the digestive system (chemical digestion)

Chemical

Digestion

The main nutrients the body needs are:

Carbohydrates for energy; proteins for growth and repair; fats to store energy; vitamins and minerals to keep the body healthy.

Enzymes-are globular proteins that control biological reactions. Digestive enzymes speed up the breakdown (hydrolysis) of food molecules into their ‘building block’ components.

Digestive enzymes

Digestive enzymes are the chemicals that break large insoluble food molecules into smaller soluble molecules.

Starchy foods contain carbohydrates which are made of long chains of identical small sugar molecules.

carbohydratemolecule

one sugar molecule

Carbohydrates are broken down into the smaller sugar molecules to be used by the body for energy.

MouthSalivary Amylase- a digestive enzyme that acts on starch in food, breaking it down into smaller carbohydrate molecules in the form of maltose.

Long carbohydrate molecule

Simple sugar molecules

Am

ylase

Proteins, like carbohydrates, are made of long chains of small molecules. In proteins, these small molecules are not identical.

protein molecule one

amino acid

Proteins are made up of chains of small molecules called amino acids. There are over 20 different kinds of amino acid.

Proteins are used by the body for growth and repair.

StomachProtease- any enzyme that breaks down protein into its building blocks, the amino acids. Three main proteases are pepsin, trypsin and chymotrypsin.

Long protein molecule

Amino acid molecules

protease

Fats are made up of fat molecules which contain fatty acids and glycerol.

fat molecule

glycerol

Fat molecules have to be broken down by the body so that they can be used for energy storage.

fatty acids

Small IntestineLipase - the enzyme responsible in breaking fats into fatty acids and glycerol.

Lipase

fat molecule

glycerol

fatty acids

Fats are digested in two stages:Firstly, bile (released by the gall bladder) allows the fat to

“mix” with water by breaking the fat into smaller droplets. This is called emulsification.

Secondly, the digestive enzyme lipase breaks each fat molecule into the smaller glycerol fatty acid molecules .

bile

Lipase +fat molecule glycerol fatty

acids

Small IntestineNuclease - this enzyme play crucial roles in various DNA repair processes, which involve DNA replication, base excision repair, nucleotide excision repair, mismatch repair, and double strand break repair. The end product will be pentoses, phosphates, nitrogenous bases which mainly the chemical structure of our DNA.

Enzymes Produces in Site of Release pH level

Carbohydrate Digestion:

Salivary amylasePancreatic amylase

Maltase

Salivary glandsPancreas

Small Intestine

MouthSmall IntestineSmall Intestine

NeutralBasicBasic

Protein Digestion:

PepsinTrypsin

Peptides

Gastric glandsPancreas

Small Intestine

StomachSmall IntestineSmall Intestine

AcidicBasic Basic

Nucleic Acid Digestion:

NucleaseNucleosidases

PancreasPancreas

Small IntestineSmall Intestine

BasicBasic

Fat Digestion:

Lipase Pancreas Small Intestine Basic