Biological Molecules

why is water a polar molecule?

uneven distribution of charge within the molecule

how are hydrogen and oxygen atoms held together in water?

covalent bonds

what is a hydrogen bond

a weak electrostatic force of attraction between slightly positively charged hydrogen of one water molecules with slightly negatively charged oxygen of another

what are the 5 roles of water in living organisms

solvent,temperature regulation,habitat,metabolite,transport medium

why is water know as the universal solvent

water is polar so it can surround and dissolve many ionic and other polar substances

why is water being a good solvent useful

most biological reactions take place in solutions and dissolved substances can be transported around the body

what does it mean for water to have a high specific heat capacity

a lot of energy is required to raise the temperature of water

why does water have a high specific heat capacity

lots of energy is required to break hydrogen bonds so lots of energy is absorbed before water’s temperature rises significantly

how does a high specific heat capacity benefit living organisms

maintains a fairly stable temperature as their bodies are made up of mostly water

what does it mean for water to have a high latent heat of vaporisation

a lot of energy is required to break the hydrogen bonds to change water from a liquid to a gas

why is a high latent heat of vaporisation important for living organisms

allows organisms to use evaporation as a method of cooling without losing too much water

why is water a suitable habitat for many organisms

has a high specific heat capacity and high latent heat of vaporisation which means it reduces temperature fluctuations providing a stable environment

why does ice float on water

ice is less dense than water due to the water molecules being further apart from one another

why is ice important for organisms living in ponds and lakes

it forms an insulating later that prevents the water below from freezing

what is cohesion

the tendency of water molecules to stick together

how does cohesion help transport water in plants

water forms a continuous column up the xylem driven by transpiration pull without the column breaking

what is adhesion

the tendency of water molecules to stick to other materials

what is the role of adhesion in plants

helps the water cling to xylem walls

what is capillary action

process where water can rise up a narrow tube against the force of gravity

what type of chemical reaction uses water to break down molecules

hydrolysis

what causes high surface tension in water

stronger cohesive forces between surface water molecules than with air molecules above

what elements make up carbohydrates

carbon,hydrogen,oxygen

what are carbohydrates used for

primary energy source,energy store and structural support

what is a monomer

small molecule which can bind to other similar molecules to form repeating unit of polymers

give 3 examples of a monomer

monosaccharides, amino acids and nucleotides

what is a polymer

large molecules made from many monomers joined together in a chain

give 3 examples of a polymer

polysaccharide,polypeptide,polynucleotide

what’s a condensation reaction

when 2 molecules are joined together with the formation of a chemical bond with water as a by product

what’s a hydrolysis reaction

when a chemical bond between 2 molecules is broken using water

what type of bond is formed from 2 monosaccharides

glycosidic

how is maltose formed

the condensation of two glucose molecules

how is sucrose formed

the condensation of glucose and fructose

how is lactose formed

the condensation of glucose and galactose

what monosaccharide is found in fruits

fructose

how is glucose adapted to carry out its function

its water soluble so it can be easily transported around organisms and its bonds store a lot of energy

what type of sugar is in table sugar

sucrose

how are glycogen and starch formed

the condensation of alpha glucose

how is cellulose formed

the condensation of beta glucose

what is an isomer

molecules with the same molecular formula but have a different structural arrangement of atoms

what’s the difference between an α- and a β-glucose molecule

the orientation of the hydroxyl group attached to carbon 1 in the ring structure

what’s the general formula for monosaccharides

(CH2O)n

what’s the difference between a hexose and a pentose

hexose has six carbon atoms but a pentose has five carbon atoms

whats the difference between glucose and ribose

glucose is a hexose monosaccharide but ribose is a pentose monosaccharide

what is the molecular formula of glucose

C6H12O6

how is a glycosidic bond formed

by the condensation between two monosaccharides releasing a molecule of water

how are polysaccharides formed

many monosaccharides join by condensation reactions forming glycosidic bonds

what is starch made from

alpha glucose monomers and it consists of amylose and amylopectin

what is the structure of amylose

alpha glucose chains in helical shape with 1,4 glycosidic bonds

what is the structure of amylopectin

branched alpha glucose chains joined by 1,4 and 1,6 glycosidic bonds

how is starch adapted for energy storage

its compact and insoluble so it doesn’t diffuse out of cells or affect water potential

what is the structure of glycogen

highly branched with 1,4 and 1,6 glycosidic bonds

how is glycogen adapted for energy storage

its compact, insoluble and highly branched to provide numerous ends for rapid hydrolysis to provide glucose for respiration

whats the structure of cellulose

chains of beta glucose joined by 1,4 glycosidic bonds

why are alternate glucose molecules in cellulose rotated

so the hydroxyl group on carbon-1 and carbon-4 can line up

how do cellulose molecules form microfibrils

hydrogen bonds form between adjacent cellulose chains bundling them into strong microfibrils

how is cellulose adapted for its function

forms strong microfibrils which provide high tensile strength to plant cell walls preventing them from bursting

what does benedicts reagent test for

reducing sugars

which dissacharides are reducing sugars

maltose and lactose

why does benedicts cause a colour change

the blue copper 2+ ions are reduced to copper 1+ which has a brick red precipitate

what temperature is benedicts solution heated up to

80 degrees

why does sucrose not reduce

it has no free reducing group

how do you test for non-reducing sugars

add hydrochloric acid to hydrolyse the glycosidic bonds then add sodium hydrogencarbonate to neutralise the solution

what type of test is the benedict’s test

qualitative

what is a quantitative method for testing for reducing sugars

using a colorimeter to measure absorption

what do you use to test for the presence of starch

iodine solution

what do you need to do to the colorimeter before using it

calibrate it using distilled water to get 100% absorption

what is a positive result for iodine test

solution changes from orange brown to blue black

what elements are found in lipids

carbon,hydrogen and oxygen

what type of molecule is a lipid

a macromolecule

how are lipids formed

the condensation reaction between the hydroxyl group of the glycerol and the hydrogen from the fatty acid forming an ester bond and releasing a molecule of water

what is the structure of a triglyceride

one glycerol molecule and three fatty acid chains joined together by an ester bond

how are triglycerides hydrolysed

by adding 3 water molecules to break the 3 ester bonds

what state are saturated fats at room temperature

solid

what state are unsaturated fats at room temperature

liquid

what is the structure of saturated fats

they contain only single bonds between carbon atoms

what is the structure of unsaturated fats

they contain one or more double bonds between carbon atoms

what type of acid are fatty acids

carboxylic

what type of substance is glycerol

an organic alcohol

why are unsaturated fats liquid at room temperature

double bonds cause a kink in the hydrocarbon chain preventing tight packing

what elements are found in phospholipds

carbon,hydrogen,oxygen and phosphorus

whats the structure of a phospholipid

one glycerol,two fatty acid chains and one phosphate head

whats the difference between the 2 tails

one is straight and saturated but the other is unsaturated and has a kink

how does the structure of the 2 tails help

they help maintain membrane fluidity

why is the phosphate head polar

it contains inorganic phosphate ions

why are phospholipids described as amphipathic

they have a hydrophilic head and hydrophobic tails

what does hydrophobic mean

repel water

what does hydrophilic mean

water loving

what are the 2 fatty acid tails hydrophobic

they are non-polar

what happens when phospholipids interact with water

hydrophilic heads face towards the water and the hydrophobic tails face inwards

what is a surfactant

a substance that lowers the surface tension of a liquid

why do phospholipids act as surfactants

they are amphipathic