Transcript Chemistry in Biology

Biochemistry Notes
Chapter 6
Chemistry in Biology
6.1 Atoms, Elements, and Compounds
Elements
 An element is a pure substance that cannot
be broken down
 There are over 100 known elements, 92 of
which occur naturally.
 Each element has a unique name and
symbol.
Chapter 6
Chemistry in Biology
6.1 Atoms, Elements, and Compounds
The Periodic Table of Elements
 Horizontal rows are called periods.
 Vertical columns are called groups.
Chapter 6
Chemistry in Biology
6.1 Atoms, Elements, and Compounds
 Chemistry = study of matter.
 Atoms are the building blocks of matter.
 Neutrons and protons are located at the
nucleus of the atom.
 Protons are positively charged particles.
 Neutrons are particles that have no
charge.
Chapter 6
Chemistry in Biology
6.1 Atoms, Elements, and Compounds
 Electrons are negatively charged particles
that are located outside the nucleus.
6.1 Atoms, Elements, and Compounds
• Atomic Number: number of protons in the
nucleus of an element (atom).
6.1 Atoms, Elements, and Compounds
• Atomic Mass: the number of protons & neutrons
in the nucleus of an element (atom).
• Find the neutrons only:
• Atomic mass-atomic number=neutrons
• Ex: Carbon Picture
Chapter 6
Chemistry in Biology
6.1 Atoms, Elements, and Compounds
Isotopes
 Atoms of the same element that have the
same number of protons and electrons but
have a different number of neutrons
Isotope Clip
• http://glencoe.mcgrawhill.com/sites/dl/free/0078695104/164155/
00038306.html
Chapter 6
Chemistry in Biology
6.1 Atoms, Elements, and Compounds
Radioactive Isotopes
 When a nucleus breaks apart, it gives off
radiation that can be detected and used for
many applications.
Chapter 6
Chemistry in Biology
6.1 Atoms, Elements, and Compounds
Compounds
 A pure substance formed when two or more
different elements combine
 Compounds cannot be broken down into
simpler compounds or elements by physical
means, must be a chemical reaction
Chapter 6
Chemistry in Biology
6.1 Atoms, Elements, and Compounds
Chemical Bonds
 Covalent bonds
 Chemical bond that
forms when
electrons are shared
 A molecule is a
compound in which the atoms are held
together by covalent bonds.
Chapter 6
Chemistry in Biology
6.1 Atoms, Elements, and Compounds
Ionic Bonds
 Electrical attraction between two oppositely
charged atoms or groups of atoms
Chapter 6
Chemistry in Biology
Chapter 6
Chemistry in Biology
6.1 Atoms, Elements, and Compounds
 Some atoms donate or accept electrons
easier than other atoms.
 The elements identified as metals tend to
donate electrons.
 The elements identified as nonmetals tend
to accept electrons.
Chapter 6
Chemistry in Biology
6.1 Atoms, Elements, and Compounds
van der Waals Forces
 When molecules come close together, the
attractive forces between slightly positive
and negative regions pull on the molecules
and hold them together.
 The strength of the attraction depends on
the size of the molecule, its shape, and its
ability to attract electrons.
Chapter 6
Chemistry in Biology
6.2 Chemical Reactions
Reactants and Products
 A chemical reaction is the
process by which atoms or
groups of atoms in
substances are reorganized
into different substances.
 Clues that a chemical
reaction has taken place
include the production of
heat or light, and formation
of a gas, liquid, or solid.
Chemical reaction
Physical reaction
Chapter 6
Chemistry in Biology
6.2 Chemical Reactions
Chemical Equations
 Chemical formulas describe the substances in
the reaction and arrows indicate the process of
change.
 Reactants are the starting substances, on the
left side of the arrow.
 Products are the substances formed during the
reaction, on the right side of the arrow.
Chapter 6
Chemistry in Biology
6.2 Chemical Reactions
 Glucose and oxygen react to form carbon
dioxide and water.
Chapter 6
Chemistry in Biology
6.2 Chemical Reactions
Balanced Equations
 The law of conservation of mass states matter
cannot be created or destroyed.
 The number of atoms of each element on the
reactant side must equal the number of atoms
of the same element on the product side.
Chapter 6
Chemistry in Biology
6.2 Chemical Reactions
Energy of Reactions
 The activation
energy is the
minimum amount of
energy needed for
reactants to form
products in a
chemical reaction.
Chapter 6
Chemistry in Biology
6.2 Chemical Reactions
 This reaction is
exothermic and
released heat energy.
 The energy of the
product is lower than
the energy of the
reactants.
Chapter 6
Chemistry in Biology
6.2 Chemical Reactions
 This reaction is
endothermic and
absorbed heat energy.
 The energy of the
products is higher
than the energy of
the reactants.
Chapter 6
Chemistry in Biology
6.2 Chemical Reactions
Enzymes
 A catalyst is a
substance that lowers
the activation energy
needed to start a
chemical reaction.
 It does not increase how
much product is made and it does not get
used
up in the reaction.
 Enzymes are biological catalysts.
Chapter 6
Chemistry in Biology
6.2 Chemical Reactions
 The reactants that bind to the enzyme are called
substrates.
 The specific location where a substrate binds on an
enzyme is called the active site.
Fits together like a lock and key
Chapter 6
Chemistry in Biology
6.2 Chemical Reactions
 The active site changes shape and forms
the enzyme-substrate complex, which helps
chemical bonds in the reactants to be
broken and new bonds to form.
 Factors such as pH, temperature, and the
concentrations of substrate & enzyme affect
enzyme activity.
What role do enzymes play in chemical
reactions within living organisms?
• Chemical reaction – process that changes 1
set of chemicals into another set of different
chemicals
– Reactants – starting chemicals
– Products – ending chemicals
– Involves breaking of bonds and forming new ones
• Energy
– Either released or absorbed
– Activation energy – energy needed to start a
reaction
Chapter 6
Chemistry in Biology
Enzyme Review
1. Enzymes are a form of ___.
a. carbohydrate b. lipid c. protein
2. Enzymes can speed up a reaction, so they are
called ___.
a. catalysts
b. reactants c. inhibitors
3. The area where the enzyme attaches to the
substrate is called the ___.
a. active site b. cohesion area c. vectors
4. If the enzyme is heated, it will change shape. This
______ affect the ability of the enzyme to work.
a. will
b. will not
5. Enzymes work because they lower the ___.
a. chemical reactant rate
b. active site location
c. activation energy
Chapter 6
Chemistry in Biology
6.3 Water and Solutions
Water’s Polarity
 Molecules that have an unequal distribution
of charges are called polar molecules.
 Polarity is the property of having two
opposite poles.
(Think of North & South Pole)
 A hydrogen bond is a weak interaction
involving a hydrogen atom and a fluorine,
oxygen, or nitrogen atom.
Chapter 6
Chemistry in Biology
6.3 Water and Solutions
Water Polarity
&
Hydrogen Bond
VideoClip
• http://glencoe.mcgrawhill.com/olcweb/cgi/pluginpop.cgi?it=swf::5
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Visualizing Properties of Water
Water properties:
 Water is cohesive
Cohesion: attraction between same
molecules, causes molecules to draw
inward at surface
Ex: allows some insects & spiders can
“walk” on the surface
Water is adhesive
Adhesion: attraction between different
molecules, causes water to bend at the
surface
Ex: capillary action-pulls column of
water up to the top of a plant
Water is called “Universal solvent”:
dissolves many other substances due
to polarity
Differences in charges pulls/pushes
substances apart (Like a magnet
attracts or repels other magnets)
 Water exhibits evaporative cooling:
removes heat when it evaporates from
a surface
Ex: sweating cools skin
 Water expands during freezing:
expands into crystal formation
releasing heat
Ex: rocks broken up by ice creating
soil; ice layer protects fruit from
freezing
Water properties:
Chapter 6
Chemistry in Biology
6.3 Water and Solutions
Homogenous Mixtures
 A mixture that has a uniform
composition throughout
 A solvent is a substance in
which another substance is
dissolved.
 A solute is the substance
that is dissolved in the
solvent.
Food coloring dissolved in
water forms a homogenous
mixture.
Chapter 6
Chemistry in Biology
6.3 Water and Solutions
Heterogeneous Mixtures
 In a heterogeneous
mixture, the
components remain
distinct.
A salad is a heterogeneous mixture.
Chapter 6
Chemistry in Biology
6.3 Water and Solutions
Acids and Bases
 Substances that release hydrogen ions (H+) when
dissolved in water are called acids.
 Substances that release hydroxide ions (OH–)
when dissolved in water are called bases.
Chapter 6
Chemistry in Biology
6.3 Water and Solutions
pH and Buffers
 The measure of concentration of H+ in a solution
is called pH.
 Acidic solutions have pH values lower than 7.
 Basic solutions have pH values higher than 7.
Chapter 6
Chemistry in Biology
6.3 Water and Solutions
 Buffers are mixtures that can react with
acids or bases to keep the pH within a
particular range.
Chapter 6
Chemistry in Biology
6.4 The Building Blocks of Life
Organic Chemistry
 The study of all
compounds containing
the element CARBON
Chapter 6
Chemistry in Biology
6.4 The Building Blocks of Life
 Carbon compounds can be in the shape of straight
chains, branched chains, and rings.
What is a macromolecule?
 A giant molecule made up of
100’s or 1000’s or smaller
units called MONOMERS
Monomers link together to
form large POLYMERS
 formed by polymerization
Chapter 6
Chemistry in Biology
6.4 The Building Blocks of Life
Macromolecules
 Carbon atoms can be joined to form carbon
molecules.
 Macromolecules are large molecules formed
by joining smaller organic molecules
together.
 Polymers are molecules made from
repeating units of identical or nearly identical
compounds linked together by a series of
covalent bonds.
The 4 types of macromolecules:
CARBOHYDRATES
LIPIDS
NUCLEIC ACIDS
PROTEINS
Chapter 6
Chemistry in Biology
6.4 The Building Blocks of Life
Carbohydrates
 Made up of carbon, hydrogen, and oxygen
Chapter 6
Chemistry in Biology
6.4 The Building Blocks of Life
 Values of n ranging from three to seven are
called simple sugars, or monosaccharides.
 Two monosaccharides joined together
form a disaccharide.
 Longer carbohydrate molecules are called
polysaccharides.
CARBOHYDRATES
 Made up of C,H,O
Used as main source of energy
 Sugars: quick source of energy
Monosaccharide-simple sugar, disaccharide-2,
polysaccharide-many
Two types:
Ex: glucose, lactose, fructose, sucrose
Starches: many sugars linked together, source of
energy breaking down slower
Used by plants for energy storage
Ex: potatoes, pasta, bread, grains
Figure 2-13 A Starch
Section 2-3
Starch
Glucose
Go to
Section:
Chapter 6
Chemistry in Biology
6.4 The Building Blocks of Life
Lipids
 Made mostly of carbon and hydrogen
 A triglyceride is a fat if it is solid at room
temperature and an oil if it is liquid at
room temperature.
Chapter 6
Chemistry in Biology
6.4 The Building Blocks of Life
 Lipids that have tail chains with only single
bonds are called saturated fats.
 Lipids that have at least one double bond in
the tail chain are called unsaturated fats.
 Fats with more than one double bond in the
tail are called polyunsaturated fats.
LIPIDS
 Made up mainly of C & H
Used to store energy,
insulation & protection
Usually not soluble in
water
Saturated: has maximum
number of H bonds, usually
solid at room temperature
Unsaturated: at least one
double bond, usually liquid
Chapter 6
Chemistry in Biology
6.4 The Building Blocks of Life
Proteins
 A compound made of small carbon
compounds called amino acids
 Amino acids are small compounds that are
made of carbon, nitrogen, oxygen,
hydrogen, and sometimes sulfur.
Chapter 6
Chemistry in Biology
6.4 The Building Blocks of Life
 The other three bonds are with an amino group
(–NH2), a carboxyl group (–COOH), and a
variable group (–R).
PROTEINS
 Made up of C,H,O,N
Made up of groups called amino
acids (20 in nature)
 proteins have a large variety of
sizes & shapes
If the shape changes, it becomes
a new protein
Ex: when you boil an egg, the
protein changes color, shape
Found in muscles, cell
membrane
Chapter 6
Chemistry in Biology
6.4 The Building Blocks of Life
 The number and the order in which the amino acids
are joined define the protein’s primary structure.
 After an amino acid chain is formed, it folds into a
unique three-dimensional shape, which is the protein’s
secondary structure, such as a helix or a pleat.
Chapter 6
Chemistry in Biology
6.4 The Building Blocks of Life
 Nucleic acids are complex macromolecules that
store and transmit genetic information.
 Nucleic acids are made of smaller repeating
subunits called nucleotides, composed of carbon,
nitrogen, oxygen, phosphorus, and hydrogen atoms.
Nucleic Acids
 Made up of H,O,N,C & P
 Store and transmit genetic
information
 Made up of nucleotides
 Two types: DNA & RNA