2. Biological molecules

What test is used to test for reducing sugars ?

benedict test

explain the Benedict's test .

add 2cm3 of a sample in a test tube

add 2cm3 of benedict solution in the test tubej

shake well

place in a water bath at 80-100 degrees for 2-5 mins

the color is brick red if positive and stays blue black if negative

Benedict's test is said to be ______________ as colors give indications of how much reducing sugar is present.

semi quantitative

what is the test used to test starch ?

iodine test

Explain iodine test.

on a sample add a few drops of iodine solution

positive if color is blue black

negative if color remains yellow brown

What is the test used to test fats and oils .

emulsion test

Explain the emulsion test.

add 2cm3 of the sample in a test tube

add 2cm3 of ethanol in the test tube

add 2cm3 of water

shake

white emulsion appears if positive

State the name of the test used for proteins.

biuret test for proteins

explain the burette test.

add 2cm3 of the sample in a test tube

add 2cm3 of sodium hydroxide

followed by a few drops of copper(II)sulfate solution

purple color if positive

For biuret test to occur , there must be at least _____________ bonds.

2 peptide

Describe the test for non-reducing sugar.

add 2cm3 of the sample in a test tube

add 2cm3 and a bit more of HCl to the test tube

place in a water bath for 5 mins

add 2cm3 of sodium hydrogencarbonate in excess

carry out benedict’s test

Name the non-reducing sugar.

sucrose

macromolecules contain ____________ or more atoms.

1000

State the general chemical formula for a carbohydrate.

Cx(H2O)y

what is the bond in disaccharide ?

glycosidic bond

molecules build up by ______________ reaction and break down by ________________.

condensation , hydrolysis

state the 2 forms of glucose molecule.

alpha-glucose and beta-glucose

State the monomers of maltose , sucrose and lactose.

maltose : alpha-glucose + alpha-glucose

sucrose : alpha-glucose + beta-fructose

lactose : alpha-glucose + beta-galactose

in alpha-glucose , the OH group is ___________ the ring and in beta-glucose , the OH group is _________ the ring.
And draw them in the mind or on paper.

below , above

explain condensation reaction.

2 molecules add up leaving a big molecule and water

Explain hydrolysis.

a big molecule breaks using water

State the bonds in :

Carbohydrates : ______________

Proteins : ____________

lipids : _____________

nucleic acids ____________

and draw then in the minds or on paper.

glycosidic , peptide , ester , phosphodiester

Draw the condensation reaction between 2 alpha-glucose molecules forming maltose.

done

Draw the condensation reaction between alpha-glucose and beta-fructose forming sucrose.

done

state the bonds of the main sugars .

maltose : alpha-1,4

sucrose : alpha-1,2

cellulose : beta-1,4

amylose : alpha-1,4

amylopectin : alpha-1,4 and alpha-1,6

What is the 2 polymers that makes starch.

amylose and amylopectin

Describe the structure of amylose. Draw the structure of amylose.

helical shape with alpha-1,4 G bonds

Describe the structure of amylopectin. Draw the structure of amylopectin.

branched every 20 monomers

alpha-1,4 and 1,6 G bonds

Describe the structure of glycogen. Draw briefly the structure of glycogen.

branched every 10 monomers

alpha-1,4 and 1,6 G bonds

from animals

Describe the structure of cellulose. Draw the structure of cellulose.

beta-1,4 G bonds

consecutive beta-glucose are rotated 180 to each other

Due to inversion of glucose , H bonds forms between chains making it strong

Outline how the structure of cellulose contributes to plants.

high tensile strength which allows it to stretch without breaking (resist turgor pressure)

fully permeable allowing water and solutes to enter or leave the cell

Triglycerides are ______________ and ______________ molecules.

non polar , hydrophobic

The monomers of triglycerides are _____________ and _________________ .

3 fatty acids , glycerol

state the 2 ways in which fatty acids can be varied ?

length of carbon chain

unsaturated and saturated

saturated fatty acids have ___________ and unsaturated fatty acids have _______________.

only single bonds , double bonds

Fatty acids have a ____________ group on one end and a _______________ on the other end.

methyl group , carboxyl group

Triglycerides are formed by a reaction called ________________ . Which is a reaction between a ________________ and an _____________.

esterification , carboxylic acid , alcohol

During formation of triglyceride _______________ are released.

3 water molecules

Draw the reaction between glycerol and 3 fatty acids to form triglycerides.

done

which one releases more energy : triglycerides or carbohydrates.

triglycerides

State some functions of triglycerides.

insulation (nerve transmission and heat insulation)

low density of fat allows animals to float

protects fragile organs

Describe the structure of phospholipids. Draw a phospholipid.

2 fatty acids and a phosphate group bonded to a glycerol molecule

The fatty acids are ____________ and _______________ and the phosphate group is _________________ and ________________.

non polar , hydrophobic , polar , hydrophilic

what is the monomer of proteins.

amino acids

State the structure and draw an amino acid molecule.

amine group on one side , carboxyl group on the other side , R group

Multiple amino acid molecules join up Via ____________ bonds.

peptide

Draw a condensation reaction to form a dipeptide.

done

Describe the primary structure of proteins.

sequence of amino acid bonded by peptide bonds

The secondary structure of protein involves the structures ___________________ and _____________________.

alpha-helix and beta-pleated sheet

Explain how alpha-helix is formed.

when H bonds form between every 4 peptide bonds

Explain how beta-pleated sheet is formed.

when the protein folds so 2 parts of the chain are parallel to each other allowing H bonds to form

Describe the tertiary structure of proteins.

bonding due to R groups :

H bonds (R groups)

ionic (charged R groups)

disulphide (only in cysteine amino acids)

weak hydrophobic interaction (non polar R groups)

Explain the quarternary structure of proteins.

more that one polypeptide chain working together

State 2 types of proteins.

Globular and fibrous

State the structure of globular proteins.

spherical

physiological

soluble

haemoglobin , insulin , antibodies

State the structure of fibrous proteins.

long strands

structural

insoluble

collagen , keratin

Haemoglobin is an example of a ______________ protein.

globular

Haemoglobin has a ______________ structure since is has ___________ polypeptide chains known as __________.

It has 2 _____________ and 2 _____________ and each has a ______________ group. Draw the structure of haemoglobin.

quarternary , 4 , globin , alpha-globin , beta-globin , haem group

The four globin are held together by ________________ bonds and arranged so their ____________ R groups face inwards.

And _____________ R groups face outwards. This helps maintain its _______________ shape and _____________.

disulphide , hydrophobic , hydrophilic , bicon cave , solubility

What can happen if the arrangement of R groups changes in haemoglobin.

sickle cell anaemia

The haem group contains _________ which can binds reversible with ____________ forming _____________.

iron 2+ , oxygen , oxyhaemoglobin

Collagen is an _____________ and _______________ protein.

insoluble , fibrous

Outline the function of collagen.

flexible structural protein forming connective tissues

many H bonds with triple helix resulting in great tensile strength

insoluble due to its length

What are the helpful properties of water ?

good solvent

high specific heat capacity

high latent heat of vaporization

high surface tension and cohesion

acts as a reagent

what is the use of water being a good solvent?

allows chemical reactions to occur

transport medium

what is the use of water having a high specific heat capacity.

optimal temperature maintained

What is the use of water having a high specific latent heat of vaporization.

coolant