Chemistry of Life UnitWhen water, H2O, is created, hydrogen

and oxygen share the electrons

• The oxygen has a slightly negative charge

• The hydrogen’s have a slightly positive charge

This uneven pattern of charge creates a polar molecule = has a positive side and negative side

Water Molecule

Hydrogen Bonding

Hydrogen Bond = an attraction between a slightly positive hydrogen atom and a slightly negative atom, often oxygen or nitrogen

Hydrogen Bonding

Properties Related to Hydrogen Bonding

Life depends on hydrogen bonds in water

• High Specific Heat = water resists changes in temp.

- helps regulate cells

Properties Related to Hydrogen Bonding (cont)

• Cohesion = attractive forces between particles of the same kind

- example: surface tension of water

• Adhesion = the attractive forces between unlike substances- example: meniscus curve in a graduated cylinder

Surface Tension

Meniscus Curve

Properties Related to Hydrogen Bonding (cont)

• Capillarity = the ability of water to move up through narrow tubes against gravity

- due to cohesion and adhesion

- example: carnations turning a different color in colored water

Carnations in Colored Water

Carnations in Colored Water

SolutionsThe polarity of water makes it very

effective at dissolving many substances

Solvent + Solute = Solution

Concentration [ ] = amount of solute in a given amount of solvent

Saturated = no more solute will dissolve in the solvent

Solvent + Solute = Solution

Mosquito injects a solution into your body that prevents clotting

Solutions (cont)

Water is the universal solvent.

All processes necessary for life take place in water.

Acids and Bases

Acid = compound that releases a hydrogen ion (H+) when dissolved in water

- increases the H+ [ ]

Base = compound that remove H+ ions from a solution

- lowers the H+ [ ]

Acids and Bases (cont)

pH scale = amount of H+ ions in a solution

0 to 6 = acidic 7 = neutral 8 to 14 = basic

buffer = compound that regulates H+ [ ]- maintains homeostasis

pH Scale

Organic CompoundsCarbon is the building block of life

- can form multiple bonds (up to 4), including other carbon atoms

More than 90 % of the mass of all living things are composed of combinations of just 4 elements

1) Carbon ( C) 2) Hydrogen (H) 3) Oxygen (O) 4) Nitrogen (N)

1) CarbohydratesExamplessugars starchescelluloseglycogen

Specifics- contain C, H, and O- main source of usable chemical

energy for cells- major part of plant cell wall

(made of cellulose)- most basic are simple sugars =

monosaccharides (glucose)- bond to form polysaccharides

1) Carbohydrates

2) LipidsExamplesFatsOilsCholesterol

Specifics- contain C, H, and O- store large amounts of energy- cell membrane made up of

phospholipids- regulate body responses and

control sexual development- are nonpolar molecules (don’t

dissolve in water)

Saturated Fats (solid at room temp)

Unsaturated Fats (liquid at room temp)

3) ProteinsExamples Specifics

- contain C, H, O, and N

- made of monomers called amino acids

- 20 different amino acids build proteins

- specific sequence determines structure and function

Red Blood Cells and Sickle Cell Anemia(SEM 3500x)

4) Nucleic Acids- work together to make proteins

Functions:

– stores info to build proteins

– helps build proteins

Types:

1) DNA

2) RNA

Chemical Reactions

= change substances into different substances by breaking and forming chemical bonds

6O2 + C6H12O6 6CO2 + 6H2O

1. Reactants = substances changed during a chemical reaction (left side)

2. Direction

3. Products = substances made during a chemical reaction (right side)

Bond Energy = the amount of energy that will break a bond

Chemical Equilibrium = when both the reactants and products are made at the same rate

* Chemical reactions release or absorb energy

Types of Chemical Reactions

Activation Energy = the amount of energy needed to start a reaction

- is very high in most chemical reactions (especially in the body)

Activation Energy

Types of Chemical Reactions (cont)

Exothermic = chemical reaction that releases more energy than it absorbs

- gives off heat (hot)

- ex: cellular respiration

Exothermic Reaction

Types of Chemical Reactions (cont)

Endothermic = chemical reaction that absorbs more energy than it releases

- absorbs heat (cold)

- ex: photosynthesis

Endothermic Reaction

EnzymesCatalyst = substance that reduces the

amount of activation energy that is needed to start a chemical reaction

Catalysts are not changed during a chemical reaction

Enzymes = a type of catalyst in living things

Enzymes- almost all are proteins

- work best in normal body conditions (temp. and pH)

- specific shape allows only certain reactants to bind

- fit like a lock and key

Lock and Key Model - Enzymes

Enzymes (cont)

- functions:

1) help bring substrates together and chemical reactions occur

2) decrease the activation energy of the reaction

3) increase the rate of the reaction

Enzymes reduce Activation Energy

Enzymes (cont)

- Reaction 1 requires more activation energy than Reaction 2- Reaction 3 has less activation energy due to a catalyst being used