BIOLOGY SBBS-1.pptx

LENNOX MAC- ANKRAH
DEPARTMENT OF MICROBIOLOGY AND IMMUNOLOGY
SCHOOL OF MEDICINE
BIOLOGY
Lecture 1

OUTLINE
• INTRODUCTION
• BRANCHES OF BIOLOGY
• BIOLOGY PIONEERS
• THEMES OF BIOLOGY
• XTICS OF LIVINGTHINGS
• SCIENTIFIC METHOD
• DOMAINS AND KINDOMS OF LIFE
• CELL STRUCTURE AND FXN
• CHEMICAL BASIS OF LIFE

3
Biology – The Study of Life
• Life arose more than
3.5 billion years ago
• First organisms
(living things) were
single celled
• Only life on Earth for
millions of years
• Organisms changed
over time (evolved)

4
• New organisms arose
from older kinds
• Today there are millions
of species
• They inhabit almost
every region of Earth
today

Branches of Biology
Major branches are botany, zoology and
microbiology
1. Zoology- the study of animals
2. Ichthyology- the study of fish
3. Mammalogy- study of mammals
4. Ornithology- the study of birds

5. Botany- the study of plants
6. Microbiology- study of microorganisms
(Bacteriology, Parasitology, Virology, Mycology)
7. Anatomy- study of an organism’s parts
8. Physiology- study of how organism’s parts work

9. Entomology- study of insects
9. Genetics- study of heredity and genetic material
(DNA/RNA, chromosomes, genes)
10.Ecology- study of all life in a particular area, the
relationships b/t those life forms and the
environment
9. Cytology- the study of cells

What about these branches?
• Morphology- how is it different from anatomy?
• Histology
• Aerobiology
• Anthropology
• Batrachology
• Bryology
• Conchology
• Cryobiology
• Embryology
• Etiology
• Hematology
• Hypnology
• Limnology

Biology Pioneers
1. Aristotle
-Greek (1st bio. teacher)
“Father of Biology and
Zoology”

More on Aristotle
• Supported spontaneous generation theory
• Created a theory of the elements
4 elements:
A. Earth B. Air
C. Water D. Fire
-1st person to start classifying organisms

2. Hippocrates
• Greek
• “Father of Medicine”
• Hippocratic Oath for
doctors (part of his life-
long legacy)

3. Leeuwenhoek
• Dutch
• His hobby was lens
grinding
** He did NOT invent the
microscope, he
perfected microscope
lenses
Father of Microbiology

• He was the first person to see:
A. Bacteria
B. Protozoans
C. Red blood cells
D. Sperm cells
-He did NOT support spontaneous generation

4. Lister
• British
• Hospital conditions
were dirty & infectious
• Used phenol as a
disinfectant
• “Father of Aseptic
Surgery”

5. Fleming
• British
• Accidentally discovered
first antibiotic
(penicillin)

Salk and Sabin
• Developed 1st polio
vaccine injection (1955)
• Didn’t patent vaccine,
didn’t want to profit
from his discovery
• Developed oral polio
vaccine (1959)
• Vaccines are weakened
forms of disease that
tricks body into making
antibodies

18
Themes of Biology
• Cell structure and function
• Stability and homeostasis
• Reproduction and
inheritance
• Evolution
• Interdependence of
organisms
• Matter, energy, and
organization Copyright Cmassengale

19
Cell Structure and
Function
• Cell basic unit of life
• All organisms are made of
and develop from cells
• Some composed of only a
single cell (unicellular)
which is usually identical to
parent
Copyright Cmassengale

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Cells
• Most organisms are
composed of many cells
(multicellular)
– Cells are different (undergo
differentiation)
• Cells are small
• Cells are highly organized

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• Cells contain specialized
structures (organelles) that
carry out the cell’s life
processes
• Many different kinds of cells
exist
• All cells surrounded by a
plasma membrane
• Contain a set of instructions
called DNA (genetic

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Stability and Homeostasis
• Organisms must Maintain very stable
internal conditions - HOMEOSTASIS
• Temperature, water content, chemical
content, etc. must be maintained

23
Reproduction and Inheritance
• All organisms produce new organisms like
themselves REPRODUCE
• Organisms transmit hereditary information to
their offspring INHERITANCE

24
DNA
• Genetic Information in all cells
• Deoxyribonucleic Acid
• DNA contains instructions for traits
GENES
• Make the structures and complex
chemicals necessary for life PROTEINS
• DNA in every body cell (SOMATIC
CELLS) is exactly alike

25
Sexual Reproduction
• Hereditary information
from two different
organisms of the same
species are combined
• Egg and sperm  zygote
(fertilized egg)
• Zygote contains hereditary
information from both
parents

26
Asexual Reproduction
• Hereditary information from
one, usually unicellular,
organism that divides
• Resulting cells contain
identical hereditary
information
• Genetic information from
single parent

27
Evolution
• Populations of organisms
change (evolve) over
generations (time)
• Explains how many different
kinds of organisms came into
existence SPECIES
• Explains how modern
organisms are related to past
organisms

28
• Explains why organisms
look and behave the
way they do
• Provides a basis for
exploring the
relationships among
different groups of
organisms

29
Natural Selection
• Natural selection is the driving
force in evolution
• Organisms that have certain
favorable traits are better able to
successfully reproduce than
organisms that lack these traits

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Natural Selection
• Survival of organisms with
favorable traits cause a
gradual change in
populations over many
generations
• Also Called “Survival of
the Fittest”

31
Interdependence of Organisms
• Interaction of organisms with
one another and with their
environment ECOLOGY
• Insects depend and flowers
DEPEND on each other for
food & pollination
COEVOLUTION

32
• All organisms need substances such as
nutrients, water, and gases from the
environment
• The stability of the environment depends on
the healthy functioning of organisms in that
environment

33
Matter, Energy and Organization
• Living things are highly organized
• Require a constant supply of energy to
maintain their orderly state

34
Energy
• ALL energy comes from the SUN (directly or
indirectly)
• Photosynthesis is the process by which some
organisms capture the energy from the sun
(solar) and transform it into energy (chemical)
that can be used by living things

35
Autotrophs
• Organisms that make their own
food are called autotrophs
• Phototrophs – use solar energy
(photosynthesis) to get energy
• Convert H2O and CO2 into sugar
and O2
• Chemotrophs – use different
chemical processes to get
energy

36
Heterotrophs
• Organisms that must take in food
to meet their energy needs are
called heterotrophs
Consume autotrophs (herbivores),
other heterotrophs (carnivores) or
both (omnivores) for their energy
needs
• Complex chemicals are broken
down and reassembled into
chemicals and structures needed
by organisms

37
What Are the Main Characteristics
of living organisms?
1. Made of CELLS
2. Require ENERGY (food)
3. REPRODUCE (species)
4. Maintain HOMEOSTASIS
5. ORGANIZED
6. RESPOND to environment
7. GROW and DEVELOP
8. EXCHANGE materials with surroundings (water,
wastes, gases)
9. MOVEMENT
copyright cmassengale

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Scientific Method

39
Observation – STEP 1
• Employing your five senses to perceive objects
or events

40
Asking a Question
• Based on observations; one or more questions
are generated

41
Forming a Hypothesis –
STEP 2
• A statement is testable if evidence can be
collected that either does or doesn’t support it
• It can never be proven beyond doubt
• Often must be refined and revised or discarded

42
The Hypothesis ---
• Is a statement made in advance that states the
results that will be obtained from testing the
hypothesis
• Often written in the form of an “if-then”
statement

43
Experimenting – STEP 3
• Testing a hypothesis or prediction by
gathering data under controlled conditions –
conducting a controlled experiment
– Based on a comparison of a control group with an
experimental group

44
– Both groups are identical except for one factor
(independent variable)
– Observations and measurements are taken for a
particular factor (dependent variable) in both
groups
• Driven by or results from independent variable

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– Measuring
• Involves quantitative data that can be measured in numbers
&/or qualitative data information that isn’t numbers
– Sampling
• Technique of using a sample – a small part – to represent the
entire population

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Organizing Data – STEP 4
• Involves placing observations and measurement
(data) in order
– Graphs, charts, tables, or maps

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Analyzing Data – STEP 4 cont)
• Collected and organized data must be analyzed
– Process of determining whether data are reliable or
whether they support or do not support a
hypothesis or prediction

48
Conclusion – STEP 5
• Conclusions are made on the basis of facts,
not observations
– Often drawn from data gathered from a study or
experiment
– Should support the hypothesis
– Should be re-testable

49
Communication – STEP 6
• Scientists must share the results of their
studies with other scientists (peers)
• Publish findings in journals
• Present their findings at scientific meetings
• Scientists must be unbiased
– Should not tamper with their data
– Only publish & report tested & proven ideas

50
Communication
• Sharing of information is essential to scientific
process
• Subject to examination and verification by other
scientists
• Allows scientists to build on the work of others

51
Theories
• A theory may be formed
after many related
hypotheses have been
tested and supported with
experimental evidence
• A broad and
comprehensive statement
of what is thought to be
true
• Supported by considerable
evidence
• Ties together related
hypotheses

Laws
• A Statement of fact that concisely explains
an action or group of actions
e.g. Law of Gravity
• Accepted to be true
• Universal
• May be expressed as a math equation
e.g. E=mc2
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Basic Classification
Domains:
• There are three Domains of
living organisms based on
their characteristics:
– Archaea (also called
Archaebacteria)
– Eubacteria (also called
Bacteria)
– Eukaryota (also called
Eukarya)
Archae
a
Eubact
eria Eukaryo
ta

Basic Classification
Kingdoms:
The Domains can also be split into Kingdoms which further
divide the organisms by their characteristics.

Domain Archaea
Archaea” means “ancient” bacteria.
Organisms in Archaea are:
• Unicellular
• Prokaryotic
• Autotrophic or heterotrophic
– Organisms that reproduce asexually
– Bacteria that have adapted to extreme environments.
• Some can survive in extremely hot environments, like around hot springs and
geysers. They are called thermophiles.
• Some can survive in extremely salty environments, like The Great Salt Lake in Utah.
They are called halophiles.
The Domain Archaea has one Kingdom, also called Archaea
Aerial view of hot spring at Yellowstone

Domain Eubacteria
“Eu” means “true” bacteria. They are:
• Unicellular
• Prokaryotic
• Organisms that reproduce asexually
• The most abundant organisms on earth. One bacterium can give
rise to 10 million in 24 hours.
• Found in almost every habitat on earth.
The Domain Eubacteria has one Kingdom, also called Eubacteria.

Terminology:
• The Domains Archaea and Eubacteria are
commonly grouped together in discussion and
called prokaryotes because they lack
membrane-bound nuclei and membrane-
bound organelles.

Domain Eukaryota (Eukarya)
• Eukaryotic
• Very diverse
• Unicellular or multicellular
• Reproduce sexually or asexually
• Can be split into 4 Kingdoms-
– Protista
– Fungi
– Plantae
– Animalia

The 4 Kingdoms in Eukaryota
Protista
Mostly unicellular and microscopic
Autotrophic or heterotrophic
Can be infectious agents
Examples:
•Amoeba
•Algae
•Daphnia
•Plasmodium (causes malaria)
Plantae
Multicellular green plants
Autotrophic through photosynthesis
Have a cell wall
Examples:
•Mosses
•Ferns
•Trees
•Flowering Plants
Fungi
Multicellular
Heterotrophic
Decomposers
Can be infectious agents
Examples:
•Mushrooms
•Athlete’s foot
•Bread Mold
Animalia
Multicellular Animals
Heterotrophic
No Cell Wall
Examples:
•Insects
•Spiders
•Crabs
•Birds
•Humans

Think Break:
• Where do Viruses fit in this classification system?
• Where do Prions fit in this classification system?

64
LEVELS OF ORGANIZATION
Nonliving Levels:
1. ATOM (element)
2. MOLECULE (compounds like carbohydrates &
proteins)
3. ORGANELLES (nucleus, ER, Golgi …)

65
Living Levels:
1. CELL (makes up ALL organisms)
2. TISSUE (cells working together
3. ORGAN (heart, brain, stomach …)
4. ORGAN SYSTEMS (respiratory, circulatory …)
5. ORGANISM

66
Living Levels continued:
1. POPULATION (one species in an area)
2. COMMUNITY (several populations in an area
3. ECOSYSTEM (forest, prairie …)
4. BIOME (Tundra, Tropical Rain forest…)
5. BIOSPHERE (all living and nonliving things on
Earth)

67
Beginning of the Cell
Theory
• In 1838, a German botanist
named Matthias Schleiden
concluded that all plants
were made of cells
• Schleiden is a cofounder of
the cell theory

68
Theory
• In 1839, a German
zoologist named
Theodore Schwann
concluded that all
animals were made of
cells
• Schwann also
cofounded the cell
theory

69
Theory
• In 1855, a German medical
doctor named Rudolph
Virchow observed, under the
microscope, cells dividing
• He reasoned that all cells
come from other pre-existing
cells by cell division

History of the Cell
Robert Hooke, 1665
Anton von Leeuwenhoek, 1674
Matthias Schleiden, 1838
Theodor Schwann,
1839
Rudolph Virchow, 1855
Janet Plowe, 1931

71
CELL THEORY
• All living things are made of
cells
• Cells are the basic unit of
structure and function in an
organism (basic unit of life)
• Cells come from the
reproduction of existing cells
(cell division)

Matthias Schleiden
all plants are made
of cells
Cell Theory
Cell Theory
Theodore Schwann
all animals are made
of cells
Rudolf Virchow
all cells came from
pre-existing cells

73
Number of Cells
Although ALL living things are made of cells, organisms may be:
• Unicellular – composed of one cell
• Multicellular- composed of many cells that may
organize into tissues, etc.

74
CELL SIZE
Typical cells range from 5 – 50 micrometers (microns) in
diameter

75
How Big is a Micron ( µ ) ?
1 cm = 10,000 microns 1” = 25,000 microns

76
Multicellular Organisms
• Cells in multicellular organisms often specialize (take on
different shapes & functions)

77
Cell Specialization
• Cells in a multi-cellular
organism become
specialized by turning
different genes on and off
• This is known as
DIFFERENTIATION

78
Specialized Animal Cells
Muscle cells Red blood cells
Cheek cells

79
Specialized Plant cells
Xylem cells
Pollen
Guard Cells

Two Types of Cells
•Prokaryotic
•Eukaryotic

81
Prokaryotes – The first
Cells
• Cells that lack a nucleus or membrane-
bound organelles
• Includes bacteria
• Simplest type of cell
• Single, circular chromosome

82
Prokaryotes
• Nucleoid region (center)
contains the DNA
• Surrounded by cell
membrane & cell wall
(peptidoglycan)
• Contain ribosomes (no
membrane) in their
cytoplasm to make proteins

83
Eukaryotes
• Cells that HAVE a
nucleus and membrane-
bound organelles
• Includes protists, fungi,
plants, and animals
• More complex type of
cells

84
Eukaryotic Cell
Contain 3 basic cell
structures:
• Nucleus
• Cell Membrane
• Cytoplasm with
organelles

85
Two Main Types of
Eukaryotic Cells
Plant Cell Animal Cell

87
Organelles
• Very small (Microscopic)
• Perform various functions for a cell
• Found in the cytoplasm
• May or may not be membrane-bound

88
Cell or Plasma Membrane
Outside
of cell
Inside
of cell
(cytoplasm)
Cell
membrane
Proteins
Protein
channel Lipid bilayer
Carbohydrate
chains
• Composed of double layer of phospholipids and
proteins
• Surrounds outside of ALL cells
• Controls what enters or leaves the cell
• Living layer

89
Phospholipids
• Heads contain glycerol & phosphate
and are hydrophilic (attract water)
• Tails are made of fatty acids and are
hydrophobic (repel water)
• Make up a bilayer where tails point
inward toward each other
• Can move laterally to allow small
molecules (O2, CO2, & H2O to enter)

90
The Cell Membrane is
Fluid
Molecules in cell membranes are
constantly moving and changing

91
Cell Membrane Proteins
• Proteins help move large
molecules or aid in cell
recognition
• Peripheral proteins are attached
on the surface (inner or outer)
• Integral proteins are embedded
completely through the
membrane

92
Recognize
“self”
GLYCOPROTEINS
Glycoproteins have carbohydrate tails to act
as markers for cell recognition

93
• Lies immediately
against the cell wall in
plant cells
• Pushes out against the
cell wall to maintain
cell shape
Cell Membrane in
Plants
Cell membrane

94
• Nonliving layer
• Found in plants,
fungi, & bacteria
• Made of cellulose in
plants
• Made of
peptidoglycan in
bacteria
• Made of chitin in
Fungi
Cell wall
Cell Wall

95
• Jelly-like
substance
enclosed by cell
membrane
• Provides a medium
for chemical
reactions to take
place
Cytoplasm of a
Cell
cytoplasm

96
• Contains organelles
to carry out specific
jobs
• Found in ALL cells
More on Cytoplasm
cytoplasm

97
• Controls the normal
activities of the cell
• Contains the DNA in
chromosomes
• Bounded by a
nuclear envelope (membrane)
with pores
• Usually the largest organelle
The Control Organelle - Nucleus

98
• Each cell has fixed
number of
chromosomes that
carry genes
• Genes control cell
characteristics
Nucleus
More on the
Nucleus

99
Nuclear Envelope
• Double membrane surrounding
nucleus
• Also called nuclear membrane
• Contains nuclear pores for materials
to enter & leave nucleus
• Connected to the rough ER
Nuclear
pores

100
Inside the Nucleus
-
The genetic material (DNA) is found
DNA is spread out
And appears as
CHROMATIN
in non-dividing cells
DNA is condensed &
wrapped around proteins
forming
as CHROMOSOMES
in dividing cells

101
What Does DNA
do?
DNA is the hereditary material of the
cell
Genes that make up the DNA
molecule code for different
proteins

102
Nucleolus
• Inside nucleus
• Cell may have 1 to 3
nucleoli
• Disappears when cell
divides
• Makes ribosomes that
make proteins

103
Cytoskeleton
• Helps cell maintain cell shape
• Also help move organelles around
• Made of proteins
• Microfilaments are threadlike &
made of ACTIN. Aid in cytokinesis
and cell motility
• Intermediate filaments made of
different proteins: keratin,vimentin,
desmin and lamin. Maintain shape
and provide support.
• Microtubules are tubelike & made
of TUBULIN. They are the largest.
Forms flagella and cilia

104
Centrioles
• Found only in animal cells
• Paired structures near nucleus
• Made of bundle of microtubules
• Appear during cell division forming
mitotic spindle
• Help to pull chromosome pairs apart
to opposite ends of the cell

105
Centrioles & the Mitotic Spindle
Made of MICROTUBULES (Tubulin)

106
Mitochondrion
(plural = mitochondria)
• “Powerhouse” of the cell
• Generate cellular energy
(ATP)
• More active cells like
muscle cells have MORE
mitochondria
• Both plants & animal cells
have mitochondria
• Site of CELLULAR
RESPIRATION (burning
glucose) copyright cmassengale

107
MITOCHONDRIA
Surrounded by a DOUBLE
membrane
Folded inner membrane called
CRISTAE (increases surface
area
for more chemical
Reactions)
Has its own DNA
Interior called MATRIX

108
What do
mitochondria do?
Burns glucose to
release energy (ATP)
Stores energy as ATP
“Power plant”
of the cell

109
Endoplasmic Reticulum -
ER
Two kinds of ER ---ROUGH & SMOOTH
• Network of hollow membrane tubules
• Connects to nuclear envelope & cell
membrane
• Functions in Synthesis of cell products &
Transport

110
Rough Endoplasmic Reticulum (Rough
ER)
• Has ribosomes on
its surface
• Makes membrane
proteins and
proteins for
EXPORT out of cell

111
Rough Endoplasmic Reticulum (Rough ER)
• Proteins are made by
ribosomes on ER
surface
• They are then
threaded into the
interior of the Rough
ER to be modified and
transported

112
Smooth Endoplasmic Reticulum
• Smooth ER lacks
ribosomes on its surface
• Is attached to the ends
of rough ER
• Makes cell products
that are USED INSIDE
the cell

113
Functions of the Smooth ER
• Makes membrane lipids
(steroids)
• Regulates calcium (muscle
cells)
• Destroys toxic substances
(Liver)

114
Endomembrane System
Includes nuclear membrane connected to ER connected
to cell membrane (transport)

115
Ribosomes
• Made of PROTEINS and rRNA
• “Protein factories” for cell
• Join amino acids to make proteins
• Process called protein synthesis


116
Ribosomes
Can be attached to
Rough ER
OR
Be free
(unattached)
in the
cytoplasm

117
Golgi Bodies
• Stacks of flattened sacs
• Have a shipping side
(trans face) and
receiving side (cis face)
• Receive proteins made
by ER
• Transport vesicles with
modified proteins pinch
off the ends
Transpor
t vesicle
CIS
TRAN
S

118
Golgi Bodies
Look like a stack of
pancakes
Modify, sort, & package
molecules from ER
for storage OR
transport out of cell

119
Lysosomes
• Contain digestive enzymes
• Break down food, bacteria,
and worn out cell parts for
cells
• Programmed for cell death
(AUTOLYSIS)
• Lyse (break open) & release
enzymes to break down &
recycle cell parts)

120
Cilia & Flagella
• Made of protein tubes
called microtubules
• Microtubules arranged
(9 + 2 arrangement)
• Function in moving cells,
in moving fluids, or in
small particles across the
cell surface

121
Cilia & Flagella
• Cilia are shorter
and more
numerous on cells
• Flagella are longer
and fewer (usually
1-3) on cells

122
Vacuoles
• In plants, they store Cell
Sap
• Includes storage of sugars,
proteins, minerals, lipids,
wastes, salts, water, and
enzymes

123
Contractile Vacuole
• Found in unicellular
protists like paramecia
• Regulate water intake by
pumping out excess
(homeostasis)
• Keeps the cell from lysing
(bursting)
Contractile vacuole animation

124
Chloroplasts
• Surrounded by DOUBLE
membrane
• Outer membrane smooth
• Inner membrane modified
into sacs called Thylakoids
• Thylakoids in stacks called
Grana & interconnected
• Stroma – gel like material
surrounding thylakoids

125
Chloroplasts
• Contains its own DNA
• Contains enzymes &
pigments for
Photosynthesis
• Never in animal or
bacterial cells
• Photosynthesis – food
making process

CHEMICAL BASIS OF LIFE
WHY CHEMISTRY IN BIOLOGY?
1. Body function depends on cellular function.
2. Cellular functions results from chemical changes
3. Biochemistry helps to explain physiological
processes, and develop new drugs and methods for
treating diseases

127
Structure of Matter
Matter – anything that takes up space and has
weight; composed of elements
Elements – composed of chemically identical
atoms
• bulk elements – required by the body in
large amounts
• trace elements – required by the body in
small amounts
Atoms – smallest particle of an element

http://www.corrosionsource.com/handbook/periodic/periodic_table.gif

130
Atomic Structure
Atoms - composed of
subatomic particles:
• proton – carries a single
positive charge
• neutron – carries no
electrical charge
• electron – carries a single
negative charge
Nucleus
• central part of atom
• composed of protons
and neutrons
• electrons move around the
nucleus

131
Atomic Number and
Atomic Weight
Atomic Number
• number of protons in the nucleus of one atom
• each element has a unique atomic number
• equals the number of electrons in the atom
Atomic Weight
• the number of protons plus the number of neutrons
in one atom
• electrons do not contribute to the weight of the
atom

132
Isotopes
Isotopes
• atoms with the same atomic numbers but
with different atomic weights
• atoms with the same number of protons
and electrons but a different number of
neutrons
• oxygen often forms isotopes (O16, O17,
O18)
• unstable isotopes are radioactive; they
emit energy or atomic fragments

133
Molecules and Compounds
Molecule – particle formed when two or more
atoms chemically combine
Compound – particle formed when two or more
atoms of different elements chemically combine
Molecular formulas – depict the elements present
and the number of each atom present in the molecule
H2 C6H12O6 H2O

134
Bonding of Atoms
• each shell can hold a limited number of
electrons
• for atoms with atomic numbers of 18 or less, the following rules apply:
• the first shell can hold up to 2 electrons
• the second shell can hold up to 8 electrons
• the third shell can hold up to 8 electrons
• bonds form when atoms combine with other atoms
• electrons of an atom occupy regions of space called electron shells
which circle the nucleus

135
Bonding of Atoms
• lower shells are filled
first
• if the outermost shell is full, the atom is stable

136
Ions
Ion
• an atom that gains or loses electrons to become stable
• an electrically charged atom
Cation
• a positively charged ion
• formed when an atom loses
electrons
Anion
• a negatively charged ion
• formed when an atom gains electrons

137
Ionic Bond
• an attraction between a cation and an anion
Ionic Bond
• formed when electrons are transferred from one
atom to another atom

138
Covalent Bond
Formed when atoms share electrons
•Hydrogen atoms form single bonds
•Oxygen atoms form two bonds
•Nitrogen atoms form three bonds
•Carbon atoms form four bonds
H ― H
O = O
N ≡ N
O = C = O

139
Ionic Compounds Covalent Compounds
Made of metal and non-metals Two or more Non-metals
Dissolve ready in water Many do not dissolve in water
Dissociate into + or – ions surrounded by hydration shells Remain intact molecules
Many inorganic compounds All organic compounds
Electrolytes in water Non-electrolytes
Crystalline structure Amorphous

140
Structural Formula
Structural formulas show how atoms bond and are
arranged in various molecules (covalent compounds)

141
Polar Molecules
Polar Molecule ( polar covalent molecules)
• molecule with a slightly negative end and a slightly
positive end
• results when electrons are not shared equally in covalent
bonds
• water is an important polar molecule

Polarity of Water
• Responsible for properties of water
• Adhesion, cohesion, surface tension
• Capillary action
• “Universal solvent” can dissolve ionic and
some covalent compounds
142

143
Hydrogen Bonds
Hydrogen Bond
• a weak attraction between the positive end of one
polar molecule and the negative end of another polar
molecule
• formed between water molecules
• important for protein and nucleic acid structure

144
Chemical Reactions
Chemical reactions occur when chemical bonds form or
break among atoms, ions, or molecules
Reactants are the starting materials of the reaction- the
atoms, ions, or molecules
Products are substances formed at the end of the
chemical reaction
NaCl  Na+ + Cl-
Reactant Products

145
Types of Chemical Reactions
Synthesis Reaction – more complex chemical structure
is formed
A + B  AB
Decomposition Reaction – chemical bonds are broken to form
a simpler chemical structure
AB  A + B
Exchange Reaction – chemical bonds are broken and new
bonds are formed
AB + CD  AD + CB
Reversible Reaction – the products can change back to
the reactants
A + B n AB

146
Acids, Bases, and Salts
Electrolytes – substances that release ions in
water
Acids – electrolytes that dissociate to release hydrogen ions
in water
HCl  H+ + Cl-
Bases – substances that release ions that can combine with
hydrogen ions
NaOH  Na+ + OH-
Salts – electrolytes formed by the reaction between an
acid and a base
NaCl  Na+ + Cl-
HCl + NaOH  H2O + NaCl

147
Buffers
Buffers are the salts of weak acids. They can
keep the pH of a solution from shifting too
rapidly. The can help maintain pH within a
narrow range.
A buffer can neutralize either an acid
or a base. With an acid it acts as a base. With a
base it can act as an acid.
An example is NaHCO3

148
Acid and Base Concentrations
pH scale - indicates the
concentration of hydrogen ions in
solution
Neutral – pH 7; indicates equal
concentrations of H+ and OH-
Acidic – pH less than 7; indicates a greater
concentration of H+
Basic or alkaline – pH greater than 7;
indicates a greater concentration of OH-

149
Organic Versus Inorganic
Organic molecules
• contain C and H
• usually larger than inorganic molecules
• dissolve in water and organic liquids
• carbohydrates, proteins, lipids, and nucleic
acids
Inorganic molecules
• generally do not contain C
• usually smaller than organic molecules
• usually dissociate in water, forming ions
• water, oxygen, carbon dioxide, and
inorganic salts

150
Inorganic Substances
Water
• most abundant compound in living material
• two-thirds of the weight of an adult human
• major component of all body fluids
• medium for most metabolic reactions
• important role in transporting chemicals in the body
• absorbs and transports heat
Oxygen (O2)
• used by organelles to release energy from nutrients
in order to drive cell’s metabolic activities
• necessary for survival

151
Inorganic Substances
Carbon dioxide (CO2)
• waste product released during metabolic reactions
• must be removed from the body
Inorganic salts
• abundant in body fluids
• sources of necessary ions (Na+, Cl-, K+, Ca2+, etc.)
• play important roles in metabolism

152
Organic Substances
Carbohydrates
• provide energy to cells
• supply materials to build cell structures
• water-soluble
• contain C, H, and O
• ratio of H to O close to 2:1 (C6H12O6)
• monosaccharides – glucose, fructose
• disaccharides – sucrose, lactose
• polysaccharides – glycogen, cellulose

153
Organic Substances
Carbohydrates

156
Organic Substances
Lipids
• soluble in organic solvents; insoluble in
water
• fats (triglycerides)
• used primarily for energy; most common lipid in the body
• contain C, H, and O but less O than carbohydrates (C57H110O6)
• building blocks are 1 glycerol and 3 fatty acids per molecule
• saturated and unsaturated

157
Organic Substances
Lipids
• phospholipids
• building blocks are 1 glycerol, 2 fatty acids, and 1 phosphate per
molecule
• hydrophilic and hydrophobic
• major component of cell membranes
2-25

158
Organic Substances
Lipids
• steroids
• four connected rings of carbon
• widely distributed in the body, various functions
• component of cell membrane
• used to synthesize hormones
• cholesterol

159
Organic Substances
Proteins
• structural material
• energy source
• hormones
• receptors
• enzymes
• antibodies
• building blocks are amino acids
• amino acids held
together with
peptide bonds
2-27

161
Organic Substances
Nucleic Acids
• carry genes
• encode amino acid sequences of proteins
• building blocks are nucleotides
• DNA (deoxyribonucleic acid) – double polynucleotide
• RNA (ribonucleic acid) – single polynucleotide

162
Organic Substances
Nucleic Acids

163
DNA RNA
A-T and G-C A-U and G-C
Double helix Single strand
Can’t leave nucleus Active in cytoplasm
Replication and Transcription Translation of proteins
1 kind Many types

164
Macro-
molecule
Elements Building blocks
(monomers)
Example
monomers
Bonding Use Key vocabulary Example
polymers
Polymer
formula
Chemistry
Carbo-
hydrates
C1H2O1 Monosaccharides
Or
simple sugars
Glucose,
Fructose, Ribose
Covalent
COH to COH
producing
-C-O-C-
bonds
Short term
energy from
Cellular
respiration
Disaccharides,
Polysaccharides
Amylose or Plant
Starch,
Glycogen,
Cellulose
(C1H2O1)n –
(H2O)n-1
Dehydration
synthesis and
Hydrolysis
Enzymes =
-ase
Lipids CHO (P) Glycerol and fatty acids Glycerol and
Essential fatty
acids such as
linoleic acid and
alpha linoleic acid
Covalent
COH to COOH
or
POOH
producing
COOC or
COOP bonds
Long term
energy
storage,
Insulation,
Cushioning
Low density lipids
LDL
High density Lipids
HDL
Saturated,
unsaturated,
polyunsaturated
fatty acids
Cholesterol
Triglycerides,
Steroids, Waxes
Phospholipids
Dehydration
synthesis and
Hydrolysis
Enzymes =
-ase
Proteins CHON (S) Amino Acids 20 essential amino
acids , groups
acidic, basic,
neutral, and rings
Covalent
COH to NH2
producing C-N
bond
Energy use,
enzymes,
Transport, cell
markers,
muscle
Dipeptides,
Polypeptides,
Enzymes, Transport
proteins, Hormones
Linear proteins,
globular proteins
(Aa)n – (H2O)n-
1
Dehydration
synthesis and
Hydrolysis
Enzymes =
-ase
Nucleic
Acids
CHONP Nucleotides Adenine, Thymine
Guanine
Cytosine
Uracil
Covalent COC
COOP and
Hydrogen
bonds
Making DNA
and RNA,
information
storage
Double Helix,
Genes, Genomes,
Ribosomes
DNA, mRNA
tRNA, rRNA, and
other RNA’s
NA Dehydration
synthesis and
Hydrolysis
Enzymes =
-ase

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