Biology a-level - Biological molecules

AQA flashcards in making

Monomers

Small units which make up large molecules

Polymers

Large molecules made up of many repeating small units joined together by chemical bonds.

Biological molecules VS Polymers

• Biological molecules are the large molecules (carbohydrates).

• Polymers are the specific type of biological molecule (starch, glycogen, cellulose).

Monomer EXAMPLES

• Monosaccharides

• amino acids

• nucleotides

Polymer EXAMPLES

• Protein

• Starch

• DNA

Carbohydrates MADE UP OF…

• carbon

• hydrogen

• oxygen

Lipids MADE UP OF…

• carbon

• hydrogen

• oxygen

Proteins MADE UP OF…

• carbon

• hydrogen

• oxygen

• nitrogen

Nucleic acids MADE UP OF…

• carbon

• hydrogen

• oxygen

• nitrogen

• phosphorous

Condensation reactions

The removal of water to form a chemical bond between two molecules. 

Hydrolysis reaction

The addition of water to break a chemical bond between two molecules. 

Carbohydrate general formula

C_x(H₂O)_y

Carbohydrates roles (5)

1. Energy supply for cells (main role)

2. Energy store (sugar → complex carbs)

3. Structural components (cellulose + chitin in cell walls)

4. Cellular recognition - (Glycoproteins help cells identify each other and communicate. )

5. Building blocks for biological molecules - (Deoxyribose + ribose→ nucleic acids)

Types of carbohydrates

• Monosaccharide

• Disaccharide

• Polysaccharide

Monosaccharide

• simplest form of carbs + simple sugars

Hexose sugars - NO. OF C ATOMS

• 6 atoms

Hexose EXAMPLES

• Glucose

• Fructose

• Galactose 

Pentose sugars - NO. OF C ATOMS

• 5 atoms

Pentose EXAMPLES

• Ribose

• Deoxyribose

Monosaccharide EXAMPLES

• glucose

• fructose

• galactose

GFG - Get frickin good

Monosaccharide MAIN FUNCTION

• Energy source

Disaccharide EXAMPLES

• Maltose

• Sucrose

• Lactose

MSL - My silly lily

What is the disaccharide maltose formed from?

• Alpha glucose

• Alpha glucose

What is the disaccharide sucrose formed from?

• alpha glucose

• Fructose

What is the disaccharide lactose formed from?

• beta glucose

• Galactose

Disaccharide MAIN FUNCTION

• Transport form

Polysaccharide EXAMPLES

• starch

• glycogen

• cellulose

Polysaccharide MAIN FUNCTION

• storage form

Isomers of glucose

1. Alpha-glucose (α-glucose)

2. Beta-glucose (β-glucose)

ALPHA-glucose (3)

• -OH group below the ring

• found in starch (easily digestible)

• energy source

BETA-glucose (3)

• -OH group above the ring

• forms cellulose (not digestible by humans)

• forms plant structures

Glucose PROPERTIES + USES

• soluble

• its bonds store a lot of energy

Which food test is used for SUGARS?

Benedict’s test

Which food test is used for PROTEINS?

Biuret

Which food test is used for STARCH?

Iodine test

Which food test is used for LIPIDS?

Sudan III

Which sugar is identified by the Benedict’s test?

REDUCING sugar