Protein Structure/Carbohydrates

IB BIO DP1

Condensation

Synthesis of complex molecules from simpler molecules. (Formation of macromolecules from monomers by condensation)

Hydrolysis

Breakdown of complex molecules into simpler molecules (Hydrolysis of macromolecules into monomers)

Polysaccharides

Large carbohydrates formed by joining multiple monosaccharides through glycosidic bonds, often serving as energy storage or structural components in cells.

Starch

A storage polysaccharide in plants, composed of glucose monomers, that provides energy.

Amylose

A type of starch where carbon #1 is bonded to carbon #4 of the adjoining glucose, the resulting molecule will be linear but in a helix shape.

Amylopectin

Not only does it have 1 - 4 glycosidic bonds but also has some 1 - 6 glycosidic bonds, making this molecule branched.

Glycogen

Animals store this as energy, it is a polysaccharide made of glucose monomers that are bonded in a very similar pattern as amylopectin 1-6 linkages.

What is the general structure of protein?

Essential amino acids

Cannot be synthesized in sufficient quantites by animal so must be obtained from diet (9/20 of amino acids are essential in humans)

Non-essential amino acid

Can be synthesized by an animal using a metabolic pathways that can transform one amino acid into another

hemoglobin

an oxygen carrying protein found in red blood cells

keratin

found in hair, nails, claws and hooves

lipase

digestive enzyme that helps hydrolyze ingested lipids

collagen

found in connective tissue in the body, includin tendons and ligaments

histones

proteins found in the nucleus of cells that help form chromatin and chromosomes

insulin

hormone that helps regulate blood sugar

Effect of pH on protein

Change in the + and - charges on the R groups

Ionic bonds within the protein either break or new ones are formed

This can alter the 3d shape

Effect of heat on proteins

Causes vibrations within the molecule that can break the intermolecular bonds

This causes denaturing

Heat tolerance varies within species

Chemical Diversity

Stems from variation in the R-groups

When an amino acid is linked to a polypeptide it is called peptide bond

R groups can be hydrophilic, hydrophobic, polar, charged…

Primary structure (Protein)

Linear sequences

Atoms are covalently bonded

Bond angles allow for rotation around the bonds between alpha carbons

This allows them to fold into different shapes called conformations

Sequences of amino acid and R group causes conformations

Conformation determines the function of the protein

Secondary Structure (Protein)

H bonds form between the H and the O, stabilizing the structure

With the frequency of these atoms within the proteins, different confirmational structures can be built

a helix - polypeptide winds into helical shape w/ H bonds between adjacent turns of the helix

b pleated sheet - 2 or more sections of polypeptide are arranged in parallel with H bonds between them

Tertiary Structure (Protein)

Folding of a whole polypeptide chain into a 3D shape

Stabilized by..

1. Ionic Bonds between positive and negative R groups

2. Hydrogen bonds between polar R groups

3. Disulphide bonds between pairs of cysteines, this is a covalent bond

4. Hydrophobic interactions between any of the non-polar R groups as they try to get away from polar water molecules

Hydrophobic (Teritary Structure of Proteins)

Non-polar amino acids are usually in contact with other non polar substances over some or all of their surfaces

Hydrophilic (Teritary Structure of Proteins)

Have hydrophilic amino acids on their surface and hydrophobic amino acid clustered in the centre

Quaternary Structure

Consists of two or more polypeptides bonded together

May have 1 or more that 1 non-polypeptide subunits

Non-conjugated protein

There are only polypeptide subunits in addition to their polypeptides

Conjugated protein

Has 1 or more non-polypeptide subunits in addition to their polypeptides

Fibrous protein

Elongated polypeptides that lack the folding of typical tertiary structure

Does not develop secondary structures

Quaternary structure is developed by linking together polypeptide chains into narrow fibers or filaments with hydrogen bonds between the chains

Globular Protein

Rounded shape, formed by the folding up of the polypeptides. Stablizied by the r groups of the amino acids that have been brough together by the folding.