biological molecules

Question 1

what is a monomer

Answer 1

small units from which a larger units are made from

Question 2

what is a polymer

Answer 2

molecules made from a large number of monomers joined together

Question 3

give an example of a monomer

Answer 3

monosaccharides-glucose, fructose or galactose
amino acids
nucleotides

Question 4

give an example of a polymer

Answer 4

protein
starch
DNA

Question 5

what is a condensation reaction

Answer 5

joining of 2 molecules with the formation pf a chemical bond and involves water as a bi-product

Question 6

what is an example of a condensation reaction

Answer 6

glucose+fructose=sucrose+water
glucose+glucose=maltose+water
galactose+glucose=lactose+water

Question 7

what is a hydrolysis reaction

Answer 7

breaking of a chemical bonds between 2 molecules and involves the use of a water molecules

Question 8

what is an example of a hydrolysis reaction

Answer 8

lactose+water=galactose+glucose

Question 9

what is an organic molecule

Answer 9

carbon containing molecules made up of:
-carbon
-hydrogen
-oxygen
-nitrogen

Question 10

what are the 6 types of bonds, explain their formation and use

Answer 10

ionic-attraction between opposite charges- fairly strong cell membranes
disulphide- occurs during protein folding- stabilises protein/ catalyst
hydrogen- H+ ion- cellulose, b-sheets and DNA- very weak
ester- condensation reactions in lipids- 3 on tri- 2 on phos
peptide- condensation in proteins- one acid to carboxyl group
glycosidic- condensation of a-glucose and b-glucose- 1-4 and 1-6 bonds

Question 11

explain how to do a test for reducing sugars

Answer 11

1. 1cm3 of sample to a test tube
2. add a few drops of Benedict’s solution
   3.shake to mix
3. heat in boiling water form 5 minutes
4. postive = blue to either green if its a low conc or red if a high conc

Question 12

why does the Benedict solution change colour if its a reducing sugar

Answer 12

it has one carbon available which means it can donate electrons(reduce) to turn the colour

Question 13

describe the test for non-reducing sugars

Answer 13

if non-reducing the benedicts won’t change colour so use this:
1. add 1cm3 of dilute hydrochloric acid to the test sample
2. gently place it into boiling water for 5 minutes
3. neutralise with sodium hydrocarbonate powder (test with ph strip)
4. do the Benedict’s test

Question 14

describe the test for lipids

Answer 14

1. add 2cm3 of sample into test tube
2. add 5cm3 of ethanol
   3.place bung in and mix then allow it to settle
3. pour the contense of the test tube into 5cm3 of distilled water
4. if it is cloudy white it contains lipids

Question 15

what should you always do before the emulsion test

Answer 15

1. if sample is solid mix with ethanol or alcohol
2. ensure test tubes are dry and clean

Question 16

describe the test for starch

Answer 16

1. add 2cm3 of test solution to a test tube
2. add several drops of dilute iodine
   3.shake to mix
3. positive result is brown to blue/black

Question 17

describe the test for proteins

Answer 17

1. prepare your sample
2. add a few drops of Biuret solution
   3.shake to mix
3. its positive if colour changes from blue to purple/violet

Question 18

can you draw alpha glucose

Answer 18

CH2OH
H I________O H
I / |
OH \____________/OH
H. OH

Question 19

can you draw beta glucose

Answer 19

CH2OH
OH I________O OH
I / |
H \____________/ H
H. OH

Question 20

can you draw a condensation reaction

Answer 20

look up if you cant

Question 21

what type of bond is formed between glucose

Answer 21

glycosidic

Question 22

what is starch used for

Answer 22

energy store in plants

Question 23

describe amylose

Answer 23

• 1-4 glycosidic bonds
• unbranched
  -helical to allow it to be compact

Question 24

describe amylopectin

Answer 24

• important to hydrolyse
• has a 1-6 glycosidic bond
  -has branches
• has a few 1-4 bonds

Question 25

what are the properties of starch

Answer 25

insoluble- doesn't affect water potential large- doesn't move out of the cell -made from a-glucose so quick release energy - branches allow rapid hydrolysis

Question 26

what is the function of glycogen

Answer 26

quick release energy

Question 27

what are so properties of glycogen

Answer 27

- made of a-glucose - it has a 1-4 and 1-6 glycosidic bonds - its branched and helical - compact - bonding makes it able to do its job

Question 28

how is glycogen broken down

Answer 28

respiration or hydrolyses

Question 29

what is the function of cellulose

Answer 29

strengthen cell walls

Question 30

what are the properties of cellulose

Answer 30

- made from b glucose -forms microfibrils - has hydrogen bonds in between each layer which makes it collectively strong -its insoluble but allows water through osmosis - it has 1-4 glycosidic bonds

Question 31

draw a cellulose molecule

Answer 31

each b-glucose molecule is inverted each time

Question 31

what are the two types of lipids

Answer 31

phospholipids triglycerides

Question 32

what are some common traits off lipids

Answer 32

- each contain carbon, hydrogen and oxygen -they are insoluble but sometimes soluble in alcohol - made of glycerol and fatty acids

Question 33

what is the difference between a saturated and unsaturated lipid

Answer 33

saturated has no double bonds between carbon and can be compact unsaturated has a double bond between carbon

Question 34

what are the 2 types of unsaturated molecules

Answer 34

mono-unsaturated- single double bond poly-unsaturated- has more than one double bond

Question 35

what is a triglyceride made of

Answer 35

1 glycerol 3 fatty acids

Question 36

what type of bond does a lipid form

Answer 36

an ester

Question 37

draw the formation of a triglyceride

Answer 37

look at notes

Question 38

draw an unsaturated and saturated lipid

Answer 38

look at notes

Question 39

what are the properties of triglycerides

Answer 39

-strong- lots of bonds -lightweight- compact - large -insoluble - non polar - releases water when oxidised

Question 40

what is a phosopholipid made of

Answer 40

-phosphate head - glycerol - 2 fatty acid

Question 41

how does a phospholipid use its hydrophilic head

Answer 41

it is used to create cell membranes as they form two layers where they attract water outside and inside this creates a layer

Question 42

how does a phospholipid use its hydrophilic tail

Answer 42

it creates a bilayer plasma- the tail is used to protect vital hormones from water as it repels them

Question 43

what is a protein used for

Answer 43

make up most things in the body- big 3D molecules

Question 44

what is the sequence for proteins

Answer 44

amino acids -> peptide -> polypeptide

Question 45

how many amino acids are their in the body

Answer 45

20

Question 46

what is the first stage sequence

Answer 46

amino acids

Question 47

what are the two groups in an amino acid

Answer 47

amino group carboxylic group

Question 48

draw an amino acid

Answer 48

look at notes

Question 49

Name and describe the 5 stages of protein production

Answer 49

Amino acids Primary - the sequence of amino acids in the polypeptide chain- determines shape/ function Secondary- the chain is then folded into either a a-helix or a b-pleated sheet Tertiary- once secondary is formed the molecule folds into a 3d shape- here it makes the 3 types of bonds ionic hydrogen and disulphide. Quaternary- multiple protein molecules bind together to form a protein

Question 50

What are the 2 types of tertiary structure

Answer 50

Globular- carries out metabolic function Fibrosis- long chains which run Parallel to another these are linked by cross bridge