Transcript BioCh6-Chemistry of Life.73

Board Work
Elements in the Human Body
(percent by mass)
1.5%
1.0%
1.5%
3.0%
9.5%
18.5%
65.0%
•
•
Oxygen
Carbon
Hydrogen
Nitrogen
Calcium
Phosphorus
Other Elements
What four elements are the most common in the human
body
What do you know about these four elements
Devotions
Ch 6: The Chemistry
of Life
6.1: Atoms and Their Interactions
Element
• A substance that can not be broken down into
smaller particles.
– 90 elements naturally occur on earth
– 25 are essential to living things
– Each element is identified by a symbol
C = Carbon
Ca = Calcium
Na = Sodium
Elements in the Human Body
1.5%
1.0%
1.5%
3.0%
9.5%
18.5%
65.0%
Oxygen
Carbon
Hydrogen
Nitrogen
Calcium
Phosphorus
Other Elements
Trace Elements
• Elements that are present in small
amounts in the human body.
– N,K,Ca,and Fe are a few examples
– Help control cell metabolism
– Plants obtain trace elements through their
roots while animals obtain trace elements
through what they eat.
Atoms
• The smallest part of an element that
still maintains all the characteristics of
that element.
• The basic building blocks of all matter
Example: Gold (Au)
The Structure of Atoms
• Nucleus: Center of the Atom
• Electrons:
– The outer particles
– Negatively charged
• Protons:
– Particles found in the nucleus
– Positively charged
• Neutrons: Particles found in the nucleus that have no
charge.
• Electron and Proton numbers are always
the same
Model of the Atom
Neutron (0)
Electron (-)
Proton (+)
Energy Levels
• Regions around the nucleus that the electrons
travel.
– Atoms like to have their outer most energy level full.
Energy Levels & Electrons
Energy Level
# of Electrons
1
2
2
8
3
18
Isotopes
Atoms of the same element that have
different numbers of neutrons.
Isotopes
• Most carbon nuclei contain six
neutrons
• Some have 7 or 8
• These three atoms are isotopes
• We refer to the isotopes in terms of the
combined total of protons and neutrons
– Carbon-12 has 6 protons and 6 neutrons
– How many protons and neutrons does
carbon-13 and carbon-14 have??
Problem Solving Lab 6.1
• Read Problem Solving Lab
6.1 in groups of twos
• Answer the 4 questions
Compounds
• A substance that is composed of two
or more different elements that are
chemically combined.
– Properties of compounds are different than
those of their individual elements. (NaCl)
– Compounds can always be described with
an equation. (H20)
Covalent Bonds
• When two elements share
electrons in their outer energy
level.
– Atoms are the happiest when their
outer energy level is full.
– Water is an example
Covalent Video
Molecule
• A group of atoms
held together by
covalent bonds and
have no overall
charge.
Ions
• Atoms that gain or lose electrons. (+ or -)
Ionic Bonds
• A bond between atoms that is
formed by losing and gaining an
electron.
–
–
–
–
NaCl is an example
Na has one electron in its outer shell
Cl has 7 in its outer shell
The two oppositely charged atoms
now attract each other like magnets.
Ionic Bonds
Chemical Reactions
• Chemical reactions occur when bonds
between compounds are broken or
formed.
– Chemical reactions must have the right
environment
•
•
•
•
pH
Temperature
Energy
Concentration
Chemical Equations
• Reactant + reactant  Product
• Reactants undergo chemical reactions
• Products are formed in chemical
reactions
2H2 + O2  2H2O
Key Point: atoms are never created or
destroyed
Metabolism
• All of the chemical reactions
that occur in the human
body.
– Produce energy
– Require energy
– Build necessary molecules for
bodily functions
Solutions & Mixtures
• Solutions
– A mixture in which
one or more
substances are
evenly distributed
in another
substance.
• Salt Water
• Kool-Aid
• Mixtures
– A combination of
substances in which
the individual
components retain
their chemical
properties.
• Sand and Salt
pH Levels
• pH is a measure of how
acidic or basic a substance
is.
– Scale of 0-14
– pH paper is used to
determine the pH level
– A pH below 7 is acidic
– A pH above 7 is basic
– 7 is actually neutral
– Water has a pH level of 7
Common pH Levels
Acids
• Any substance that forms hydrogen
ions in water.
– When HCl is put into water H+ and
Cl- ions.
Base
• Any substance that forms
hydroxide ions in water.
– OH– When NaOH is put in water
you get Na+ and OH- ions.
Common Acids and Bases
• Acids
– Orange Juice
– Stomach Acids
– Tomato Juice
• Bases
– Egg
– Some soils for
plants
MiniLab 6.1 - Determine pH
• With your Lab Partner, complete
MiniLab 6.1 on page 155
Board Work
• What are some characteristics of water
• How do organisms use water to live and grow?
Devotions
Review
• What is an Element?
• What are the basic building block of all
matter?
• If there are 5 protons in an atom, how
many electrons are there?
• If a solution has a pH of 9, is it an acid
or a base
• Name 3 kinds of bonds.
Ch 6 - The
Chemistry of Life
6.2 - Water And Diffusion
The Importance of Water
• Most life processes occur only in water
• Helps to transport materials in
organism
• 70 to 95% of most organisms is . . .
Water
What makes water so “cool”?
• Water is polar
• Water sticks but isn’t sticky
– Capillary action: able to creep up thin tubes
• Water resists temperature changes
• Water expands when it freezes
Water is polar
• Water (H2O) contains two hydrogen
atoms and one Oxygen atom that are
covalently bonded to each other
• The Shared electrons are more
attracted to the Oxygen atom than to
the hydrogen atoms (Unequal sharing)
• Results in a polar molecule: It has a
positive and a negative end
• Polar likes polar (i.e. Ionic compounds
like salt and other polar molecules like
sugar)
Hydrogen Bonds
• Because water
molecules have a
positive end and a
negative end, there
will be an attraction
between water
molecules
Water resists temperature changes
• It takes a lot of heat to increase its
temperature
• Loses a lot of heat when it cools
• These features help maintain a steady
environment (i.e. in cells)
Water expands when it freezes
• Ice Floats - less
dense
• What would happen
to lake Michigan if
ice was more dense
than water.
Problem-Solving Lab 6.2
Diffusion
• Anything that is moving has kinetic
energy
• If you look at the molecules of gasses,
liquids and some solid molecules under
a very powerful microscope, you will
see that they are randomly moving -->
Brownian motion
Diffusion
• Diffusion: The net movement of
particles from an area of higher
concentration to an area of lower
concentration.
• A very slow process --> Relies on
random molecular motion (Brownian
motion)
• Affected by 3 factors
– Concentration (most important factor)
– Temperature
– Pressure
Brownian Motion
Diffusion
• Diffusion continues until the two
substances are distributed evenly -->
Dynamic Equilibrium
• Concentration gradient: the difference
in concentration of a substance across
space.
• At dynamic equilibrium, there is no
concentration gradient
Life Substances
Carbon
• Carbon has 4 electrons in its outer
energy level
• Can form 4 covalent bonds with other
elements
• Can also bond with other carbon atoms
• 3 types of bond:
– Single bond: each atom shares 1 electron
– Double bond: each atom shares 2 electrons
– Triple bond: each atom shares 3 electrons
Carbon
• Carbon atoms can form straight chains,
branched chains, or rings and can bind
to other elements
• Can form a whole bunch of carbon
structures.
Simple formulas
• Water H2O
• Glucose C6H12O6
• Isomers: Same
simple formula but
different 3D
structure
• Glucose and
Galactose are both
C6H12O6
Molecular Chains
• Large molecules are called macromolecules
(e.g. proteins)
• Macromolecules are formed by binding
together smaller molecules into chains
(Polymer)
Condensation and Hydrolysis
• Condensation: Chemical reaction by which
polymers are formed (water is removed)
• Hydrolysis: Chemical reaction by which
polymers are broken apart (water is used)
Carbohydrates
• Organic compound composed of Carbon,
hydrogen and oxygen.
• 2 H’s and 1 O for every carbon
• Simplest type is monosaccharides like glucose
and fructose.
• Two monosaccharides bind to form a
disaccharide (i.e. Sucrose = glucose +
fructose)
• Many monosaccharides bind to form
polysaccharides (i.e. starch and cellulose glucose polymers.)
Carbohydrates
Lipids
• Lipids are fats and oils.
• Organic compound with a large
proportion of C-H bonds and less
oxygen than carbohydrates.
• Nonpolar
• Used in cells for energy storage,
insulation and protection.
Lipids
• Most commonly 3 fatty acids bound to
a glycerol molecule. (pg 164)
Proteins
• Provide structure for tissues and
organs
• Carry out cell metabolism
• Large, complex polymer made of
Carbon, hydrogen, oxygen, nitrogen and
usually sulfur.
• Building blocks are various
combinations of amino acids
• Amino acids join together with peptide
bond
Proteins
• An Enzyme is a protein that changes the rate of
a chemical reaction
– Involved in almost all metabolic processes.
– Speeds up chemical reaction
Nucleic Acids
• Stores cellular information in the form
of a code.
• Polymer of smaller subunits called
nucleotides.
• Nucleotides consist of C, H, O, N, P
atoms.
• Nucleotides make up our DNA
Nucleic Acids
• Nucleic acids have 3 parts:
– A Base
– A Simple sugar
– A Phosphate group
Nucleic Acids