Transcript chapter 6 - Avon Community School Corporation

CHAPTER 6
CHEMISTRY IN BIOLOGY
• CHAPTER 6.1 – ATOMS, ELEMENTS, &
COMPOUNDS
• MAIN IDEA – Matter is composed of tiny
particles called atoms.
• QUESTIONS:
• What is the smallest unit of matter?
• How are atoms and elements related?
• ATOMS
• Chemistry is the study of
matter, its composition, and
properties
• Matter is anything that has
mass and takes up space.
• Atoms are the building blocks
of matter
• THE STRUCTURE OF AN ATOM
• Atoms are extremely small – millions can fit on the head of pin.
• Composed of:
– Protons
• Positively charged
• Located in nucleus (center of atom)
– Neutrons
• No charge
• Located in nucleus (center of atom)
– Electrons
• Negatively charged
• Located outside nucleus in energy levels
• Constantly moving
• Electrons attracted to protons = atom no charge
• ELEMENTS
• Element is a pure substance that
cannot be broken down into other
substances by physical or chemical
means.
–Elements made of 1 type of atom.
–# of protons = the atomic # of the
element
–# of protons = # of electrons
• ISOTOPES
• Isotopes have the same # of protons & the same #
of electrons, but the # of neutrons is different.
• Isotope of the element has the same chemical
characteristics
• Isotopes of an element are identified by adding the
number of protons and neutrons in the nucleus.
– Ex: Carbon has 6 protons, carbon as element has
6 neutrons = 12 or C12
– EX: Carbon has 6 protons, carbon as isotope has
8 neutrons = 14 or C14
• FIGURE OUT WHAT THE MISSING NUMBERS ARE?
ELEMENT
Lithium
Carbon
CHEMICAL
SYMBOL
ATOMIC
NUMBER
NUMBER OF
PROTONS
3
C
P
NUMBER OF
NEUTRONS
MASS
NUMBER
5
8
12
6
15
16
• RADIOACTIVE ISOTOPES
• Changing the # of neutrons DOES NOT change
the charge of the atom
• When an isotope break down they give off
radiation
• Use radioactive isotopes to determine the age
of objects
–Scientists know how long it takes for the
radioactive material to break down
completely.
• Use radioactive isotopes in medicine also.
RADIOACTIVE DECAY
yellowtang.org
• COMPOUNDS
• Compound is a pure substance formed when 2 or more different
elements combine.
– EX: water = H2O salt = NaCl
• Compounds have unique characteristics
– Always formed from a specific combination of elements in a
fixed ratio.
• Ex: water is always 2 hydrogen & 1 oxygen
• EX: salt is always one sodium & 1 chlorine
– Compounds are chemically and physically different from the
elements that they are made from.
– Compounds cannot be broken down into simpler compounds
or elements by physical means (tearing, crushing, etc.)
• Can be broken down by chemical means into simpler
compounds or their original elements
• CHEMICAL BONDS
• The force that holds compounds together is called a chemical
bond.
• Electrons are involved directly in forming the chemical bonds.
– Electrons located outside the nucleus in energy levels
– Each energy level can only hold so many electrons
• First energy level closest to nucleus can only hold 2
electrons
• 2nd energy level can only hold 8 electrons
• 3rd energy level can only hold 8 electrons
– Partially filled energy levels are not as stable as full energy
levels
• Atoms become more stable by either losing or gaining
electrons in the partially filled energy levels. They form
bonds to do this
• 2 main types of chemical bonds:
– Covalent bonds
– Ionic bonds
• COVALENT BONDS
• Chemical bonds that form when electrons are
shared are called covalent bonds.
– Ex: water = H2O, pg. 152, fig. 9
• Most compounds in living organisms have covalent
bonds holding them together. These substances are
called molecules
– Depending on the # of pairs of electrons that are
shared, covalent bonds can be single, double, or
triple bonds
• Pg. 153, fig. 10
• IONIC BONDS
• Atoms are neutral (no charge because protons = electrons)
• Some atoms will give away (donate) or gain (accept) electrons to fill
or empty the outer energy level to become more stable.
• Ion is an atom that has gained or lost one or more electrons and now
carries an electrical charge.
– EX: salt = NaCl
• Sodium gives 1 electron away = + charge
– Metals tend to donate electrons
• Chlorine gains/accepts the electron = - charge
– Nonmetals tend to accept electrons
• Pg. 153 fig. 11
• Ionic bond is an electrical attraction between two oppositely charged
atoms or groups of atoms called ions
– Substances formed by ionic bonds are called ionic compounds
– Most will dissolve in water
• Ions help to maintain homeostasis as they travel in & out of cells
• Ions help transmit signals among cells that allow you to see, taste,
hear, feel & smell
Section 1
Chemistry in Biology
• SECTION 6.2 – CHEMICAL REACTIONS
• MAIN IDEA – Chemical reactions allow living
things to grow, develop, reproduce, and
adapt.
I have 3 pieces of paper. One paper is burned,
1 piece is folded, one piece has a hole cut in
the middle.
• Identify which piece of paper(s) have
undergone chemical or physical changes.
• REACTANTS AND PRODUCTS
• Chemical reaction is the process by which atoms or
groups of atoms in substances are reorganized into
different substances.
– Bonds are broken & formed during the chemical
reactions
– Ex: rust
– Clues to help know when chemical reactions have
taken place include the production of heat or
light, formation of a new gas, liquid, or solid
• Physical change alters a substance’s appearance,
but not its composition.
• CHEMICAL EQUATIONS
• In written chemical equations, chemical
formulas describe the substances in the
reaction with arrows indicating the process of
change
• Reactants are the substances that you started
with and will be on the left side of the arrow
• Products are the substances that are formed
during the reaction and will be on the right
side of the arrow
–Ex:
reactants
products
• ENERGY OF REACTIONS
• Most compounds in living things cannot
undergo chemical reactions without
energy.
• ACTIVATION ENERGY
• Activation energy is the minimum
amount of energy (can be in the form of
heat) needed for reactants to form
products in a chemical reaction.
–Some reactions rarely happen because
they have a very high activation energy
• ENZYMES
• All living things carry out chemical reactions.
–Proceed very slowly because activation
energy is high
• Catalyst is a substance that lowers the
activation energy needed to start a chemical
reaction.
–Job of catalyst – speed up chemical
reactions
• Does not increase amount of product
• Does not get used up in the reaction
• ENZYMES CONTINUED
• Enzymes are special proteins whose job is to be a biological
catalysts
– Essential for life
– Enzymes not use up in the reaction
– Has an “ase” ending
• Ex: amylase, used in the breakdown of amylose (starch)
– Enzymes are specific for one reaction
– Substrates are reactants that bind to the enzyme at a specific
location called the active site.
• Have complementary shapes
– Ex: puzzle pieces fit exactly into one another
– Decrease the activation energy necessary to initiate the
chemical changes
• ENZYMES CONTINUED
–Enzyme-substrate complex = substrate
bound to active site on the enzyme
• Helps chemical bonds in the reactants to
be broken and new bonds to form
creating the products
–Factors such as pH, temperature, & other
substances affect enzyme activity.
• Human enzymes are most active at the
optimal temperature close to 37°C
• ENZYME-SUBSTRATE COMPLEX
• SECTION 6.3 – WATER AND SOLUTIONS
• MAIN IDEA – The properties of water make it
well suited to help maintain homeostasis in an
organism.
• QUESTIONS: What is the chemical equation
for liquid water?
• What is the chemical equation for ice? Water
Vapor?
• WATER’S POLARITY
– With the water molecule the electrons spend
more time around the oxygen than the hydrogen.
– Creates a slightly negative charge around the oxygen and
a slight positive charge around the hydrogen.
– Molecules that have an unequal distribution of charges
are called polar molecules.
• MIXTURES WITH WATER
• Mixture is a combination of two or more substances in
which each substance retains its individual characteristics
and properties
• HOMOGENEOUS MIXTURES
• If the mixture has a uniform composition throughout it is called
homogeneous.
– Ex: Kool-aid & water
• Solution is another name for a homogeneous mixture.
• Solutions are made up of 2 components:
– Solvent is a substance in which another substance is
dissolved
• EX: water
– Solute is the substance that is dissolved in the solvent.
• EX: Kool-aid
• HETEROGENEOUS MIXTURES
• In the heterogeneous mixture you can see the individual
substances.
– EX: salt & pepper, sand & water
• ACIDS AND BASES
• Acids release a hydrogen ion (H+)
– The more hydrogen ions = more acidic solutions
• Bases release a hydroxide ions (OH-)
– The more hydroxide ions = more basic solutions
• Ph AND BUFFERS
• pH is the measure of concentration of H+ (hydrogen
ions) in the solution
– Neutral is 7 on the pH scale
– Acidic solutions have a high concentration of H+
and are lower than 7 on the pH scale
– Basic solutions have more OH- than H+ and are
higher than 7 on the pH scale
• Most biological processes carried out by cells occur
between the range of 6.5 & 7.5 on the pH scale.
• Buffers are mixtures than can react with acids or
bases to keep the pH within a particular range.
• Blood has buffers to keep the pH about 7.4
• pH SCALE
• SECTION 6.4 – THE BUILDING BLOCKS
OF LIFE
• MAIN IDEA – Organisms are made up
of carbon-based molecules.
• QUESTION: How many bonds can
carbon form with other atoms?
• ORGANIC CHEMISTRY
• Life is considered carbon based because
carbon is in almost all biological molecules.
• Carbon has 4 electrons in its outer most
energy level leaving space for 4 more
electrons.
–Carbon likes to covalently bond with 4 other
atoms creating compounds in the shape of
straight chains, branched chains, and rings
• MACROMOLECULES
• Macromolecules are large molecules that
are formed by joining smaller organic
molecules together.
–Also called polymers (poly means
many)
• Polymers are molecules made from
repeating units of identical or nearly
identical compounds called monomers
held together by covalent bonds.
–EX: resembles a chain
• CARBOHYDRATES
• Carbohydrates are compounds composed of
carbon, hydrogen and oxygen in a ratio of 1 oxygen
and 2 hydrogen atoms for each carbon atom.
• Monomer for carbohydrates are called
monosaccharides
– Ex: glucose
• Disaccharide are two monosaccharides joined
together.
– Ex: sucrose & lactose
• Polysaccharides are many monosaccharides joined
together
– Ex: glycogen, cellulose
• CARBOHYDRATES – CONTINUED
• Carbohydrates function is to provide
short term energy and structural support
–Glucose and glycogen are used as an
energy source
• EX: sugars, starches (bread, noodles,
potatoes)
–Cellulose are tough fibers that provide
structural support for plants
• LIPIDS
• Lipids are molecules made mostly of
carbon and hydrogen
• Lipids make up the group of fats, oils
and waxes
• Function of lipids is to store long term
energy and provide barriers
• SATURATED AND UNSATURATED FATS
• Basic structure of a lipid includes a fatty acid tail
• Tails with all single carbon bonds are called
saturated fats
– Ex: solid at room temperature = Butter
• Tails with at least one double bond in the tail are
called unsaturated fats.
– Ex: liquid at room temperature = olive oil
• Tails with more than one double bond in the tail are
called polyunsaturated fats
– Ex: liquid at room temperature
• PHOSPHOLIPIDS
• Phospholipids are responsible for the structure and
function of the cell membrane
• Lipids are hydrophobic (means it does not dissolve
in water)
– Serves as a barrier for biological membranes
• STEROIDS
• Steroids include substances such as cholesterol and
hormones
– Cholesterol provides the starting point for other
necessary lipids such as vitamin D and the
hormones estrogen & testosterone
• PROTEINS
• Protein is a compound made of amino acids
(monomer)
• Amino acids are small compounds that are made of
carbon, nitrogen, oxygen, hydrogen, and sometimes
sulfur.
– All amino acids share the same general structure
• AMINO ACID STRUCTURE
• There are 20 different amino acids
• Proteins are made from combining different amino
acids together by covalent bonds called peptide
bonds
• 3 DIMENSIONAL PROTEIN STRUCTURE
• After the amino acids are joined the amino acid chain will
fold into a unique 3 dimensional shape
• Some proteins will combine with other proteins
• PROTEIN FUNCTION
• Proteins make up about 15% of your total body mass and
are involved in nearly every function of your body
• Cells contain almost 10,000 different proteins that:
– provide structural support
– transport substances inside the cell and between cells
– communicate signals within a cell and between cells
– speeds up chemical reactions
– control cell growth
• NUCLEIC ACIDS
• Nucleic acids are complex macromolecules that store and transmit
genetic information.
• Nucleic acids are made up of smaller repeating subunits called
nucleotides, which contain carbon, nitrogen, oxygen, phosphorus,
and hydrogen atoms
– Nucleotide is the monomer
– Each nucleotide has a nitrogenous base, a sugar and phosphate
• There are 2 types of nucleic acids:
– DNA – deoxyribonucleic acid
• Contains the sugar deoxyribose
– RNA – ribonucleic acid
• Contains the sugar ribose
• When nucleotides join together the sugar molecule will bond to the
phosphate of the next nucleotide
• Nitrogen bases will form hydrogen bonds between them in DNA
• NUCLEIC ACIDS – CONTINUED
• A nucleotide that is made up of 3 phosphates, sugar
& nitrogen base is called ATP (adenosine
triphosphate)
• ATP is a storehouse of chemical energy that can be
used by cells in a variety of reactions.
– ATP will release energy when you break the bond
between the 2nd and 3rd phosphate group
– Less energy is released when the bond between
the 1st & 2nd phosphate group is broken