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Chapter 2 Chemistry comes alive. For Quiz 2c. Biochemistry. The study of the chemical composition and reactions of living matter. Biochemistry. Organic compounds Contain carbon, are covalently bonded, and are often large Inorganic compounds All other chemicals in the body - PowerPoint PPT Presentation
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For Quiz 2c
BiochemistryBiochemistry
The study of the chemical composition and reactions
of living matter.
Biochemistry
• Organic compounds–Contain carbon, are covalently bonded, and are often large
• Inorganic compounds–All other chemicals in the body–Do not contain carbon–Water, salts, and many acids and bases
Today
• We will go over–Water–Salts–Acids–Bases–pH–Buffers
The Chemistry of Life
Water is the single most abundant substance on
Earth!
What are What are the the
PropertieProperties of s of
Water?Water?
Water is Water is different different
than other than other substances – substances – it expands it expands
as it freezes!as it freezes!
WaterWater
Most abundant and important inorganic compound in living
material.
Makes up 60% - 80% of the volume of most living
cells.
Properties of Water• High heat capacity High heat capacity
– absorbs and releases large amounts of heat before changing temperature
– This prevents sudden changes in body temperature cased by external factors like sun or wind or internal factors like heat released during vigorous muscle activity
– As a part of blood, water redistributes heat among body tissues, ensuring temperature homeostasis
Properties of Water
• High heat of vaporization High heat of vaporization
–changing from a liquid to a gas requires large amounts of heat
–As we sweat, perspiration (mostly water) evaporates from our skin removing large amounts of heat
–This is a very efficient cooling mechanism for our bodies!
Properties of Water
• Polar solvent propertiesPolar solvent properties
–Water is often called the universal solvent
–dissolves ionic substances
– forms hydration layers around large charged molecules
–serves as the body’s major transport medium
Properties of Water• ReactivityReactivity
–an important part of hydrolysis and dehydration synthesis reactions
–Food is digested to their building blocks by adding a water molecule to each bond - Hydrolysis reactions
–Carbohydrates and proteins are synthesized from smaller molecules by removing a water molecule for each bond formed – dehydration synthesis
Properties of Water
• CushioningCushioning
– resilient cushion around certain body organs
–Helps protect organs from physical trauma
–Cerebrospinal fluid surrounding the brain is an example
SaltsSalts
Salts
•Inorganic compounds•Contain cations other than H+
and anions other than OH–
•Are electrolytes; they conduct electrical currents
Salts
•Maintaining proper ionic balance in our body fluids is one the most crucial homeostatic roles of the kidneys.
•When this balance is severely disturbed, virtually nothing in the body works.
Acids and Bases
Acids and Bases are also electrolytes,
Conduct electrical current
Acids•Tastes sour•Dissolves many metals•Acids release H+ and are
therefore proton donorsHCl H+ + Cl –
Acids are proton donors!
Bases•Tastes bitter•Feel slippery•Bases release OH– and are proton acceptors
NaOH Na+ + OH–
Bases are proton acceptors!
Acid-Base Concentration (pH)
•AcidicAcidic solutions have higher H+ concentration and therefore a lower pH
•Alkaline (basic)Alkaline (basic) solutions have lower H+ concentration and therefore a higher pH
•Neutral Neutral solutions have equal H+
and OH– concentrations
Acid-Base Concentration (pH)
•Acidic: pH 0–6.99
•Basic: pH 7.01–
14
•Neutral: pH 7.00
Figure 2.12
Neutralization
• When acids and bases are mixed, they react with each other in a displacement reaction to form water and a salt.
HCl + NaOH -> NaCl + H2O
Buffers• Systems that resist abrupt and
large swings in the pH of body fluids are buffering systems
• If blood pH varies from the narrow range of 7.35 – 7.45 by more than a few tenths, it can be fatal!
• Homeostasis of acid-base balance is regulated by the kidneys and lungs and by chemical systems called Buffers.
Buffer systems• Carbonic acid-bicarbonate system
is a very important chemical blood buffer–Carbonic acid dissociates reversibly, releasing bicarbonate ions and protons
–The chemical equilibrium between carbonic acid and bicarbonate resists pH changes in the blood
QuizQuiz
2dNow!