Biological molecules

Question 1

What is water

Answer 1

• a polar molecules
• allows hydrogen bonds between molecules giving water important properties

Question 2

How is water a good solvent

Answer 2

• polar molecules will dissolve in water
• and are transported

Question 3

How is water a good metabolite

Answer 3

• water is a reactant in photosynthesis and hydrolysis
• produced in aerobic respiration and condensation reactions

Question 4

Why does water have a high specific heat capacity

Answer 4

• a lot of energy is required to change the temperature of water
• aquatic/cellular environments remain stable

Question 5

Why does water have a high latent heat of vaporasiation

Answer 5

• Evaporative cooling

Question 6

Why does water have surface tension

Answer 6

• support
• bouyancy

Question 7

What are proteins

Answer 7

• Proteins are constructed of 20 different types of amino acid
• The R group is different in each of the 20
• two amino acids linke to form a dipeptide
• a polymer is called a polypeptide

Question 8

What is an amino acid made up of

Answer 8

• amino group NH2
• variable group R
• CH
• carboxyl group COOH

Question 9

What is the primary structure of proteins

Answer 9

• the sequence of amino acids as coded by DNA
• amino acids are linked together by condensation reactions that form peptide bonds

Question 10

What is the secondary strucutre of a protein

Answer 10

• Hydrogen bonds from between the amino acids in the chain
• cause it to fold into an alpha helix of beta pleated sheet

Question 11

What i the tertiary structure of a protein

Answer 11

• hydrophobic interations betwen variable groups within secondary structures
• form disulphide and ionic bonds
• form as specific folded structure e.g. active site of an enzyme

Question 12

What is the quantenary structure of a protein

Answer 12

• more than one polypeptide chain linked to form a molecule
• fibrous proteins eg keratin - structural function
• globular proteins eg enzymes - metabolic functions

Question 13

What is the test for proteins

Answer 13

• biuret solution - blue
• positive reaction - a purple/violet colour seen

Question 14

What is triose sugar

Answer 14

• 3 carbons
• important in respiration and photosynthesis

Question 15

What is a pentose sugar

Answer 15

• 5 carbons
• important in nucleotides

Question 16

What are hexose sugars

Answer 16

• 6 carbons
• glucose is important as used in respiration

Question 17

What are the two isomers of glucose and there differences

Answer 17

• alpha glucose OH down on carbon 1 but on beta glucose up

Question 18

What is sucrose

Answer 18

• disaccharide
• glucose and fructose
• transport of sugar in plants

Question 19

What is maltose

Answer 19

• disaccharide
• alpha glucose
• in germinating seeds

Question 20

What is lactose

Answer 20

• disaccharide
• glucose and galactose
• found in milk

Question 21

What is starch

Answer 21

• polyacchaird
• alpha gluocse
• straight chain amylose curls into helical shape - alpha 1-4 glycosidic bonds
• branched amylopectin alpha 1-4, 1-6 glycosidic bonds
• compact energy storage in plants with little osmotic effect

Question 22

What is glycogen

Answer 22

• polysaccharide
• alpha glucose
• energy storage in animals
• similar to amylopectin

Question 23

What is cellulose

Answer 23

• polysacchairde
• beta glucose
• adjacent monomers twited 180 to each other
• allowing hydrogen bonds between chains forming microfibril
• strong structure for plant cell walls

Question 24

What is chitin

Answer 24

• as cellulose but with ssome OH groups replaces by nitogen containging acetylamine groups
• strong, lightweight and waterproof ffor exoskeletons

Question 25

What is the test for starch

Answer 25

• idodine solution - yellow/orange
• positive reaction - a blue/black colour seen

Question 26

What is the test for reducing sugar

Answer 26

• Benedicts reagent - blue
• positive reaction - a semi quantative test - from green to red with higher concentration toward red
• non reducing must be hydrolysed by boiling in hydrochloric acid firt then add NaOH

Question 27

What is an inorganic ion

Answer 27

an ion that contains no more than one carbon atom

Question 28

What is the use of magnesium ions

Answer 28

• make chlorophyll

Question 29

What is the use of iron ions

Answer 29

• to form haemoglobin

Question 30

What is the use of phosphate ions

Answer 30

• nucleic acids - nucleotides
• phospholipids

Question 31

What is the use of calcium ions

Answer 31

• strengthen bones and teeth in animals
• cell walls in plants

Question 32

What is the test for lipids

Answer 32

• mix with ethanol then equal volume of water
  loudy emulsion is formed

Question 33

What is a trigylceride

Answer 33

• type of lipid
• glycerol linked to 3 fatty acid chains
• form ester bonds

Question 34

What are phospholipids

Answer 34

• glycerol linked to two fatty acids chains and a phostphate molecule
• a phospholipid has a hydrophillic head and a hydrophobic tail
• explain plasm membraine lipid bilayer

Question 35

What are unsaturated fatty acids

Answer 35

• contain at least one carbon to carbon double bonds

Question 36

What are saturated fatty acids

Answer 36

• have single carbon to carbon bonds only

Question 37

Describe why a high intake of saturated fats can cause heart disease

Answer 37

• raises the low density lipoprotein cholesterol level increases atheromas in coronary arteries