Welcome to Bio11
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Class schedule - see my website
Texts: Human Biology by S. Mader
 Bio11 Lab Manual: Instructor Ann Reisenauer
My faculty website
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Chemistry of life
http://www.deanza.edu/faculty/reisenauerann/
Lecture outlines, lab worksheets, extra credit
How to contact me:
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Email: [email protected]
Office hours: TuTh 1-1:30 pm in Science Center 1, 2nd floor or
by appt
Preview: Chemistry basics
What are atoms?
We’ll start with the basics
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Atoms
How atoms hook up make molecules
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Ionic bonds
Covalent bonds
Hydrogen bonds
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Unique properties of water
Extremely small
Definition: the smallest
particle that retains the
chemical properties of its
substance
The basic building blocks
of everyday objects.
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The structure of atoms
A desk, the air, even you are
made up of atoms!
Electrons
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All atoms have the same structure
 dense nucleus composed of
 protons (positively charged)
 neutrons (not charged)
 a cloud of negative charge
 electrons
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Negatively charged
Orbit around the
nucleus in electron
shells
They are the parts of
the atom that come
close enough to interact
with other atoms
What are the most common
atoms found in living organisms?
Chemical symbol?
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Hydrogen
Carbon
Nitrogen
Oxygen
H
Periodic table of the elements
Elements cannot be broken down
into other substances.
There are 92 naturally occurring
elements.
C
N
O
Figure 2.2
Isotopes
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What are Molecules?
different forms of an element
Isotopes have the same number of protons and
electrons, but different number of neutrons.
Groups of atoms held
together by chemical
bonds
3 types of chemical
bonds:
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1.
2.
Carbon-14 is unstable
or radioactive: the
nucleus decays giving
off particles and energy
How atoms hook up ...
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3.
Ionic bonds
Covalent bonds
Hydrogen bonds
Electrons are found in “shells”
Electrons determine how an atom
behaves when it encounters other
atoms
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Inner shell holds 2 electrons
Most electron shells hold up to 8
electrons
Atoms react with other atoms in order to
fill the outer electron shell
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Nitrogen (N)
Atomic number = 7
atoms that have incomplete electron
shells will lose, gain, or share electrons
in order to fill their outermost electron
shell
This is the basis of chemical bonds
Chemical Bonds
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Ionic Bonds
Atoms give up or acquire
electrons in order to
complete their outer
shells.
These interactions
usually result in atoms
staying close together.
The atoms are held
together by chemical
bonds.
Table salt (NaCl)
– an example of ionic bonding
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Electron transfer
Cl
sodium atom (Na)
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chlorine atom (Cl)
–
+
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Na + Cl–
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Cl
Na
sodium ion (Na+ )
a.
Ionic bonds form when ions
of opposite charges are
attracted to each other
Covalent bonds form when
two atoms share electrons
Covalent bonds are stronger
than ionic bonds
Most biological molecules are
held together by covalent
bonds
Water molecules contain 2
covalent bonds
H2O
chloride ion (cl– )
sodium chloride (NaCl)
Charged atoms are called
ions.
Covalent bonds
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Na
When an atom loses or
gains electrons, it becomes
electrically charged.
b.
b(crystals): © Charles M. Falco/Photo Researchers, Inc.; b(shaker): © The McGraw- ill Companies,
Inc./Evelyn Jo Johnson, photographer
Covalent and ionic bonds
Hydrogen bonds
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http://www.youtube.com/watch?v=QqjcCvzWwww&feature=related
Weak bonds
Form when the slightly positive
end of one molecule is attracted to
the negative end of another
The shared electrons in H2 O are
unevenly distributed, giving the
molecule a slightly positive end
and a slightly negative end.
Scientists use chemical formulas
to describe molecules
Hydrogen bonds
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Very important in biology
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Hold water molecules
together
Hold protein molecules in
their proper 3D shape
Hold the two DNA strands
together
And much more
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O
H
H2 O
2 hydrogen atoms
1 oxygen atom
Ions – atoms that have gained or lost
one or more electrons
The body is about 70%
water
Found both inside and
outside the cells
Functions
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Isotopes – atoms that have the same
number of protons and electrons but
different numbers of neutrons
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What are the properties of
water?
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Liquid at room temperature
The temp of liquid water changes
slowly, preventing drastic changes
High heat of vaporization
Water molecules cling together
A solvent for charged (polar) molecules
H
Water is critical for body
functions
How are ions and isotopes
different?
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The chemical
formula for water is
H2 O. What does
that mean?
A water molecule
contains
Helps regulate body
temperature
Transports nutrients
Excretion of waste
products
What bond holds water
molecules together?
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
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Hydrogen bonds occur
between a hydrogen in
a covalent bond and
a negatively charged
atom
These are relatively
weak bonds
δ–
H
O
H
δ+
hydrogen
bond
δ+
Water’s Life-Supporting
Properties
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How does water support life?
 Because it forms hydrogen bonds
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Hydrogen bonds are responsible for
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Water’s cohesive nature
Water’s ability to moderate temperature
Versatility of water as a solvent
Biological Molecules
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A cell is mostly water.
The rest of the cell consists of 4 types
of macromolecules:
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Building BIG Molecules
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Macromolecules – or giant molecules
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Carbohydrates
Lipids
Proteins
Nucleic acids
Many Biological Molecules Connect to
Form Macromolecules
Monomers – Small Molecules/Building Blocks
Examples: carbohydrates, protein, DNA,
Most macromolecules are polymers
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made by stringing together many smaller building
blocks, or monomers
Polymers – Large Molecules
Carbohydrates
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Carbohydrates include:
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Simple sugars – in soft drinks
Polysaccharides or polymers of simple sugars
 Long starch molecules – in pasta and potatoes
Carbohydrate Monomers
(simple sugars or monosaccharides)
Monomers or
Building Blocks
Primary source of energy for living
organisms
Also Called a “Monosaccharide”
Sucrose–the most common
disaccharide
Carbohydrate Polymers
Polysaccharides (Sugars/Starches)
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Disaccharide
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The amount of sugar the average
American eats in a year
Polysaccharides
Polar
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Sucrose – common table
sugar – is made of
glucose linked to fructose
Lactose intolerance
Polysaccharides
Lactose is another
type of disaccharide.
Some people have
trouble digesting
lactose–they lack
the digestive
enzyme that breaks
down lactose.
• Polymers – long chains of monosaccharides
Lipids
Lipids
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Fats and other organic compounds
that are not soluble in water
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Nonpolar
Function: to store energy
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Dietary fat consists largely of the molecule
triglyceride.
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Triglyceride is a combination of glycerol and 3
fatty acids.
Cholesterol/Steroids
Kinds of Fats
Grouped with Lipids
Unsaturated Fatty Acids
(Some Double Bonds C=C)
Reduce Heart Disease
Risk
Saturated Fatty Acids
(All Single Bonds C-C)
Heighten Heart
Disease Risk
Trans-Fatty Acids (Hydrogenated)
Heighten Heart
Disease Risk
Not Found Naturally!
Nonpolar
X
Synthetic anabolic steroids
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Variants of testosterone
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Proteins
Use is controversial.
Some athletes use anabolic
steroids to build up their
muscles quickly.
Anabolic steroids pose serious
health risks
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Polymers constructed from amino
acid monomers
Mood swings
Depression
Liver damage
High cholesterol
Protein Monomers
Protein Polymers
Polar
Come in 20 Different Flavors!
(Lysine, Valine, Tryptophan, Proline, etc.)
and
X
Nonpolar
Polypeptides
Function of proteins:
body structures
Nucleic Acids
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Enzymes that Help Do Work
Nucleic Acid Monomers
Information storage molecules.
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Function of proteins:
They provide the directions for building proteins.
Found in nucleus
Nucleotides
Come in 5 flavors!
(A, C, G, T/U)
There are 2 types of nucleic acids:
 DNA, deoxyribonucleic acid
 RNA, ribonucleic acid
DNA Nucleotide
RNA Nucleotide
The structure of DNA
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Two strands of DNA
join together to form
a double helix.
Note the hydrogen
bonds between the
base pairs
Summary of DNA and RNA
structural differences
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DNA
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Sugar is deoxyribose
Bases include A, T,
C and G
Double stranded
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RNA
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Sugar is ribose
Bases include A, U,
C and G
Single stranded