Transcript The Chemistry of Life

The Chemistry of Life
1. Matter and Organic Compounds
2. Water, Acids, and Bases
3. Biochemical Reactions
1. Matter and Organic Compounds
• Matter = anything that takes up space and has
mass
• All “things” are made of matter
• Matter is made up of chemical substances
– Chemical substance = definite composition
throughout
• Either “element” or “compound”
• Elements = pure substances
– Found in the Periodic Table of Elements
• Roughly 93 elements are found in nature, with more
created by man (mostly radioactive)
– Metals – copper, magnesium, iron
– Nonmetals – oxygen, hydrogen, nitrogen,
phosphorus
– Metalloids - silicon
Compounds
• Compound = a substance that is made of
1 or more elements in a fixed ratio
– The smallest particle of a compound =
molecule
– Example = water (H2O)
• Created by chemical reactions
– Making and breaking of bonds (ionic,
covalent, hydrogen)
• Forces keep elements together
Elements Quiz Friday ~ September 28
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Know the element name &
symbol for…
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Hydrogen (H)
Carbon (C)
Nitrogen (N)
Oxygen (O)
Phosphorus (P)
Sulfur (S)
Potassium (K)
Sodium (Na)
Calcium (Ca)
Chlorine (Cl)
Magnesium (Mg)
Iron (Fe)
Also know…
 The
5 most
abundant elements
in the human body
 The uses for 2
elements of your
choice
Chemical Bonding
Graphic Organizer
Chemical Bonding is about…
2
or more atoms combining
in relation to one another
(like a friendship)
Ionic Bonding
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One atom GIVES an electron to
another atom
Forms ions (any atom with a
charge)
Outer electron shell of each atom
is full
Ionic Bonds
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Some atoms become stable by losing or
gaining electrons
Atoms that lose electrons are called
positive ions
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Atoms that gain electrons are called
negative ions
Because positive and negative electrical
charges attract each other ionic bonds
form
Covalent Bonding
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Forms when 2 atoms SHARE
electrons
The number of bonds an atom will
form usually equals the number of
additional electrons that will fill its
highest energy level
Forms a molecule
Covalent Bonds
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Formed when two atoms share one or
more pairs of electrons
What is important to understand
about chemical bonding?
 Bonds
form molecules
that living organisms
need to survive & exist
(ex. Food)
2. Water, Acids, and Bases
• Water (H2O)
– Almost 75% of Earth’s surface is covered in water
– 3 states of matter (most abundant first)
1.
2.
3.
Liquid
Solid
Gas
– Composed of 2 hydrogen atoms bonded to 1 oxygen
atom
Water’s Properties
• Colorless, tasteless and odorless
• Polar molecule – due to uneven sharing of e– Oxygen – slight negative charge
– Hydrogens – slight positive charge
• Hydrogen bonding, due to polarity between
H2O molecules, is responsible for:
– Adhesion (between H2O and other molecules)
– Cohesion (between H2O molecules)
– Relatively High boiling point
– Solid form (ice) is less dense than liquid form
Water & Life
• Human body is composed of approximately
70% water.
• Water dissolves many substances that
organisms depend on
• Water is needed for many biochemical
reactions
– Photosynthesis 6 CO2  6 H 2O  energy  C6 H12O6  6 O2
– Cellular respiration C6H12O6  6 O 2  6 CO2  6 H 2O  energy
Solutions
• mixtures of two or more substances that has
the same composition throughout
• Made up of a solute that is mixed into a
solvent
– H2O is a universal solvent
• Some solutions are acidic or basic
– Acids = excess hydronium ions(H3O+)
– Bases = excess hydroxide ions (OH- )ions
Acids, Bases & pH
• Acidity = measure of hydronium ions (H3O+) in
a solution
– Use pH scale to measure
• pH 7 = neutral (pure water)
• pH below 7 = acidic strongest is closer to 1
• pH above 7 = basic
strongest is closer to 14
• Acids – taste sour, can damage proteins (organisms)
and materials at really low pH levels
• Bases – taste bitter, can damage proteins (organisms)
and materials at really high pH levels
Macromolecules
1.
2.
3.
4.
Carbohydrates
Lipids
Proteins
Nucleic Acids
The Significance of Carbon
• Organic compounds – compounds made of
mainly carbon
– Make up many compounds found in
• Cells
• Other structures of organisms
• Compounds that perform life processes
• Carbon can form 4 stable bonds with other
carbons and other elements
• Roughly, 10,000,000 carbon-based
compounds in living things
Energy from Carbon
• Living things can use organic compounds as an
energy source.
– Carbon’s capability to form 4 bonds is the reason
for carbon’s success
• Bonds = energy
– Breaking bonds -> release energy
– Forming bonds -> store energy
Macromolecules
• Large organic molecules.
• Also called POLYMERS.
• Made up of smaller “building blocks”
called MONOMERS.
• Examples:
1. Carbohydrates
2. Lipids
3. Proteins
4. Nucleic acids (DNA and RNA)
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Type of Organic
Compound
Examples
Carbohydrates Sugars, starches,
cellulose
Elements
Functions
Carbon, hydrogen,
oxygen
provides energy to
cells, stores energy,
forms body structures
Carbon, hydrogen,
oxygen
stores energy, forms
cell membranes, carries
messages
Lipids
Fats, oils, waxes,
cholesterol,
phospholipids
Proteins
Enzymes,
Carbon, hydrogen,
antibodies, keratin, oxygen, nitrogen,
collagen
sulfur
helps cells keep their
shape, makes up
muscles, speeds up
chemical reactions,
carries messages and
materials
Nucleic Acids
DNA, RNA
contains instructions
for proteins, passes
instructions from
parents to offspring,
helps make proteins
Carbon, hydrogen,
oxygen, nitrogen,
phosphorus
Question:
How are
Macromolecules
formed?
Answer: Dehydration Synthesis
• Also called “condensation reaction”
• Forms polymers by combining
monomers by “removing water”.
HO
H
HO
H
H2O
HO
H
Question:
How are
Macromolecules
separated or
digested?
Answer: Hydrolysis
• Separates monomers by “adding
water”
HO
H
H2O
HO
H
HO
H
Carbohydrates
• the most common type of organic compound.
• Functions
– Store energy (sugars, starch, glycogen)
– Structural support (cellulose, chitin)
• built of small, repeating units that form bonds
with each other to make a larger molecule
– the small repeating units are called
monosaccharides
Monosaccharides
• simple sugars
– Monomers of carbohydrates
• Job : sugars contain stored energy
• Examples:
• Glucose- generally results from the digestion of other
carbohydrates.
– Glucose is used for energy by the cells
• Fructose- is found in fruit
• Galactose- is found in milk (makes up lactose)
Carbohydrates
• Disaccharides: double sugars
Examples: Sucrose – table sugar
maltose – malt sugar (grain)
lactose – milk sugar
Polysaccharides
• A complex carbohydrate that forms when
simple sugars bind together in a chain.
• 2 main functions:
– storing energy
– forming structures of living things.
• Some examples of complex carbohydrates are
on the next slide
Some Complex Carbohydrates
Name
Function
Example
Starch
Used by plants to store
energy
A potato stores starch
in underground tubers.
Glycogen
Used by animals to
store energy
A human being stores
glycogen in liver cells.
Cellulose
Used by plants to form
rigid cell walls around
cells
A ragweed plant uses
cellulose for cell walls.
Chitin
Used by some animals
to form an exoskeleton
A housefly uses chitin
for its exoskeleton.
Build a Glucose Monomer…
CARBON - 6
HYDROGEN 12
OXYGEN - 6
Lipids
• Lipids are fats, oils & waxes
Three major roles:
1. Store energy (more energy per
gram
than carbohydrates)
2. Form membranes
3. Used as chemical messengers
Lipids
Monomer:
• Formed by a combination of fatty acids &
glycerol.
Saturated Fatty Acids
• In saturated fatty acids, carbon atoms are
bonded to as many hydrogen atoms as
possible.
– This causes the molecules to form straight chains
• The straight chains can be packed together very tightly
– allowing them to store energy in a compact form
• explains why saturated fatty acids are solids at room
temperature.
• Animals use saturated fatty acids to store
energy.
• Example: butter and lard
Unsaturated Fatty Acids
• In unsaturated fatty acids, some carbon atoms
are not bonded to as many hydrogen atoms as
possible
• some double and triple bonding between carbons
– It causes chains to bend
• The bent chains cannot be packed together very tightly
• unsaturated fatty acids are liquids at room
temperature.
• Plants use unsaturated fatty acids to store
energy.
• Example: Oils
Examples of fatty acids that make
up fats
Saturated fatty acids
The rest are
unsaturated fatty
acids
Polyunsaturated fatty
acids = multiple double
bonds in the chain
Types of Lipids
• Lipids may consist of fatty acids alone, or they
may contain other molecules as well.
– some lipids contain alcohol or phosphate groups.
They include
1. triglycerides: the main form of stored energy in
animals
2. phospholipids: the major components of cell
membranes
3. steroids: serve as chemical messengers and have
other roles such as cholesterol in the cell membrane
Proteins
• Made up of C, H, O and N
• Monomers are called Amino Acids
• Amino Acids are carbon chains with an
amino group attached to one end and a
carboxyl group on the other end.
Amino
Acids
• Amino acids
vary by their
“side” group,
also known as
the “R” group
Protein Structure
• When amino acids bind together, they form a
long chain called a polypeptide.
• A protein consists of one or more polypeptide
chains.
– four levels of structure.
• The lowest level, a protein’s primary structure, is its
sequence of amino acids.
• The complex structures of different proteins give
them unique properties, which they need to carry
out their various jobs in living organisms.
Proteins
• Jobs:
1. Help carry out chemical reactions
(enzymes)
2. Pump small molecules in & out of
cells. (channels)
3. Responsible for cell movement
(cilia and flagella)
Nucleic Acids
• Made of: C, O, H, N & P
• Monomer:
Nucleotide:
1. 5 carbon sugar (pentose)
2. Phosphate Group
3. Nitrogenous Base
Example of a nucleotide
Nucleic Acid
• Ribonucleic Acid (RNA)
Contains the sugar Ribose
• Deoxyribonucleic Acid (DNA)
Contains the sugar Deoxyribose
(“deoxy” means less oxygen)
Nucleic Acid
• Job – Transmit Genetic Information
Chemical Reactions and
Enzymes
4. Biochemical Reactions
• A biochemical reaction is a process that
changes some chemical substances into
others.
– a substance that starts a chemical reaction is
called a reactant
– a substance that forms as a result of a chemical
reaction is called a product.
• During a chemical reaction, the reactants are
used up to create the products.
reactant + reactant → product(s)
Combustion = chemical reaction
Example:
Methane gas + oxygen gas burns to create
carbon dioxide and water
OR
CH4 + 2O2 → CO2 + 2H20
Arrow represents a reaction has occurred!
Conservation of Matter
• The QUANTITY of each element does not
change
– Reactants’ elements = Products’ elements
– Same # of atoms of each element appears on each
side of the reaction arrow
Chemical reactions & Energy
Exothermic reactions
• Releases energy (as heat)
• Reactants  Products + Heat
• Example - combustion
Endothermic reactions
• Absorbs energy from the
environment (feels cold)
• Reactants + Heat  Products
• Example – chemical ice pack
Activation Energy
ALL CHEMICAL REACTIONS NEED ENEWRGY TO
GET STARTED!
• Starting energy = activation energy
• Activation energy gives the “push” needed for
chemicals to start interacting  reacting with
each other
– Some reactions require more energy than others
Biochemical Reactions
• Reactions that take place inside cells
• Metabolism = sum of all biochemical reactions
in an organism
– Catabolism – exothermic reaction
• Breakdown molecules into smaller ones
• Example – digesting food, using glucose
– Anabolism – endothermic reaction
• Build-up large molecules from smaller ones
• Example – storing fat, building muscle
Enzymes
• Proteins that speed up biochemical reactions
• allow biochemical reactions to proceed with
less activation energy
• Are not used up during reaction (recycled)
• Depend on several factors:
– Temperature
– Ionic conditions
– Surrounding pH