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Chapter 2
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Chemicals are responsible for directing
virtually all of our bodily functions.
Basic chemical reactions occur in the body to
maintain homeostasis.
Basic concepts of biochemistry contribute to
homeostasis.
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What are examples of chemicals that are used
in the body?
What are examples of basic chemical
reactions that occur in the body?
What are examples of basic concepts of
biochemistry?
◦ Molecules = a group of atoms bound together
◦ Elements = a pure substance
 Compounds = substances whose molecules have more
than one kind of atom
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An element is a substance that is composed
of only one kind of atom.
Elements are represented by symbols. (i.e.
periodic table)
http://www.webelements.com/webelements/
scholar/
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Which elements are important to our bodies?
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Carbon = C
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Hydrogen = H
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Nitrogen = N
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Iodine = I
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Oxygen = O
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Chlorine = Cl
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Phosphorus = P
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Calcium = Ca
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Sodium = Na
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Sodium = Na
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Magnesium = Mg
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Hydroxide = OH
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Phosphate = PO
Chloride = Cl
Potassium = K
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Calcium = Ca
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Hydrogen = H
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Sodium = Na+
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Magnesium = Mg+
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Hydroxide = OH-
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Phosphate = PO4-
Chloride = ClPotassium = K+
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Calcium = Ca+
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Hydrogen = H+
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Name and define three kinds of particles
within an atom.
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At the core of each atom is a nucleus
composed of positively charged protons and
uncharged neutrons. Electrons inhabit the
outer regions called “electron shells.”
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Atom = a unit of matter that makes up a
chemical element.
Protons
Electrons
Neutrons
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Nucleus= at the core of each atom
Atomic number = # of protons in nucleus of
atom
Atomic mass = # of protons and neutrons
combined.
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What is an energy level?
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Energy levels are regions surrounding the
atomic nucleus that contain electrons, which
are negatively charged particles. Each level
may contain up to eight electrons. Energy
increases with distance from the nucleus.
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What is a chemical bond?
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A chemical bond is formed to make atoms
more stable. This can take place when two or
more atoms share, donate, or borrow
electrons which enhances their stability.
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What are the two different ways compounds
are formed?
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Ionic bonding occurs when one or more
electrons are transferred or donated from one
atom to another. Pg. 24
i.e. NaCL = sodium chloride
Covalent bonds are formed when two atoms
share a pair of electrons. Pg. 25
i.e. H2
ionic
covalent
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What is a solvent?
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A solute?
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Solvent is a liquid holding another substance
in a solution or a liquid that reacts with the
solvent to bring it into a solution.
Solute is a substance that is dissolved in a
solution.
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Water
◦ Water is a solvent (liquid into which solutes are
dissolved), forming aqueous solutions in the body
◦ Water is involved in chemical reactions
 Dehydration synthesis (water removed)
 Hydrolysis ( water added)
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What is an acid?
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A base?
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Acid is a concentration of hydrogen ions. As
the concentration of H+ ions increases the
solution becomes more acidic and the pH
value decreases.
Base or alkaline occurs when OH–
concentration increases as does pH, making
the solution more basic.
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What is an electrolyte?
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An ion?
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An electrolyte is a substance that ionizes in
solution, rendering the solution capable of
conducting an electric current.
An ion is an electrically charged atom or
group of atoms.
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Acids, bases, and salts
◦ Water molecules dissociate to form equal amounts
of H+ (hydrogen ion) and OH– (hydroxide ion)
◦ Acid—substance that shifts the H+/OH– balance in
favor of H+; opposite of base
◦ Base—substance that shifts the H+/OH– balance
against H+; also known as an alkaline; opposite of
acid
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What is an organic compound?
What is an inorganic compound?
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Organic compound refers to chemicals that
contain covalently bound carbon and
hydrogen atoms and are involved in
metabolic reactions.
Inorganic compounds have chemical
constituents that do not contain both carbon
and oxygen.
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What four elements make up about 96% of
the material in the human body?
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Carbon
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Oxygen
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Hydrogen
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Nitrogen
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As hydrogen ion concentration of a solution
increases, does it become more acid or
alkaline? Would the pH increase or decrease?
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How would you explain the concept of pH?
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Answer: The term pH is a symbol used to
mean hydrogen ion (H+) concentration of a
solution. As the concentration of H+
increases, the solution becomes more acid
and the pH value decreases. As the OH–
concentration increases, the pH value also
increases and the solution becomes more
basic or alkaline.
High H+
Low H+,
(High OH -)
Open link to the pH website:
http://www.phsciences.com/about_ph/ph_foods.asp
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Find something really acidic that surprised
you.
What has a high basic value for a food?
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Zwiebach 4.84 - 4.94
Watermelon 5.18 - 5.60
Orange, Juice Florida 3.30 - 4.15
Cranberry Juice, canned 2.30 - 2.52
Conch 7.52 - 8.40
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? Where on the scale would stomach acid be?
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Why such a strong acid in stomach?
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Cindy, 5 years old, has been ill for several
days with nausea and vomiting. If the pH of
the vomitus is tested, would it be alkaline or
acid?
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With the loss of acid from the stomach due to
excessive vomiting, the gastric contents
would most likely be alkaline.
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As acid increases the pH decreases.
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The stomach produces hydrochloric acid,
which normally aids in the process of _______.
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Digestion
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What is the pH of the following:
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(a) arterial blood?
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(b) venous blood?
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(c) urine?
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(d) water?
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(e) coffee?
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(f) wine?
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(a) 7.41 = arterial blood
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(b) 7.36 = venous blood
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(c) approx. 6.2 = urine
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(d) 7 = water
(e) 5 = coffee
(f) 3.5 = wine
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Your blood normally has a pH of around 7.4.
Is your blood alkaline, acidic, or neutral?
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Blood pH is slightly alkaline.
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More complex than inorganic!
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Major types found in body:
◦
◦
◦
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Carbohydrates
Lipids
Proteins
Nucleic acids
◦ Note: Table 2-3 gives examples, and functions of
each.
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Structure: Proteins are large molecules
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Function: Proteins participate in chemical
formed by linkage of amino acids by peptide
bonds; one of the basic building blocks of the
body.
processes of the body. Functional proteins
include some of the hormones. Most
hormones are proteins, growth factors, cell
membrane channels, receptors, and enzymes.
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Structure: Lipids are organic compounds
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Function: Triglycerides are a major source of
composed of hydrogen, carbon, and oxygen.
The building blocks that make up lipids are
glycerol and fatty acids. The types of lipids
are triglycerides, phospholipids, and steroids
(cholesterol).
stored energy. They also function to insulate
and protect body organs.
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Structure: Carbohydrates are organic
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Function: To store energy for later use.
compounds such as carbon, hydrogen, and
oxygen. They are made up of six-carbon
subunits called monosaccharide units (e.g.,
sucrose, lactose) and polysaccharides, which
are made up of many monosaccharide units
(e.g., glycogen, made up of many glucose
units).
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Structure: Nucleic acids are a group of high-
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Function: By directing the formation of
molecular-weight substances found in cells
of all living things. They consist of (1)
nucleotide units, (2) DNA, and (3) RNA.
structural and functional proteins, nucleic
acids ultimately direct overall body structure
and function.
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What mechanism does DNA use to regulate
all of the body’s structures and functions?
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Answer: Proteins play a vital role in the
body’s structure and function. In a real sense
we are what our proteins are. Protein
synthesis constructs an exact arrangement of
amino acids in a specific sequence which
produces a protein-synthesizing mechanism
in each cell. The cell knows the exact pattern
and assembly of the amino acid because it is
coded and stored within the deoxyribonucleic
acid (DNA) molecule.
A.
B.
C.
D.
E.
Slide 63
Atom
Ion
Molecule
Element
Electron
A.
B.
C.
D.
E.
Slide 64
Ozone
Covalent
Chemical
Electrical
Ionic
A.
B.
C.
D.
E.
Slide 65
Water H2O
Carbon dioxide CO2
Glucose C6H12O6
Nitric oxide NO
Oxygen O2
A.
B.
C.
D.
E.
Slide 66
pH
pH
pH
pH
pH
7.1
7.0
12.4
6.9
8.3
A.
B.
C.
D.
E.
Slide 67
Proteins
Lipids
Carbohydrates
Nucleic acids
Inorganic
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Questions?
Questions?
Questions?
Questions?
Questions?
Questions?
Questions?