Cell Metabolism - Lecture 1 - Bio Molecules

Chemistry of Life

You need to know a small amount of chemistry to understand biology!

Why do we need to know a small amount of chemistry? • To understand why think of some of the characteristics of living organisms e.g. • They reproduce. • They grow. • They can move

Still don’t get it! • In order to grow, reproduce or move etc, the organism needs a supply of: • Energy (batteries or mains adapter no use.) • Building materials (no not MDF!)

Guess what organisms use to generate energy and as building materials?

Chemicals

Important Biological Compounds 1. 2. 3. 4. 5. 6.

Carbohydrates Lipids Proteins Nucleic Acids Vitamins Minerals

Molecules of Life • The chemistry of carbon accounts for the chemistry of organic compounds. – Organic compounds contain carbon and hydrogen atoms

• Macromolecules = polymers that arise when their specific monomers (unit molecules) are joined together. – Carbohydrates, lipids, proteins, and nucleic acids are macromolecules with specific functions in cells.

Carbohydrates • Carbohydrates often function as a ready source of energy in most organisms. • Glucose is a simple, six-carbon sugar (carbohydrate monomer) most utilized by cells for "quick" energy. • Cn(H2O)n

Carbohydrates • Carbohydrates also form major structural components in plants and insects.

• Cellulose, lignin, chitin etc. etc

3 Types of Carbohydrates 1.

Monosaccharides

2.

Disaccharides

3.

Polysaccharides

Hexoses i.e., they all contain 6 carbon atoms

Carbohydrate Synthesis and Break Down • Condensation synthesis forms carbohydrate polymers from two or more sugar monomers • Hydrolysis reaction splits bonds to form smaller molecules. • Plants store glucose as starch, and animals store glucose as glycogen. – These compounds are polymers of glucose.

Cellulose is a indigestible plant carbohydrate

Functions of carbohydrates • As a source of energy • As a building material • Signalling function.

Lipids • Lipids (triglycerides, phospholipids, & sterols) are varied in structure and function – Most lipids are not soluble (don’t dissolve) in H2O

• Fats and oils (triglycerides) are used for long-term energy storage – Triglycerides have glycerol & 3 fatty acids • Fatty acids can be saturated (no double bonds) or unsaturated (one or more carbon-carbon double bond) .

Fatty acids • Fatty acids (FAs) are aliphatic molecules with a carboxyl group at one end.

20 not 18

Saturated vs. unsaturated FAs • Saturated FAs are solid at room temperature. • Unsaturated FAs are ‘liquid’ at room temperature

A Triglyceride

Lipids: Phospholipids • Plasma membranes contain phospholipids that have a polarized end. • Phospholipids are composed of glycerol, fatty acids, and a phosphate group (charged = “polarized”). • The phosphate group end of phospholipids is soluble in water

Lipids: Sterols • Steroids (sterols) are lipids, but with a very different structure. – Cholesterol, a complex ring compound, is a steroid.

• Certain steroid hormones (including sex hormones) are derived from cholesterol. • Cholesterol is also an important component of cell membranes.

Functions of lipids • Energy storage molecules • Insulation • Signalling • Cushioning

Proteins: Consist of Amino Acids • Proteins help form structures (e.g., muscles and membranes) or function as enzymes. • The primary structure of a polypeptide (a polymer) is the sequence of amino acids (monomers) that comprise it. – There are 20 possible types of amino acids that are the building blocks of proteins.

Functions of amino acids • The building blocks of proteins. • Neurotransmitters (e.g. dopamine [from tyrosine]) • Protection (e.g. histamine [from histidine])

Protein Structure • Secondary structure: – Formed by hydrogen bonds between non-adjacent amino acids – Often an alpha (a) helix or a beta (ß) pleated sheet.

• Tertiary structure: – When a polypeptide bends and twists into a 3-D shape due to covalent bonds between amino acids in certain regions of the polypeptide.

• Quaternary structure: – When a protein contains several polypeptides.

Bonds involved in maintaining the tertiary structure of a protein

Functions • • • • • •

Structural (e.g. hair, fingernails, claws etc) Signalling/information (e.g. hormones) Transport (e.g. haemoglobin, serum albumin) Protective (e.g. antibodies, lysozyme [an enzyme]) Movement (e.g. muscle) Catalysis (e.g. enzymes)

For more information on proteins visit: http://fajerpc.magnet.fsu.edu/Education/2010/Lectures/10_Proteins.htm

Nucleic Acids • Nucleic acids are polymers of nucleotides. • Each nucleotide has 3 components: a sugar, a base, and phosphate group (phosphoric acid). • DNA (deoxyribonucleic acid) • RNA (ribonucleic acid)

Ribose

Nucleic Acids - DNA – Contains the sugar ribose – Contains the bases adenine, thymine, guanine and cytosine – Very large molecule – Double stranded

Nucleic Acids - RNA – Contains the sugar deoxyribose – Contains the bases adenine, uracil, guanine and cytosine – Not as large as DNA – Double stranded

http://165.134.116.28/301/origin/RNA.jpg

Functions of nucleic acids • DNA – stores genetic information.

• RNA – structural, recognition & transport

Nucleotides • ATP (adenosine triphosphate) is the energy currency of cells. – Its unstable phosphate bonds can be easily broken, releasing energy = Hydrolysis of ATP to ADP (adenosine diphosphate) + Pi (inorganic phosphate) releases energy that is used by cells to do metabolic work.

Others • Nicotinamide adenine dinucleotide (NAD) • Flavine adenine dinucleotide (FAD) • NAD and FAD can carry high-energy electrons