Transcript b). - Quia

UNIT I
Chapter 2
The Chemistry of Life
I. The Nature of Mature
A. Atoms- basic unit of matter. Most made up
of three kinds of particles.
1. Nucleus (center of atom)
contains both protons and
neutrons.
a. Protons- (+) charged
particle
b. Neutrons- (neutral) charged
particle (same mass as protons)
2. Electrons- (-) charged particle.
1/1836 mass of proton
a). Number of (-) charged
particles = number of (+)
charged particles. Therefore
atom as a whole is neutral
b). Electrons move in space
around the nucleus (opposite
charge of protons help to hold
electrons in their orbitals
B. Elements and Isotopes
1. Element– a pure substance consisting
entirely on one type of atom (i.e.. Carbon,
Oxygen, Hydrogen, etc.)
a. More than 100 known. Two dozen found
in living things
b. Element represented by one or two-letter
chemical symbol (i.e. C = Carbon, Cl =
Clorine, etc.)
c. Number of protons in element is atomic
number (identifies an atom)
Atomic number
2. Isotopes– atoms of same element with
different number of neutrons
a. Isotopes represented by adding up protons
and neutrons to determine mass number. The
mass number is written above the chemical
symbol. The three isotopes of Carbon are:
Mass number
12
6
C
13
6
C
14
6
C
Atomic number
b. Atomic mass– the average mass of one
elements isotopes
Atomic number
Atomic symbol
Atomic mass
3. Radioactive isotopes– nuclei are unstable
and break down at a constant rate over time
giving off matter or energy or both in form of
radiation. Many have important scientific uses.
C. Chemical Compounds– substance formed by
combination of two or more elements in definite
proportions.
1. Composition shown by chemical formula
(i.e. H2O, NaCl) (gives ratios of elements that
make up compound)
C6H12O6
2. Molecule– smallest unit of most chemical
compounds. (i.e..
Molecule of water- H2O)
D. Chemical bonds– links that hold atoms
together. Two main types
1. Covalent bonds– formed by sharing
electrons between two atoms
a. forms tight link between atoms.
(can join 3, 4, thousands of atoms
together)
b. Bond found in organic
compounds
2. Ionic bonds- formed by transfer of 1 or
more electrons from 1 atom to another
a. Ion– (+) or (-) charged atom that results from
gaining or losing electron
b. Attraction of opposite charges holds atoms
together
3. Van der Waals Forces– hold
together surfaces with closely
matching shapes. (i.e. Geckos
use these forces to grip tin
irregularities on glass and other
surfaces)
D. Properties of Water1. Single most abundant compound in living things
2. Is liquid at temperature found over much of
Earth’s surface
3. The unequal sharing of
electrons in covalent
bonds causes water
molecule to be polar
(slightly charged at each
end)
a. Hydrogen bonds– weak attraction between
positive and negative ends of water molecule
(opposites attract)
b. Cohesion– attraction
between molecules of the same
substance (because of
hydrogen bonds, water is very
cohesive)
c. Adhesion– attraction
between different substances.
Adhesion between water and
other charged or polar
substances very important force.
(responsible for capillary action)
E. Solutions and Suspensions1. Mixture– substance composed of two or
more elements or compounds that are mixed
together but not chemically combined. Two
types can be made with water
a. Solutions– a mixture of two or more
substances in which the molecules of the
substances are evenly mixed.
1). Solvent– substance in which solute is
dissolved
(water is world’s greatest solvent)
2). Solute– the substance that is dissolved.
b. Suspensions– mixture of water and
non-dissolved materials that are too small to
settle out.
2. Some of most important fluids in the body are
both solutions and suspensions.
Water is called “Universal
solvent”: dissolves many other
substances due to polarity
Differences in charges pulls/pushes
substances apart
 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:
F. Acids, Bases, and pH
1. One of most important properties of water is
that it can break apart (dissociate into 2
charged ions)
H2O
water
+
H
Hydrogen
ion
+
+
-
OH
Hydroxide
ion
Acids, Bases and
the
pH
scale
The pH scale measures the
concentration of H+ ions (how
acidic something is)
Ranges from 0-14
At 7: H+ ions and OH- ions
are equal so it is neutral
 0-7: acidic, has more H+
ions
 7-14: basic, has more OHions
 ACIDS: release H+ when
mixed with water
Sour, corrosive
Ex: HCl, H2SO4
Always have H at front of
formula
BASES: release OHwhen mixed with water
Bitter, slippery, usually in
cleaners
NaOH, CaOH
Always have OH at end of
formula
a. H+ ion is one of most
reactive ions in nature
b. pH scale– used in indicate
concentration of H+ ions
1). Scale ranges from 0 to
14 (decreases with acidity)
2). Pure water has pH of 7
3). Each step on scale
represents a factor of 10 in
H+ ion concentration.
2. Acids–
compound that
forms H+ ions
in
solution (more H+
ions than pure
water)
3. Basescompound that forms
OH– (hydroxide) ions
in solution.
(Contains less H+
ions than pure water)
What is a buffer?
 Buffers are weak acids or bases that react with
strong acids and bases to prevent sharp
changes in pH
Helps to neutralize
Help to control pH in blood, digestive tract, etc.
to maintain homeostasis
4. Buffers– dissolved compounds that help
prevent sharp, sudden swings of pH which might
cause damaging chemical changes within living
tissue (they absorb or release hydrogen ions to
stabilize pH. Ie.– Carbonic acid buffers blood)
G. Chemical Compounds in Living things
1. Inorganic Compounds- primarily,
compounds that do not contain Carbon.
a. Natural world dominated by inorganic
compounds
b. Include water, minerals
that make up sand, soil,
stone
1). Macromolecules- “giant molecules”.
Consists of thousands or hundreds of
thousands of smaller molecule
a). Macromolecules formed
byprocess called
polymerization (large
compounds built be joining
together smaller ones)
b). Monomers– smaller
compounds
c). Polymers– large
molecules
2. Organic Compounds– Carbon containing
compounds
a. Important because can form strong stable
covalent bonds
b. Can form long chains almost unlimited length
c. Can form huge variety of molecules
4 types of Macromolecules:
CARBOHYDRATES
LIPIDS
NUCLEIC ACIDS
PROTEINS
2. Organic Compounds– Carbon containing
compounds
a. Important because can form strong stable
covalent bonds
b. Can form long chains almost unlimited length
c. Can form huge variety of molecules
CARBOHYDRATES
Monomer: simple sugar (glucose)
Polymer: Starches (cellulose)
 Function: main source of energy for respiration, use by
plants for energy storage
Examples: Monosaccharide, disaccharide, glucose, lactose,
fructose, potatoes, pasta, bread, grains
d. Four groups of organic compounds found in
living things (carbohydrates, lipids, nucleic
acids, and proteins)
1). Carbohydrates- made up of Carbon,
Hydrogen, and Oxygen usually in ratio of
1 : 2 : 1
Sugars are joined together
to form starch molecules.
Energy is stored in the
chemical bonds. When
bonds are broken, energy
is released
C6H12O6
b). Plants and some animals use for structural
purposes
c). monosaccharides– single sugar molecule
(building blocks of carbohydrates)
d). Polysaccharides–
macromolecule formed
by linking together
hundreds or thousands
of sugars (starch,
glycogen, cellulose)
 Monomer: Fatty Acid
Polymer: Triglycerides, oil, waxes
Steroids
Function: store energy, insulation,
protection, waterproofing, form
membranes
Usually not soluble in water
Saturated: has maximum number of
H bonds, usually solid at room
temperature
Unsaturated: at least one double
bond, causes “kinks”, usually liquid
LIPIDS
2). Lipids– fats, oils, waxes and Steroids Made
mostly of Carbon and Hydrogen atoms (some
Oxygen)
a). Not soluble in water–
help form biological
membranes
b). Store energy
c). Some are chemical
messengers (ie. Steroids)
d). Lipids formed by combining glycerol with
fatty acids
dehydration synthesis– reaction in which small
molecules join to for a large molecule, removing water
in the process.
hydrolysis– reverse of dehydration synthesis. When large
molecule is split into smaller molecules producing water in
the process
Nucleic Acids
 Monomer: nucleotides
 Polymer: DNA & RNA
 Function: Store and transmit
genetic information, produce new
cell parts
 Examples: DNA & RNA
3). Nucleic Acids– macromolecules of Carbon,
Hydrogen, Nitrogen, Oxygen, and Phosphorus.
a). Polymers formed from individual
monomers known as nucleotides.
1). Made up of three basic
parts: 5-carbon sugar,
phosphate group,
nitrogenous base
2). Nucleotides joined by
covalent bonds to form
polynucleotides (nucleic
acids)
b). Nucleic acids store and transmit hereditary, or
genetic information (ie. DNA, RNA)
PROTEINS
 Monomer: amino acids (only
20 on entire planet!)
Polymer: enzymes, hormones,
muscle
Function: form muscles
Examples: meat, nuts,
amylase, lactase, insulin
Large variety of sizes & shapes
If the shape changes, it
becomes a new protein
Ex: hard boiled egg vs. raw egg
4). Proteins– contain Nitrogen, Carbon,
Hydrogen, and Oxygen atoms. Polymers of
amino acids
a). More than 20 different amino acids found
in nature
b). Amino acids can be joined together by
covalent bonds (peptide bonds) to form large
number of different proteins
c). Protein two main roles: structural or
functional
d). Proteins fold into 3-dimensional shapes–
important to their function (ie. Enzymes)
e). Functions of proteins are at the very center
of life itself.
***WRITE THIS ON THE
BOTTOM OF IN 25***
Organic Compound Tests
Organic
Compounds
What do
you use?
Starch Test
Iodine
Sugar Test
Lipid Test
Protein Test
Positive
(+)
Blue/black
Glucose
Darker color
strips
Brown paper Translucent
towel
spot
Biuret
Dark
solution
lavender
Negative
(-)
yellowish
No
change
none
Light
blue
H. Chemical Reactions and Enzymes
1. Chemical Reactions– process that
changes one set of chemicals into another set
of chemicals.
CO2 + H2O
H2CO3
a. Chemical reactions always involve
changes in chemical bonds that join
atoms in compounds
b. Reactants– elements or compounds
that enter into chemical reactions
c. Products– elements or compounds
produced by chemical reactions
2. Energy in Reactions– energy is released or
absorbed whenever chemical bonds are made or
broken
a. Energy changes are
single most important
factor determining how
easily chemical
reaction will occur
1). Chemical reactions
that absorb energy will
not occur without
source of energy
2). Activation energy– energy needed to get
reaction going
3. Enzymes– specialized proteins that act as
biological catalysts
(catalysts– a substance that speeds up rate of
chemical reaction by lowering a reactions
activation energy)
a. Living cells use
enzymes to speed up
virtually every important
chemical reaction that
takes place in cells.
b. Enzymes are very
specific
c. Name of enzyme derived
from reaction it catalyzes
d. Enzymes are not used up
in a chemical reaction.
4. Enzyme action– can
increase reaction speed 1010
times
1). reactants are known as
substrates
2). Substrates bind to
enzymeat Active site (shape
of active site fits substrate like
“lock and key”)
3). Once products made
enzyme continues process
b. Enzymes affected by
pH, temperature
c. Cells can regulate activities of enzymes.
Proteins turn “on” “off”
Review
Chapter 2
The Chemistry
of Life
The three particles that make up an atom are
a.
protons, neutrons, and isotopes.
b.
neutrons, isotopes, and electrons.
c.
positive, negatives, and electrons.
d.
protons, neutrons, and electrons.
The three particles that make up an atom are
a.
protons, neutrons, and isotopes.
b.
neutrons, isotopes, and electrons.
c.
positive, negatives, and electrons.
d.
protons, neutrons, and electrons.
The space surrounding the nucleus of an atom
contains
a.
protons.
b.
electrons.
c.
neutrons.
d.
ions.
The space surrounding the nucleus of an atom
contains
a.
protons.
b.
electrons.
c.
neutrons.
d.
ions.
The nucleus is made up of
a.
protons and electrons.
b.
electrons and neutrons.
c.
protons and neutrons.
d.
protons, neutrons, and electrons.
The nucleus is made up of
a.
protons and electrons.
b.
electrons and neutrons.
c.
protons and neutrons.
d.
protons, neutrons, and electrons.
If atom X had 17 protons and 18 neutrons, it would
be called
a.
17X.
b.
18X.
c.
35X.
d.
1X.
If atom X had 17 protons and 18 neutrons, it would
be called
a.
17X.
b.
18X.
c.
35X.
d.
1X.
Isotopes are atoms of the same element with the
same number of protons and
a.
a different number of electrons.
b.
a different number of molecules.
c.
a different number of neutrons.
d.
the same number of neutrons.
Isotopes are atoms of the same element with the
same number of protons and
a.
a different number of electrons.
b.
a different number of molecules.
c.
a different number of neutrons.
d.
the same number of neutrons.
If an atom contains 11 protons and 12 neutrons, its
atomic number is
a.
1.
b.
11.
c.
12.
d.
23.
If an atom contains 11 protons and 12 neutrons, its
atomic number is
a.
1.
b.
11.
c.
12.
d.
23.
Which of the following terms describes a substance
formed by the combination of two or more elements
in definite proportions?
a.
compound
b.
isotope
c.
nucleus
d.
enzyme
Which of the following terms describes a substance
formed by the combination of two or more elements
in definite proportions?
a.
compound
b.
isotope
c.
nucleus
d.
enzyme
A covalent bond is formed as the result of
a.
transferring electrons.
b.
sharing an electron pair.
c.
transferring protons.
d.
sharing a proton pair.
A covalent bond is formed as the result of
a.
transferring electrons.
b.
sharing an electron pair.
c.
transferring protons.
d.
sharing a proton pair.
What type of electrons is available to form bonds?
a.
valence
b.
nucleus
c.
ionic
d.
covalent
What type of electrons is available to form bonds?
a.
valence
b.
nucleus
c.
ionic
d.
covalent
What type of ion forms when an atom loses
electrons?
a.
neutral
b.
positive
c.
negative
d.
possibly positive or negative
What type of ion forms when an atom loses
electrons?
a.
neutral
b.
positive
c.
negative
d.
possibly positive or negative
The most abundant compound in most living things
is
a.
carbon dioxide.
b.
water.
c.
sodium chloride.
d.
sugar.
The most abundant compound in most living things
is
a.
carbon dioxide.
b.
water.
c.
sodium chloride.
d.
sugar.
Water molecules are polar, with
a.
the oxygen side being slightly positive and the
hydrogen side being slightly negative.
b.
the oxygen and hydrogen sides being slightly
positive.
c.
the oxygen and hydrogen sides being slightly
negative.
d.
the oxygen side being slightly negative and the
hydrogen side being slightly positive.
Water molecules are polar, with
a.
the oxygen side being slightly positive and the
hydrogen side being slightly negative.
b.
the oxygen and hydrogen sides being slightly
positive.
c.
the oxygen and hydrogen sides being slightly
negative.
d.
the oxygen side being slightly negative and
the hydrogen side being slightly positive.
Which of the following illustrates the different types
of chemical bonds in order of increasing attraction?
a.
ionic, covalent, hydrogen
b.
covalent, ionic, hydrogen
c.
hydrogen, covalent, ionic
d.
hydrogen, ionic, covalent
Which of the following illustrates the different types
of chemical bonds in order of increasing attraction?
a.
ionic, covalent, hydrogen
b.
covalent, ionic, hydrogen
c.
hydrogen, covalent, ionic
d.
hydrogen, ionic, covalent
A solution is a(an)
a.
breaking of a chemical bond.
b.
chemical reaction.
c.
evenly-distributed mixture of two or more
substances.
d.
combination of two or more liquids.
A solution is a(an)
a.
breaking of a chemical bond.
b.
chemical reaction.
c.
evenly-distributed mixture of two or more
substances.
d.
combination of two or more liquids.
When salt is dissolved in water, water is the
a.
reactant.
b.
solution.
c.
solute.
d.
solvent.
When salt is dissolved in water, water is the
a.
reactant.
b.
solution.
c.
solute.
d.
solvent.
Suspensions are mixtures
a.
of water and undissolved material.
b.
in which the components are evenly distributed
throughout the solution.
c.
both a and b.
d.
neither a nor b.
Suspensions are mixtures
a.
of water and undissolved material.
b.
in which the components are evenly distributed
throughout the solution.
c.
both a and b.
d.
neither a nor b.
If the pH of stomach acid and of oven cleaner were
measured,
a.
both would be below 7.
b.
both would be above 7.
c.
the pH of stomach acid would be above 7, but
the pH of oven cleaner would be below 7.
d.
the pH of stomach acid would be below 7, but
the pH of oven cleaner would be above 7.
If the pH of stomach acid and of oven cleaner were
measured,
a.
both would be below 7.
b.
both would be above 7.
c.
the pH of stomach acid would be above 7, but
the pH of oven cleaner would be below 7.
d.
the pH of stomach acid would be below 7,
but the pH of oven cleaner would be above 7.
A substance with a pH of 6 is called
a.
an acid.
b.
a base.
c.
both an acid and a base.
d.
neither an acid nor a base.
A substance with a pH of 6 is called
a.
an acid.
b.
a base.
c.
both an acid and a base.
d.
neither an acid nor a base.
Amino acid is to protein as
a.
fat is to lipid.
b.
DNA is to RNA.
c.
sugar is to fat.
d.
simple sugar is to starch.
Amino acid is to protein as
a.
fat is to lipid.
b.
DNA is to RNA.
c.
sugar is to fat.
d.
simple sugar is to starch.
A monosaccharide is a
a.
carbohydrate.
b.
lipid.
c.
nucleic acid.
d.
protein.
A monosaccharide is a
a.
carbohydrate.
b.
lipid.
c.
nucleic acid.
d.
protein.
Which of the following organic compounds is the
main source of energy for living things?
a.
carbohydrates
b.
lipids
c.
nucleic acids
d.
proteins
Which of the following organic compounds is the
main source of energy for living things?
a.
carbohydrates
b.
lipids
c.
nucleic acids
d.
proteins