UNIT: 1.1 CHEMICAL ELEMENTS JOINED TOGETHER TO FORM COMPOUNDS

Question 1

The function of Mg2+

Answer 1

component of chlorophyll and essential for photosynthesis

Question 2

The function of fe2+

Answer 2

component of haemoglobin which transports oxygen in red blood cells

Question 2

The function of PO4^3-

Answer 2

used for making nucleotides, including ATP and are a component of phospholipids

Question 2

The function of Ca2+

Answer 2

structural component of bones in teeth in mammals
component in plant cell walls

Question 2

what is the structure of water?

Answer 2

Dipole - it has a positively charged end ( hydrogen) and a negatively charged end ( oxygen) but no overall charge.

Question 3

What are the properties of water?

Answer 3

metabolite
high specific heat capacity
high latent of vaporisation
cohesion
high surface tension
high density
transparency

Question 4

metabolite?

Answer 4

used in many biochemical reactions as a reactant e.g with carbon dioxide to produce glucose in photosynthesis. Many reactions in the body involve hydrolysis ( water splits a molecule)

Question 5

High specific capacity

Answer 5

a large amount of heat energy is needed to raise its temperature. This is due to the hydrogen bonds between water molecules restrict their movement, resisting an increase in kinetic energy and therefore resisting an increase in temperature. Prevents large fluctuations in temperature - important in keeping aquatic habitats stable.

Question 6

High latent heat of vaporisation

Answer 6

lot of heat energy is needed to change it from a liquid to vapour . Important e.g for temp control.

Question 7

Cohesion

Answer 7

water molecules attract each other forming hydrogen bonds. The molecules are able to stick together in a lattice.

Question 8

High surface tension

Answer 8

at ordinary temperatures - water = highest surface tension of any liquid but mercury. ( in a pond cohesion between water molecules at the surface produces surface tension so that the body of an insect = supported)

Question 9

High density

Answer 9

water = denser than air and as a habitat for aquatic organisms produces support and buoyancy.

Question 10

water transaparency

Answer 10

allows light to pass through - lets aquatic plants photosynthesise effectively

Question 11

what are carbohydrates?

Answer 11

organic compounds which contain the atoms carbon,hydrogen and oxygen

Question 12

what are monosaccharides?

Answer 12

basic unit of a carbohydrate
2 = disaccharide
many = polysaccharides

Question 13

what are Monosaccharides like?

Answer 13

sweet and soluble - building blocks for larger carbohydrates

Question 14

what is their general formula?

Answer 14

(CH2O)n - grouped according to the number of carbon atoms they have

Question 15

triose?

Answer 15

3 carbon atoms
important in metabolism
intermediates in the reactions of respiration and photosynthesis

Question 16

pentose?

Answer 16

5 carbon atoms
components of nucleotides e.g deoxyribose in DNA, ribose in RNA , ATP and ADP

Question 17

Hexose?

Answer 17

6 carbon atoms
for example glucose - source of energy in respiration
carbon-hydrogen and carbon - carbon bonds = broken to release energy which = transferred to make ATP

Question 18

what are isomers?

Answer 18

same chemical formula and the same number of atoms but atoms are simply arranged differently

Question 19

what are the isomers of glucose called?

Answer 19

alpha glucose
beta glucose
both have same chemical formula C6H12O6 but the H and Oh atoms = differently arranged at carbon 1
at carbon 1 - alpha glucose has a hydrogen atom above and a OH group below but at beta glucose - carbon 1 has a OH above and a H atom below
H and OH atoms at carbon 1 have been flipped - this is the only difference between alpha and beta glucose

Question 20

what are disaccharides?

Answer 20

composed of 2 monosaccharide sub units bonded with the formation of a glycosidic and the elimination of water
example of a condensation reaction

Question 21

what are the 3 types of disaccharides?

Answer 21

sucrose
maltose
lactose

Question 22

maltose?

Answer 22

glucose and glucose in germinating seeds

Question 23

sucrose?

Answer 23

glucose and fructose product of photosynthesis = transported in the phloem

Question 24

lactose?

Answer 24

glucose and galactose found in mamallian milk

Question 25

benedicts reagant

Answer 25

used for glucose if positive turns brick red

Question 26

what are polysacchrides?

Answer 26

large complex polymers formed from very large units of identical monosacchride units = monomers linked by glysosidic bonds formed by condensation reaction

Question 27

what is starch made of?

Answer 27

alpha glucose monomers, added one at a time by condensation reaction

Question 28

what does starch do?

Answer 28

allows plant to store glucose

Question 29

what types of polysacchride does starch have?

Answer 29

amylose and amylopectin

Question 30

structure of amylose?

Answer 30

unbranched and coils; each α glucose monomer added forms a C1 – C4 glycosidic bond with the adjacent glucose molecule.

Question 31

structure of amylopectin?

Answer 31

is branched as it forms C1 - C4 gylcosidic bonds and C1 – C6 glycosidic bonds.

Question 32

what is glycogen?

Answer 32

main storage product in animals

Question 33

what is the difference between glycogen and amylopectin?

Answer 33

The main difference between amylopectin and glycogen is that glycogen has shorter C1 – C4 α glucose chains and there are more C1 – C6 branch points. Glycogen is more branched than amylopectin.

Question 34

how is glycogen and amylopectin similar?

Answer 34

It is similar in structure to amylopectin. In glycogen the α glucose molecules are joined by C1 – C4 and C1 – C6 glycosidic bonds. The main difference between amylopectin and glycogen is that glycogen has shorter

Question 35

what is cellulose?

Answer 35

structural polysacchride found in plant cell walls

Question 36

structure of cellulose?

Answer 36

Cellulose consists of many long, parallel chains of β glucose units. The β glucose monomers are joined by C1 – C4 glycosidic bonds. The β bond rotates adjacent glucose molecules by 180 this allows hydrogen bonds to form between OH groups of adjacent cellulose chains. Between 60 and 70 cellulose molecules become tightly cross-linked to form bundles called microfibrils. Microfibrils are bunched together in bundles to form fibres.

Question 37

what is the structure of chitin

Answer 37

Chitin is composed of long chains of β glucose molecules linked by C1 – C4 glycosidic bonds. Chitin differs from cellulose in that each monomer has a group derived from amino acids added, called an acetylamine group. Like cellulose alternate glucose molecules are rotated by 180 this allows hydrogen bonds to form between the OH groups of adjacent chitin chains. The cross-linked parallel chains form microfibrils.

Question 38

properties of chitin?

Answer 38

strong,waterproof and lightweight

Question 39

what are triglycerides?

Answer 39

most common types of lipids fats and oils

Question 40

properties of tryglycerides?

Answer 40

insoluble in water -non polar but soluble in other solvents e.g ethanol, chloroform and ether

Question 41

how are they formed?

Answer 41

formed by condensation reaction between glycerol and fatty acids 3 molecules of water are released

Question 42

what is the bond formed called?

Answer 42

an ester bond tryglyceride - has 3 ester bonds

Question 43

unsaturated structure fatty acids?

Answer 43

have double bonds between neigbouring carbon atoms

Question 44

what don't they contain?

Answer 44

they do not contain the maximum possible number of hydrogen atoms.

Question 45

what do double bonds do?

Answer 45

make fatty acids and lipids melt more easily; most oils are unsaturated.

Question 46

what is monosaturated?

Answer 46

there is only one double bond between carbon atoms the fatty acid double bond forms a kink which is why unsaturated fatty acid molecules cannot be tightly packed together and therefore are not solid.

Question 47

what is polyunsaturated?

Answer 47

there are two or more double bonds between carbon atoms

Question 48

saturated?

Answer 48

have no double bonds between neighbouring carbon atoms in the hydrocarbon tail. A saturated fatty acid carries the maximum possible number of hydrogen atoms.

Question 49

what are the main causes of heart disease?

Answer 49

fatty deposits in the coronary arteries (atherosclerosis) and high blood pressure (hypertension). A diet that is high in saturated fatty acids, smoking, lack of exercise and ageing are all contributory factors.

Question 50

what happens with a diet high in saturated fats?

Answer 50

low-density lipoproteins (LDL) build up. Fatty material called atheroma is deposited in the coronary arteries, restricting blood flow and, therefore, oxygen delivery to the heart tissue. restricted blood flow = angina

Question 51

what happens if the diet = high proportion of high unsaturated fats?

Answer 51

body makes more high density lipoproteins which carry harmful fats to the liver for disposal

Question 52

what are phospholipids?

Answer 52

a special type of lipid

Question 53

properties of phospholipids?

Answer 53

hydrophilic heads and 2 hydrophobic fatty acid tails

Question 54

what is the difference between trigylcerides and phospholipids?

Answer 54

triglycerides have 3 fatty acid tails no phosphate group non polar phospholipids 2 fatty acid tails phosphate group polar head = hydrophilic fatty acid tails = hydrophobic

Question 55

what is the test for fats and oils ?

Answer 55

lipids test

Question 56

how you undergo it?

Answer 56

substance is mixed thoroughly with absolute ethanol and any lipid present in the sample will dissolve in the ethanol sample turns cloudy white if present

Question 57

functions of lipids?

Answer 57

energy store in plants and animals thermal insulator protection metabolic water source waterproofing low density and buoyancy nerve transmission steroids ad cholestrol cell membrane formation

Question 58

what do proteins contain?

Answer 58

carbon hydrogen oxygen and nitrogen

Question 59

what are proteins made up of?

Answer 59

monomers called amino acids

Question 60

what is a chain of amino acid called?

Answer 60

polypeptide chain

Question 61

what do all amino acids have?

Answer 61

amino group carboxyl group hydorgen atom R-group

Question 62

how is a dipeptide formed?

Answer 62

when the amino group of one amino acid reacts with the carboxyl group of another by condensation reaction; water is eliminated and a peptide bond is formed

Question 63

what are the 4 levels of protein structure?

Answer 63

primary secondary tertiary quaternary

Question 64

primary?

Answer 64

primary structure in the sequence of amino acids in a polypeptide chain sequence of amino acids = determined by dna 1 gene codes for 1 polypeptide bond between each amino acid = peptide bond

Question 65

secondary?

Answer 65

shape that the polypeptide chain forms due to hydrogen bonding. the bonds twist and form the polypeptide forming a alpha helix

Question 66

tertiary?

Answer 66

alpha helix of a secondary protein = further folded and twisted to give a more complex , compact 3D structure shape = maintained by disulphide, ionic, covalent hydrophobic and hydrogen bonds. enzymes have a tertiary structure - bonds maintain the shape of the enzyme's active site

Question 67

quartenary?

Answer 67

arises from a combination of 2 or more polypeptide chains in tertiary form associated with non protein groups and form large complex molecules such as haemoglobin haemoglobin has 4 polypeptide chains Four genes are needed to code for haemoglobin; one gene for each polypeptide.

Question 68

what are proteins classified into?

Answer 68

gloubular and fibrous proteins

Question 69

what is the difference between haemoglobin and collagen

Answer 69

haemoglobin = 4 polypeptide molecules each polypeptide chain = different haemoglobin = associated with non protein groups highest level of protein = quartenary whereas collagen = 3 polypeptide molecules each polypeptide = same collagen = not associated with non protein groups highest level of protein = secondary

Question 70

what is the biuret test used to test for?

Answer 70

proteins