1.2- biological molecules 1

Question 1

what are organic compounds?

Answer 1

-compounds which contain carbon atoms
-they also contain; hydrogen, oxygen and sometimes nitrogen suplfur and phosphorus

Question 2

how many bonds can each carbon make

Answer 2

4

Question 3

why are carbohydrates important?

Answer 3

-important in cells as a usable energy store
-storing energy, and in plants, fungi and bacteria and form an important part of the cell wall
-

Question 4

basic structure of carbs

Answer 4

-made up of carbon, hydrogen and oxygen
-3 main groups; monosaccharides, disaccharides, polysaccharides

Question 5

what are monosaccharides?

Answer 5

-simple sugars in which there is one oxygen atom and two hydrogen atoms for each carbon atom present in the molecule
-general formula can be written as (CH2O)n+

Question 6

triose sugars

Answer 6

-n=3
-have 3 carbon atoms and the molecular formula C3H6O3
-they are important in mitochondria, where glucose is broken down into triose sugars during respiration

Question 7

pentose sugars

Answer 7

-n=5
-have 5 carbon atoms and the molecular formula C5H1O5
e.g. ribose and deoxyribose

Question 8

hexose sugar

Answer 8

-n=6
-have six carbon atoms and the molecular formula C6H12O6
-often taste sweet including glucose, galactose and fructose

Question 9

examples of monosaccharides

Answer 9

glucose
fructose
ribose

Question 10

examples of disaccharides

Answer 10

sucrose
maltose
lactose

Question 11

exmaples of polysaccharides

Answer 11

starch
cellulose
glycogen

Question 12

how do monosaccharides form disaccharides

Answer 12

condenstaion reaction occurs to join the 2 monosaccharides, monosacs joined by a glycosidic bond (covelant)
-a molecule of water is removed

Question 13

which disaccharide is not a reducing sugar

Answer 13

sucrose

Question 14

test for reducing sugars

Answer 14

-add benedicts solution
-heat in hot water bath 90degrees
-reducing sugar reacts with benedicts and reduces copper (ii) ions to copper (i) ions
-colour changes from blue to orange/red

Question 15

test for non reducing sugars

Answer 15

-heat non reducing sugar with few drops of hydrochloric acid
-neutralise with sodium hydrogen carbonate
-this produces sugars which are monosacs to give a pos benedicts test

Question 16

why are monosaccharides soluble in water

Answer 16

have lots of hydroxyl (OH) groups which can readily engage in H bonding with water

Question 17

what are polysaccharides

Answer 17

-polymers containing monosaccharides linked by glycosidic bonds
-formed by condensation reactions
-mainly used as energy store and structural components
e.g. starch and cellulose

Question 18

oligosaccharides vs polysaccharides

Answer 18

-3-10 is a oligosaccharide
-more than 11 sugar units is a polysaccharide

Question 19

why are polysaccharides so good for storage

Answer 19

-the glygosidic bond is easily broken meaning monosaccharides can be released quickly for respiration
-can be very compact, so many stored in cells
-not soluble, no no effect on water potential

Question 20

starch- amylose

Answer 20

-long chain of a glucose
-unbranched with 1,4 glycosidic bonds
-coiled to make it compact and good for storage

Question 21

starch-amylopectin

Answer 21

-long chains of a glucose
-branched
-1,4 and 1,6 glycosidic bonds
-branches allow enzymes to break down easily so glucose can be released quickly

Question 22

cellulose

Answer 22

-polymer of b glucose
-each monomer inverted
-forms chains which run parallel with H bonds between the chains to form microfibrils
-these are very strong
-structurally important in plant cell walls as it is fibrous

Question 23

glycogen

Answer 23

-animals store carbs as glycogen
-made of a glucose
-1,6 glycosidic bonds
-branched structure
-glycogen stored as small granules
-broken down more rapidly than starch, less dense and more soluble
-to meet higher metabolic demand in animals

Question 24

what are the 2 types of lipids

Answer 24

1.triglycerides
2.phospholipids

Question 25

2 examples of triglycerides

Answer 25

1.fats 2.oils

Question 26

what 2 molecules make up triglycerides

Answer 26

glycerol 3 fatty acids

Question 27

what bond joins glycerol and fatty acids

Answer 27

ester

Question 28

triglyceride formation

Answer 28

-triglyceride formed when each hydroxyl group on the glycerol combines with carboxyl group on fatty acid -this is a condensation reaction -esterfication -water removed in reaction

Question 29

how to tell if it is saturated or unsaturated

Answer 29

-unsaturated have double bonds -they have a low melting point and tend to be liquid at normal temps

Question 30

saturated fatty acids

Answer 30

-carbons joined by single covelant bond -carbon atoms bonded to max number of atoms -chain is relatively straight -tend to be solids (fats) at room temp

Question 31

unsaturated fatty acids

Answer 31

-one or more double covelant bond present in carbon chain -not bonded to max number of other atoms -2 or more have double bonds -usually liquid at room temp (oils)

Question 32

phospholipid structure

Answer 32

-2 fatty acid chains attached to glycerol -polar phosphate group

Question 33

what do phospholipids make up

Answer 33

plasma membranes -hydrophillic (polar) head and hydrophobic tail

Question 34

summary of phospholipids

Answer 34

-Glycerol phosphate (polar) head is hydrophilic. -non polar, oily, hydrophobic tail -said to be amphipathic -gived cell membranes fluid properties and allow lipid soluble substances through

Question 35

bonds in proteins

Answer 35

-peptide between amino acids -hydrogen -disulphide' -ionic

Question 36

hydrogen bonds

Answer 36

singally weak -collectively strong -easily broken

Question 37

disulphide bond

Answer 37

Formed in an oxidation reaction between 2 sulfur containing groups. Results in a strong covalent bond.

Question 38

ionic bonds

Answer 38

-Not as common -Form between strongly positive and negative amino side chains. -Can be known as salt bridges.

Question 39

primary protein structure

Answer 39

-sequence of amino acids in polypeptide chain -peptide bonds

Question 40

secondary protein structure

Answer 40

-a helices -b pleated sheets -form as a result of hydrogen bonding between different amino acids in the chain

Question 41

tertiary protein structure

Answer 41

-secondary structure folds up to form a very precise 3D structure forces responsible; 1.hydrogen bonds 2.ionic bonds 3.disulphide bonds 4.van der waals forces

Question 42

how can all 4 forces be split

Answer 42

hydrogen- high temp and altered pH ionic- changing pH disulphide- reducing agent van der waal- rise in temp

Question 43

what is van der waals forces

Answer 43

-weak forces of attraction between non polar groups

Question 44

quaternary structure

Answer 44

- Some proteins consist of more than one polypeptide chain held together in a precise three-dimensional structure -2 main types are globular and fibrous -can also involve the addition of non-amino acid derived groups known as prosthetic groups

Question 45

globular proteins

Answer 45

-form a spherical mass -They fold up so that hydrophillic groups are on the outside and hydrophobic groups are inside the molecule -e.g.haemoglobin

Question 46

fibrous proteins

Answer 46

-form long chains or fibres -fibrous nature makes them insoluble in water -form triple helix of polypeptide chains -held by hydrogen bonds -e.g. collagen