Transcript Chapter 2

Chapter 2
The chapter that defines all that
follow after…
Section 1: The Nature of Matter
•
Atoms: the smallest
particle of an
element that has the
properties of that
element
–
electron
neutron
Parts of an atom:
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Protons – positively
charged, found in
core
Neutrons – no
charge, found in core
Electrons –
negatively charged,
found in a cloud
around the core
proton
Atoms bond together …
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Elements
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consists of only one kind of atom,
cannot be broken down into a simpler type of matter by either physical
or chemical means, and
can exist as either atoms (e.g. argon) or molecules (e.g., nitrogen).
NOTE: A molecule consists of two or more atoms of the same element, or different elements, that are
chemically bound together. Note that the two nitrogen atoms which comprise a nitrogen
molecule move as a unit.
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Compounds
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consists of atoms of two or more different elements bound together,
can be broken down into a simpler type of matter (elements) by
chemical means (but not by physical means),
has properties that are different from its component elements, and
always contains the same ratio of its component atoms.
Ions
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Charged (positive/negative) atoms due to loss or gain of an electron
Cations - have more protons than electrons and are positively charged
Anions - have more electrons than protons and are negatively charged
Three Types of Bonds
Covalent Bonds – (electron sharing) –
formed when electrons are shared
between two elements – strongest
type of bond Ex. H + Cl = HCl
Ionic Bonds – (electron donating) –
electrons from one atom are
donated to another creating an ion
(atoms that are positively charged
due to the loss of electrons or
negatively charged due to addition
of electrons) - positive and negative
atoms are attracted to each other
creating the bond Ex. Na + Cl =
Na+ClHydrogen Bonds – (weak electrical
attractions) – larger Oxygen
molecules pull smaller Hydrogen
molecules closer – “almost” share
an electron
Ex. 2H + O = H2O
Section 2: Water and Solutions
• Properties of Water
– Water is polar – it has a positive and negative side
• Solutions – substances dissolved in water (Ex. Salt water)
– Polar molecules can dissolve in water creating a solution
– Non-polar molecules (like oil) can not dissolve in water and do not
create a solution
– Water is cohesive – water molecules stick together
– Water is adhesive – Water molecules stick to other
substances
– Water stores heat efficiently (High Specific Heat, High Heat
of Vaporization)
– Water is less dense as a solid
Water is polar …
Water is a good
solvent.
- Water dissolves
polar molecules
and ions.
-hydrophilic: “waterloving”
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Water is polar …
• Water organizes nonpolar molecules.
• hydrophobic: “waterfearing”
- Water causes
hydrophobic
molecules to
aggregate or assume
specific shapes.
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Cohesion
Cohesion is the property of water that causes it to be
attracted to itself.
http://www.realeyz.com/photo/macro/photos/leaf_drops.jpg
Surface Tension
•Surface tension measures the strength of water
molecules attracting to one another.
•This property allows insects to walk on the
surface of water and the creation of waves.
Adhesion
Attraction between molecules of different
substances
Ex: glass and water
Or a visit to the doc
Capillarity Water molecules will “tow” each
other along when in a thin glass tube.
http://staff.um.edu.mt/rlib1/sm/wpe32.jpg
Did you ever wonder: How does water
move from roots to leaves when a tree
doesn’t have a heart to pump the
water?
Cohesion-Adhesion Theory
(aka Transpiration)
-As water evaporates from leaves,
it tugs on the water molecules
below
-Cohesion and adhesion pull water
up and replace missing water
molecules
-Water enters the roots by osmosis
www.emc.maricopa.edu/.../BioBookPLANTHORM.html
High Specific Heat
•Water resists temperature change, both for
heating and cooling.
•Water can absorb or release
large amounts of heat energy
with little change in actual
temperature.
High Heat of Vaporization
• In order for water to evaporate, hydrogen bonds
must be broken. As water evaporates, it removes a
lot of heat with it.
•Thus, the heat of vaporization refers to the
amount of energy required to convert water from a
liquid to a gas.
Water is Less Dense as a Solid
•Which is ice and which is water?
Density of Ice
•Most solids are more
dense than their liquids
•This makes solids sink
•Ice is less dense than
liquid water
•Due to H-Bonds
•Important to life
because bodies of water
freeze top down
•Allows life to survive
below
http://shiftingbaselines.org/blog/images/Iceberg.jpg
Acids & Bases
pH Scale
Measurement of the
concentration of hydrogen ions
Acid: forms H+ when
dissolved in water
High concentration of [H+]
(or hydronium ion);
low conc. of [OH-]
Base: reduces H+Stomach
whenAcid = pH
dissolved in water
High [OH-]
(a.k.a. hydroxide ion);
low [H+]
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Section 3: Chemistry of Cells
Organic Compounds
• Organic compounds are
those that contain carbon.
(with a few exceptions such
as carbon dioxide and
diamonds)
• There are four major types
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Carbohydrates
Lipids
Proteins
Nucleic Acids
Carbohydrates
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Carbohydrates – Made of carbon, hydrogen,
and oxygen in the proportion of 1:2:1
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1 carbon:2 hydrogen:1 oxygen
main source of energy;
provide structure in plants
3 Types of Carbohydrates
Monosaccharide (simple sugars) – the building
blocks of carbohydrates Ex. Glucose and
Fructose (fruit sugars)
Disaccharides (double sugars) – 2 or more
monosaccharides put together Ex. Sucrose
(table sugar) and Lactose (milk sugar)
Polysaccharides (many sugars) – 3 or more
monosaccharides put together Ex. Rice,
potatoes, beans, corn, pasta, bread
Monosaccarides (simple sugars)
the building blocks of carbohydrates
• EXAMPLES:
• Glucose (product of photosynthesis, used
in cellular respiration)
• Fructose (fruit sugar)
Disaccharides (double sugars)
2 or more monosaccharides put
together
• EXAMPLES
• Sucrose (table sugar)
• Lactose (milk sugar)
Polysaccharides (many sugars)
3 or more monosaccharides put
together
Examples of polysaccharide groups
Starches: plants store energy (extra glucose)
in this form (rice, potatoes, beans, corn)
Glycogen: animals store energy (extra glucose) in this form in two
areas, the muscles and liver, when these are full the remaining
energy is stored in fats.
Cellulose – used in the structure of the cell wall of plants. Cannot be
digested by humans but is essential for digestive health.
Lipids
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insoluble organic compounds (do not dissolve in
water);
made of fatty acids and glycerol in the proportion
of 1:3;
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1 glycerol : 3 fatty acids
held together by hydrogen bonds;
store a lot of energy
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Contain almost 2x the energy found in carbohydrates (9
calories VS 4 calories)
4 Types of Lipids
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Fats/Oils
Waxes
Phospholipids
Steroids
Fats and oils
provide long term energy storage and act
as insulation to keep animals warm
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Fat is solid at room Temp, oils are
liquid
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Saturated fats – stick butter, lard, that
whitish waxy looking stuff that forms
on a steak or hamburger in the
refrigerator; unhealthy fats, effect
heart/liver functions, weight gain, and
cholesterol levels
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Unsaturated fats – olive oil, fish oil, etc
are much better for you and can even
raise your level of “good” cholesterol.
Waxes & Phospholipids
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Waxes – provide protection by repelling water (Ex.
Cuticle of plants); naturally occur on fruits and
vegetables to prevent dehydration
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Phospholipids –
make up the cell membrane
Steroids
• Serve structural and control functions in
the body
• Examples
– Hormones such as Estrogen and
Testosterone
– Cholesterol that is produced by the body
Proteins
Large complex molecules made of amino acids
(20 amino acids are used to make a variety of protein combinations)
How the amino acids are arranged is key to biodiversity.
• 6 Major Protein Functions:
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Movement – actin and myocin are proteins needed for contraction and relaxation of muscle fibers
and therefore muscle movement
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Structure – collagen is the most abundant protein in the human body, it gives elasticity and firmness
to skin; forms bones, tendons, ligaments, and cartilage.
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Defense – antibodies are proteins that help animals fight off invasion by viruses and bacteria
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Transport – hemoglobin is the protein in red blood cells that carries oxygen through the
bloodstream; a lack of red blood cells is called anemia
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Nutrition – casein is a protein in breast milk that stores amino acids for use by newborn mammals;
many proteins are used to build muscles and repair injuries
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Regulation – enzymes catalyze (speed up) chemical reactions in the cells; we get them from eating
raw vegetables (note the verb catalyze is from the non catalyst – a chemical that speeds a chemical
reaction without being altered itself)
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MSDTNR
Nucleic Acids
Large complex molecules that contain
hereditary or genetic information
• 2 Types of nucleic acids
– DNA (deoxyribonucleic acid) – caries
instructions that control the activities of the
cell
– RNA (ribonucleic acid) – responsible for
protein synthesis
One more important biological
molecule
ATP
• adenosine triphosphate
• energy currency of the cell; contains 2
extra energy storing phosphate groups
• cells need a steady supply of ATP to
function
Section 4:
Energy and Chemical Reactions
• Energy – the ability to move or change matter; many types
including chemical, light, heat, mechanical, and electrical
• Energy can be stored or released in a chemical reaction
» Chemical reactions are processes in which
chemical bonds between atoms are broken and
new ones formed producing one or more new
substances;
» summarized as …
reactants → products
• Metabolism – all the chemical reactions that occur within an
organism
• Activation Energy – energy needed to start a reaction (like the
first push to get a large object rolling downhill)
• Enzymes – act as a catalyst to speed up reactions once started
– Enzymes affect specific substances (ex. Amylase affects starch &
glucose) and are affected by factors like temperature and pH
Steps in the Enzyme Reaction
• Coordinating enzyme and substrate are available
• Substrate binds to enzyme’s active site
• Chemical bonds in substrate break; substrate is
converted into its products
• Products are released; enzyme is unchanged