The Chemical Basis of Life

Organic Compounds Compounds containing carbon (Actually contain carbon, hydrogen, and oxygen) Compounds that come from living things

Q1)Give two examples of organic compounds? Sugar, Starch

Inorganic compounds Don’t contain carbon Don’t come from living things Exceptions: Carbon dioxide, Carbon monoxide

Q2) Give 2 examples of inorganic molecules Water, Salt

Unique bonding properties of carbon Carbon has four electrons in its outer shell Carbon can form 4 covalent bonds Carbon can form complex molecules because of its ability to form 4 bonds at the same time

Chemistry of carbon Carbon can form Single covalent bonds Shares 1 electron with one other atom. Double covalent bonds Shares 2 electrons with one other atom Triple covalent bonds (rare) Shares 3 electrons with one other atom (See examples of these bonds on the bottom of page 49)

Functional groups Common parts used molecule building Hydroxyl -OH Carboxyl -COOH Amino -NH2

Monomers Simple building block molecules

Polymers Two or more monomers covalently bonded together. Can be two or two thousand… Allow very large molecules to built with only a few basic parts.

Two chemical reactions used Dehydration Synthesis Covalent bond is formed by the removal of water. Two monomers become joined together.

Dehydration Synthesis Reaction

Two Chemical Reactions Used Hydrolysis Separation of two monomers by adding water and breaking the covalent bond

Hydrolysis Reaction

Carbohydrates Made from glucose molecules (sugars) Carbohydrates are used by living things as a source of energy.

Monosaccharides Simple sugars Have the formula C6H12O6 Mono = one Saccharide = sugar Have the formula C6H12O6 Form rings when in water

Some Sample Monosaccharides

Q2) Where do people get glucose molecules? Plants produce glucose during photosynthesis and animals get glucose by eating plants.

Disaccharides Di = Two Saccharide = sugar

Polysaccharides Two or more monosaccharides joined together by a covalent bond. The bond forms by a Dehydration Synthesis Reaction.

Four types of polysaccharides Made of Glucose

Starch Energy storage in plants

Glycogen Energy storage in plant seeds and short term energy storage in animals (1 day)

Cellulose Structural support in plants

Starch Vs. Cellulose STARCH CELLULOSE

Chitin Used in insect exoskeletons for structural support Harvested and used as surgical stitches

Lipids Fats Oils Waxes Do not dissolve in water!!!

Molecules made from lipids Fats Energy storage in animals and plant seeds A gram of fat stores more than twice as much energy as a gram of a polysaccharide.

Phospholipids Used in cell membranes Separations between inside and outside of cell

Waxes Water proof molecules, many uses Example: Waxy coating on leaves prevents water loss

Chemistry of Fats Glycerol 3 fatty acids Chains of carbons with a carboxyl (acid) group at one end of each fatty acid

Two major types of fats Saturated fats – single bonds between carbon atoms Unsaturated fats – double bonds between carbon atoms

Q3) Which type of fat is unhealthy? Saturated fats

What is the difference between fats and oils? Fats are solid at room temperature and oils are liquids at room temperature.

Proteins The molecules that do the work inside of the cell. Proteins are responsible for most of what happens inside of the cell.

Functions of a protein Movement Structural support Storage Defense Regulation of chemical processes

What are two examples of things made of protein? Enzymes (thousands of different types) Speed up chemical reactions Hemoglobin Used in red blood cells to transport oxygen

Structure of protein Amino acid The monomer of proteins There are 20 different amino acids They can make billions of different proteins

Peptide Bond Holds these monomers together. Formed by a dehydration synthesis reaction

Polypeptides Many amino acids bonded together making a long chain

How proteins are formed Proteins are complexly folded polypeptide chains There are four levels of protein structure Each level of folding makes the protein more complex.

One change can be devastating

Stop for today.

The function of enzymes Enzymes are Protein Catalysts Increase the speed of chemical reactions without being used up themselves. NOT CHANGED BY REACTION  

Substrates The molecule that binds to the enzyme These are the ones changed in the reaction

Enzyme-substrate complex Active site The space where the substrate fits Lock and key Each enzyme is specific for one substrate!! 

Activation Energy Energy needed to get a reaction started. Bonds are weakened by activation energy New bonds form to make products

Activation Energy Enzymes lower a reaction’s activation energy A lower activation energy makes a reaction happen faster

Enzymes Catalysts in the body are enzymes Enzymes work best at a certain temperature and pH

If the temperature or pH changes, the enzyme may not function. If the bonds that hold the enzyme’s shape are changed, the enzyme will come apart. If this happens, the enzyme will denature.

Nucleic Acids Polymers which are used to store genetic information 

Nucleotide Monomer of nucleic acids Made from 1 sugar 1 base 1 phosphate

 

Two types of nucleic acids and their uses: Deoxyribonucleic Acid DNA Stores genetic information and passes it on to the next generation Ribonucleic Acid RNA Takes information and uses it to make proteins

The information is stored in bases The differences in the nucleotides is in the bases. The order of these bases makes up the genetic CODE.

DNA Bases There are four bases used in DNA Cytosine (C), Thymine (T) Adenine (A), Guanine (G)

RNA Bases There are four bases used in RNA Cytosine (C), Uracil (U) Adenine (A), Guanine (G) Thymine is replaced by Uracil in RNA