Biological Molecules: Carbohydrates

Question 1

what are some examples of reducing sugars

Answer 1

all monosaccharides and maltose

Question 2

why are carbohydrates, proteins and lipids all organic compounds

Answer 2

they contain the elements Carbon and Hydrogen

Question 3

why are carbon atoms key to the organic compounds

Answer 3

• each carbon atom can form four covalent bonds which makes the compounds very stable (as covalent bonds are very strong and so require a large amount of energy to break them)
• they can form covalent bonds with oxygen, nitrogen and sulfur
• they can bond to form straight chains, branched chains or rings

Question 4

what are macromolecules

Answer 4

very large molecules that contain 1000 or more atoms and therefore having a high molecular mass

Question 5

difference between macromolecules and polymers

Answer 5

polymers can be macromolecules but not all macromolecules are polymers as the subunits of polymers have to be the same repeating units

Question 6

what is the general formula for carbohydrates

Answer 6

Cx(H20)y

Question 7

what are the three types of carbohydrates

Answer 7

• monosaccharides, disaccharides and polysaccharides

Question 8

definition of a monosaccharide

Answer 8

• single sugar monomer
  (all are reducing sugars)

Question 9

definition of a disaccharide

Answer 9

a sugar formed from two monosaccharides joined by a glycosidic bond

Question 10

definition of a polysaccharide

Answer 10

a polymer formed by many monosaccharides joined by glycosidic bonds

Question 11

what is maltose made up of

Answer 11

two alpha glucose molecules

Question 12

what is sucrose made out of

Answer 12

an alpha glucose and a fructose molecule

Question 13

what monomers is cellulose made out of

Answer 13

beta glucose

Question 14

what monomers is starch made out of

Answer 14

alpha glucose in the form of amylose and amylopectin

Question 15

what monomers is glycogen made out of

Answer 15

alpha glucose

Question 16

how many carbons in a glyceraldehyde molecule

Answer 16

3

Question 17

how many carbons in a ribose molecule

Answer 17

5

Question 18

how many carbons in a glucose

Answer 18

6

Question 19

are lipid molecules polymers

Answer 19

no because each fatty acid joins to a glycerol molecule rather than to each other

also separate molecules (such as triglycerides) are not held together by covalent bonds so they cannot be classed as polymers

Question 20

what are the two types of covalent bonds

Answer 20

nonpolar - when the electrons are shared equally
or
polar - where the electrons are shared unequally due to an electronegative atom

Question 21

what is a condensation reaction

Answer 21

when monomers combine together by covalent bonds accompanied by the release of a water molecule

Question 22

how do you reverse a condensation reaction

Answer 22

using hydrolysis (add water and break the bonds)

Question 23

what covalent bonds exist within carbohydrates ????

Answer 23

glycosidic bonds

Question 24

what covalent bonds exist within lipids ?????

Answer 24

esters

Question 25

what covalent bonds exist within nucleic acids ?????

Answer 25

phosphodiester

Question 26

what is a reducing sugar

Answer 26

a sugar that can donate electrons (its carbonyl group becomes oxidised) -> the sugar becomes the reducing agent

Question 27

why can reducing sugars be detected using Benedict's solution

Answer 27

they reduce the soluble copper sulphate to insoluble (brick-red) copper oxide

Question 28

what are some examples of reducing sugars

Answer 28

all monosaccharides and maltose

Question 29

how are glucose, fructose and galactose linked

Answer 29

they all have the same molecular formula but have a different structural formula the different arrangements of atoms in them gives them slightly different properties

Question 30

how can we adapt the Benedict's solution to detect non-reducing sugars

Answer 30

they must first be hydrolysed (heat it with acid) to break the disaccharide into its two monosaccharides

Question 31

what is a triose

Answer 31

a monosaccharide formed from 3 carbon atoms

Question 32

structure of alpha glucose

Answer 32

H H OH OH

Question 33

structure of beta glucose

Answer 33

H OH OH H

Question 34

why are monosaccharides bonded together to form disaccharides and polysaccharides in cells

Answer 34

- so they are more suitable for transport and storage - so they have less influence of a cell's osmolarity

Question 35

how are di- and poly-saccharides formed

Answer 35

when two hydroxyl groups on different saccharides interact to form a strong covalent bonds call a glycosidic bond

Question 36

how are two alpha glucose molecules joined to form a disaccharide

Answer 36

the OH groups are affected on the ends: the OH of one is removed and the H from the OH of the other is removed 1st picture from 1.1.5 the glycosidic bond

Question 37

how do glycosidic bonds find the energy to form between saccharides

Answer 37

they are catalysed by enzymes specific to which OH groups are interacting

Question 38

what type of glycosidic bonds does maltose have

Answer 38

- alpha 1,4

Question 39

what type of glycosidic bonds does sucrose have

Answer 39

alpha 1,2

Question 40

what type of glycosidic bonds does cellulose have

Answer 40

beta 1,4

Question 41

what type of glycosidic bond does amylose have

Answer 41

alpha 1,4

Question 42

what type of glycosidic bond does amylopectin have

Answer 42

alpha 1,4 and 1,6

Question 43

what are some examples of hydrolytic (hydrolysis) reactions

Answer 43

- the digestion of food in the alimentary tract - the breakdown of stored carbohydrates in muscle and liver cells for use in cellular respiration

Question 44

what type of sugar is sucrose

Answer 44

non-reducing

Question 45

how do we prove sucrose is a non-reducing sugar

Answer 45

- benedict's test - negative result - heat with (hydrochloric) acid - benedict's test - positive result

Question 46

why does a non-reducing sugar give a positive result after it has been heated in acid

Answer 46

the heating with acid provides the water that hydrolyses the glycosidic bond resulting in two monosaccharides which are reducing sugars

Question 47

what is a glycosidic bond

Answer 47

a strong covalent bond with an oxygen link that results from the interaction between two hydroxyl groups

Question 48

how do we make polysaccharides into monosaccharides

Answer 48

through MANY hydrolysis reactions

Question 49

what two phases do all chromatography techniques use

Answer 49

- mobile phase - stationary phase

Question 50

1.1.6 chromatography: monosaccharides

Question 51

what chemical bond forms between monosaccharides

Answer 51

glycosidic bond

Question 52

how to calculate the chemical formula of a disaccharide using the formulas of two monosaccharides

Answer 52

- add all the carbons, hydrogens and oxygens of both monomers then subtract 2H and 1O (the water molecule lost)

Question 53

what are three common disaccharides

Answer 53

- maltose - sucrose - lactose

Question 54

what monosaccharides is maltose made out of

Answer 54

alpha glucose and alpha glucose

Question 55

what monosaccharides is sucrose made out of

Answer 55

alpha glucose and fructose

Question 56

what monosaccharides is lactose made out of

Answer 56

alpha glucose and galactose

Question 57

what are three common monosaccharides

Answer 57

- glucose - galactose - fructose

Question 58

why are starch and glycogen good storage molecules

Answer 58

- compact (so large quantities can be stored) - insoluble (so will have no osmotic effect)

Question 59

where and how is starch stored in plants

Answer 59

stored as granules in plastids

Question 60

what two polysaccharides is starch made out of and what percentage composition are they

Answer 60

- amylose (10-30%) - amylopectin (70-90%)

Question 61

what is the structure of amylose

Answer 61

- 1,4 glycosidic bonds between alpha glucose - which creates an unbranched molecule

Question 62

between starch and glycogen, which is quicker to be broken down and why

Answer 62

glycogen because it is more branched which means more enzymes can work on it simultaneously on the many terminal glucose molecules

Question 62

why does 'being branched' help a polymer be broken down quicker

Answer 62

it enables more free ends where glucose molecules can be removed [or added] (more enzymes can work simultaneously) allowing for hydrolysis [or condensation] reactions to occur more rapidly

Question 62

what is the structure of amylopectin

Answer 62

- 1,4 and 1,6 glycosidic bonds between alpha glucose molecules - which creates a branched molecule

Question 63

what is glycogen the storage molecule for

Answer 63

animals and funghi

Question 63

why is it important that glycogen is more branched than starch

Answer 63

- so it is able to be broken down quicker than starch because glycogen is used as a storage molecule in animals which have a higher metabolic rate than plants (whereas starch is used as a storage molecule in plants) - so it is more compact which helps animals store more

Question 64

where in animals has a high concentration of glycogen

Answer 64

in the liver and muscles as the cellular respiration rate is high in these cells