Chapter 2 –

Chemical Basis of Life

Fact or Fiction?

• In your notes, write the numbers 1-7

• Then

– Which of these statements about the world

around us and inside us are fact, and which

are fiction?

READY?

Statement 1

If birds stored energy as

carbohydrates instead of fat,

they would weigh so much that they couldn’t fly.

FACT

• Fat stores energy in a

highly concentrated

form that is also very

light – it contains more

than twice as much

energy per gram as

carbohydrates do.

Statement 2

The hydra, an organism the size of a pencil

point, has fewer chromosomes than an

alligator.

FICTION

Both organisms have 32 chromosomes,

structures that contain genetic material.

Size doesn’t matter.

Sta

tem

en

t 3

Celery has zero

calories.

FICTION

Celery has 18 Calories

per 100-gram serving.

You may burn more

calories chewing.

Statement 4

Bacteria reproduce so rapidly that the number

of bacteria produced in just two days

surpasses the number of humans that have

ever lived.

FACT

In the right

environment,

some bacteria

reproduce every

20 minutes.

Statement 5

• Spider silk is stronger than steel.

FACT

• A strand of spider web, which is made of protein, is stronger

than a piece of steel of the same thickness.

Sta

tem

en

t 6

• Muscles get sore

during exercise

because they

overheat.

FICTION

Lactic acid makes

muscles sore.

Produced during

anaerobic respiration.

Sta

tem

en

t 7

There are more cells in your body than there

are stars in the Milky Way.

FACT

50 trillion cells in an

adult human.

100 times more than

the number of stars

in our galaxy.

Chapter 2

The Chemistry of Life

Chemistry in Life Processes

5 general ways

in which

chemistry influences

life processes

1. Metabolism and Energy

• Chemical reactions

(chm rxns) can store or

release energy

• Metabolism is all of the

chm rxns that take place

in an organism

2. Growth and Repair

• Organisms use

macromolecules to

grow and repair

damage to cells

• Proteins, lipids and

carbohydrates are

directed by nucleic

acids to cause

growth or repair

Growth

the increase in

the size of a cell or

organism

Repair

the replace of

cells that have been

damaged or worn out

3. Homeostasis & Control

• Stable internal

conditions are

CRITICAL

• Most chm rxns need

a controlled

environment and

must be regulated

Homeo = the same

Stasis = condition

4. Communication & Response

• pheromonescan be smelled or tasted

– Send a signal or stimuli to other organisms (comm.)

• Neurotransmitterscarry electrical impulses between nerve cells

– Activates a response to stimuli

5. Reproduction • DNA

(deoxyribonucl

eicacid)

– Carries chm

instructions for

making new

life (cells)

2-1: The Nature of Matter

• What three subatomic particles

make up atoms?

• How are all the isotopes of an

element similar?

• What are the different types of

chemical bonds?

Objectives:

Elements• ~100 natural elements

– make up all the matter on Earth

• living and nonliving

• cannot be broken down by chemical

process into simpler substances

• What three subatomic

particles make up atoms?

• Protons -

• Neutrons -

• Electrons -

Positively charged (+)

Not charged (neutral)

Negatively charged (-)

Bind together

to form the

nucleus

Electrons

Protons

Neutrons

Nucleus

Atoms

are the basic units of matter.

make up an element.

as a whole, have a neutral charge.

Periodic Table Information

• Atomic Number:

number of protons in an atom

• Atomic Symbol:

one or two letters chosen to

represent an element

• Atomic Mass (protons + neutrons):

average mass of an element. an

average of the various isotopes.

Isotopes –

atoms of the same element that differ

in the number of neutrons

So what else is different?

Nonradioactive carbon-12 Nonradioactive carbon-13 Radioactive carbon-14

6 electrons

6 protons

6 neutrons

6 electrons

6 protons

8 neutrons

6 electrons

6 protons

7 neutrons

• How are all the isotopes of an element

similar?

Nonradioactive carbon-12 Nonradioactive carbon-13 Radioactive carbon-14

6 electrons

6 protons

6 neutrons

6 electrons

6 protons

8 neutrons

6 electrons

6 protons

7 neutrons

same number of electrons = same chemical properties.

Radioactive isotopes

• Can be dangerous

• Can be used

practically

http://www.chem.duke.edu/~jds/cruise_chem/nuclear/uses.html

Radioisotopes

• Used in many biological applications

– can label critical molecules in cellular function

•Routinely used since the

1950's

•Allows organ function and

pathology to be determined

non-invasively

• What are the two main

types of chemical bonds?

- involves the sharing of electrons between

atoms to form a molecule.

Covalent bond

Covalent bond

• Covalent Bond

• Ionic Bond

- involves the transfer of electrons

between ions (charge atoms).

Sodium (Na) – soft, silver metal.

Chlorine (Cl) –

poisonous

green gas

used to kill

many people

in WWII.

Sodium atom (Na) Chlorine atom (Cl) Sodium ion (Na+) Chloride ion (Cl-)

Transfer

of electron

Protons +11

Electrons -11

Charge 0

Protons +17

Electrons -17

Charge 0

Protons +11

Electrons -10

Charge +1

Protons +17

Electrons -18

Charge -1

Na+ + Cl- = NaCl

Table Salt

ADDITIONAL BONDS OF

IMPORTANCE

Hydrogen Bonds

• a relatively strong form of

intermolecular attraction

• have about a tenth of the strength

of an average covalent bond, and

are being constantly broken and

reformed in liquid water.

• are strong enough to significantly

increase the boiling point of

molecules with hydrogen in their

formula

Van der Waals Ineractions

• relatively weak

compared to covalent

bonds, but play a

fundamental role in

organic molecules

Elements in Biology

• The four primary elements

– C forms 4 bonds with other elements

– H forms one bond with other elements

– O forms two bonds with other elements

– N forms three bonds with other elements

Compound

• substances

made up of two

or more different

elements

– combined in

definite

proportions

Organic Compounds

• almost all contain the element carbon

– generally associated with living things

2-2: Properties of Water – the

most important substance

necessary to life.

Objectives:

• Why are water molecules polar?

• What are acidic solutions?

• What are basic solutions?

*Carbon is #2 – next section.

• Why are water molecules

polar?

Polarity –

the uneven

distribution of

electrons.

(-)

(+)

The oxygen atom has a

stronger attraction for

electrons so it has a slight

negative charge.

(+)

• Why are water molecules

polar?

The hydrogen ends have a slight positive charge.

Waters partial charges attract

each other and create weak

hydrogen bonds.

Think

of these as

attractions;

not commitments.

Waters ability to create multiple

hydrogen bonds gives it many

unique properties.

• water to water attraction

• Results in high surface

tension.

• Lots of bonds between water

molecules hold them

together.

1. Cohesion

water to other compound.

Results in capillary action – water

rising in a narrow tube. Movement of

water moves through a plant.

meniscus

2. Adhesion

- able to absorb a lot of heat without much

change in temperature.

3. High Heat Capacity

Solid ice floating on liquid water.

This is not normal behavior for most substances!

4. Less Dense as a Solid

dissolves other polar and ionic compounds.

(Like dissolves like.)

Cl-

Water

Cl-

Na+

Water

Na+

A solution of saltwater. Salt is the solute and water is the solvent.

5. Excellent Solvent

• What are acidic and basic

solutions?

Acids release H+ (hydrogen) ions in solution.

ex. HCl – hydrochloric acid

H2SO4 – sulfuric acid

H2CO3- carbonic acid

Bases release OH- (hydroxide) ions in solution.

ex. NaOH – sodium hydroxide

NH4OH – ammonium hydroxide

Ca(OH)2 – calcium hydroxide

pH scale

a number related to the concentration of H+

• Each number (0-14) is a 10-fold difference

in H+

• describes how acid or basic a solution is

Neutral

Acid

Base

More H+

More OH-

H+ = OH-

The pH scale –

Indicates the

concentration

of H+ ions

in solution.

Chapter 2.3 – Carbon

Compounds

Chemicals in Organisms

Objective: What are the functions

of each of the 4 major groups of

organic compounds?

Chemicals in Organisms

• Organic compounds

– Made by living things

– Contain CARBON as their backbone

– This makes them ORGANIC, not inorganic

• 4 major groups of organic compounds

(macromolecule)

4 Major Groups of Organic

Compounds (macromolecules)

• Carbohydrates

• Proteins

• Lipids

• Nucleic acids

• Carbon makes up the basic structure, or

“backbone,” of most organic compounds.

• Each atom of carbon has 4 e- in its outer

energy level (4 valence e-) it wants 8. – This makes it possible for carbon atoms to form

four covalent bonds with other atoms.

Section 2-3

Interest Grabber

The Chemistry of Carbon

Carbon atoms can

– bond to other carbon atoms by single, double, or triple bonds (the # indicates the number of pairs of electrons that are shared).

– form long chain or rings.

– form huge number of different carbon compounds, each with a unique structure.

Methane Acetylene Butadiene Benzene Isooctane

Important Things about Carbon

Macromolecule Organization

• Monomers (mono=one) – base unit

• Dimers (di=two)

• Polymers (poly=many) – macromolecule

Macromolecules “giant molecules”

Made when monomers – single subunits - are joined

together to form polymers – large molecules.

How are monomers joined

and broken down?

Dehydration Synthesis

Dehydration Synthesis

4 Major Groups of Organic

Compounds (macromolecules)

• Carbohydrates

• Proteins

• Lipids

• Nucleic acids

1. Carbohydrates (CHOs)

• The basis of all food webs on earth

– Can be produced through two processes

• Photosynthesis (photo = light, synthesis = to make)

• Chemosynthesis (chem = chemical, synthesis = to

make)

• Form the structural components of plants

and many invertebrates

• Compounds made up of

–C, H, and O atoms

– (usually in a ratio of 1:2:1)

• 3 General Types– classified by number of monomers

Carbohydrate Chemistry

a. Monosaccharide – single or simple sugar (1 monomer)

ex. Glucose – C6H12O6

- product of photosynthesis

- blood sugar in vertebrates

b. Disaccharide – double sugar (2 monomers)

Ex. Fructose + glucose = sucrose

(monomer) + (monomer) = dimer

- plant sap or table sugar

Function – major short term energy for

cells

c. Polysaccharide s– many sugars (polymer)

Function – longer term energy

storage or physical structure

• Energy storage

• in plants – starch

• in animals – glycogen

• Physical Strucuture

• in plants – cellulose

• in fungi and arthropods - chitin

All polymers of glucose

All of these are polymers of glucose, so what’s

different?

Some Simple Sugars

(Monosaccharides) are Isomers

• Isomer –– same chemical formula, different structural formula

Word Part Alert!

• Sugar names end with the suffix -ose

• Common examples are

– glucose (grape sugar)

– fructose (fruit sugar)

– sucrose (cane sugar)

– lactose (milk sugar)

2. Lipids (Mostly CHs)

• Compounds made mostly from C and H

atoms

• Types

– Fats and oils

– Phospholipids

– Steroids

– Waxes

• Lipids do not dissolve in water – they are

NON-POLAR (Hydrophobic)

Lipid Functions

• Long term energy storage

• Insulation

• Repels water

• Cell membrane

• Regulation

Saturated fat –

fatty acid tail with no double bond

(is saturated with hydrogen)

- animal source

- solid at room temperature

- ex. butter, lard

Unsaturated fat –

fatty acid tail with double bond

(is NOT saturated with hydrogen)

- plant source

- liquid at room temperature

- ex. olive oil, corn oil

Fats – Long Term

Energy Storage

Trans-Fats = hydrogenated oil

– a polyunsaturated fat (liquid) that is synthetically

converted to saturated fat (solid) by adding hydrogens.

- ex. peanut butter, margarine, Crisco

Glycerol

3 Fatty Acids

Long hydrocarbon tail –

Hydrophobic –” water-fearing”

(non-polar)

Carboxyl head – Hydrophilic –

“water-loving” (polar)

Triglycerides are a blood lipid that help enable the bidirectional

transference of adipose fat and blood glucose from the liver.

http://www.phschool.com/science/biology

_place/biocoach/bioprop/building.html

Phospholipids make up cell membrane’s

- made of a phospholipid bilayer (2 layers)

(is a diglyceride with 2 fatty acid tails, not 3)

Water outside of cell

Water inside of cell

Polar heads point out

towards aqueous (water)

environment .

Non-polar tails point in

away from water.

tails

3. Proteins

• Macromolecules that contain

–N, C, H, and O

• Proteins are

–polymers of monomers called amino

acids– Polymers are called polypeptides

– Covalent bonds between amino acids are

called peptide bonds

Proteins

• Hundreds of different lengths, shapes

• Made from amino acids (20)

Protein Functions

– Movement

– Structure

– Regulation

– Transport

– Nutrition

– Defense

– Enzymes

Amino Acids

Car

General structure Alanine Serine

Difference

between amino

acids

Amino

group

Carboxyl

group

More than 20 different amino acids, only difference is the “R” group.

Can join to any other amino acid by peptide bonds between the amino

group of one and the carboxyl group of the other . Dehydration synthesis

Amino

Acids

A protein’s shape determines its chemical nature and activity.

Heat and chemicals can denature a protein – they change its

shape so it no longer works.

4. Nucleic Acids

• Macromolecules containing – C,H,O,N,P

• Monomers are nucleotides.

• Each nucleotide consists of:

Nucleic Acids

• Polymer Types

– RNA (single strand)

– DNA (double strand)

Nucleic Acids

• Functions

– Pass down traits

of parent to

offspring

– Provide

instructions for

making proteins

2.4: Chemical Reactions

and Enzymes

Objectives

• What happens to chemical bonds

during chemical reactions?

• How do energy changes affect

whether a chemical reaction will

occur?

• Why are enzymes important to

living things?

The Big Idea

• Living things are made up of

chemical compounds

• Everything that happens to an

organism is based on chemical

reactions

Chemical Reaction

a process that changes or

transforms one set of chemicals

into another by changing the bonds

that join the atoms

Reactant Product

Example Reaction: the release of carbon dioxide from living

organisms (see your book)

• In the blood:

CO2 + H2O H2CO3 (carbonic acid)

• In the lungs:

H2CO3 CO2 + H2Oreleased as you

breathe

Energy in reactionsEnergy-Absorbing Reaction Energy-Releasing Reaction

Products

Products

Activation energy

Activation

energy

Reactants

Reactants

Products have more energy

than the reactants. This rxn

uses energy. Does not occur

spontaneously – needs energy

Products have less energy

than the reactants. This rxn

releases energy. Will occur

spontaneously.

Activation Energy

• The energy that is needed to get

any reaction started.

Enzyme – Biological Catalysts

• Some rxns

– Are too slow to be useful in living organisms

– Require too much activation energy

• Catalysts

– Substances that can speed up a rxn by

lowering the activation energy needed

• Enzymes

– Proteins that act as biological catalysts in

living organisms

Enzymes – biological catalysts

• very specific

• named for reaction they catalyze

• names almost always end in “ase”

• are not changed or used up during

rxn – are recyclable

Reaction pathway

without enzyme Activation energy

without enzyme

Activation

energy

with enzymeReaction pathway

with enzyme

Reactants

Products

Each enzyme (catalyst) attaches to specific

substances – substrate (reactant).

The substrate attaches at a particular spot – the

active site

Active site

What factors affect enzyme

function?

Predict the effect of temperature, pH and

enzyme concentration of enzyme action in

living cells given data and various scenarios

Regulation of Enzyme Activity