Transcript 06The Chemistry of Life

1.
Which four elements are the most common in living
things?
2. What do you know about these four elements?
The Life of a Cell
The Chemistry of Life
Atoms and Their Interactions
Elements
• Everything – whether it is a rock, frog, or
flower – is made of substances called elements.
• Element: a substance that can’t be broken
down into simpler chemical substances. It is
made of one type of atom.
Natural elements in living things
• Of the naturally occurring elements on Earth,
only about 25 are essential to living
organisms.
• Carbon, hydrogen, oxygen, and nitrogen
make up more than 96 percent of the mass of
a human body.
Trace elements
• Trace elements such as iron and copper, play
a vital role in maintaining healthy cells in all
organisms.
• Plants obtain trace elements by absorbing
them through their roots; animals get them
from the foods they eat.
Table 6.1 Some Elements That Make Up the Human Body
Percent By
Percent By
Element
Element
Symbol Mass in
Symbol Mass in
Human Body
Human Body
Oxygen
Fe
O
65.0
Iron
trace
Zn
Zinc
Carbon
C
18.5
trace
Hydrogen
Cu
H
9.5
Copper
trace
I
Iodine
Nitrogen
N
3.3
trace
Calcium
Ca
1.5
trace
Manganese Mn
Boron
B
1.0
Phosphorus P
trace
Cr
K
Potassium
0.4
Chromium
trace
trace
Molybdenum Mo
Sulfur
S
0.3
Cobalt
Sodium
Co
trace
Na
0.2
Se
Chlorine
0.2
Selenium
trace
Cl
Fluorine
F
Magnesium Mg
0.1
trace
Atoms: The Building Blocks of Elements
• Atom: the smallest particle of an element
that has the characteristics of that element.
• Atoms are the basic building blocks of all
matter.
The structure of an atom
• Nucleus: the center of an atom
• All nuclei contain positively charged
particles called protons (p+) and particles
with no charge, called neutrons (n0).
The Structure of an atom
• The region of space surrounding the nucleus
contains extremely small, negatively charged
particles called electrons (e-)
Nucleus
Electron
energy
levels
• This region of
space is referred
to as an electron
cloud.
The Structure of an atom
• Protons and neutrons are approximately the
same size and mass, at around 1 AMU.
• Electrons are far smaller, and they are
1⁄1836 the size of protons and neutrons
• Because opposites attract, the negatively
charged electrons are held in the electron
cloud by the positively charged nucleus.
Electron energy levels
• Electrons exist
around the nucleus
in regions known
as energy levels.
Nucleus
8 protons (p+)
8 neutrons (n0)
Oxygen atom
Electron energy levels
• The first energy level can hold only two
electrons. The second level (there are two
of these) can hold a maximum of eight
electrons. The third level can hold up to
18 electrons.
• An atom of fluorine has nine electrons.
How many electrons are in its second
energy level?
Electron energy levels
• Atoms contain equal numbers of electrons
and protons; therefore, they have no net
charge.
• If an atom of fluorine has nine electrons,
how many protons are in an atom of
fluorine?
Isotopes of an Element
• Atoms of the same element always have the
same number of protons but may contain
different numbers of neutrons.
• Isotopes: atoms of the same element that have
different numbers of neutrons
• Carbon-12, carbon-13 and carbon-14 are
examples of isotopes.
Compounds and Bonding
• Compound: a substance that is composed of
atoms of two or more different elements
that are chemically combined.
• Table salt (NaCl)
is a compound
composed of the
elements sodium
and chlorine.
Chemical
formula
How covalent bonds form
• Atoms combine with other atoms only when
the resulting compound is more stable than
the individual atoms.
• For many elements, an atom becomes stable
when its outermost energy level is full.
• Sharing electrons with other atoms is
one way for elements to become stable.
How covalent bonds form
• Two hydrogen
atoms can combine
with each other
by sharing their
electrons.
• Each atom
becomes stable
by sharing its
electron with
the other atom.
Hydrogen molecule
How covalent bonds form
• The attraction of
the positively
charged nuclei
for the shared,
negatively
charged
electrons holds
the atoms
together.
Hydrogen molecule
How covalent bonds form
• Covalent bond : an
attractive force between
two atoms that share
electrons.
• Molecule : a
group of atoms
held together by
covalent bonds.
It has no overall
charge.
Water
molecule
How ionic bonds form
• An atom (or group of atoms) that gains or
loses electrons has an electrical charge and is
called an ion.
• Ion: a charged particle made of atoms.
• Ionic bond : attractive force between two
ions of opposite charge
• Example: A chlorine atom becomes a
chloride ion when it gains an electron.
Chemical Reactions
• Chemical reactions occur when bonds are
formed or broken, causing substances to
recombine into different substances (ex.
burning paper).
• Metabolism : all of the chemical reactions that
occur within an organism
Writing chemical equations
• In a chemical
reaction, substances
that undergo
chemical reactions,
are called reactants.
• Substances formed
by chemical
reactions, are called
products.
Writing chemical equations
• A molecule of table sugar can be represented
by the formula: C12H22O11.
•How many atoms are in a molecule of table
sugar (sucrose)?
• The easiest way to understand chemical
equations is to know that atoms are neither
created nor destroyed in chemical reactions.
They are simply rearranged.
Mixtures and Solutions
• Mixture : a combination of substances in
which the individual components retain their
own properties.
• Neither component of the mixture changes.
Mixtures and Solutions
• Solution : a mixture in which one or more
substances (solutes) are distributed evenly in
another substance (solvent).
• Sugar molecules
in a powdered
drink mix
dissolve easily in
water to form a
solution.
Acids and bases
• Chemical reactions can occur only when
conditions are right.
• A reaction may depend on:
- energy availability
- temperature
- concentration of a substance
- pH of the surrounding environment
Acids and bases
• pH : a measure of how acidic or basic a
solution is.
• A scale with values ranging from below 0 to
above 14 is used to measure pH.
More acidic
Neutral
More basic
Acids and bases
• Substances with a pH below 7 are acidic.
•Acid : any substance that forms hydrogen
ions (H+) in water
• A solution is neutral if its pH equals seven.
More acidic
Neutral
More basic
Acids and bases
• Substances with a
pH above 7 are
basic.
•Base : any
substance that forms
hydroxide ions (OH-)
in water.
pH 11
Question 1
Which of the following is an element?
A. chlorophyll
B. carbon
C. sodium chloride
D. water
Question 2
The smallest particle of an element that has the
characteristics of that element is a(n)
__________.
A. proton
C. nucleus
B. electron
D. atom
Question 3
Which of the following can contain two types
of particles?
A. nucleus
B. protons
C. neutrons
D. electrons
Question 4
Sodium and chlorine combine to form table
salt. What do you know to be true?
A. Sodium and chlorine are sharing electrons in
their outer energy levels.
B. Sodium and chlorine atoms have no overall
electrical charge.
Question 4
Sodium and chlorine combine to form table
salt. What do you know to be true?
C. Sodium and chlorine are less stable in the
compound sodium chloride.
D. Sodium and chlorine atoms in table salt have
full outer energy levels.
Question 5
What is it called when atoms share electrons?
Water
molecule
A. covalent bonding
C. hydrogen bonding
B. ionic bonding
D. diffusion
Question 6
Which of the following combinations will
produce a solution?
A. chocolate chips and cookie dough
B. sand and sugar crystals
C. powdered drink mix and water
D. oil and vinegar
Question 7
What type of substance forms hydrogen ions in
water?
A. enzyme
B. acid
C. base
D. polar
Question 8
Which of the following best describes a
molecule with an unequal distribution of
charge?
A. polar
B. acidic
C. basic
D. diffuse
Question 9
An oxygen atom has 8 protons and 8 neutrons.
How many electrons does it have?
A. 8
B. 18
C. 32
D. 0
Question 10
What is the difference between a compound
and an element?
# 1 Answer
The answer is B. An element can't be broken
down into simpler chemical substances.
Chemical elements combine in different ways
to form a variety of substances useful to living
things.
Table 6.1 Some Elements That Make Up the Human Body
Percent By
Percent By
Element
Element
Symbol Mass in
Symbol Mass in
Human Body
Human Body
Oxygen
Fe
O
65.0
Iron
trace
Zn
Zinc
Carbon
C
18.5
trace
Hydrogen
Cu
H
9.5
Copper
trace
I
Iodine
Nitrogen
N
3.3
trace
Calcium
Ca
1.5
trace
Manganese Mn
Boron
B
1.0
Phosphorus P
trace
Cr
K
Potassium
0.4
Chromium
trace
trace
Molybdenum Mo
Sulfur
S
0.3
Cobalt
Sodium
Co
trace
Na
0.2
Se
Chlorine
0.2
Selenium
trace
Cl
Fluorine
F
Magnesium Mg
0.1
trace
#2 Answer
The answer is D. Atoms are the basic building
blocks of all matter and have the same general
structure, including a nucleus and electrons.
Elements found in both living and nonliving
things are made of atoms.
Nucleus
Electron energy levels
An atom has a
nucleus and
electrons in
energy levels.
# 3 Answer
The answer is A. The nucleus is the center of
the atom and may contain both positively
charged particles and particles that have no
Nucleus
charge.
8 protons (p+)
8 neutrons (n0)
Oxygen atom
#4 Answer
The answer is D. Sodium and chlorine
atoms combine because the resulting
compound, table salt, is more stable than
the individual atoms. Sodium loses an
electron in its outer energy level, chlorine
gains that electron in its outer energy
level, and an ionic bond is formed.
#5
The answer is A.
Covalent bonds differ
from ionic bonds in
that the shared
electrons move about
the nuclei of both
atoms of the covalent
compound.
Water
molecule
#6
The answer is C. All of
the combinations are
mixtures because the
individual components
retain their own
properties. A solution is a
mixture in which one or
more substances is
dissolved in another and
will not settle out of
solution.
Water
molecules
Sugar
molecules
Sugar
crystal
#7
The answer is B. Any substance that forms
hydrogen ions (H+) in water is an acid. The
pH of a substance is a measure of how acidic
or basic a solution is.
#8
The answer is A. Each polar molecule has a
positive end and a negative end. Polar water
molecules attract ions and other polar
molecules, and can dissolve many ionic
compounds.
#9
The answer is A. Atoms contain equal
numbers of electrons and protons and have no
net charge.
Nucleus
8 protons (p+)
8 neutrons (n0)
Oxygen atom
• # 10 Answer
• A compound is a substance that is composed
of atoms of two or more different elements
that are chemically combined. An element is a
substance that can't be broken down into
simpler chemical substances
1. What are some characteristics of
water?
2. How do organisms use water to live
and grow?
The Life of a Cell
The Chemistry of Life
Water and Diffusion
Water and Its
Importance
• Water is perhaps the
most important
compound in living
organisms.
• Water makes up 70
to 95 percent of most
organisms.
Water is Polar
• Sometimes, when atoms form covalent bonds
they do not share the electrons equally. This
is called a polar bond.
Water is Polar
• Polar molecule : a molecule with an
unequal distribution of charge; that is,
each molecule has a positive end and a
negative end.
• Water is an example of a polar molecule.
• Water can dissolve many ionic
compounds, such as salt, and many other
polar molecules, such as sugar.
Water is Polar
• Water molecules also attract other water
molecules.
Hydrogen atom
• Weak hydrogen
bonds are formed
between positively
charged hydrogen
atoms and negatively
charged oxygen
atoms.
Hydrogen atom
Oxygen atom
Unique properties of water
• Water resists changes in temperature.
Therefore, water requires more heat to
increase its temperature than do most other
common liquids.
•Water can move UP because of capillary
action.
Unique properties of water
• Water is one of the
few substances that
expands when it
freezes.
• Ice is less dense
than liquid water so
it floats as it forms
in a body of water.
Early observations: Brownian motion
• In 1827, Scottish scientist Robert Brown used a
microscope to observe pollen grains suspended
in water. He noticed that the grains moved
constantly in little jerks, as if being struck by
invisible objects.
• This motion is now called Brownian motion.
• Today we know that Brown was observing
evidence of the random motion of atoms
and molecules.
The process of diffusion
• Diffusion : the net movement of particles from
an area of higher concentration to an area of
lower concentration.
• Diffusion results because of the random
movement of particles (Brownian motion).
• Three key factors—concentration,
temperature, and pressure—affect the rate
of diffusion.
The results of diffusion
• When a cell is in
dynamic equilibrium
with its environment,
materials move into
and out of the cell at
equal rates.
Material moving
out of cell equals
material moving
into cell
•As a result, there is no net
change in concentration
inside or outside the cell.
Diffusion in living systems
• The difference in concentration of a substance
across space is called a concentration gradient.
• Ions and molecules diffuse from an area of
higher concentration to an area of lower
concentration, moving with the gradient.
• Dynamic equilibrium occurs when there
is no longer a concentration gradient.
Diffusion in living systems
• Diffusion continues until there is no longer a
concentration gradient and dynamic
equilibrium has been reached.
1. Explain why water is important to living
organisms.
2. Define diffusion in your own words
3. Explain what dynamic equilibrium means
Answers
1. Living organisms must have water for life
processes, because critical molecules and ions
must be free to move and collide, which only
happens when they are dissolved in water.
Water also transports materials in living
organisms, such as in blood or sap.
2. Diffusion is the movement of particles from
high concentration to low concentration
3. Dynamic equilibrium happens when an
equilibrium of particles exist between the
gradient
Bellwork 9/9/15
• Get out your vocabulary
• Add the following prefix to your prefix/suffix
sheet:
Macro— Large
Your quiz on the 10 pre/suffixes
will be Friday!
The Life of a Cell
The Chemistry of Life
Life Substances
The Role of Carbon in Organisms
• Carbon compounds that come from living
organisms are called organic compounds.
• A carbon atom has four electrons available for
bonding in its outer energy level.
• In order to become stable, a carbon atom forms
four covalent bonds that fill its outer energy
level.
The Role of Carbon in Organisms
• Two carbon atoms can form various types of
covalent bonds—single, double or triple.
Single Bond
Double Bond
Triple Bond
Molecular chains
• Carbon compounds vary greatly in size.
• When carbon atoms bond to each other, they
can form straight chains, branched chains, or
rings.
Molecular chains
• Small molecules bond together to form
large chains called polymers.
• Polymer : a large molecule formed when
many smaller molecules bond together.
• Polymers usually form by covalent
bonding.
The four major macromolecules
•
•
•
•
Carbohydrates
Lipids
Nucleic Acids
Proteins
The structure of carbohydrates
• Carbohydrate : a biomolecule composed
of carbon, hydrogen, and oxygen with a
ratio of 2 hydrogen atoms and 1 oxygen
atom for every 1 carbon atom.
The structure of carbohydrates
• Monosaccharide : the simplest type of
carbohydrate; a simple sugar (ie. glucose,
fructose)
• Glucose and fructose combine in a
condensation reaction to form sucrose (table
sugar)
The structure of carbohydrates
• The largest carbohydrate molecules are
polysaccharides, polymers composed of
many monosaccharide subunits. (ie.
potatoes, liver)
• Plant energy is stored in the form starch,
animal energy is stored in the form of
glycogen
The structure of lipids
• Lipids : large biomolecules that are made
mostly of carbon and hydrogen with a small
amount of oxygen. (ie. fats, oils, waxes)
The structure of lipids
• They are insoluble
in water because
their molecules are
nonpolar and are not
attracted by water
molecules.
The structure of lipids
• A fatty acid with single bonds is saturated; with
double bonds is unsaturated
The structure of proteins
• Protein : a large, complex polymer composed of
carbon, hydrogen, oxygen, nitrogen, and
sometimes sulfur.
The structure of proteins
• Amino acids : the basic building blocks of
proteins
• There are about 20 common amino acids that
can make literally thousands of proteins.
The structure of proteins
• Peptide bonds : covalent bonds formed between
amino acids.
The structure of proteins
• Proteins are the building blocks of many
structural components of organisms.
The structure of proteins
• Enzymes are important proteins found in
living things.
• Enzyme : a protein that changes the rate of a
chemical reaction.
• They speed the reactions in digestion of food.
The structure of nucleic acids
• Nucleic acid : a complex biomolecule that
stores cellular information in the form of a
code.
• Nucleotides : small subunits that make up
nucleic acids
The structure of nucleic acids
• Nucleotides are arranged in three groups—a
nitrogenous base, a simple sugar, and a
phosphate group.
Phosphate
Sugar
Nitrogenous
base
The structure of nucleic acids
• DNA, which stands for deoxyribonucleic acid
is a nucleic acid.
Phosphate
Sugar
Nitrogenous
base
The structure of nucleic acids
• The information coded in DNA contains the
instructions used to form all of an organism’s
enzymes and structural proteins.
• Another important nucleic acid is RNA, which
stands for ribonucleic acid. RNA is a nucleic
acid that forms a copy of DNA for use in
making proteins.
• What is a polymer?
• How many types of bonds does Carbon make?
• What is a Carbon Compound?
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Question 1
How many covalent bonds does a carbon atom
need to form in order to become stable?
A. 1
B. 2
C. 3
D. 4
Question 2
A __________ is a biomolecule composed of
carbon, hydrogen, and oxygen with a ratio of
about two hydrogen atoms and one oxygen
atom for every carbon atom.
A. carbohydrate
C. protein
B. lipid
D. fatty acid
Question 3
In which type of molecule will you find peptide
bonds?
A. carbohydrate
C. protein
B. lipid
D. fatty acid
Question 4
What biomolecule is represented in this
diagram?
Phosphate
Sugar
Nitrogenous
base
A. carbohydrate
C. protein
B. nucleotide
D. lipid
Question 5
Describe an enzyme and its function.
Question 6
Based on your
knowledge of
biomolecules,
which of the
following
substances
would be most
effective at
breaking down
this polymer?
HO
CH2OH
O
A. nuclease
OH
B. lipase
OH
O
D. water
O
HOCH2
HO
OH
C. pepsin
CH2OH
#1
The answer is D. A carbon atom has four
electrons available for bonding in its outer
energy level and needs to form four covalent
bonds in order to become stable.
#2
The answer is A. Lipids are made mostly of
carbon and hydrogen, and proteins contain
nitrogen in addition to carbon, hydrogen and
oxygen.
#3
The answer is C. Amino acids are the basic
building blocks of proteins and are linked
together by peptide bonds.
#4
The answer is B. Nucleotides are the smaller
subunits that make up nucleic acids. Nucleotides
are composed of three groups: a nitrogenous
base, a simple sugar, and a phosphate group.
Phosphate
Sugar
Nitrogenous
base
#5
An enzyme is a protein that enables other
molecules to undergo chemical changes to form
new products. Enzymes increase the speed of
reactions that would otherwise proceed too
Substrate
slowly.
Active
site
#6
The answer is D. This is a sucrose molecule,
formed from glucose and fructose in a
condensation reaction. The products of this
reaction are the sucrose molecule and water. If
water is added to sucrose, hydrolysis occurs and
breaks the covalent bonds between the subunits.
What to study for the test:
1. All of your notes and/or the PowerPoint
slides on the blog
2. All worksheets we have done throughout
this unit
3. Your vocabulary
4. Your macromolecule foldable
5. Look at your objective sheet and make sure
you know the things listed