Biological Molecules

Question 1

What are the key molecules which enables organisms to function?

Answer 1

Carbohydrates
Proteins
Lipids
Nucleic acids
Water

Question 2

What are monomers and polymers?

Answer 2

Monomers are smaller units
Polymers are molecules made from lots of monomers

Question 3

Name monomers of lipid

Answer 3

Glycerol and fatty acids
(Lipids are not polymers)

Question 4

Name monomer and polymer of nucleic acid

Answer 4

Monomer is nucleotide
Polymer is DNA

Question 5

Name monomer and polymer of protein

Answer 5

Monomer is amino acid
Polymer is polypeptide

Question 6

Name monomer and polymer for carbohydrate

Answer 6

Monomer is monosaccharide
Polymer is polysaccharide

Question 7

What compounds are carbohydrates, proteins, lipids and nucleic acids? And why?

Answer 7

Organic compounds
Contain elements carbon and hydrogen

Question 8

What is maltose made up of?

Answer 8

2 alpha- glucose

Question 9

What is sucrose made up of?

Answer 9

Alpha glucose and fructose

Question 10

What is lactose made up of?

Answer 10

Alpha glucose and beta galactose

Question 11

What is condensation reaction?

Answer 11

When monomers combine together by covalent bonds to form polymers and water is removed

Question 12

How does alpha glucose look like in a bond diagram

Answer 12

C1 bonded with H at the top and OH at bottom

Question 13

How does beta glucose look like in diagram

Answer 13

C1 bonded to H at the bottom and OH at top
(Opposite to alpha)

Question 14

What is hydrolysis?

Answer 14

When polymers are hydrolysed into monomers when water is added

Question 15

What is the name of the bond which forms bewteen carbohydrate monomers

Answer 15

Glycosidic bond ( when O is bonded to two C )

Question 16

What are reducing sugars

Answer 16

includes all monosaccharides and some disaccharides like maltose and lactose.
They can donate electrons ( become oxidised)
Sugars become the reducing agent
Can be detected using Benedict’s test

Question 17

What are non-reducing sugars

Answer 17

Cannot donate electrons (cannot be oxidised)
In order to detect the sugar must be first hydrolysed to break the disaccharide into monosaccharides before Benedict’s test
Eg sucrose

Question 18

What is an isomer

Answer 18

Organic molecules that have the same molecular formula but diff. structures regulating in diff. properties

Question 19

Name two isomers

Answer 19

Alpha and beta glucose

Question 20

What is a glycosidic bond

Answer 20

When two hydroxyl OH groups on diff saccharides interact forming disaccharides and polysaccharides
Formed by condensation

Question 21

what is the result of benedicts test when postive

Answer 21

form a coloured precipitate-solid particles suspended in the solution
green-yellow-orange-brick red

Question 22

what are all carbohydrates made up of

Answer 22

C, H and O

Question 23

how to test for non-reducing sugars

Answer 23

only test the solution which did not show a positive result as reducing sugar

needed to break down into monosaccharides by getting a sample and adding dilute HCl acid and heat using a water bath. then use sodium hydrogencarbonate to neutralise.

Question 24

what is starch made up of ( plant glucose)

Answer 24

a mixture of two polysaccharides of alpha glucose= amylose and amylopectin

(plants store excess glucose as starch)

Question 25

what is the structure of amylose

Answer 25

long, unbranched chain of a-glucose coiled structure due to angle of glycosidic bonds which makes it compact so good for storage

Question 26

what is the structure of amylopectin

Answer 26

long, branched chain of a-glucose side branches allow enzymes to get to the glycosidic bond easily so glucose can be released quickly 1,4 and 1,6 glycosidic bonds

Question 27

is starch soluble or insoluble

Answer 27

insoluble in water and doesnt affect water potential- water wont enter cells by osmosis so good for storage

Question 28

what bond helps to stabilize and hold the amylose in its helical shape

Answer 28

hydrogen bonds

Question 29

what is the structure of glycogen ( animal glucose)

Answer 29

same as amylopectin but with shorter chains and highly branched 1,4 and 1,6 glycosidic bonds

Question 30

why does glycogen have loads of branches

Answer 30

stored glucose can be released quickly which is important for animals

Question 31

what is the structure of cellulose

Answer 31

long, unbranched chains of beta- glucose when b-glucose molecules bond, they form straight cellulose chains which the chains are linked by hydrogen bonds to form microfibrils

Question 32

what is the test for starch

Answer 32

iodine test- if present changes from browny orange to a dark, blue-black colour

Question 33

what is triglycerides made up of

Answer 33

one glycerol molecule and three fatty acids

Question 34

why is triglyceride insoluble in water

Answer 34

the hydrocarbon tail is hydrophobic

Question 35

what are the two types of fatty acids

Answer 35

saturated- no double bonds between carbons unsaturated- at least one double bond between carbons

Question 36

what bond is formed by condensation reaction between fatty acid and glycerol

Answer 36

ester bond- releases water

Question 37

where are phospholipids found

Answer 37

cell membrane

Question 38

what is a phospholipid made up of

Answer 38

one glycerol, two fatty acids and one phosphate group( hydrophilic)

Question 39

why is triglyceride good for energy storage

Answer 39

hydrocarbon tails of fatty acids contain lots of chemical energy which can be released when broken dwon

Question 40

why does triglyceride not affect water potential

Answer 40

insoluble-triglycerides bundle together as droplets since tails are hydrophobic - so all tails face inwards

Question 41

what does the phospholipid make up in cell membranes

Answer 41

phospholipid bilayer in cell membranes

Question 42

why does phospholipids form a double layer

Answer 42

heads are hydrophilic and their tails are hydrophobic- centre is hydrophobic so water soluble substances cannot easily pass

Question 43

what is the test for lipids

Answer 43

shake substance with ethanol and then pour into wtaer lipid will show up as milky emulsion

Question 44

whats the general structure of amino acid

Answer 44

a carboxyl group(COOH), an amino group(NH2), an R group attached to carbon atom

Question 45

what bond is formed between amino acids

Answer 45

peptide bonds- by condensation reaction

Question 46

what is the primary structure of amino acids

Answer 46

the sequence of amino acids in the polypeptide chain

Question 47

what is the secondary structure of amino acids

Answer 47

H bonds makes the chains either coil into an alpha helix or fold into beta pleated sheet

Question 48

what is the tertiary structure of amino acids

Answer 48

almost like a big tangled up spring- coiled or folded chain is further coiled or folded. forms H bonds, ionic bonds, disulfide bridges( form when two cysteine molecules come close- covalently bonded)

Question 49

what is the quaternary structure of amino acids

Answer 49

some proteins are made of several different polypeptide chains held by bonds. the way these polypeptide chains are assembled together

Question 50

what is the test for proteins

Answer 50

biuret test- solution must be alkaline so add drops of sodium hydroxide solution and then add some copper (II) sulfate solution if present turns from blue to purple

Question 51

are phospholipids and triglycerides polymers

Answer 51

no they are not made from repeating units they are macromolecules