Lecture 3 Flashcards

Question

What is an ion?

Answer 1

If an atom gives up or gains electrons to fill its outer shell, it becomes an ion. Ionisation is the process of giving or gaining electrons. Ions are written with their corresponding – or + charge.

Answer 2

Covalent bonds occur when two elements share electrons. This kind of bonding tends to happen when the two atoms are similar or when there are a lot of spaces to be filled to reach a full outer shell.

Answer 3

Polar covalent bonds form where electrons are shared unequally. This happens because some atoms have a lot of ‘electron-pulling power. One of the most important examples of a polar bond are the bonds between Oxygen and Hydrogen in water. These interactions are called hydrogen bonds and are what give water many of its special properties such as surface tension and the ability to dissolve so many different things.

Answer 4

The elements that have lots of protons compared to the number of electron shells (i.e. a strong positive centre) and they tend to pull the shared electrons towards themselves. These very electronegative atoms are able to pull the electrons in a bond towards them, leading to an uneven distribution of charge.

Answer 5

Water serves as the medium for most chemical reactions in the body. As water contains polar bonds, it is an ideal solvent for dissolving chemicals into their separate ions. In addition, the different electrical charges in water can allow water molecules to become attracted to other molecules (hence water dissolves salt).

Answer 6

Hydrophilic molecules are molecules which have polar bonds. They dissolve easily in water (e.g. alcohol). Hydrophobic molecules contain non-polar covalent bonds, so they do not dissociate easily in water (e.g. fats)

Answer 7

An electrolyte is formed when an ionic compound (e.g. salt) dissolves in water. Electrolytes can conduct electricity.

Answer 8

Sodium, Potassium, Chloride, Calcium, Magnesium, Phosphate, Bicarbonate.

Answer 9

- Conduction of electricity is essential for nerve & muscle function. - Exert osmotic pressure (important for water balance). - Some play an important role in acid-base balance.

Answer 10

An acid is a substance that releases a high amount of H+ ions when dissolved in water. Anything with a pH lower than 7 is an acid.

Answer 11

A base is a substance which binds to hydrogen ions in solution. This creates lots of OH-. Anything higher than 7 is considered a base (alkali).

Answer 12

Because for every H+ released an OH- is also created. The pH of water is 7.

Answer 13

The blood closely monitors and maintains an optimal pH of 7.35-7.45 for chemical reactions to occur, whilst the stomach has an optimal pH of 2-3.

Answer 14

Fruit and vegetables contain organic acids and hence may have a low pH before consumption. Yet these organic acids can be metabolised by the body and intestinal bacteria to become alkaline. These foods are also high in alkaline minerals, e.g. potassium, magnesium and calcium which contribute to their net alkaline effect. Before consumption, dairy is not very acidic and is also high in calcium, an alkaline mineral. Yet dairy is considered more "acidic" because of the higher protein/sulphur amino acid content. The sulphur amino acids increase sulphuric acid formation, which then disrupts blood pH drawing more calcium from bones and increasing calcium loss in urine. For this reason, meat, also high in sulphur amino acids, will have a net acid effect.

Answer 15

Chemical reactions occur when new bonds are formed or old bonds are broken between different molecules. The starting materials are known as the reactants and the end molecules are known as the products.

Answer 16

- There needs to be the opportunity for two molecules to collide (‘collision theory’). - Chemical reactions are reliant on the correct temperature and enough reactants. - The higher the energy of the molecules, the faster they move and the greater chance they have of reacting. - Changes in pressure can also change the speed of reactions, with increasing pressure forcing molecules closer together.

Answer 17

A catalyst speeds up reactions by lowering the activation energy required (the reaction is faster or can occur at a lower temperature). Catalysts that the body produces are called ‘enzymes’. For example, the enzyme ‘HMGCoA reductase’ in the production of cholesterol and CoQ10.

Answer 18

Inhibitors act antagonistically to catalysts. They stop the catalyst from being so effective by making the activation energy higher and hence slow down the reaction time. Many drugs are inhibitors e.g. ‘Statins’ are HMG-CoA reductase inhibitors.

Answer 19

Anabolic reactions are synthesis (building) reactions. This occurs when the body is making new substances and building new bonds. For example, taking amino acids and building a protein. This requires energy.

Answer 20

Catabolism describes reactions where “breaking down” occurs. For example, when breaking down food, releasing energy from them. We trap that energy as ‘ATP’.

Answer 21

When water is the medium that breaks down the molecule into smaller pieces.

Answer 22

When water is formed as the waste product of a reaction; this is normally when larger molecules are being made. E.g. when making carbohydrates.

Answer 23

Chemical reactions whereby the products of the reaction can react together to produce the original reactants (meaning it can go back the other way). This is done using enzymes and mechanisms in place that allow us to remove starting materials and products.

Answer 24

CO2 + H2O ↔ H2CO3 ↔ H+ + HCO3–

Answer 25

Buffers are substances that maintain the H+ concentration in the body within normal limits. They can bind to H+ ions and OH- to ensure the blood pH remains between 7.35-7.45. -The most important buffer system in the bloodstream is the bicarbonate (HCO3-) buffer system, which “mops up” excess acidity. -The kidneys can also produce the HCO3- buffer and excrete excess H+ ions. It is fairly slow and strenuous upon the organ.

Answer 26

Catalysed by carbonic anhydrase, carbon dioxide from cellular respiration reacts with water in the blood to form carbonic acid, which rapidly dissociates to form a bicarbonate & hydrogen ion. These reactions are reversible. When extra hydrogen ions accumulate in the blood (after strenuous exercise ↑lactic acid), the reaction is able to adjust to “mop up” the extra H+ ions, making more carbon dioxide and water. This is then accounted for by increasing breathing rate and hence the exhalation of carbon dioxide through the lungs.

Answer 27

The removal of electrons from an atom or molecule. Oxidation reduces the potential energy in a compound. Generally, most oxidation occurs by removing electrons with the help of hydrogen. Because hydrogen is lost, this is often called a dehydration reaction.

Answer 28

When something is ‘reduced’, it gains electrons, resulting in the increase of energy in that molecule. A gain of hydrogen is normally indicative of something being reduced.

Answer 29

Molecules or compounds with an unpaired electron in their outer shell try to ‘steal’ electrons from other stable molecules, causing ‘oxidation’. Can even take electrons from DNA, which can damage genes and ultimately result in cancerous changes.

Answer 30

Cancer, atherosclerosis (endothelial damage), fibromyalgia and neurodegenerative diseases.

Answer 31

Processes within our bodies such as aerobic respiration, metabolism & inflammation. They can also come from the environment, e.g. pollution, sunlight, strenuous exercise, X-rays, smoking, alcohol.

Answer 32

Antioxidants work by donating an electron to the free radicals to convert them to harmless molecules, without being damaged themselves. Antioxidants consist of a group of vitamins, phytochemicals and enzymes that work to neutralise free radicals before they harm our bodies.

Answer 33

They can recycle each other. They do not work in isolation. The key to a good antioxidant is that it must be stable once it has given away its electron.

Answer 34

Beta-Carotene, vitamin E, vitamin C, quercetin, Glutathione Peroxidase.

Answer 35

Living things are characterised by molecules made from carbon. Any other groups of atoms that are attached to the carbon skeleton are known as ‘functional groups'. They contribute to the structure and function of that molecule.

Answer 36

Polar and hydrophilic. Dissolve easily in water. Alcohols.

Answer 37

Polar and hydrophilic. Common in some protein chains. Found in the sulphur-containing amino acid cysteine.

Answer 38

Hydrophilic and can interact as a weak acid or as negative particle. Found in amino acids.

Answer 39

Hydrophilic and can interact as a weak acid or as negative particle. Found in amino acids.

Answer 40

The -NH2 group can act as a weak base if necessary (mopping up H+). Found in amino acids.

Answer 41

Predominate bond in triglycerides.

Answer 42

Very hydrophilic (dissolve easily in water), as they can form a double negative charge. Found in ATP.

Answer 43

Carbohydrates include starches (bread, pasta), cellulose (plants) and sugars. All carbohydrates are made of C-H-O. The carbon atoms are normally arranged in a ring with oxygen and hydrogen atoms attached.

Answer 44

monosaccharides, disaccharides & polysaccharides.

Answer 45

Monosaccharides are simple sugars that can exist as single molecules. All end in -ose. Glucose Fructose (the sweetest) Galactose Deoxyribose Ribose

Answer 46

According to the number of carbon atoms within that type of sugar. – Triose (3 carbons). – Pentose (5 carbons). – Hexoses (6 carbons). – Heptose (7 carbons).

Answer 47

Two monosaccharides joined together in a dehydration synthesis (‘removing water' to create a ‘glycosidic bond’). Can be broken apart by hydrolysis (putting water back into the bond). Sucrose = glucose + fructose Lactose = glucose + galactose Maltose = glucose + glucose

Answer 48

Typically long chains of glucose molecules joined together e.g. starch, glycogen (most common) & cellulose.

Answer 49

Normally insoluble in water (because they have given up many –OH groups).

Answer 50

Isomers have the same chemical formula but different structures.

Answer 51

Starch. It is made up of two different polysaccharide components. – 20-25% Amylose: single chain of glucose units. – 75-80% Amylopectin: branch-like structure.

Answer 52

Highly branched, leaving more surface area available for digestion. It’s broken down quickly, which means it produces a higher rise in blood sugar (glucose) and subsequently, a higher rise in insulin.

Answer 53

A straight chain, which limits the amount of surface area exposed for digestion. Foods high in amylose are sometimes referred to as sources of resistant starch as they are digested more slowly. Due to its slower digestion, some resistant starch ends up in the large intestine where it can act as a food source for the bacteria there.

Answer 54

It is made and stored primarily by the liver and the muscles. Primary short-term energy storage. Glycogen in the liver can be used to help maintain blood sugar levels.

Answer 55

Cellulose is the structural material of plants – found in plant cell walls. Humans lack the correct enzymes to break the ‘unique’ bonds between glucose molecules in cellulose, so we cannot digest it. Instead, cellulose acts as fibre which assists with the movement of materials through the intestines.

Answer 56

– Needed for proper bowel function. – Protects against cardiovascular disease. – Protects against diabetes. – Increase satiety & aid weight loss. – Protects against colorectal cancer.

Answer 57

Salivary amylase starts working on the end of the long glucose chains in starches. It works well at a fairly neutral pH, but is deactivated by stomach acid. In the small intestine, the pancreas releases pancreatic amylase which continues carbohydrate digestion, but this time into disaccharide units. The last stage of carbohydrate digestion involves brush border enzymes in the small intestine (lactase, maltase and sucrase).

Answer 58

Because lipids have fewer polar -OH groups

Answer 59

To move around the body, they are often bonded to a protein to make them more soluble (proteins act like “taxis”). They are then called ‘lipoproteins’.

Answer 60

Contain a single glycerol molecule and three fatty acid chains (saturated or unsaturated). Fatty acids are attached to glycerol by a dehydration synthesis reaction and the bond formed is known as an ‘ester’ (different from the glycosidic bond seen in carbohydrates).

Answer 61

* Source of energy (less efficient than carbohydrates). * Convenient form to store excess calorific intake (extra glucose is also turned into triglycerides). * Insulation. * Protection of body parts and organs (e.g. kidneys).

Answer 62

Contain single covalent bonds between each of the fatty acid carbon atoms. Each carbon atom is saturated with hydrogen atoms. Saturated fatty acids are very straight (can line up close to each other). Saturated fats are generally solid at room temperature e.g. coconut oil.

Answer 63

Contain fatty acids with one double covalent bond between two carbons. The double bond forces the molecule into a bent configuration. Generally are liquids at room temperature because the molecules can’t pack very closely together e.g. olive oil.

Answer 64

Contain more than one double bond in the carbon chain. These molecules are ‘kinked’ so they are liquids at room temperature e.g. sunflower oil, rapeseed oils, vegetable oils.

Answer 65

According to the closest double bond to the end of the chain. – Omega-3 - the double bond is three carbons up from the end. – Omega-6 - the double bond is 6 carbons up from the end.

Answer 66

When the H atoms are on the same side of the double bond. Nearly all fats in nature. Our body recognises these and can use them. Cis-fatty acid is bent and makes the cell membrane more flexible. Can be turned into trans-fats by heating to high temperatures or heating oil repeatedly (the H spins around).

Answer 67

When the H atoms are on separate sides the double bond. Formed in laboratories/industry during hydrogenation reactions (processed foods and margarine). Trans-fatty acid is more linear and 'stiffen' cell membranes, prone to oxidative damage and making cell membranes leaky.

Answer 68

Polyunsaturated fatty acids that cannot be constructed within the body from other components and, therefore, must be obtained from the diet.

Answer 69

ALA — flax seeds, walnuts, green leafy vegetables. EPA & DHA — oily fish.

Answer 70

LA — vegetable oils, most nuts / seeds. GLA — borage oil, evening primrose oil. AA — meat, dairy and eggs.

Answer 71

* Fluidity and structure of cell membranes. * Synthesis of prostaglandins. * Regulate oxygen use, electron transportation and energy production. * Help to form haemoglobin. * Support the production of digestive enzymes. * Help make the lubricants for joints. * Help transport cholesterol in the blood. * Help generate electric currents and keep the heart rate regular. * Needed by the tissues of the brain, retina, adrenal glands and testes. * Help balance the immune system and prevent allergies. * Ensure proper nerve transmission especially in the brain.

Answer 72

Polyunsaturated fats such as EFAs are very prone to becoming free radicals. When these fats are heated, electrons can be lost. This means that a fat is formed that becomes a free radical. This then further reacts with the oxygen in the air over the cooking pan which becomes even more damaging. Radical formation is accelerated by light, oxygen and heat.

Answer 73

A fat molecule that has been joined to a protein molecule, enabling the lipid to move around the bloodstream. Lipoproteins contain triglycerides and cholesterol internally.

Answer 74

By the liver

Answer 75

Carry newly synthesised triglycerides from the liver to adipose tissue (if high: a sign of over-eating).

Answer 76

Carry cholesterol from the liver to cells of the body. Needed to repair cells, support cell membranes and synthesise sex and adrenal hormones.

Answer 77

Collect cholesterol from the body's tissues, bringing it back to the liver.

Answer 78

Contain a glycerol part and two fatty acid chains. The phosphate head contains lots of -OH molecules which make it hydrophilic. It is, therefore, polar and water-soluble. The fatty acid tails are non-polar and interact only with other lipids. They are hydrophobic and fat-soluble. The fatty acid tails can contain saturated and unsaturated fats.

Answer 79

They are soluble on one side and insoluble on the other

Answer 80

Are lipids that are formed from cholesterol. They differ in shape from triglycerides, where they are formed of four rings of carbon atoms joined together at their base. Sterols are steroid bases that contain an -OH group.

Answer 81

To create hormones, e.g., oestrogen, testosterone, cortisol, etc.

Lecture 3 Flashcards

(106 cards)