biology Basis of Life

8/10/2019 biology Basis of Life

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The Basis of Life

Dr Mirna N. Chahine

Week 2

Feb 18th -22nd


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1. Matter, Energy, and Life


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All living things can use MATTER and ENERGY

to their advantage.

MATTER= anything that has a mass and takes

up space.

ENERGY= The ability to do work or causethings to move

Matter & Energy


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Work is being done

whenever some

physical force is

being used to move

an object some

distance

Energy


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Energy means that birds can fly,

tigers can roar,

wind can blow,

sun can shine,

cars can go fast, factories can make things,

light bulbs can glow and

your computer can work.

Without energy, there would be nothing: nolife, no movement, no light, nothing


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Energy All objects contain energy in one form or

another

Can take the form of:

Motion Position

Heat

Light

Sound

Electricity


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Kinetic Energy

-Potential Energy


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The amount of energy contained in anobject at rest;

The energy of position;

Stored energy (ex: in chemicals)

Ex: Stretched bow

Ex: Skiing (maintainingitself at top of the

slope)

Potential Energy


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Potential Energy

o Potential energystored within thechemical bonds of an object


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o Potential energystored within thechemical bonds of an object

Potential Energy


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Kinetic

Energy

vs

PotentialEnergy


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Kinetic

Energy

vs

PotentialEnergy


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Kinetic

Energy

vs

PotentialEnergy


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Kinetic

Energy

vs

PotentialEnergy


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Moving car

Tree branch Balloon filled with air

Balloon squirting around room

Potential or Kinetic Energy?


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Potential or Kinetic Energy?

Moving car: Kinetic Energy

Tree branch: Potential Energy

Balloon filled with air: Potential Energy

Balloon squirting around room : Kinetic Energy


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In conclusion : Energy

Energy can _______________

Energy can _______________

But ENERGY can_______________

from one form to another

never be created

never be destroyed

only be converted

LAW OF CONSERVATION

OF ENERGY


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2. The Nature of Matter


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Introduction: Matter / Chemistry

In Science, living things are not

composed of pure energy

In Science, living things are alsocomposed of matter

CHEMISTRY: Basic principles of MATTER Composition,

Structure,

Properties of matter


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Matter


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2. The Nature of Matter2.2. The Structure of an Atom

Neutrons

Protons

Electrons


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Elements

Pure substancesthat cannot be broken down

chemically into simpler kinds of matter

More than 100 elements (92 naturallyoccurring)

Elements


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90% of the mass of an organism is

composed of 4 elements (oxygen,

carbon, hydrogen and nitrogen) Each element unique chemical

symbol:

Consists of 1-2 letters

Firstletter is always capitalized

Elements


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ATOMS are the simplest particle ofan elementthat retains all theproperties of that element

Properties of atomsdetermine thestructure and properties of thematter they compose

Atoms


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AtomsThe study of chemistry begins with

the basic unit of matter, the atom.


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Placed side by side, 100

million atoms would

make a row only about 1centimeter long.

Atoms contain

subatomic particles

that are even smaller.

Atoms


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The subatomic

particles that makeup atoms are:

protons

neutrons

electrons

Atoms


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The Nucleus

Centralcore

Consists of positive

charged protons and

neutral neutrons

Positively charged

Contains most of the

mass of the atom

The subatomic particles


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The subatomic particles

in a helium atom.

XA: MASS NUMBER

Z: ATOMIC NUMBER

=PROTONS NUMBER

N= A-Z=NEUTRONS NUMBER

PROTONS NB= ELECTRONS NB

He4

2

=2

=2

=2


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2. The Nature of Matter2.1. The Structure of an Atom2.2. Elements may vary in Neutrons but not in

Protons


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Elements and Isotopes

A chemical element is a pure substance that consists

entirely of one type of atom.

Isotopes are atoms of the same element that differ in

the number of neutrons they contain.

N= 12-6= 6 N= 14-6= 8


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Because they have

the same number of

electrons, all isotopesof an element have

the same chemical

properties.

The differenceamong the isotopes

is the number of

neutrons in their

nuclei.

Elements and Isotopes

6 electrons

6 protons

8 neutrons


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Protons

2.3. The positions of Electrons


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The Electrons

Negatively chargedhigh energy particles with little

or no mass

Travel at very high speedsat various distances

(energy levels)from the nucleus


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Electrons in the same energy level areapproximately the same distance from the

nucleus

Outer energy levels have more energythan inner levels

Each levelholds only a certain number ofelectrons


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Energy Levels

Atoms have 7energy levels

The levels are K (closest to the nucleus), L, M, N,O, P, Q(furthest from the nucleus)

The K level can only hold 2electrons Levels LQ can hold 8electrons (OCTET RULE)


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Periodic Table Elements are arranged by their atomic

number on the Periodic Table

The horizontal rows are called Periods & tell

the number of energy levels Vertical groups are called Families & tell the

outermost number of electrons


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Protons

2.3. The positions of Electrons2.4. The formation of Molecules/Compounds


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Molecules/ Compounds

CO2 H2OO3

Moleculesare the simplest part of a substance thatretains all of the properties of the substance and

exists in a free state; They are composed by 2 or

more atoms of the same element ex: H2, O2, O3

Compounds are molecules composed by more than

one element ex: CO2, H20, CH4

The Formation of


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The Formation of

Molecules and Compounds


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Chemical Compounds

A chemical compoundis a substance formed bythe chemical combination of two or moreelements in definite proportions.


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Copyright Pearson Prentice Hall

Chemical Formula

Water

Table Salt

Hydrochloric Acid

Glucose



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Chemical Formula

Water: H2O

Table Salt: NaCl

Hydrochloric Acid: HCl

Glucose: C6H12O6



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Protons2.3. The positions of Electrons

2.4. The formation of Molecules/Compounds

2.5. State of a compound: Physical and ChemicalChanges

f f


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States of Matter ofthe compound

Atoms are in constant motion

The rate at which atoms or molecules in asubstance move determines its state

f f


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Solid Molecules tightly linked together in a definite shape

Vibrate in place

Fixed volume and shape

Liquids

Molecules not as tightly linkedas a solid

Maintain fixed volume

Able to flow and conform to shapeof container

Gas

Molecules have little or no attraction to each other

Fill the volumeof the occupied container

Move most rapidly

States of Matter ofthe compound


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The tendency of elements to combine andform compounds depends on the number andarrangement of electrons in their outermostenergy level

Atoms are most stable when their outer most

energy level is filled Most atoms are not stable in their natural

state Tend to react(combine) with other atoms in

order to become more stable (undergo

chemical reactions) In chemical reactionsbonds are broken;

atoms rearranged and new chemical bondsare formed that store energy

Stability of atoms


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The atoms in

compounds are held

together by chemicalbonds.

The electrons that

are available to formbonds are called

valence electrons.

Chemical Bonds


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Chemical Bonds

The main types of chemical bonds are:

ionic bonds

covalent bonds

Ionic Bond


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An ionic bondis formed when one or more electronsare transferred from one atom to another.

These positively and negatively charged atoms areknown asions.

Because positive and negative electrical chargesattracteach other ionic bonds form

Ionic Bond

Ionic Bond
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Chemical Bonds

Protons +17

Electrons - 18

Charge -1

Protons +11

Electrons - 11

Charge 0

Protons +11

Electrons - 10

Charge +1

Protons +17

Electrons - 17

Charge 0

Sodium ion (Cl-)Sodium atom (Na)

Sodium atom (Cl)Sodium ion (Na+)

Ionic Bond

Ionic Bond
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Ionic Bond


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They are formed when electrons are shared

between atoms instead of being transferred.

Covalent Bonds


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single covalent

bond:

1 pair of e- is shared

double bond2 pairs of e- are shared

triple bond3 pairs of e- are shared

Covalent Bonds


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2.2. Elements may vary in Neutrons but not in

Protons

2.3. The positions of Electrons2.4. The formation of Molecules/Compounds

2.5. State of a compound: Physical and Chemical

Changes2.6. Water the Essence of Life


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The Water Molecule

A water molecule is polar because there is an unevendistribution of electrons between the oxygen and

hydrogen atoms.

The hydrogen end

of the molecule is

slightly positive

The oxygen end isslightly negative.


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Hydrogen BondsBecause of their partial positive and negativecharges, polar molecules can attract each

other.


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Solutions and Suspensions

Amixtureis a material composed of two or more

elements or compounds that are physically

mixed but not chemically combined.

Two types of mixtures can be made with water

solutions

suspensions


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SolutionsAll the components of a solution are evenly distributed

throughout the solution.

-solute: the substance that is dissolved: ex: NaCl-solvent: the substance in which the solute dissolves: ex: H2O;

Water is the universal solvent

Solutions and Suspensions

Suspensions

Some materials do not dissolve when placed

in water but separate into pieces so small

that they do not settle out easily.


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Protons


2.4. The formation of Molecules/Compounds2.5. State of a compound: Physical and Chemical

Changes

2.6. Water the Essence of Life2.7. Acids, Bases, pH, and Buffers


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Acids, Bases, and pH

A water molecule is neutral, but can react to form

hydrogen and hydroxide ions.

H2O H+ + OH-

A id B d H


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Acids, Bases, and pH

The pH scale : Chemists devised a measurement system calledthe pH scale to indicate the concentration of H+ions in solution:

The pH scale ranges from 0 to 14.

Acid: is any compound that forms H+ions in solution; ex: HCl

Base: is a compound that produces OH-ions in solution; ex: NaOH


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the lowerthe pH the stronger the acid

the higherthe pH the stronger the base pH 7.0 is neutral


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h f


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Protons


2.4. The formation of Molecules/Compounds2.5. State of a compound: Physical and Chemical

Changes

2.6. Water the Essence of Life2.7. Acids, Bases, and pH

2.8. Chemical reactions

FIVE t i t t


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FIVE most important

Chemical Reactions

1- Oxidation- Reduction Reactions

2- Acidbase reactions 3- Dehydration synthesis reactions

4- Hydrolysis reactions

5- Phosphorylation reactions


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Reduction-Oxidation Reactions

Many of the chemical reactions that help transfer

energy in living organisms involve the transfer of

electrons (reduction-oxidation = redox reactions)

1- Oxidation reactionreactant

loses electron(s) becoming more

positive

2- Reduction reactionreactant

gains electron(s) becoming more

negative


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Acid-Base Reactions

They take place when the ions of an acid interact

with the ions of a base;

This occurs in organisms and their environment inorder to protect them from damage

H Cl + Na OH Na Cl + HOH+ + +- - -

Hydrochloric

acid

Sodium

Hydroxide

Sodium

Chloride

Water :

H2O


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