Chapter 2

Chemistry of Life

A water molecule is polar b/c there is an uneven distribution of electrons between oxygen and hydrogen atoms

POLARITY: Oxygen end - slightly negative Hydrogen end - slightly positive

The Amazing Properties of Water

Polar Molecule One region more negative and other

more positive Water molecule is bent oxygen is at

one end and hydrogen is at other

+

+

-

Hydrogen Bonds

Water molecules attract each other b/c of their charges

This bond is called a hydrogen bond.

Not very strong, but responsible for unique properties of water.

One water molecule can have up to 4 hydrogen bonds at the same time

Cohesion

An attraction between molecules of the same substanceWater is very cohesive because it sticks to itself

Why? – The pull of hydrogen bonds causes the water molecules to be drawn inward.

AdhesionThe attraction between molecules of different substances.Water is very adhesive because it sticks to other substances

Example:Meniscus in a graduated cylinder. The adhesion between water molecules glass

molecules.

Solutions

Components are evenly mixed throughout the solution.The solution looks uniform throughout. Example: table salt and water

2 parts: solute and solvent

Cl-

Water

Cl-

Na+

Water

Na+

Figure 2-9 NaCI Solution

Figure 2-9 NaCI Solution

Cl-

Water

Cl-

Na+

Water

Na+

Solute vs. Solvent

Solute is dissolved by the solvent.Solute-substance that is dissolvedSolvent-substance that does the actual dissolvingWhat is the universal solvent???

Suspensions

Materials do not dissolve but they are so small they do not settle; they remain suspended.Mixtures of water and non-dissolved material

Example: cloudy river water

What is Blood?

Solution and a suspension

Solution - dissolved sugars, sodium, potassium, Oxygen, Carbon Dioxide

Suspension - white blood cells, red blood cells

Acids, Bases, and pH

Acids

Any compound that produces H+ (hydrogen ions) in solutionpH < 7 (less than 7)Also called acidic

Bases

Any compound that produces OH- (hydroxide ions) in solution

pH > 7 (greater than 7)

Also called alkaline

pH Scale

Measures the H+ concentration0 – 147 is a neutral solution = pure water

Oven cleaner

Bleach

Ammonia solution

Soap

Sea water

Human bloodPure water

MilkNormalrainfall

Acid rainTomatojuice

Lemon juice

Stomach acid

NeutralIn

crea

sing

ly B

asic

Incr

easi

ngly

Aci

dic

pH Scale

Buffers

pH in most human cells must be between 6.5 and 7.5If higher or lower affects chemical reactions in human cellsTherefore, controlling pH is very important for maintaining internal balance (homeostasis). This is done through buffers.Buffers: Weak acids and bases that react with strong acids and bases to prevent sharp changes in pH. Example: Tums (stomach antacid)

2-3

Organic (Carbon) Compounds

Organic Chemistry

Study of compounds with bonds between carbon atomsCarbon – 4 outer electrons can form 4 strong covalent bonds (sharing electrons)

Macromolecules/Polymers

Giant moleculesFormed by bonding smaller moleculesMonomers- smaller units Join to form Polymers process

called polymerization

Organic Compounds

1. Carbohydrates = sugars2. Lipids3. Nucleic Acids4. Proteins

Carbohydrates

C, H, ORatio of 1:2:1 – C6H12O6

Main source energyStructural purposes3 groups…

Monosaccharides – simple sugars

Used for quick energyMonomers

Examples:

Glucose – blood sugar

Fructose – fruit sugar

Galactose – milk sugar

Disaccharides – 2 sugars

Quick energy

Examples:

Sucrose – sugar cane

Lactose – milk sugar

Maltose – important for fermentation

Polysaccharides – many sugars (complex)

Long chains of simple sugars PolymersStored energy – released slowly

Examples:Starch – stored in plants

ex. Grains, pastas

Glycogen – stored in animal muscle

Cellulose – used for structural purposes (cell walls)

Starch

Glucose

Figure 2-13 A Starch

Lipids - FatsConsist mainly of C and Hfat, oil, wax

**Saturatedheart diseaseUses

Structural Purposes – cell membranes/water proof coveringsEnergy StorageChemical Messengers – component of steroids

Nucleic Acids – DNA/RNA

Consist of H, C, O, N and PStore and transmit genetic (hereditary) informationMade of nucleotides (monomers)

Proteins

Made of amino acids (monomers)Consist of C, H, N, and O

Used for:Control and regulate chemical reactions (enzymes)Structural purposes (muscle and bone)Transportation in and out of cells Fighting Disease

General structure Alanine Serine

Figure 2-16 Amino Acids

Amino group Carboxyl group

Aminoacids

Figure 2-17 A Protein

• Proteins can have up to 4 levels of organization1. Sequence of amino acids in chain2. Amino acids within chain twist/fold3. Chain itself is folded4. If more than one chain, each chain has specific

arrangement

http://www.dnatube.com/video/235/How-bunch-of-aminoacids-organise-to-form-functional-protein

EXAMPLE

WHICH ARE CHAINSOF

NUCLEOTIDES

ORGANICCOMPOUNDS

MADE OF 1 SUGAR

MADE OF 2SUGARS

MADE OFMANY SUGARS

WHICH ARE CHAINS OF

SOME ARE BIOLOGICALCATALYSTS CALLED

WHICH ARE ALSO KNOWN AS

CAN BE

FOUND INBUTTER

FOUND INOILS

EXAMPLE

EXAMPLE

EXAMPLE EXAMPLE

WHICH HAS THECHEMICAL FORMULA

C6H12O6

WHICH IS A MAJORCOMPONENT OF

MILK

FOUND IN FOUND IN

PLANTS

WHICH LOWERACTIVATION ENERGYFOR CHEMICAL REACTIONS

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2-4

Chemical Reactions and Enzymes

Chemical Reactions

Process that changes one set of chemicals into another set of chemicals (slow=rust, fast=H gas ignited with O)Reactants- elements/compounds that enter into reaction (left side)Products- elements/compounds produced by reaction (right side)

CO2 + H2O H2CO3

Which are the reactants???

Which are the products???

Energy in Chemical Reactions

Exothermic- reaction that releases energy Usually spontaneous Energy released in form of heat/light/sound Reactants have more energy than products Ex. Thunder & Lightning

Endothermic- reaction that absorbs energy Products have more energy than reactants Ex. Digesting food

All of this energy is required for life processes

Activation Energy- amount of energy needed to start reaction

Energy-Absorbing Reaction Energy-Releasing Reaction

Products

Products

Activation energy

Activation energy

Reactants

Reactants

Figure 2-19 Chemical Reactions

Energy-Absorbing Reaction Energy-Releasing Reaction

Products

Products

Activation energy

Activation energy

Reactants

Reactants

Figure 2-19 Chemical Reactions

Enzymes

Proteins that act as biological catalystsCatalyst- substance that speeds up rate of chemical reaction by lowering activation energyCells use enzymes to speed up reactions that take place inside cells

Reaction pathwaywithout enzyme Activation energy

without enzyme

Activationenergywith enzymeReaction pathway

with enzyme

Reactants

Products

Effect of Enzymes

Reactants are called SUBSTRATES if enzymes are involved in the chemical reaction

Enzymes provide a site where SUBSTRATES (reactants) can be brought together activation siteThis site reduces amount of energy needed for reaction lowers activation energy

Glucose

Substrates

ATP

Substratesbind toenzyme

Substratesare convertedinto products

Enzyme-substratecomplex

Enzyme(hexokinase)

ADPProducts

Glucose-6-phosphate

Productsare released

Figure 2-21 Enzyme Action

Active site

Glucose

Substrates!

ATP

Substratesbind toenzyme

Substratesare convertedinto products

Enzyme-substratecomplex

Enzyme(hexokinase)

ADPProducts

Glucose-6-phosphate

Productsare released

Figure 2-21 Enzyme Action

Active site

Glucose

Substrates!

ATP

Substratesbind toenzyme

Substratesare convertedinto products

Enzyme-substratecomplex

Enzyme(hexokinase)

ADPProducts

Glucose-6-phosphate

Productsare released

Figure 2-21 Enzyme Action

Active site

Glucose

Substrates!

ATP

Substratesbind toenzyme

Substratesare convertedinto products

Enzyme-substratecomplex

Enzyme(hexokinase)

ADPProducts!Glucose-6-phosphate

Productsare released

Figure 2-21 Enzyme Action

Active site

Suffixes to note…

- OSE = SUGAR - ASE = ENZYME

Example: Lactase breaks down Lactose

enzyme activity animation!