Transcript Understanding Our Environment

Chapter 2
Lecture Outline
The Nature of Life
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Outline

Attributes of Living Organisms

Chemical and Physical Bases of Life
• The Elements: Units of Matter
• Molecules
• Valence, Bonds and Ions
• Acids, Bases and Salts
• Energy
• Chemical Components of Cells
• Monomers and Polymers
–
–
–
–
Carbohydrates
Lipids
Proteins
Nucleic Acids
Attributes of Living Organisms

Composition and Structure
• Cells: All Complex Cells Have
•
–
Cytoplasm
–
Cell Membrane
–
Nucleus
Plant Cells also
Have:
– Cell Walls
Drawing of plant cell
Attributes of Living Organisms …

Growth

Reproduction
Attributes of Living Organisms …

Response to:
Attributes of Living Organisms …

Metabolism
• All chemical reactions
–
Photosynthesis
–
Digestion
–
Respiration – release of energy from food
–
Assimilation - Conversion of raw materials
into cell substances
Attributes of Living Organisms …

Complexity of Organization
• Elements/atoms 
• Molecules 
• Cells  Tissues  Organs  Organ Systems
 Organism
Microscopic View of the Cells within a Leaf
Attributes of Living Organisms …

Environmental Adaptation– Natural Selection
• Many generations
• Some Organisms have genetic characteristics 
survive and reproduce
–
Their offspring have the same genetic characteristics
• Other Organisms without these characteristics
won’t do so well!
• The Population will have more and more
individuals with the survival characteristics
Attributes of Living
Organisms …

Movement
-
Organismal level
-
Cell level
– Cytoplasmic streaming
occurs within cell:
Chemical and Physical Bases of Life
THE ELEMENTS: UNITS OF MATTER

Energy

Matter
• Mass
•
Composed of elements
–
Examples:
–
composed of ATOMS
Model of an
oxygen atom

Elements & Atoms
• Atoms
o
o
Nucleus
•
Protons
•
Neutrons
Electron Orbitals
•
Electrons:
• Atomic Number =
•
identifies elements
• Atomic Mass =
Model of an oxygen atom

Isotope = ____________________________
• Radioactive isotopes are:
Oxygen
isotopes

IONS =
Sodium Atom
Sodium Ion
Chlorine Atom
Chloride Ion
Chemical and Physical Bases of Life
MOLECULES

Molecule - Two or more atoms bound
together
• Smallest independently existing particle :
 Compound - Two or more different elements
bond together
PRACTICE QUESTIONS

Two or more elements bonded together in a
particular ratio is called a(an) _____________

An atom that has lost or gained electrons is
called a(an) _____________

If temperature is increased, the motion of a
molecule ________________

The smallest, stable subdivision of an element
is a(an) _________________
Chemical and Physical Bases of Life
VALENCE, BONDS, AND IONS

Bonds =
• 1 bond = ____ electrons
• 4 Types of Bonds
–
Based on what happens to the electrons of the bond
•
Covalent Polar
• Covalent Nonpolar
• Ionic
• Hydrogen bonds between molecules

Covalent Bonds
• Form when:
• Electrons travel ___________________
• Nonpolar –
• Polar -
H
O O
H
O
Water
Oxyen
• Water has Polar Covalent Bonds
–
Water’s Shape:
–
Polar molecule:
• Slightly positive hydrogen atoms are attracted to:
• Cohesion - Attraction of:
– Capillary movement in plants
• Adhesion - Attraction of:
IMPORTANCE OF WATER
1) Solvent
2) Water Movement in Plants
Cohesion of
water

Ionic Bonds
• Ionic bonds form when:

Hydrogen Bonds
• Bond between two _____
• Usualy involve what
elements:
• Are Polar molecules
•
Are Weak Bonds
Cohesion of water
molecules
PRACTICE QUESTIONS

A chemical bonds is formed by two __________

When a molecule is Polar:
a) The electrons in the bonds are equally shared
b) Radioactive Isotopes give up neutrons to form the
bond
c) The molecule has an end that is partially positive
charged and another end that is partially negative
charged
d) Its motions stops in very low temperatures

CHEMICAL REACTIONS
• Reactants and Products
• Collisions of Reactants cause: ______
• Catalyst: ___________________________
–
Enzyme: _______________________________
Sucrase
Sucrose ------ Glucose + Fructose
–
If an organism has no chemical reactions in its body it
is ____________

Chemical Reactions …
Sodium metal + Chlorine gas  Salt
Reactants

Products
Water molecule
PRACTICE QUESTIONS

Cohesion is the attraction of _________
molecules.

Chemical Reactions involve which of the
following:
1. random collisions of the reactants
2. the removal of protons from one or more
chemicals
3. keeping all the same bonds in the reactants
4. Catalyst is required
a) “1” only
c) “1” and “3”
b) “4” only
d) “1” and “4”
e) “1,” “2,” and “4”
Chemical and Physical Bases of Life
ACIDS AND BASES

Acids:

Bases:
• pH scale =
Range =
7
=
Neutral
1-7
=
Acidic
7-14
=
Alkaline
IMPORTANCE: Soils
Movement of Chemicals

DIFFUSION

ACTIVE TRANSPORT
• Energy
• Protein Carrier Molecule
• Low  High
OSMOSIS
Chemical and Physical Bases of Life
CHEMICAL COMPONENTS OF CELLS

About 96% of a cell is:

Categorizing Chemicals
• INORGANIC
–
Examples:
• ORGANIC
–
BIOCHEMICALS
Chemical and Physical Bases of Life
BIOCHEMICALS …

Polymers -
• Monomers
PRACTICE QUESTIONS

The movement of a substance from a higher
concentration to a lower concentrations is called
___________.

Name the 4 elements which make up the
majority of a living organisms: ___ ___ ___ ___

Organic Chemicals always have a framework
made of ___________.

A small subunit that is used to make a polymer
is called a(an) ____________.
Carbohydrates

Carbohydrates most abundant
• Elements:
• Ratio of Elements:
• General Function:
• TYPES
•
Monosaccharides - Simple
sugars
Structure
Examples:
•
Disaccharides:
• Examples
•
Polysaccharides:
• Structure:
• Examples
–
Starch = coils of glucose molecules
o Function:
–
Cellulose = unbranched chain of glucose molecules
o Function
Lipids

Lipids:
• General Function:
• Contain Elements:
• Element Ratios:
• Fats and oils are produced from one
molecule of glycerol and three fatty acid
molecules.
•
Most fatty acids consist of:
Structure of a fat molecule
–
Saturated -
–
Unsaturated -

Waxes - long-chain fatty acids bonded to a
long chain alcohol
• Location & Function in Plants:

Phospholipids - Constructed like fats, but one
of the fatty acids is replaced by a phosphate
group
• Function:
PRACTICE QUESTIONS

What Biochemical does not mix with water?
_____________

What Biochemical has a ratio of 1 C: 1 O: 2 H ?
_____________

A Phospholipid differs from a Fat molecule in
that is has a Phosphate and ____ Fatty acids.

Starch in plants functions in what:
a) storage form of energy
b) as an enzyme
c) as an insulation in leaves
Proteins, Polypeptides, and Amino Acids

Proteins:
- General Functions:
- Contain Elements:
• Polypeptides: simplest form; are composed of:
–
Each amino acid is composed of: Repeats of CCN
o
Amino group (-NH2)
o
Carboxyl group (-COOH)
o
R group Structure of amino acid,
glycine
Proteins, Polypeptides, and Amino Acids

Polypeptide Structure
• Primary Structure
• Secondary Structure
–
Formation of an alpha
helix or of pleated
sheets due to:
Proteins, Polypeptides, and Amino Acids

Polypeptide Structure
• Tertiary Structure
• Quaternary Structure
Protein Types According to Functions

Structural

Storage

Movement

Transport and Carrier

Enzymes
Enzymes

Enzymes
• Breaking bonds:
• Increase reaction rates
• Lower the energy needed for a chemical
reactions to occur– Energy of activation
• Active Site:
Enzymes

Enzymes temporarily
bond with substrate.
• Substrate fits into
active site of enzyme.
• Reaction occurs
rapidly and products
are released.
• Enzyme remains
unchanged and
capable of catalyzing
another reaction.
Mode of action of an enzyme
PRACTICE QUESTIONS

The subunit of Proteins is _________________.

The tertiary structure of a protein is the:
a) Linear sequence
b) 3-dimensional shapes
b) 3-dimensional shapes c) helixes and/or sheets
e) two or more polypeptides

T or F: Enzymes become part of the product of
a reaction.

T or F: Carrier proteins help move substances
from a lower to a higher concentration inside or
outside of a cell.
Nucleic Acids

Nucleic acids
• 4 Major elements contained:
• There are two types:
–
Deoxyribonucleic Acid (DNA)
–
Ribonucleic Acid (RNA)
Nucleotide structure

DNA consists of a double helix of repeating
subunits of 4 kinds of nucleotides.
• Nucleotides are composed of a nitrogenous base,
a five-carbon sugar and a phosphate.

CODE:

DNA

Functions:
RNA
* Functions:

Gene: Sequence of DNA that:
• That protein then causes a particular
characteristic
PRACTICE QUESTIONS

Name the 3 parts of a Nucleotide: __ __ __

The basic shape of DNA is what? _________

T-F: DNA is important because it codes for all
the proteins in an organisms and thereby control
all the traits of the organism.

T-F: RNA functions by helping DNA translate its
code into proteins
Outline

Attributes of Living Organisms

Chemical and Physical Bases of Life
• The Elements: Units of Matter
• Molecules
• Valence, Bonds and Ions
• Acids, Bases and Salts
• Energy
• Chemical Components of Cells
• Monomers and Polymers
–
–
–
–
Carbohydrates
Lipids
Proteins
Nucleic Acids
Copyright © McGraw-Hill Companies Permission Required for Reproduction or Display