Non-Polar side chains

what are these amino acids made of

Carbon and hydrogen

Do they like water ?

no . their hydrophobic

Non-polar = no charge difference so because of this

• their side chain doesnt attract to water 

• they dont accpet or donate protons. not acidic or basic 

No hydrogen or ionic bonding so because of this 

• they dont have electronegative atoms O and N in side chains 

• cant form hydrogen bonds or ionic bonds.

Shape and size vary because of this …

come in different types rings,

 hydrogen side chain.

Some are largerhave carbon chains

Alanine; Ala: A

saturated hydrocarbon R groups

Valine; Val; V

saturated hydrocarbon R groups

Leucine; Leu; L

saturated hydrocarbon R groups

Isoleucine; Ile; I.

saturated hydrocarbon R groups

Non-polar Side Chains (Extra Details)

These amino acids still have hydrophobic (non-polar) side chains

but some have special features that affect protein structure.

Methionine; Met; M

has a sulphur atom in the R group

Glycine; Gly; G

Glycine; Gly; G features

its R group is just a hydrogen (H).

its not chiral Because both side groups on the central carbon are hydrogens

small size makes it very flexible to polypeptides 

Proline; Pro; P

Proline; Pro; P features 

Has a cyclic ring r group side chain, that connects back to its own amino group

forms imino group 

Because its ring locks the structure, proline is stiff and restricts movement in the polypeptide chain.

Water and “Oily” (Hydrophobic) Amino Acids

Water is polar — it has a positive side and a negative side

Non-polar R groups (the side chains of some amino acids) are like oil — they don’t mix well with water.

call them hydrophobic,

What Happens in Proteins:

f the protein is in water (aqueous solution):

• The hydrophobic (oily) R groups try to avoid water.

• They stick together and hide inside the protein’s center.

• The outside of the protein has polar (water-loving) amino acids that can interact with water.

f the protein is in a membrane (fatty environment):

• The membrane is made of lipids (fats), which are also non-polar.

• So here, the hydrophobic R groups face outward to interact with the fatty membrane.

• The polar parts stay inside, away from the lipids.