ANP Ch 2 old

When do chemical reactions occur

occur when chemical bonds are formed,

rearranged, or broken

chemical equation contents

Reactants: substances entering into reaction

Product(s): resulting chemical substances

Synthesis reactions

reactions involve atoms or

molecules combining to form larger, more

complex molecule

Used in anabolic (building) metabolism
A + B = AB

Decomposition reactions

reactions

involve breakdown of a molecule

into smaller molecules or atoms

(reverse of synthesis reactions)

Involve catabolic (bond-

breaking) reactions
AB = A + B

Exchange reaction

reactions involve

both synthesis and

decomposition

Bonds are both made and

broken
AB + C = AC + B

Redox Reaction

In living systems, an example of exchange reactions is oxidation-

reduction or redox reactions

Atoms are reduced when they gain electrons and oxidized

when they lose electrons

Cellular Respiration Chemical Reaction

Redox reactions

Principle source of energy on the planet

Ex: Cellular respiration - carbon is oxidized and oxygen is

reduced

What does a catalyst do to rate of chemical reaction

Increase rate of

reaction without

becoming part of the

product

Lowers

activation

energy

Biochemistry

study of chemical composition and reactions of living

matter

Inorganic compounds/chemical

Do not contain carbon backbone

Water, salts, and many acids and bases
Both equally essential for life (organic)

Organic compounds/chemical

Contain CARBON backbone covalently bonded

Usually large

Carbohydrates, fats, proteins, and nucleic acids
Both equally essential for life (inorganic)

Inorganic Compounds - Water in Body

Most abundant

inorganic compound

Accounts for 60%–80% of

the volume of living cells

Inorganic Compounds - Water in Body
What properties does water have to make it the most important inorganic compound?

High heat capacity

High heat of vaporization

Polar solvent properties

Reactivity

Cushioning

Water Properties - High heat capacity

Ability to absorb and release heat with little temperature

change

Prevents sudden changes in temperature

Water Properties - High heat of vaporization

Evaporation requires

large amounts of heat

Useful cooling

mechanism

Sweating to cool body

down

Water Properties - Polar solvent properties

Dissolves and

dissociates ionic

substances

Forms hydration

(water) layers around

large polar molecules

Body’s major transport

medium

Water Properties - Reactivity

Necessary part of hydrolysis and dehydration synthesis

reactions

Important for metabolism

Dehydration Synthesis

Hydrolysis

Water Properties - Cushioning

Protects certain organs from physical trauma

Example: cerebrospinal fluid cushions nervous system

organs

Inorganic Compounds - Salts

Salts are ionic compounds that dissociate into separate ions in water

• Separate into cations (+) and anions (-)

• Called electrolytes because they can conduct electrical currents in solution

• Ions play specialized roles in body functions

• Example: Na+, K+, Cl-

• Ionic balance is vital for homeostasis

Inorganic Compounds - Acids and bases

Acids and bases are both electrolytes

• Ionize and dissociate in water

Inorganic Compounds - Acid

Are proton donors: they release hydrogen ions (H+, have

no electrons) in solution

Acidity involves only free H+ in solution

Inorganic Compounds - Basic

Are proton acceptors: they pick up H+ ions in solution

• When a base dissolves in solution, it releases a hydroxyl

ion (OH –)

Acids and Bases - pH

measurement of H+ concentration in a

solution

• Ranges from 0-14

• Is negative logarithmic

• Each pH unit represents a 10-fold

difference

• Ex: pH 5 solution is 10x more acidic

than a pH 6 solution

• ↑ H+ concentration, ↑ acidity, ↓ pH

• Water has a pH of 7

Acids and Bases - Buffers

Resist abrupt and large swings in pH

• Can release hydrogen ions if pH rises

• Can bind hydrogen ions if pH falls

• Important for homeostasis

• Carbonic acid–bicarbonate system (important buffer

system of blood):

Homeostatic Imbalance

Blood must stay within a very narrow pH range: 7.35-7.45

• An arterial pH of 7.0 during cardiopulmonary resuscitation

predicts a poor outcome

• Patients presenting with an arterial pH of less than 6.85

rarely survive

Organic Compounds

contain carbon
exceptions: CO2 and CO are inorganic

Electroneutral

Carbon is electroneutral
shares electrons; never gains or loses them
forms four covalent bonds with other elements

Major organic

compounds

(macromolecules)

1. Carbohydrates

2. Lipids

3. Proteins

4. Nucleic acids

Organic Compounds: Polymerization

Most macromolecules are

polymers

• Composed of chains of

similar units monomers

(building blocks)

Synthesis and Hydrolysis -

Polymers are

• Synthesized by

dehydration

(synthesis) reactions

• Water is released

• Broken down by

hydrolysis

(decomposition)

reactions

• Water is consumed

Carbohydrates

Contain C, H, and O

•Cn(H2O)n

n = number of carbon atoms

Carbohydrate Classes

Monosaccharides: monomer, one single sugar

Disaccharides: two sugars

Polysaccharides: many sugars

Carbohydrate Monosaccharides

Simple sugars containing three to seven carbon atoms

• Important monosaccharides

• Pentose sugars

• Ribose and deoxyribose

• Hexose sugars

• Glucose (blood sugar)

Carbohydrates Disaccharides

Important disaccharides

• Sucrose, lactose

• Formed by dehydration synthesis of two monosaccharides

Carbohydrates Polysaccharides

Important polysaccharides

• Starch: carbohydrate storage form used by plants

• Glycogen: carbohydrate storage form used by animals

• Cellulose: fiber

Lipids

Contain C, H, O, and sometimes contain P

• Mostly C-H bonds (non-polar bonds)

• Mostly insoluble in water (does not dissolve in water)

• No monomers

•

Lipids Main Types

Main types:

• Triglycerides

• Phospholipids

• Steroids

Lipids Triglycerides

Called fats when solid and

oils when liquid

• Composed of three fatty

acids (linear hydrocarbons)

bonded to a glycerol

molecule

• Main functions

• Energy storage

• Insulation

• Protection

Lipids Phospholipids

Glycerol and two fatty acids

plus a phosphorus-

containing group

• Head is polar and

hydrophilic (attracted to

water)

• Tails are nonpolar and

hydrophobic (water

fearing)

• Important in cell membrane

structure

Lipids Steroids

Consist of four interlocking ring structures

• Most important steroid is cholesterol

• Made by liver and also found in animal products

• Necessary for synthesis of vitamin D, steroid hormones,

and bile salts

• Important in cell plasma membrane structure