent enzyme L-carnitine is then needed to transport fatty acids into the mitochondria.
91
What nutrients are required for beta-oxidation?
Beta-oxidation requires vitamin B2, vitamin B3 and sulphur. This produces energy.
92
What happens during beta-oxidation?
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.
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.
93
What does the brain use for energy if carbohydrates are in short supply? Describe the process.
Ketone bodies if sufficient glucose is not available, e.g., fasting.
* The mitochondria of liver cells can convert acetyl CoA into ketone bodies.
* 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.
94
What is ketosis and when does it occur?
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.
95
What is ketoacidosis and when does it occur?
In some pathological states, ketone bodies form in excessively high quantities. 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.
96
Therapeutic uses for ketogenic diet
* For children with refractory epilepsy, to help control seizures (increases the amount of the inhibitory neurotransmitter GABA in the brain).
* In neurodegenerative diseases such as Alzheimer’s and Parkinson’s (enhances mitochondrial function).
* Cancer (cancerous cells rely solely on glucose for their metabolism).
97
Why is fasting beneficial for the body?
* Prevents the body from expending excess amounts of energy digesting food.
* Allows the body to focus its energy on other functions such as healing and regenerating.
* Encourages the body to enter a state of ketosis (fats also yield more energy than carbohydrates). This can be an effective way of increasing energy levels.
98
What is gluconeogenesis? Give examples.
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.
99
Co-factor for gluconeogenesis.
Biotin
100
What are the major sources of energy for the body?
– Glucose: From carbohydrates.
– Fatty acids: From fat metabolism.
– Ketone bodies: From fat or amino acid metabolism.
– Amino acids: From protein (or body if starving).
