Bio 20: Digestion

Components of food

The food we eat is made up of carbohydrates, lipids, and proteins.

Digestion of food

Our bodies digest food and break it down into essential nutrients.

Enzymes

Proteins that speed up chemical reactions.

Metabolism

The chemical reactions that take place within a cell to support and sustain its life functions.

Hydrolysis

The process where larger molecules are broken down into smaller molecules by the addition of water.

Dehydration synthesis

The process where larger molecules are formed by the removal of water from two smaller molecules.

Carbohydrates

Provide short term or long term energy storage for the body.

Sources of carbohydrates

Potatoes, bread, corn, rice and fruit.

Carbohydrate composition

Carbohydrates contain carbon, hydrogen, and oxygen in a 1-2-1 ratio

Monosaccharide

A simple sugar consisting of a single sugar unit. Example: glucose

Disaccharide

Consists of two sugar units. Example: sucrose.

Polysaccharide

Consists of many, repeating monosaccharide sugar units bonded together. Example: amylose (starch)

Lipids

Non polar compounds, such as fats and oils.

Lipids composition

Made of the subunits glycerol and fatty acids by the process of dehydration synthesis.

Functions of lipids

Important for energy storage, components in cell membranes, cushions for organs, carriers of vitamins, and raw materials for hormone synthesis.

Groups of lipids

Triglycerides, Phospholipids, Waxes.

Proteins

Used to form the structural parts of cells and to repair cell damage.

Amino Acids

Subunits of proteins, composed of an amino group, an acid group, and a R group.

Denaturation

The process where the bonds in a protein are disrupted causing a temporary change in the protein's shape.

Factors causing denaturation

Excess heat, radiation, and change in pH.

Nucleic Acids

The genetic material that directs cell activity.

Types of nucleic acids

DNA and RNA.

DNA

Deoxyribonucleic acid.

RNA

Ribonucleic acid.

Substrate

The molecule that the enzyme acts upon.

Active site

The area of the enzyme that joins with the substrate molecules.

Factors that affect enzyme reactions

pH, temperature, substrate molecule concentration, competitive inhibition.

Digestion

All the processes of digestion are used to break down food to smaller molecules to be absorbed by the cells.

Taste Buds

Cells on our tongues and cheeks that detect food particles dissolved in saliva.

Stomach Functions

1. To mix food and store food for short periods of time 2. Begin protein digestion 3. Destroy bacteria found in food 4. Push food into the smaller intestine.

Gastric Juice

A secretion from the stomach lining consisting of water, mucus, salts, hydrochloric acid (HCl), and enzymes.

pH of the Stomach

The pH level of the stomach is 2

Pepsin

A protein

Small Intestine

The primary site for chemical digestion, lined with villi to increase surface area for absorption.

Villi

Finger

Microvilli

Tiny projections on villi that further increase the absorptive surface area in the small intestine.

Accessory Organs

Pancreas, liver, and gall bladder that secrete substances aiding in digestion.

Bicarbonate Ions (HCO3)

Substances in pancreatic fluid that neutralize hydrochloric acid from the stomach.

Trypsin

An enzyme in pancreatic fluid that digests proteins by breaking down polypeptides into shorter chain peptides.

Liver

The largest internal organ that continually produces bile for fat digestion.

Bile

A substance produced by the liver that contains bile salts, aiding in fat digestion.

Gallbladder

An organ that stores bile between meals and releases it into the small intestine when fat is present.

Emulsification

The process by which bile salts break up fat into smaller droplets to increase surface area for digestion.

Large Intestine

The part of the digestive system responsible for water reabsorption.