Living things are made up of molecules just like all other matter. These molecules often form special substances that are needed and used by the organism for life processes and activities.
More often these molecules are in the form of compounds.
Compounds can either be Inorganic or Organic. These compounds are nutrients which provide energy or materials for all cell activities.
Living things are mostly made of organic compounds that contain carbon and hydrogen. Often they contain oxygen too
These organic compounds can also have amounts of nitrogen, calcium and phosphorous. They may have varying small amounts of other elements called “trace elements” like potassium, iodine, sulfur, iron, magnesium and sodium.
Living things also need inorganic compounds like water and salts.
Water is an essential part of every living thing. Plants use water in deriving some of their nutrients from minerals in the soil. These minerals have to be dissolved in water in order to be absorbed by the plants.
Water being liquid can easily hold and transport other materials. Water provides a way for substances to reach all the cells in an organism.
Animals and especially man depend much on water. Water is taken into the body by eating plants and meats and by drinking beverages. Humans can go for a month without eating but will die in 3 to 5 days without water because our bodies are made up of about 70 percent water. The body uses water in maintaining its temperature, breathing, digesting food, and lubricating moving joints.
Carbon compounds vary greatly in size
Carbon can form straight chains, branched chains, or rings
A molecule that contains carbon is called an organic compound
Two carbon atoms can form various types of bonds
Single Bond Double Bond Triple Bond
Carbon compounds with the same number of atoms can form in different ways
C 6 H 12 O 6 Glucose Fructose
A polymer is a large molecule formed when many smaller molecules bond
Polymers formed from organic molecules are called biomolecules
The Organic Substances
Monosaccharide Organic Bases Amino Acids Fatty Acids and Glycerols Disaccharides Polysaccharides Nucleotides Lipids Proteins Nucleic Acids ( DNA and RNA ) Carbohydrates
A carbohydrate is a biomolecule composed of carbon, hydrogen, and oxygen
It has about two H atoms for every C and O
Carbohydrates are used by cells for energy
The general formula for a carbohydrate is
C x (H 2 O) y
C 6 H 12 O 6 Glucose C 12 H 22 O 11 Sucrose
types of carbohydrate
1. The simplest carbohydrate is a sugar called a monosaccharide (one-sugar)
Glucose, fructose, ribose, deoxyribose
2. Disaccharides contain two sugars
Maltose (in milk), sucrose (table sugar)
3. Polysaccharides are most complex
Made of long chains of monosaccharides
Cellulose, starch, glycogen
Plants store carbohydrates in form of starch
Animals store carbohydrates in form of glycogen in the liver
Cellulose is found in the walls of plant cells that makes it rigid.
Many foods contain carbohydrates.
Lipids are large biomolecules composed of C and H and very little O
Fats, oils, waxes and steroids are all lipids
Lipids are insoluble in water because they are non-polar
Lipids have several important functions
Form protective coverings
Lipids are major components in membranes surrounding all cells ( Phospholipids)
Triglycerides consist of three long hydrocarbon chains known as fatty acids attached to each other by a molecule called glycerol.
Because they include three fatty acids, fats and oils are also known as triglycerides.
Steroids are the primary structure in hormones, substances that play important signaling roles in the body.
Cholesterol is the central steroid from which other steroids, such as the sex hormones, are synthesized. Cholesterol is only found in animal cells.
Example of sex hormones are Estrogen, Progesterone and testosterone
A protein is a complex polymer composed of carbon, hydrogen, oxygen, nitrogen and sometimes sulfur
The basic building blocks of proteins are amino acids
There are about 24 kinds of amino acids that form thousands of proteins.
Each different protein contains different combinations of amino acids in terms of numbers and arrangement.
In the human body there are over 100000 different kinds of protein.
Insulin is an example
Proteins are essential to all life
Transporting oxygen in bloodstream
Chemical reactions (messengers and enzymes)
Materials such as hair, feathers, fingernails and scales are made of protein.
Good food sources for proteins are meat, fish, poultry, dairy products and dried peas and beans.
Enzymes are important proteins found in living things
An enzyme is a protein that changes the rate of a chemical reaction
A nucleic acid is a biomolecule that stores cellular information in the form of a code
The genetic code is the set of rules by which information encoded in genetic material provides the hereditary traits
Nucleic acids are polymers composed of nucleotides
Nucleotides- consist of three main units: a nitrogenous base (a compound made with nitrogen), a phosphate group, and a sugar.
There are two main types of nucleotides, differentiated by their sugars: deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) .
DNA molecules store genetic information for the cell, while RNA molecules carry genetic messages from the DNA in the nucleus to the cytoplasm for use in protein synthesis and other processes