Download Chapter 2 Chemistry of Life - OnCourse Systems For Education

Chapter 2 Mystery
• THE GHOSTLY FISH
• Page 33…
– How do these animals manage to survive
without red blood cells?
What’s the matter?
• What states of matter exist?
• Is all matter visible?
• Does all matter take up space?
Chapter 2
Chemistry of Life
Section 2.1
The Nature of Matter
Objectives
• What 3 subatomic particles make up
atoms?
• How are all of the isotopes of an element
similar?
• In what ways do compounds differ from
their component elements?
• What are the main types of chemical
bonds?
What 3 subatomic particles make
up atoms?
• Atoms – basic unit of matter
– 100 million atoms side by side = 1 cm long
• Subatomic particles = protons, neutrons,
and electrons
Protons and Neutrons
• Protons and neutrons =
same size
• Protons = + charge
• Neutrons = 0 charge
• Nucleus – formed by
protons and neutrons bound
by strong forces at the center
of an atom
Electrons
• Electron - - charge;
• 1/1840 mass of a proton
– In constant motion in space around nucleus
Atomic charge
• In all atoms:
#protons = #electrons
– + and – charges
balance out
– Electrically neutral
Atomic Number
•Atomic number = # protons
•Element – pure substance – consists of entirely one type of atom
•Each element has its own unique atomic number
•Each element represented by unique 1 or 2 letter symbols
Isotopes
• Isotope – atoms of the same element that
differ in number of neutrons
– Mass number – number of protons and
neutrons in nucleus of an atom
– Atomic mass – weighted average of masses
of an element’s isotopes
• b/c they have same # of electrons, all
isotopes of an element have the same
chemical properties
In what ways to compounds differ
from their component elements?
• Compound – substance
formed by chemical
combination of 2 or more
elements in definite
proportions
• Chemical formula – shows
composition
– Physical and chemical properties of a
compound are usually very different
from those of the elements from which
it is formed
•
Example – H & O = gases at room temp; combine =
liquid water
What are the main types of
chemical bonds?
• Involves electrons that surround each
nucleus
• Valence electrons - Electrons that are
available to form bonds
Ionic Bond
• Formed when one or more electrons are
transferred from one atom to another
• Atom that loses electrons - positively charged
• Atom that gains electrons - negatively charged
• Ions – positively and negatively charged
atoms
• Example - NaCl
Covalent Bonds
• Electrons are shared between 2 atoms
• The moving electrons travel about the nuclei of
both atoms = covalent bond
– Single covalent – when atoms share 2 electrons
– Double bond – atoms share 4 electrons
– Triple bond – atoms share 6 electrons
• Molecule – structure that results when atoms
are joined by covalent bonds; smallest unit of
most compounds
• Example – oxygen molecule, water molecule
Radioactive Isotopes
• Radioactive – nuclei are unstable and
break down at a constant rate over time
– Radiation given off can be dangerous
– Have scientific & practical uses:
•
•
•
•
determine ages of rocks and fossils
detect and treat cancer
kill bacteria
labels “tracers” to follow movements of substances
w/in organisms
Van der Waals Forces
– Atoms have different abilities of attraction to electrons
so sharing is not always equal between 2 atoms
– Even when sharing is equal, rapid movement of
electrons can create regions w/ tiny + or – charge
• Van der waals forces – slight attraction b/w
oppositely charged regions of nearby molecules
– Not as strong as ionic or covalent bonds
– Can hold molecules together (especially large
molecules)
Mystery Clue
• Page 37…..
– Fish do not break water molecules into their
component atoms to obtain oxygen.
– Rather, they use oxygen gas dissolved in the
water.
– How are the atoms in an oxygen molecule
joined together?
Atom Activity
•
•
Intro to atoms discussion
Choose an element from the periodic table
1. Using the beads, construct a 3D diagram of an atom &
show me for 1 grade
–
–
–
Red = protons
Blue = neutrons
Pencil marks = electrons
2. Choose a partner (or 2 if needed) with an atom that
your atom can bond with
3. Identify the type of bond (ionic or covalent)
4. Answer the questions that follow on a separate sheet of
paper for a second grade
Atoms lab follow up questions
•
1.
2.
3.
4.
5.
6.
Due on next lab day
Name of your atom
Diagram of your atom
Which atom(s) did you bond with?
Diagram of bond
Was the bond covalent or ionic?
Explain how you knew if it was covalent or
ionic.
- use valence electrons; tranferred or shared in your
explanation
Section 2.2
Properties of Water
• How much water is on Earth? (gallons)
• How much water is drinkable? (gallons)
• If all the water on Earth was contained in
__________, how much would represent
the drinkable amount? _____________
• Demonstration!!
Objectives
• How does the structure of water contribute
to its unique properties?
• How does water’s polarity influence its
properties as a solvent?
• Why is it important for cells to buffer
oslutions agains rapid changes in pH?
How does the structure of water
contribute to its unique properties?
• Water = H2O
• Neutral (10 protons; 10 electrons)
• Liquid state over most of Earth’s surface
Polarity
• Greater probability of finding the shared electrons
in water close to O than H
– Angles of chemical bonds cause O and H to
be on opposite ends of molecule
• O = slight – charge & H = slight + charge
• Polar – charges are unevenly distributed
Hydrogen Bonding
• Partial + & - charges  attract other H2O
molecules
• Hydrogen bond – attraction b/w H on
one H2O molecule and O of another
• Not as strong as covalent or ionic
• H2O – able to form multiple H-bonds
Cohesion
• Cohesion – attraction b/w
molecules of same substance
• 1 H2O molecule can be involved in 4
H-bonds at the same time
• H2O molecules drawn together 
drops of water form beads on
smooth surface
– Cohesion produces surface
tension
• Allows some animals to walk on
surface of water
Adhesion
• Adhesion – attraction b/w molecules of
different substances
– Capillary action – attractions b/w water &
another substance which causes water to rise
in narrow tube against force of gravity
• Draws water out of roots of plant up to stem &
leaves
Heat Capacity
• Heat capacity – amount of
heat energy required to
increase its temperature
– A lot of energy to cause
water molecules to move
faster
– B/c multiple H-bonds b/w
water molecules
• Organisms protected from
drastic changes in temp b/c
large amt. of heat w/ small
change in temp (ocean/lake)
• Water absorbs heat produced
by cell processes  regulates
temp of cell  helps w/
homeostasis
Mystery Clue
• Page 42…..
• The solubility of gases increases as
temperatures decrease. Think about when a
can of warm soda is opened – the carbon
dioxide dissolved in it fizzes out more rapidly
because the gas is less soluble at warm
temperatures.
• How might the temperature of antarctic waters
affect the amount of dissolved oxygen available
for ice fish?
How does water’s polarity influence
its properties as a solvent?
• Mixture – material composed of 2 or more
elements or compounds physically mixed
together but not chemically combined
• Salt + pepper
• Sugar + sand
• 2 types w/ water:
– Solutions
– Suspensions
Solutions
• Solution – all components
are evenly distributed
– Solute – substance
dissolved
– Solvent – substance in
which solute dissolves
• Example: salt + water
– Saturated – given amount
of water has dissolved all of
the solute it can
Suspensions
• Suspensions – water and nondissolved
material
– Some materials separate into pieces so small
that they do not settle out
– Movement of water molecules keeps the
small particles suspended
• Example: blood = mostly water
– Cells/undissolved particles remain in suspension
pH scale
• pH scale – measurement system devised
to indicate the concentration of H+ ions in
solution
– Water = neutral = 7 on pH scale
– <7 = acidic = have more H+ ions
– >7 = basic = have more OH- ions
Quick Lab
• P. 43
• Acidic and Basic foods
Acids
• Acid – any compound that forms H+ ions
in solution
– HCl – produced by stomach – helps digest
food
Bases
• Base – compound that produces OH- ions
in solution
– Lye (NaOH) – used in soap making – strong
base
Buffers
– Human cells must stay
b/w 6.5 & 7.5 pH
• Will effect chemical
reactions
• Important to maintain
homeostasis
• Buffers – dissolved
compounds – weak
acids or bases that can
react w/ strong acids or
bases to prevent sharp,
sudden changes in pH
Section 2.3
Carbon Compounds
Objectives
• What elements does carbon bond with to
make up life’s molecules?
• What are the functions of each of the four
groups of macromolecules?
Chemistry of Carbon
• Carbon atoms have 4 valence electrons
allowing them to form strong covalent
bonds with many other atoms
– Form chains, rings, multiple bonds, complex
structures
• H, O, P, S, N bonds = molecules of life
Macromolecules
• Macromolecules – “giant molecules”
– polymerization – small compounds join to
form larger compound
• Monomers – smaller units joined together
• Polymers – final product of monomer
joining
– Monomers may be identical (metal watch
band) or may be different (beads on
multicolored necklace)
Polymer
Carbohydrates
• Carbohyrates – made of C, H, and O
atoms (usually 1:2:1 ratio)
– Breakdown of sugars (glucose) provide
immediate energy for cellular activities
– Many organisms store extra sugar as complex
carbohydrate= starches
Simple Sugars
• Single sugar molecules =
monosaccharides
•
•
•
•
Glucose
Galactose (milk)
Fructose (fruits)
Sucrose (table sugar) = glucose + fructose
disaccharide (compound made by joining 2
simple sugars
Complex Carbohydrates
• Polysaccharide –
marcromolecules formed from
combinations of
monosaccharides
– Many animals store excess
sugar in polysaccharide called
glycogen in muscles (animal
starch)
• When glucose levels in blood
runs low  glycogen is broken
down into glucose  glucose
released into blood
• Supplies energy for muscle
contraction (movement)
Complex Carbohydrates
– Plants use starch to store excess sugar
– Plants also use cellulose to give strength and
rigidity
• Wood/paper
Lipids
• Lipids – made mostly from C and H atoms
• Not soluble in water
• Fats, oils, waxes
– Store energy
– Form membranes / waterproof coverings
– Make steroids in the body
• Ex: hormones – chemical messengers
**Formed when
glycerol molecule
combines w/ fatty
acids
Lipids
• Saturated – each C atom in a lipid’s fatty acid
chain is joined to another C atom by a single
bond
– Fatty acid contains max possible # of H atoms
• Polyunsaturated – at least one C-C double bond
in a fatty acid
• Liquid at room temp
• Olive oil, corn oil, sesame oil, canola oil, peanut oil
Nucleic Acids
• Nucleic Acids – macromolecules
containing H, O, N, C, and P
– Store and transmit hereditary
(genetic) information
• RNA – ribonucleic acid (ribose = sugar)
• DNA – deoxyribonucleic acid
(deoxyribose = sugar)
• Nucleotides – Polymers
assembled from individual
monomers
– 3 parts: 5-carbon sugar, phosphate
group (PO4), and nitrogen base
– Can be joined by covalent bonds to
form polynucleotide or nucleic acid
Protein
• Protein – macromolecules that contain N, C, H, and O
– Made of polymers of molecules called amino acids
– Protein is functional molecule built from one or more
polypeptides
• Amino Acids – compounds w/ an amino group (NH2) on
one end and carboxyl group (COOH) on the other
– Peptide bonds – covalent bonds that link amino acids together
to form polypeptide
Functions of Proteins
• Some proteins control rate of reactions
and regulate cell processes
• Others form cell structures
• Others transport substances into or out of
cells
• Help fight disease
Structure and Function
• All amino acids are identical in regions where
may be joined together by covalent bonds
– Allows any amino acid to be joined to any other amino
acid (amino or carboxyl group)
• Amino acids differ from each other b/c each has
a different side chain (R group)
– Some acidic & some basic
– Some polar & some nonpolar
– Some contain large ring structures
Levels of Organization
• Amino acids assembled into polypeptide chains
according to instructions coded in DNA
• 4 levels of structure in proteins:
– Primary structure – sequence of its amino acids
– Secondary – folding or coiling of polypeptide chain
– Tertiary – complete, 3-dimensional arrangement of
polypeptide chain
– 4th level – have more than one chain – describes the
way different polypeptides are arranged w/ respect to
each other
• Shape of protein is maintained by variety of forces: ionic,
covalent, van der Walls forces, hydrogen bonds
Section 2.4
Chemical Reactions and Enzymes
Objectives
• What happens to chemical bonds during
chemical reactions?
• How do energy changes affect whether a
chemical reaction will occur?
• What role do enzymes play in living things
and what affects their function?
Chemical Reactions
• Chemical Reaction – process that
changes, or transforms, one set of
chemicals into another
• Vary in speed
– Reactants - Elements/compounds that enter
into a chemical reaction
– Products – elements/compounds produced
by a chemical reaction
• Chemical reactions change chemical
bonds that join atoms
Energy in Reactions
• Energy can be released or absorbed
whenever chemical bonds are formed or
broken in chemical reactions
Sodium added to
water releases a
great amount of
energy.
Reaction of sulfuric
acid and sugar
creates a mound of
black carbon and
steam.
Energy Changes
• Chemical reactions that
release energy often
occur spontaneously
• Ex: burning H gas (H reacts
w/ O to produce water vapor)
• Energy released in form of
heat
• Chemical reactions that
absorb energy will not
occur without a source of
energy
– Ex: water changed into H
and O
• Absorbs so much energy that
doesn’t occur by itself
Energy Sources
• Every organism needs energy to carry
out chemical reactions
– Plants get energy by trapping and storing
energy from sunlight in energy-rich
compounds
– Animals get energy when they consume
plant or animals
– Humans release energy through chemical
reactions when we metabolize (break
down) digested food
Activation Energy
• Activation Energy – energy needed to
get a reaction started
– Example: lighting a match to start fire gets
reaction started
Enzymes
• Catalyst – substance that speeds up the
rate of a chemical reaction
– Lowers a reaction’s activation energy for
reactions that are too slow to be practical for
living tissue
Nature’s Catalysts
• Enzymes – proteins that act as biological
catalysts
– Enzymes speed up chemical reactions in cells
– Lower activation energies
• Ex: carbonic anhydrase speeds up reaction by 10
million times than natural removal of carbon
dioxide from blood
Enzyme-Substrate Complex
– For chemical reaction to occur, reactants must collide
w/ enough energy so existing bonds will be broken
and new bonds will be formed
• Substrates – reactants of enzyme-catalyzed
reactions
• Active Site – site on enzyme where substrates
bind
– Active site and substrates have complementary
shapes – so precisely fit – like lock and key
Regulation of Enzyme Activity
• Enzymes: control chemical pathways, make
materials cells need, release energy, transfer
information
• Temperature, pH, and regulatory molecules can
affect activity of enzymes
• Many affected by temp (37oC in human body)
• Work best at certain ionic conditions and pH values
– Ex: stomach enzyme (pepsin) – begins protein digestion –
works best under acidic conditions
• Regulated by molecules that carry chemical signals w/in cells
(switch on or off as needed)
Mystery Clue
• P. 53….
– The chemical reactions of living things,
including those that require oxygen, occur
more slowly at low temperatures.
– How would frigid antarctic waters affect the
ice fish’s need for oxygen?
Solve the Mystery
• Ice fish produce antifreeze proteins to keep their blood
from freezing; their body temperature stays below 0oC.
How does low body temperature affect the blood’s ability
to carry dissolved oxygen?
• People living at high altitudes generally have more
hemoglobin in their blood than people living at sea level.
Why do you think this is so?
• If the antarctic oceans were to warm up, how might this
affect ice fish?
• The chemical reactions in all living things slow down at
low temperatures. Since some of the most important
reactions in our body require oxygen, how would low
temperatures affect the ice fish’s need for oxygen?