BIOLOGY A - (3.1.1 - 3.2) BIOLOGICAL MOLECULES

MONOMERS AND POLYMERS

MONOMERS AND POLYMERS

Define monomers

Small, repeating subunits that form larger, complex polymers (monosaccharides)

Define Polymers

Molecules made from many monomers joined together

What happens during a condensation reaction

One water molecule is eliminated per bond as two monomers are joined together. (Anabolic reaction)

What is the name of the bond formed in a condesation reaction

A glycosidic bond (One oxygen atom holding the two saccharides together)

What is hydrolysis

Opposite of a condensation reaction and is when water is added to break a chemical bond between two molecules (Catabolic reaction) Essentially electrolysis but with water and requires an enzyme***

Define carbohydrates

Molecules that only consist of carbon, hydrogen and oxygen which are large chains of sugar units called saccharides

Define monosaccharides

A singular monomer. Glucose is an example of a monosaccharide which contains 6 carbon atoms in each molecule and is the substrate for respiration making it very important

Define isomers

Molecules with the same number of atoms but arranged differently

Name the two isomers of glucose and their difference

Alpha (H on top) and Beta (H on bottom) glucose

What does fructose look like

50p coin with oxygen atom at the centre

Name 3 common monosaccharides

Glucose

Fructose

Galactose

Name 3 qualities of these monosaccharides

Sweet tasting

Soluble

Crystalline with general formula (CH₂O)n where “n” can carry any number from 3 - 7

Define disaccharide

Two monosaccharides joined together in a condensation reaction

What is maltose formed by

Condensation of two alpha glucose molecules which are held together by glycosidic bond

What is sucrose formed by

Condensation of alpha glucose and fructose

What is lactose formed by

Formed by condensation of alpha glucose and galacWhstose

What is cellulose formed by

Condensation of two beta glucose molecules (Only thing in the world made from beta glucose)

What are sucrose and lactose both

Disaccharides / Simple sugars

What is cellulose

Polysaccharide / Complex sugar

What colour does glucose and Benedict’s solution go

Brick red/Orange

What colour does sucrose and Benedict’s go

Blue

Is glucose reducing or non reducing

Glucose is reducing because it gives the Cu²⁺ an electron which makes it Cu⁺ and “reduces” it. This causes the colour of the copper solution to change from blue to brick red/orange

Is sucrose reducing or non reducing

Glucose is a non reducing sugar because it gives no electrons to the Cu²⁺ So₄^2- solution

Are monosaccharides reducing or non reducing sugars

Reducing sugars (ie glucose)

Are disaccharides reducing or non reducing sugars?

Non reducing sugars (ie sucrose)

Are lipids hydrophobic or hydrophilic

Lipids are hydrophobic

Are lipids soluble in water / ethanol

Water = NO (Float to top because of hydrophobia)

Ethanol = YES

Why do lipids not dissolve in water

To dissolve in water you need a charge and fats do not have a charge (non-polar) therefore they do not dissolve in water

What happens during a condensation reaction

During condensation, an enzyme is added to a solution which causes one monosaccharide gives up its hydroxyl group and the other gives up its hydrogen group which makes a H₂ O molecule. The remaining oxygen atom holds two monosaccharides together (Glycosidic bond)

What is starch and what are the two products that make it up

Starch is a polymer of alpha glucose

Amylase (Straight chained molecule) Stored as helix in plant to make it more compact

Amylopectin (Branched molecule)

Where is glycogen stored and why is it highly branched

Mammalian liver and muscles

Not many places where it can be stored since it is stored as granules so it must be highly branched to fit as much as possible in the limited space available

What is cellulose a polymer of

Beta glucose

Why does cellulose have a HIGH tensile strength

The cell wall is made from cellulose which needs to be strong to stop the cell bursting

Cellulose, unlike starch, is NOT a storage polymer

What is the name of the cell membrane

The cell SURFACE membrane