module 2 - chapter 3 ( biological molecules)

Question 1

draw the electron cross dot diagram for

• hydrogen
• water
• carbon dioxide
• methane
• ammonia

Answer 1

.

Question 2

draw the displayed formula for

• hydrogen
• water
• carbon dioxide
• methane
• ammonia

Answer 2

.

Question 3

what is a polymer

Answer 3

.polymers are long chain molecules made up by the linking of multiple individual molecules called monomers in a repeating pattern.

Question 4

what are saccharides

Answer 4

.in carbohydrates the monomers ( molecules) are sugars known as saccharides or sugars

Question 5

in protein what are the monomers known as

Answer 5

.amino acids

Question 6

explain fully what ‘polar molecules’ are

Answer 6

.A polar molecule has positive and negative region from polar bonds arranged asymmetrically. Water (H2O) is an example of a polar molecule since it has a slight positive charge on one side and a slight negative charge on the other.

.usually occurs in covelent bonds as one element tends to have a greater share of negative electrons making the other atom slightly positive.

Question 7

which element has more electrons in a covelent bond, and is therefore more negative? oxygen or hydrogen

Answer 7

.oxygen always has a much greater share of electrons in an O-H bond making it more negative

Question 8

what is a hydroxyl group

Answer 8

.when hydrogen and oxygen bond together its called a hydroxly group

Question 9

what is a hydrogen bond

Answer 9

.A hydrogen bond is a partially electrostatic attraction between a hydrogen atom which is bound to a more electronegative atom such as nitrogen, oxygen, or fluorine.

Question 10

list 3 characteristics of water

Answer 10

.high boiling point
.water is a liquid at room temp,due to hydrogen bonding
.when water is turn to ice it becomes less dense due to hydrogen bonds.

Question 11

explain fully why ice is less denser then water

Answer 11

.as water is cooled 4 degrees,the hydrogen bonds fix the position of the polar molecules slightly further apart then the average distance in the liquid state

.this produces a rigid but open structure with every oxygen atom at the centre of the arrangement of hydrogen atoms,resulting in a solid less dense then the liquid,hence why ice floats.

Question 12

how does water have cohesive properties

Answer 12

.cohesive- cohesion refers to the sticking together of alike molecules, such as water molecule being attracted to another water molecule. Cohesion also causes water molecules to form drops.

Question 13

how does water have adhesive properties

Answer 13

.adhesive-Adhesion may refer to the joining of two different substances due to attractive forces that hold them,and why water sticks to other materials

Question 14

what is capillary action

Answer 14

.the process by which water can rise up a narrow tube against the force of gravity.

Question 15

what is a monosaccharide ,give 3 examples

Answer 15

.a single sugar is known as a monosaccharide

.for example glucose,fructose and ribose

Question 16

what is a disaccharide,give 2 examples

Answer 16

.when two monosaccharide join together they form a disaccharide

.for example lactose,sucrose and maltose

Question 17

what is a polysaccharide,give 3 examples

Answer 17

.when a lot of monosaccharide join together they form a polymer called polysaccharide

.for example glycogen ,cellulose and starch

Question 18

what are the 2 structural variations of glucose molecules

Answer 18

.alpha glucose and beta glucose (make sure you know how to draw them both)

Question 19

explain why glucose dissolves in the crytosol of a cell.

Answer 19

.glucose molecules are polar and soluble in water

.this is due to the hydrogen bonds that form between the hydroxyl groups and water molecules.

.this means glucose is dissolved in the cytosol of the cell.

Question 20

explain what happens when two alpha glucose molecules are side by side.

Answer 20

.when two alpha glucose molecules are side by side,two hydroxyl groups react forming maltose(dissacharide)

.two hydrogen atoms and an oxygen atom are removed from the glucose monomers and joined to form a water molecule ,its therefore a CONDENSATION REACTION as a water molecule was formed.

.a covelent bond called glycosidic bond is forms between two glucose molecules.because carbon 1 and 4 and the molecules joined the bond is known as a 1,4 glycosidic bond.

Question 21

explain the sugars fructose and galactose.

Answer 21

.fructose and galatose are also hexose monosaccharides ,fructose occurs in fruit

.galactose and glucose form the disaccharide lactose .lactose found in milk.

Question 22

what are the two forms of starch

Answer 22

.amylose

.amylopectin

Question 23

explain amylose

Answer 23

many alpha glucose molecules can be joined by a glycosidic bond to form 2 slightly different polysaccharides known as starch

.one of the polysaccharide in starch is called amylose

.amylose is formed by alpha glucose molecules joined ONLY by 1-4 glycosidic bond.

.the angle of the bond means that this forms a helix

.this makes the polysaccharide more compact and less soluble then the glucose molecule used to make it.

Question 24

explain amylopectin

Answer 24

.many alpha glucose molecules can be joined by a glycosidic bond to form 2 slightly different polysaccharides known as starch:

.one of the polysaccharide in starch is called amylopectin

.like amylose,amylopectin is also made by 1-4 glycosidic bond between alpha glucose molecules ,but unlike amylose,in amylopectin there is also some GLYCOSIDIC BONDS formed by CONDENSATION REACTION between carbon 1 and carbon 6 on two glucose molecules.

.this means amylopectin has a branched structure with the 1-6 branching points.

Question 25

explain glycogen

Answer 25

.the functionally equivalent energy storage molecule to starch in animals and fungi is called glycogen.

.glycogen forms more branches than amylopectin,which means its more compact and less space is needed for it to be stored.

.this is important as animals are more mobile unlike plants.the branches of the polysaccharied make them compact,ideal for storage.

Question 26

what key properties make amylopectin and glycogen ideal for storage

Answer 26

.they are insoluble,branched and compact

Question 27

explain how to release glucose for respiration

Answer 27

.glucose is stored as starch by plans or glycogen by animals and fungi,until needed for respiration

.to release glucose for respiration starch or glycogen undergo HYDROLYSIS REACTION , requiring the addition of water molecule

Question 28

explain cellulose

Answer 28

.beta glucose molecules aren’t able to react as the hydroxyl group on carbon 1 and carbon 4 are too far away.

.the only way beta glucose molecules can join together and form a polymer is if alternate beta glucose molecules are turnt upside down.

.the oh groups of the two b-glucose are now close enough to react and a 1,4 glycosidic bond is formed.

when a polysaccharide is formed from glucose in this way it is unable to coil and a straight chain molecule is formed called cellulose.

Question 29

explain micro fibrils and macro fibrils

Answer 29

.cellulose molecules make hydrogen bonds with each other forming microfibrils.

.these microfibrils join together to form macrofibrils which combine to produce fibres.

.these fibres are strong and insoluble and are used to make cell walls.

Question 30

name 3 types of lipids

Answer 30

.triglycerides
.phospholipids
.sterols

Question 31

explain lipids

Answer 31

.lipids ,commonly known as fats and oils ,are molecules containing the elements carbon,hydrogen and oxygen.

.lipids are non-polar molecules as the electrons in the outer orbitals , that form the bonds, are more evenly distributed than in polar molecules

.since there’s no positive or negative areas within the molecule lipids are not soluble in water.oil and water dont mix.

.lipids are large complex molecules known as MACROMOLECULES which aren’t built from repeating units.

Question 32

explain what a triglycerides is made out of

Answer 32

.a triglyceride is made up of one glycerol molecule with three fatty acids.

.glycerol is a member of a group of molecules called alcohols

.fatty acids belong to a group of molecules known as carboxylic aids,they consist of a carboxylic group (COOH) with a hydro carbon chain attached.

Question 33

explain esterfication and how it occurs in a triglycerides

Answer 33

.both of these molecules contain hydroxyl groups.the hydroxyl groups interact (condensation reaction) forming 3 water molecules and bonds between the fatty acids and glycerol.

.these are called ester bonds also known as esterfication in a reaction,esterfication is another way of condensation.

Question 34

explain what a phospholipid is made out of

Answer 34

phospholipid are modified triglycerides , instead of 3 fatty acids one is replaced by a phosphate group forming phospholipid

Question 35

explain were inorganic phosphate ions are found is found

Answer 35

inorganic phosphate ions are found in the cytoplasm of every cell

Question 36

why is phosphate ions soluble in water

Answer 36

.the phosphate ions have extra electrons and are negatively charged,making it soluble in water.

Question 37

why is the tails in a phospholipid considered to be hydrophobic

Answer 37

.the non-polar tails are repelled by water

Question 38

why is the head in a phospholipid considered to be hydropholic

Answer 38

.the charge heads interact with water

Question 39

explain the bilayer arrangement

Answer 39

as a result of the phospholipid structure it forms a structure based on a two-layered sheet formation with the tails towards the centre of the sheet.