Transcript elements cannot be further broken down by a chemical reaction

Elements are the building blocks
for all matter. Elements contain a single
type of atom; elements cannot be further
broken down by a chemical reaction.
Elements important for the purposes of
this course include hydrogen, oxygen,
nitrogen, and carbon. All naturally
occurring elements are listed in the
periodic table.
Why water is important to the human body
• Chemical Properties
• Universal solvent: Water can dissolve hydrophilic
(water-loving) substances such as proteins, gases, salts,
and carbohydrates and transport them inside the cells, in
and out of cells, and between different cells. It cannot
dissolve hydrophobic (water-fearing) substances.
• Chemically active: Water can participate in many
chemical reactions.
• Physical Properties
• Heat transfer: Water remains a liquid over a wide range of
temperatures and conducts heat well. Think of a pot of
water on the stove—only the water at the bottom of the pot
is in contact with the heat source yet all of the water is
heated. Water (in blood) is necessary for cooling or
warming purposes throughout the body.
Chemical Bonds
Atoms interact chemically to alter neutrality
of atoms and form bonds.
Ionic bonding.
Ionic Bonds
• Electrons transferred between atoms form
ionic bonds.
• Electrolytes— ionic bonds form
compounds that release ions when they
are in solution
– Influence homeostasis (stable condition of
normal organism)
– Conduct electronic current
Covalent Bonds
A chemical bond in which atoms share
electrons
• Non-polar covalent bond
• Polar covalent bond
Compounds: Acids, Bases, and
Salts
Compounds are chemical substances with
specific properties
•Acid can donate hydrogen ion (H+)
•Base (alkali) can accept hydrogen ion (H+)
•Salt is formed by a reaction between an
acid and a base
The pH Scale
• Represents relative concentrations of
hydrogen and hydroxide ions in a solution
• Scale from 0 (most acidic) to 14 (most
basic)
• Each unit represents a 10-fold change
• Body fluids usually 7.35-7.45 pH
Buffers
Chemicals that prevent sharp changes in
hydrogen ion concentration and maintain
relatively constant pH in body fluids
Checkpoint 2-8: The pH scale is used to
measure acidity and alkalinity of fluids. What
number is neutral on the pH scale? What
kind of compound measures lower than this
number? Higher?
Checkpoint 2-9: What is a buffer?
Chemistry of Living Matter
Living matter contains 26 of 92 natural
elements.
• 96% of body weight—four elements
• 4% of body weight—nine elements
• 0.1% of body weight—13 elements
Organic Compounds
Chemical compounds that characterize
living things
• Contain carbon, hydrogen, and oxygen
– Carbohydrates
– Lipids
– Proteins
Question:
True or False?: The three main
organic compounds are
carbohydrates, proteins, and
amino acids.
Answer:
False: The three main organic
compounds are carbohydrates,
proteins, and lipids
Carbohydrates
• Monosaccharides (simple sugars)
– Glucose
• Disaccharides
• Polysaccharides
– Starch
– Glycogen
Examples of carbohydrates.
ZOOMING IN: • What are the building blocks of disaccharides and
polysaccharides?
Lipids
• Triglycerides
– Glycerol (glycerin)
• Phospholipids
• Steroids
– Cholesterol
– Steroid hormones
– Sex hormones
Proteins
• Amino acids
• Enzymes
– Catalysts
– Substrates
Proteins.
ZOOMING IN
• What part of
an amino acid
contains
nitrogen?
Diagram of enzyme action.
ZOOMING IN • How does the
shape of the enzyme before
the reaction compare with its
shape after the reaction?
Checkpoint 2-13: Enzymes are proteins
that act as catalysts. What is a catalyst?
End of Presentation