Biochemistry

The Chemistry of Living Things

Introduction

• Biochemistry is the chemistry of the living world.

• Plants, animals, and single-celled organisms all use the same basic chemical compounds to live in the biosphere.

• Biochemistry is about the smallest parts of those organisms, the molecules.

• It's also about the cycles that happen to make those compounds.

• It could be the constant process of photosynthesis in plants or the building of complex proteins in the cells of your body.

Introduction

• Living organisms require a supply of available energy.

• They also require an adequate supply of water.

• Water is unique.

Introduction

• Biochemical molecules are large.

• They are built from smaller, more readily available molecules.

• Their synthesis requires energy.

• Energy must be obtained from plant photosynthesis.

• Living organisms are highly organized.

Introduction

• Most biopolymers essential for life belong to four main groups.– Proteins– Polysaccharides(carbohydrates)– Lipids– Nucleic acids

Proteins

• Polymers of amino acids

• Hydrophilic colloids

• Do not pass through membranes

• Least soluble at the isoelectric point

• Can be denatured

Proteins

• Four types of structures within a protein– Primary– Secondary– Tertiary– Quaternary

Proteins

• Importance

– Enzymatic catalysts

– Oxygen carriers

– Structural materials

– Hormone regulation

Proteins

• Tests– biuret – violet – indicates peptides with

at least 2 linkages– zanthoproteic – yellow – indicates

amino acids containing a benzene ring– Millon – red – indicates the presence of

tyrosine in the protein– ninhydrin – blue – indicates the

presence of at least one free amino and one free carboxy group in the protein

Proteins

• Amino acids are the building blocks of proteins.

– There are over twenty amino acids.

– Ten are synthesized in the body.

– The others are considered “essential amino acids” and must be ingested.

Proteins

• Amino acids have a carboxylic acid part and a basic part called an amine. One amino acid links to another to form a protein because of the attraction of opposite charges. This linkage is a peptide bond, which is an amide formation.

The amino acid is doubly charged at pH = 7. It is called a zwitterion.

Biochemical Compounds

• Carbohydrates give you energy. They may be simple or complex. – Starch is a carbohydrate which is

composed of units of the simple sugar glucose.

– Glucose is a carbohydrate and is the simplest sugar.

Carbohydrates• Carbohydrate is a fancy way of saying "sugar."

Sugars end with the suffix -ose.• They contain carbon, hydrogen and oxygen. • The hydrogen and oxygen are always in a ratio

of 2 to 1. • Sugars provide living things with energy and

act as substances used for structure. Some examples of structures might be the shell of a crab or the stem of a plant.

• Scientists also use the word saccharide to describe sugars. If there is only one sugar molecule, it is called a monosaccharide. If there are two, it is a disaccharide. If there are three, it is a trisaccharide.

Carbohydrates• A sugar called glucose is the most important

monosaccharide on Earth. It is also the simplest sugar. Glucose is used in cellular respiration and created by photosynthesis. When you think of table sugar, like the kind in candy, it is actually a disaccharide. The sugar on your dinner table is made of glucose and another monosaccharide called fructose. Table sugar is sucrose.

• When several carbohydrates combine, it is called a POLYsaccharide ("poly" means many). Hundreds of sugars can be combined in a chain. These chains are also known as starches which are found in foods such as pasta and potatoes. They are very good sources of energy for your body.

Structures of sugars

glucose fructose

sucrose

DNA• DNA stands for Deoxyribonucleic Acid. It is

special because it holds the code for every cell in your body. Every cell in your body uses DNA for an instruction manual. DNA is a long spiral chain of nucleotides.

• So you get all of those nucleotides in two long chains that twist around each other. That twisting shape is called a double-helix. The spiral ladder has the ability to wind and unwind so that the nucleic acid chain can duplicate itself. That duplication process happens every time a cell divides.

DNA

• DNA is the instruction manual for an organism. Even though all organisms use the same five base pairs to build DNA, it is the order that makes us who we are. Our DNA has cytosine paired with guanine and adenine paired with thymine. Every organism on Earth has a different number and order of base pairs. That order determines your physiology.