Condensation & Hydrolysis Reaction

Carbohydrates

Condensation Reaction

Condensation is a chemical reaction whereby 2 simple molecules are joined together to form a larger molecule with the removal of 1 molecule of water

Hydrolysis/ Hydrolytic Reaction

Reaction where a water molecule is added to split complex sugar into simpler component molecules by

-Heating with dilute acids at 100°C (chemical method)

-Treating with suitable enzyme at room temperature/ optimum temperature of the enzyme (enzymatic method)

Function

General uses of monosaccharides and disaccharides

Building blocks for larger molecules (e.g. DNA, cellulose, starch, glycogen)
Source of respiratory energy (glucose)
Transport compound (sucrose in plant phloem)
Infant milk (lactose)
Attraction – flower nectuary, fruit (fructose)
Honey – Bees food storage

General uses of polysaccharides

Polysaccharides are many monosaccharides linked by glycosidic bonds
Examples – starch, glycogen, cellulose
Energy Storage - starch (plant) and glycogen (animal)
Structural - Cellulose cell wall (plant) and Chitin (insects/crab/shrimp)

Contain the elements C, H, O
They are either made from single monosaccharide monomers or from several monosaccharides joined together

Classified as:

Monosaccharides eg glucose, fructose, galactose
Disaccharides eg sucrose, maltose, lactose
Polysaccharides eg cellulose, glycogen, starch
Other polysaccharides and polysaccharide derivatives eg pectins, chitin and mucopolysaccharides

Many monosaccharides are joined in a chain to form polysaccharides.
Glycogen and starch are storage carbohydrates in animals and plants respectively.

Monosaccharides

Trioses – C3H6O3 e.g. glyceraldehyde

Pentoses – C5H10O5 e.g. deoxyribose
Hexoses – C6H12O6 e.g. glucose, fructose
General Formula: (CH2O)n

Monosaccharides differ ONLY in terms of the details of arrangement of atoms within a molecule, which gives them their different chemical and biological properties
Hence, they show isomerism
Isomers have different structural formulae but same molecular formula
Types of isomers: aldose and ketose, open-chain and ring forms, alpha and beta

Disaccharides

Made by combining 2 monosaccharides together

This is a condensation reaction producing a glycosidic bond (broken by hydrolysis)
Disaccharides made from hexoses have the formula C12H22O11
Examples – sucrose (glucose + fructose), maltose (glucose + glucose)

Starch and Glycogen (energy stores)

Their molecules have many side branches where glucose molecules can be removed from their tips (by enzymes)
Their insolubility stops them interfering with osmosis
Their compactness provides an efficient way to store lots of glucose for future cellular respiration

Cellulose

Made from long, straight chains of glucose
Chains cross-linked by H-bonds which holds them tightly together (excludes water)
Chemically very inert and insoluble – few ‘tips’ on molecule make it difficult to digest
Many molecules form strong fibrils
Only some bacteria, fungi and a very small number of animals can secrete cellulase enzymes

Proteins

Sensitive to pH and heat
Shape determines its function
Special group of proteins are enzymes

Basic unit of proteins

Amino acids
20 essential amino acids for protein formation

Protein Structures

Primary
Order in which amino acids are linked to form a polypeptide chain
Individual amino acids join to form primary structure
Secondary
Way the polypeptide chain is coiled and folded, alpha-helix and beta-pleated
Helix or sheet
Tertiary
Large globular proteins formed by the coiling and folding the already coiled and folded chain eg enzymes
3 dimensional
Quaternary
Proteins made from 2 more polypeptides eg haemoglobin

Structural classification

Fibrous proteins / Globular proteins
Properties:
Water insoluble
Very touch physically; may be supple or stretchy
Parallel polypeptide chains in long fibres or sheets / Properties:
Water soluble
Tertiary structure critical to function
Polypeptide chains folded into a spherical shape
Function:
Structural role in cells and organisms (eg collagen found in connective tissue, cartilage, bones, tendons, blood vessel walls)
Contractile (eg myosin, actin) / Function:
Catalytic (eg enzymes)
Regulatory (eg hormones, insulin)
Transport (eg haemoglobin)
Protective (eg antibodies)
Collagen consists of 3 helical polypeptides wound around each other to form a ‘rope’. Every 3rd amino acid in each polypeptide is a glycine molecule where hydrogen bonding occurs, holding the 3 strands together / Bovine insulin is a relatively small protein consisting of 2 polypeptide chains. These 2 chains are held together by disulfide bridges between neighbouring cysteine molecules.

Denaturation of Proteins

Loss of 3D structure and biological function
Often permanent
Results from alteration of bonds that maintain secondary and tertiary structure of protein
Amino acid sequence remains unchanged
Agents that cause denaturation:
Strong acids and alkalis: disrupt ionic bonds, result in coagulation of protein
Heavy metals: disrupt ionic bonds, reduce protein charge, causes precipitation of protein
Heat and radiation: cause disruption of bonds in protein through increased energy
Detergents and solvents: form bonds with non-polar groups in protein, disrupting hydrogen bonding

Fats

Function

Mammals

Water repellent properties – waterproof fur and skin.
Structural – Cell membranes, phospholipids and polar nature
Electrical insulation – myelin, insulates neurones, impulse transmission more rapid.
Hormones – steroids e.g. testosterone and oestrogen
Physical protection – shock absorb, found round delicate organs e.g. kidneys
Thermal insulation – conducts heat poorly, so insulates. Blubber in diving animals.
Energy storage– yield twice as much energy compared with carbohydrates

Plants

Attraction – plant scents contain fatty acids
Waterproofing – wax for the cuticle (not glycerol, different alcohol used)
Energy storage – Oil droplets in plant cells

Other

Honey comb– Bees wax

Properties

Forms: oil, wax, fat
Insoluble
Water- repelling
Are usually insoluble in water, but soluble in organic solvents.
Contain C, H and O. (CH3(CH2)nCOOH)
Less oxygen than carbohydrates
Identified using the emulsion test.

Triglycerides (fats & oils)

These are NOT made from monomers
Each contains 1 glycerol and 3 fatty acid molecules (elements: C, H, O)
They are linked by ester bonds
These form during condensation reactions
Fats (solid) contain saturated fatty acid chains, oils (liquid) have unsaturated chains
Triglycerides (fats) are formed using ester bonds

Saturated and Unsaturated

Saturated fatty acid e.g. Stearic acid
More hydrogen atoms
No double bonds
No kinks
Unsaturated fatty acid e.g. Oleic acid
Less hydrogen atoms
Have double bonds
Have kinks

Phospholipids

Consist of organic group, phosphate group, glycerol and fatty acid
Bonds between the glycerol and fatty acid are broken by hydrolysis
Major component of the plasma membrane, because they have a hydrophilic head and hydrophobic tail (polar molecules), which form a bilayer
Heads outside, tails inside
One fatty acid in triglyceride swapped for phosphate base

Water

Inorganic molecules
Polar molecules
Environment in which metabolic reactions can occur
Water takes part in, and is a common product of many reactions
Dipole nature
Small positive charge on each of the two hydrogens and a small negative charge on the oxygen

Attracted to each other, creating hydrogen bonds

Strong bonds determine almost every physical property of water and many of its chemical properties

Thermal properties

Absorbs or releases more heat than many substances for each degree of temperature increase or decrease
Widely used for cooling/transferring heat in thermal and chemical processes
Evaporation of water in sweat or in transpiration causes marked cooling
Much heat is lost by the evaporation of a small quantity of water
Contents of cells and aquatic environments are slow to freeze in cold water

Colourless

Plants can photosynthesize at depth in water
Light can penetrate deeply into living tissues

Surface tension

Measure of strength of water’s surface film
Attraction between water molecules creates strong film
Permits water to hold up substances heavier and denser than itself
High surface tension
Sticky and elastic
Hydrogen atoms are “attached” to one side of the oxygen atom, so it has a positive charge on the side (hydrogen) and a negative charge on the other side (oxygen)
Since opposite electrical charges attract, water molecules tend to attract each other
Small animals can land on and move over surface of water
Water forms droplets on surfaces and runs off

Molecules in motion

Surface tension is responsible for capillary action
Allows water (and dissolved substances) to move through roots of plants and through blood vessels in our bodies
Water molecules also bind to other substances – adhesion
For example, in a thin glass tube, when the molecules at the edge adhere to the molecules of glass just above them, they also tow other water molecules along with them. The water surface pulls the entire body of water to a new level until the downward force of gravity is too great to be overcome.
Capillary action: movement of water within spaces of a porous material, due to the forces of adhesion, cohesion and surface tension
Can move through extremely narrow spaces (eg between soil particles, and in cell walls)
Water column does not break or pull apart under tension
Plants and trees need capillary action to transport water from roots to leaves

Universal solvent

Ability to dissolve other substances
Transfers nutrients vital to life in animals and plants
Medium for chemical reactions of life

Boiling and freezing point

Freezes at 0 oC and boils at 100 oC
Solid form (ice) is less dense than liquid form, which is why ice floats
Ice forms on surface of water, insulating water below
When surface water does freeze, aquatic life can survive below the ice
Liquid at room temperature: liquid medium for living things

Neutral pH of 7

Not acidic nor basic
Pure water

Specific heat index

High specific heat index: Can absorb a lot of heat before it begins to get hot
Valuable to industries as a coolant
Regulate rate at which air changes temperature, which is why temperature change between seasons is gradual rather than sudden (especially near oceans)
Bulky organisms have a stable temperature in the face of fluctuating external temperatures

Viscosity

Resistance to internal friction between molecules
Water has low viscosity (vs honey, shampoo)
Affected by temperature
At higher temp, viscosity decreases as the molecules take on more kinetic energy, allowing them to move past each other faster
Flows readily through narrow capillaries

Vital Minerals

Mineral / Function / Source
Calcium / Formation of bones and teeth
Blood clotting
Normal muscle and nerve activity / Milk, cheese, nuts, whole grains
Phosphorus / Formation of bones and teeth
Regulation of blood pH, muscle contraction and nerve activity
Component of enzymes, DNA, RNA, ATP / Milk, whole-grain cereals, meat, vegetables
Iron / Component of haemoglobin (carries oxygen to body cells) and cytochromes (ATP formation) / Liver, egg yolk, pease, enriched cereals, whole grains, meat, raisins, leafy vegetables
Iodine / Part of thyroid hormone, required by thyroid gland / Seafood, eggs, milk, iodized table salt
Sodium / Regulation of body fluid pH
Transmission of nerve impulses / Bacon, butter, table salt, vegetables
Potassium / Transmission of nerve impulses
Muscle contraction
Involved in controlling plant water balance / Vegetables, bananas, ketchup
Magnesium / Muscle and nerve function
Bone formation
Enzyme function
Component of chlorophyll / Potatoes, fruits, whole-grain cereals, vegetables
Fluorine / Tooth structure / Fluoridated water
Manganese / Enzyme activator for carbohydrate, protein and fat metabolism
Important in growth of cartilage and bone tissue / Wheat germ, nuts, bran, leafy green vegetables
Copper / Ingredient in several respiratory enzymes
Needed for development of red blood cells / Kidney, liver, beans, wholemeal flour, lentils
Sulphur / Component of insulin
Builds hair, nails, skin / Nuts, dried fruits, barley, oatmeal, eggs, beans, cheese

Inorganic ions
Important for structure and metabolism of all living organisms
Ion = atom that has gained or lost one or more electrons
Usually soluble in water