Biochemistry

Front 1

Inorganic ions are also called _________ or _________.

Back 1

Inorganic ions are also called electrolytes or minerals.

Front 2

What are three processes that ions are important in?

Back 2

Some cellular processes that ions are important in include: muscle contraction, nervous coordination and maintaining osmotic pressure in cells and blood.

Front 3

There are two kinds of nutrients. ___________ are needed in small concentrations, and _____________ are needed in minute (trace) concentrations (eg copper and zinc)

Back 3

There are two kinds of nutrients. Macronutrients are needed in small concentrations, and micronutrients are needed in minute (trace) concentrations (eg copper and zinc)

Front 4

There are two kinds of nutrients. Macronutrients are needed in _______ concentrations, and micronutrients are needed in _________ (_____) concentrations (eg copper and zinc)

Back 4

There are two kinds of nutrients. Macronutrients are needed in small concentrations, and micronutrients are needed in minute (trace) concentrations (eg copper and zinc)

Front 5

One macronutrient is iron (Fe^2+): What is its main use in the body?.
Lack of iron leads to ________.

Back 5

One macronutrient is iron (Fe^2+): it is a constituent of haeomoglobin, which transports oxygen in red blood cells.

Lack of iron leads to anaemia.

Front 6

Another macronutrient, magnesium (Mg^2+): What use does it have in plants?

Back 6

Another macronutrient, magnesium (Mg^2+): it is an important constituent of chlorophyll and thus essential for photosynthesis.
Plants without magnesium in their soil cannot make chlorophyll and so the leaves are yellow, a condition known as chlorosis (Plant growth is shunted by a lack of glucose). Mammals need magnesium for their bones.

Front 7

Macronutrient phosphate (PO4^3-): what is it used for?

Back 7

Macronutrient phosphate (PO4^3-): used for making nucleotides, including ATP. Also a constituent of phospholipids, found in biological membranes.

Front 8

Macronutrient calcium (Ca^2+): what is it used for?

Back 8

Macronutrient calcium (Ca^2+): important structural component of bones and teeth in mammals and is a component of plant cell walls, providing strength.

Front 9

Water molecules have a 'dipole', which means_______________________.

Back 9

Water molecules have a dipole, which means it has a positively charged end (hydrogen) and a negatively charged end (oxygen), but no overall charge.

Front 10

The _______ bonds in water give water a wide range of physical properties vital to life.

Back 10

The hydrogen bonds in water give water a wide range of physical properties vital to life.

Front 11

Water's main 8 properties that make it essential for life are (list):

Back 11

Water's main 8 properties that make it essential for life are (list):

• water is a metabolite (used in reactions)
• water is a solvent
• it has high specific heat capacity
• it has high latent heat of vaporisation
• cohesion
• high surface tension
• high density
• it is transparent

Front 12

Describe property: water is a solvent

Back 12

Living organisms obtain their key elements from aqueous solution. Water is an excellent solvent. Due to the dipoles, charged particles such as ions and other polar molecules like glucose are attracted. These then dissolve in water so chemical reactions take place in solution.

This property also allows water to act as a transport medium, e.g. in animals plasma transports dissolved substances and water transports minerals in the xylem and sucrose and amino acids in the phloem.

Non-polar molecules e.g. lipids do not dissolve in water.

Front 13

Describe property: water is a metabolite

Back 13

Water is used in many biochemical reactions as a reactant e.g. with carbon dioxide to produce glucose in photosynthesis.

Many reactions involve hydrolysis, where water splits a molecule e.g. maltose + water -> glucose + glucose

Front 14

Describe property: high specific heat capacity

Back 14

A large amount of heat energy is needed to raise its temperature because hydrogen bonds between water molecules restrict their movement, resisting an increase in kinetic energy and therefore, resisting an increase in temperature.

This prevents large fluctuations in water temperature, which is important in keeping aquatic habitats stable. It also allows enzymes to work efficiently.

Front 15

Describe property: latent heat of vaporisation

Back 15

A lot of energy is needed to change it from a liquid to vapour. This is important in temperature control, where heat is used to vaporise water from sweat on the skin or from a leaf's surface. As the water evaporates, the body cools.

Front 16

Describe property: cohesion

Back 16

Due to the large number of hydrogen bonds the molecules stick together in a lattice. This sticking together is called cohesion and allows columns of water to be drawn up xylem vessels in plants.

Front 17

Describe property: high surface tension

Back 17

At ordinary temperatures water has the highest surface tension out of any liquid except mercury. In a pond, cohesion between the water molecules at the surface produces surface tension so that the bodies of insects are supported.

Front 18

Describe property: high density

Back 18

Water is denser than air, and, as a habitat for aquatic organisms, provides support and buoyancy. Water has a maximum density at 4C. Ice is less dense than liquid water, because the hydrogen bonds hold the molecules further away. So ice floats on water. It is a good insulator and prevents large bodies of water losing heat and freezing completely, so organisms beneath it survive.

Front 19

What elements do carbohydrates contain?

Back 19

Carbohydrates organic compounds containing carbon, hydrogen, and oxygen.

Front 20

The basic carbohydrate unit is a ___________. Two of these make a ____________. Many of them joined together make a ________________.

Back 20

The basic carbohydrate unit is a monosaccharide. Two of these make a disaccharide. Many of them joined together make a polysaccharide.

Front 21

Monosaccharides have the general formula:

Back 21

Monosaccharides have the general formula (CH2O)n

Front 22

Monosaccharides' names are determined by the number of _______ atoms in the molecule. This makes glucose a ________ sugar. All _______ sugars share the formula:

Back 22

Monosaccharides' names are determined by the number of carbon atoms in the molecule.

This makes glucose a hexose sugar. All hexose sugars share the formula: C6H12O6

Front 23

How many isomers does glucose have. What are they?

Back 23

Glucose has 2 isomers, which are alpha-glucose and beta-glucose.

Front 24

What is the structural diagram of alpha-glucose?

Back 24

Front 25

What is the structural diagram of beta-glucose?

Back 25

Front 26

Monosaccharides have several functions and can act as: (4 uses)

Back 26

A source of energy in respiration. E.g. C-H and C-C bonds are broken to release energy, which is transferred to make adenosine triphosphate (ATP).

Building blocks for larger molecules. For example monosaccharide glucose makes starch, glycogen, and cellulose.

Intermediates in reactions e.g. trioses are intermediates in the reactions of photosynthesis and respiration.

Constituents of nucleotides e.g. deoxyribose in DNA, ribose in RNA, ATP, and ADP.

Front 27

Disaccharides are composed of two monosaccharides bonded together with the formation of a _________ bond. This is known as a ________ reaction because ______________.

Back 27

Disaccharides are composed of two monosaccharides bonded together with the formation of a glycosydic bond. This is known as a condensation reaction because water is released.

Front 28

What is hydrolysis?

Back 28

Hydrolysis is when a glycosydic bond is broken with a water molecule e.g. in the disaccharide maltose, it can be hydrolysed into into two glucose molecules.

Front 29

Glucose + ____________ = maltose

which is used for _______________.

Back 29

Glucose + glucose = maltose

which is used in germinating seeds.

Front 30

Glucose + ____________ = sucrose

which is used for _______________.

Back 30

Glucose + fructose = sucrose

which is used in the transport in phloem of flowering plants.

Front 31

Glucose + ____________ = lactose

which is used for _______________.

Back 31

Glucose + galactose = lactose

which is used for in mammalian milk.

Front 32

What is a Benedict's test used to detect the presence of?

Back 32

A Benedict's Test is used to test for the presence of reducing sugars.

Front 33

Describe the process of a Benedict's Test procedure.

Back 33

Equal volumes of Benedict's Reagent and the solution being tested are heated to 70C.

Front 34

Positive test result is _____________.

Back 34

From blue, through green, yellow, orange, and finally a brick-red precipitate.

Front 35

Why is this the positive result of a reducing sugar?

Back 35

Reducing sugars donate an electron to reduce copper (II) ions in copper sulphate, to red copper (I) oxide.

Front 36

Non-reducing sugars, such as sucrose, can only be detected if:

Back 36

Non-reducing sugars, such as sucrose, can only be detected if it is first broken down to its constituent monosaccharides. For example by heating with hydrochloric acid. Benedict's reagent needs alkaline conditions to work so alkali is added. Benedict's reagent is then added and heated as before. Positive result = non-reducing sugar was initially present.

Front 37

Another way of detecting sucrose would be:

Back 37

Use enzyme sucrase, which hydrolyses sucrose into gluctose and fructose. The Benedict's Test will then give a positive result. However enzymes are specific so sucrase will only hydrolyse sucrose, not other non-reducing sugars.

Front 38

Giving an actual value to the concentration of sugar present is much more useful. i.e. when a quantitative measurement is needed such as when testing for blood-glucose levels. This can be done using a _________.

Back 38

Giving an actual value to the concentration of sugar present is much more useful. i.e. when a quantitative measuremunt is needed such as when testing for blood-glucose levels. This can be done using a biosensor.

Front 39

_________ is the main source of energy in cells and it must be stored in an appropriate form.

Back 39

Glucose is the main source of energy in cells and it must be stored in an appropriate form.

Front 40

As glucose is soluble, it would increase the concentration of cell contents, and consequently cause osmosis. This problem is avoided by ____________.

Back 40

As glucose is soluble, it would increase the concentration of cell contents, and consequently cause osmosis. This problem is avoided by converting glucose into a polysaccharide, starch, which is insoluble, cannot diffuse out of the cell, is compact, and carries lots of energy in its C-H and C-C bonds.

Front 41

Starch is the main store of glucose for _______. Starch grains are found in high concentrations in _______ and storage units such as ______________.

Back 41

Starch is the main store of glucose for plants. Starch grains are found in high concentrations in seeds and storage units such as potato tubers.

Front 42

Starch is made of ______________ molecules bonded together in two different ways, forming two polymers: ___________ and ___________.

Back 42

Starch is made of alpha-glucose molecules bonded together in two different ways, forming two polymers: amylose and amylopectin.

Front 43

Describe amylose:

Back 43

Amylose is a linear, unbranched molecule, with alpha-1,4-glycosidic bonds. A long chain is formed, which coils into an alpha-helix.

Front 44

Describe amylopectin:

Back 44

Amylopectin also has chains of glucose monomers joined with alpha-1,4-glycosidic bonds. The chains are cross-linked with alpha-1,6-glycosidic bonds and fit inside the amylose.

Front 45

What is the test for the presence of starch?

Back 45

The iodine-potassium test. Iodine solution (iodine dissolved in an aqueous solution of potassium iodide) reacts with starch, resulting in a colour change from orange-brown to blue-black. The depth of blue-black colour gives an indication of relative concentration.

Front 46

The main storage product in animals is ___________. It is very similar to _______________.

Back 46

The main storage product in animals is glycogen. It is very similar to amylopectin.

It also has alpha-1,4 and alpha-1,6 bonds. The difference is that glycogen molecules have shorter alpha-1,4 chains and so are more branched than amylopectin.

Front 47

Cellulose is a ___________ polysaccharide found in plant ______________. It consists of many long, parallel chains of __________________, and each molecule is rotated by ________.

Back 47

Cellulose is a structural polysaccharide found in plant cell walls. It consists of many long, parallel chains of beta-glucose units, and each molecule is rotated by 180 degrees.

Front 48

Each adjacent molecule is rotated because:

Back 48

Each adjacent molecule is rotated because this allows hydrogen bonds to form between the (OH) groups of adjacent parallel chains, contributing to cellulose's structural ability.

Front 49

Between 60 and 70 cellulose molecules become tightly cross-linked to form bundles called ____________.

Back 49

Between 60 and 70 cellulose molecules become tightly cross-linked to form bundles called microfibrils.

Front 50

Microfibrils are, in turn, held in bundles called _________.

Back 50

Microfibrils are, in turn, held in bundles called fibres.

Front 51

A cell wall has several layers of fibres, which run _______ within a layer but ______________ adjacent layers. This laminated structure also contributes to the strength of a cell wall.

Back 51

A cell wall has several layers of fibres, which run parallel within a layer but at an angle to adjacent layers. This laminated structure also contributes to the strength of a cell wall.

Front 52

Cellulose fibres are freely permeable, because ___________. ___________________ can penetrate through these spaces in the cell wall, to the cell membrane.

Back 52

Cellulose fibres are freely permeable, because there are spaces between the fibres. Water and its solutes can penetrate through these spaces in the cell wall, to the cell membrane.

Front 53

Chitin is a ___________ polysaccharide, found in the __________ of insects, and in _________________.

Back 53

Chitin is a structural polysaccharide, found in the EXOSKELETON of insects, and in fungal cell walls.

Front 54

Chitin resembles cellulose, with its ________________________, but has groups derived from _____________ added, to form a ______________________.

Back 54

Chitin resembles cellulose, with its long chains of beta-1,4-linked monomers, but has groups derived from amino acids added, to form a heteropolysaccharide.

Front 55

Chitin is _______, ___________ and ____________. Like cellulose, the monomers are rotated through 180 degrees, and the long parralel chains are cross-linked to each other by hydrogen bonds, forming _________.

Back 55

Chitin is strong, waterproof, and lightweight. Like cellulose, the monomers are rotated through 180 degrees, and the long parrallel chains are cross-linked to each other by hydrogen bonds, forming microfibrils.

Front 56

Lipids, like carbohydrates, contain carbon, hydrogen, and oxygen. But, in proportion to the carbon and hydrogen they contain much ____ oxygen.

Back 56

Lipids, like carbohydrates, contain carbon, hydrogen, and oxygen. But, in proportion to the carbon and hydrogen they contain much less oxygen.

Front 57

Lipids are non-polar compounds and so are __________ in water, but dissolve in _____________.

Back 57

Lipids are non-polar compounds and so are insoluble in water, but dissolve in organic solvents such as propanone and alcohols.

Front 58

What are triglycerides?

Back 58

Triglycerides are formed by the combination of one glycerol molecule and three molecules of fatty acids.

The fatty acids join to glycerol by condensation by condensation reactions.

Front 59

In the condensation reaction, _______ molecules of water are removed and ______ bonds are formed between the _________ and ______________.

Back 59

In the condensation reaction, three molecules of water are removed and ester bonds are formed between the glycerol and fatty acids.

Front 60

Phospholipids have one end that is ________ in water, and one that isn't.

Back 60

Phospholipids have one end that is soluble in water, and one that isn't.

Front 61

One end of a phospholipid molecule has a lot of ___________ atoms, in the _________ group-- the phosphate and the choline, and so this end of the molecule reacts with water and is ____________.

Back 61

One end of a phospholipid molecule has a lot of oxygen atoms, in the glycerol group-- the phosphate and the choline, and so this end of the molecule reacts with water and is hydrophilic.

It is described as the polar head of the molecule.

Front 62

The fatty acid tails do not have any ________ atoms and do not interact with water so they are ______________ and are non-polar.

Back 62

The fatty acid tails do not have any oxygen atoms and do not interact with water so they are hydrophobic and are non-polar.

Front 63

Waxes are lipids and melt above about _______. They have a waterproofing role in both animals, such as in the insect _____________, and plants, in the leaf's ________.

Back 63

Waxes are lipids and melt above about 45 degrees. They have a waterproofing role in both animals, such as in the insect EXOSKELETON, and plants, in the leaf's cuticle.

Front 64

The differences in the properties of fats and oils come from the variations in the __________.

If the hydrocarbon chain only has single C-C bonds, then the fatty acid is saturated (with hydrogen atoms). They remain solid at body temperature and so are useful for storage in mammals.

Back 64

The differences in the properties of fats and oils come from the variations in the fatty acids.

If the hydrocarbon chain only has single C-C bonds, then the fatty acid is saturated (with hydrogen atoms). They remain solid at body temperature and so are useful for storage in mammals.

Animal lipids often contain saturated fatty acids.

Front 65

If any C-C bond is not a single bond, the molecule is ___________, and the chain gets a kink. The molecules cannot align uniformly and the lipid does not solidify readily.

Back 65

If any C-C bond is not a single bond, the molecule is unsaturated, and the chain gets a kink. The molecules cannot align uniformly and the lipid does not solidify readily.

This is why unsaturated lipids are oils, which remain liquid at room temperature. Plant lipids are often unsaturated and occur as oils, such as olive oil and sunflower oil.

Front 66

If one C-C double bond is present, the lipids are _____________________. If there are many C-C double bonds present, the lipid is described as _____________________.

Back 66

If one C-C double bond is present, the lipids are mono-unsaturated. If there are many C-C double bonds present, the lipid is described as polyunsaturated.

Front 67

Two roles of phospholipids are:

Back 67

Two roles of phospholipids are: in biological membranes, and electrical insulation - the myelin sheath that surrounds the axons of nerve cells.

Front 68

4 roles of triglycerides are:

Back 68

4 roles of triglycerides are: Energy reserves in both plants and animals, because lipids contain more C-H bonds than carbohydrates.

Thermal insulation - when stored under the skin lipids insulate against heat loss in the cold or heat gain when it is hot.

Protection - fat is stored around delicate internal organs such as kidneys, protecting against physical damage.

Metabolic water - this is water released during chemical reactions in the body. Triglycerides produce a lot of metabolic water when oxidised.

Front 69

What is a role of waxes?

Back 69

A role of waxes is waterproofing - in terrestrial organisms, waxes reduce water loss, such as in the insect exoskeleton and in the cuticle of plants.

Front 70

The test for fats and oils is called the _______________. The procedure and positive result is as follows:

Back 70

The test for fats and oils is called the emulsion test. The procedure and positive result is as follows: A sample to be tested is mixed with absolute ethanol, which dissolves any lipids present. It is shaken with an equal volume of water. The dissolved lipids come out of solution, because they are insoluble in water. They form an emulsion, making the sample cloudy white.

Front 71

What are the main causes of heart disease?

Back 71

The main causes of heart disease are fatty deposits in the coronary arteries (atherosclerosis) and high blood pressure (hypertension) A diet high in saturated fats, smoking, lack of exercise and ageing are all contributory factors.

Front 72

When food has been absorbed at the small intestine, ____________________________________________, which travel around the body in the bloodstream.

Back 72

When food has been absorbed at the small intestine, lipids and proteins combine to make lipoproteins, which travel around the body in the bloodstream.

Front 73

If the diet is high in saturated fats, ______________________ build up and cause harm. Fatty material called _______ gets deposited in the ____________, restricting blood flow, and therefore ___________ delivery to the heart. It can result in _________, and, if the vessel is completely blocked, a _______________ or ______________ occurs.

Back 73

If the diet is high in saturated fats, low-density lipoproteins (LDL) build up and cause harm. Fatty material called atheroma gets deposited in the coronary arteries, restricting blood flow, and therefore oxygen delivery to the heart. It can result in angina, and, if the vessel is completely blocked, a myocardial infarction or heart attack occurs.

Front 74

If the diet has a high proportion of unsaturated fats, the body makes more ______________________________, which carries harmful fats away to the ______ for disposal. The higher the ratio of ______:_______ in a person's blood, the lower their risk of ___________ and ____________ heart disease.

Back 74

If the diet has a high proportion of unsaturated fats, the body makes more high-density lipoproteins (HDL), which carries harmful fats away to the liver for disposal. The higher the ratio of HDL:LDL in a person's blood, the lower their risk of cardio-vascular and coronary heart disease.

Front 75

The inner wall of an artery has smooth _________ lining. __________ is deposited on the __________, reducing volume for blood flow. Eventually the _____ of the artery is almost entirely blocked with _________.

Back 75

The inner wall of an artery has smooth endothelium lining. Atheroma is deposited on the endothelium, reducing volume for blood flow. Eventually the lumen of the artery is almost entirely blocked with Atheroma.

Front 76

What four elements do proteins always contain?

Back 76

Proteins always contain the elements: carbon, hydrogen, oxygen, and nitrogen.

Front 77

What other two elements do proteins often contain?

Back 77

Proteins often contain sulphur, and some contain phosphorus.

Front 78

What is the monomer of proteins?

Back 78

The monomer of proteins is amino acids.

Front 79

Chains of amino acids are called ________________.

Back 79

Chains of amino acids are called polypeptides.

Front 80

How many different amino acids are used to make up proteins?

Back 80

There are about 20 amino acids are used to make up proteins.

Front 81

What is a protein's shape determined by?

Back 81

A protein's shape is determined by the sequence of amino acids it has.

Front 82

All amino acids have the same basic structure. Attached to a central carbon atom are:

Back 82

Attached to a central carbon atom are:

An amino group -NH2, at one end (called the N-terminal), a carboxyl group -COOH at the other end (C-terminal), a hydrogen atom, and the R group which is different for each amino acid.

Front 83

The amino group is (basic/acidic). At Ph7 (Ph of the cell), it gains an H and becomes ________ charged. The Carboxyl group is (basic/acidic) and at Ph7 it loses an H becoming negatively charged. So at Ph7 an amino acid has both a positive and negative charge, such ion is called a __________.

Back 83

The amino group is basic. At Ph7 (Ph of the cell), it gains an H and becomes positively charged. The Carboxyl group is acidic and at Ph7 it loses an H becoming negatively charged. So at Ph7 an amino acid has both a positive and negative charge, such ion is called a zwitterion.

Front 84

What is a peptide bond?

Back 84

A peptide bond is a chemical bond formed by a condensation reaction between the amino group of one amino acid and the carboxyl group of another.

Front 85

The resulting compound of two amino acids combining in a condensation reaction is a ____________.

Back 85

The resulting compound of two amino acids combining in a condensation reaction is a dipeptide.

Front 86

The dipeptide can be written as NH2-R1-R2-COOH, or NH2-R2-R1-COOH.

Back 86

The dipeptide can be written as NH2-R1-R2-COOH, or NH2-R2-R1-COOH.

ORDER IS IMPORTANT

Front 87

The four different protein structures are:

Back 87

The four different protein structures are: primary, secondary, tertiary, and quaternary.

Front 88

What is the primary structure?

Back 88

The primary structure is simply the order of the amino acids in a polypeptide chain. The amino acids can be joined in any number, order and combination, so there is a huge number of possible polypeptides.

The sequence of amino acids in a protein is determined by the sequence of nucleotides in the gene (DNA) encoding it.

Front 89

What is the secondary structure?

Back 89

The secondary structure is the shape that the polypeptide chain forms as a result of hydrogen bonding between the =O on -CO groups and the -H on -NH groups in the peptide bonds along the chain. This causes the long polypeptide chain to be twisted into a 3D shape, an alpha-helix. A less common arrangement is the beta-pleated sheet.

Protein keratin has a high proportion of alpha-helix and the protein fibroin in silk has a high proportion of beta-pleated sheet.

Front 90

What is the tertiary structure?

Back 90

The alpha-helix can be folded and twisted to give a more complex, compact 3D structure. This is the tertiary structure which is maintained by hydrogen bonds, ionic bonds, disulphide bonds, and hydrophobic interactions.

These bonds are important in giving globular proteins, e.g. enzymes their shape.

Front 91

What is the quaternary structure?

Back 91

In some cases, polypeptide chains may combine with each other, such as in the insulin molecule, which has two chains.

They may also be associated with non-protein groups and form large, complex molecules, such as haemoglobin.

Front 92

What is a fibrous protein?

Back 92

Fibrous proteins have long, thin molecules and are insoluble in water, so they have structural functions, as in bone. The polypeptides are in parallel chains or sheets, with many cross-linkages forming fibres, e.g. keratin, protein in hair. They are strong and tough.

Collagen is a fibrous protein providing strength and toughness in tendons.

Front 93

What are globular proteins?

Back 93

Globular proteins are compact, and folded into spherical molecules. This makes them soluble in water and so have many different functions, including enzymes, antibodies, plasma proteins and hormones.

Haemoglobin is a globular protein, consisting of folded polypeptide chains, at the centre of which is the iron-containing group, haem.

Front 94

What is the test for protein?

Back 94

Add a few drops of biuret reagent (sodium hydroxide and copper II sulphate). They react to make blue copper hydroxide, which interacts with the peptide bonds present in protein to make biuret, which is purple.

The more concentrated the protein is, the darker the purple. Qualitative result.

Front 95

Exoskeleton? (Yes/No)

Back 95

Exoskeleton? Yes.