Biological Molecules

4 main groups of large carbon-based compounds

• carbohydrates

• lipids

• proteins

• nucleic acids

Functions of carbohydrates as a biological molecule (2)

• respiratory substrates (cells)

• form structural compounds in plasma membranes + cell walls

Functions of proteins as a biological molecule (2)

• form structure of cells + tissues

• form transport proteins, enzymes, antibodies, chemical messengers, hormones, receptors, blood components

Functions of lipids as a biological molecule (3)

• form hormones

• form plasma membranes

• respiratory substrates

Functions of nucleic acids as a biological molecule (2)

• carry genetic code for producing proteins

• involved in expression of genetic code

Which elements make up nucleic acids + nucleotides

C,H,O,N,P

Which elements make up carbohydrates

C,H,O

Which elements make up lipids

C,H,O (usually lower proportion of O2 than in carbs)

Which elements make up amino acids + proteins

C,H,O,N + S (sometimes)

Empirical formula of carbohydrates

CnH2nOn

Properties of water (10)

• high surface tension

• low relative density of ice

• adhesion

• hydrostatic pressure

• solvent

• metabolic reactant

• high specific heat capacity

• cohesion

• high latent heat of vaporisation

• transparency

What is a hydrogen bond

An attraction between an electropositive HYDROGEN atom + electronegative atom

Are charged ions hydrophilic or hydrophobic?

Hydrophilic + dissolves in water

Are non-polar molecules hydrophilic or hydrophobic?

• hydrophobic + insoluble in water

• if mixed with water, attracted to other non-polar molecules

3 main groups of carbohydrates

• monosaccharides

• disaccharides

• polysaccharides

How are disaccharides formed?

When 2 monosaccharide molecules are chemically bonded in a condensation reaction

What is a condensation reaction?

Occurs when 2 molecules join with a covalent bond and water is released

What is a glycosidic bond?

A covalent bond that joins a carbohydrate molecule to another group (doesn’t have to be another carbohydrate)

Name 3 hexosugars

• glucose

• fructose

• galactose

Name 2 pentosugars

• deoxyribose

• ribose

Glucose

• C₆H₁₂O₆

• main sugar used for respiration

Fructose

• C₆H₁₂O₆

• sugar found in fruit, honey + some veg

• much sweeter than glucose

Galactose

• C₆H₁₂O₆

• constituent of lactose

Deoxyribose

• C₅H₁₀O₄

• forms part of nucleotides that make up DNA

Ribose

• C₅H₁₀O₅

• forms part of nucleotides that make up RNA and ATP