Download Chapter 2: The Chemical Level of Organization

Chapter 2: The Chemical
Level of Organization
KEY CONCEPT
• All Matter is made up of atoms
• Atoms join together to form chemicals
with different characteristics
• Chemical characteristics determine
physiology at the molecular and
cellular level
Atomic Particles
• Proton:
– positive, 1 mass unit
• Neutron:
– neutral, 1 mass unit
• Electron:
– negative, low mass
Isotopes
• 2 or more elements with equal
numbers of protons but different
numbers of neutrons
Elements in the Human Body
Table 2–1
Molecules and Compounds
• Molecules:
– atoms joined by strong bonds
• Compounds:
– atoms joined by strong or weak bonds
States of Matter
• Solid:
– constant volume and shape
• Liquid:
– constant volume but change shape
• Gas:
– change volume and shape
Chemical reactions & Physiology?
• Energy:
– the power to do work
• Work:
– a change in mass or distance
Forms of Energy
• Kinetic energy - energy of motion
• Potential energy - stored energy
• Chemical energy - potential energy
stored in chemical bonds
KEY CONCEPT
• When energy is exchanged, heat is
produced, but cells cannot capture it
or use it for work
Break Down, Build Up
• Decomposition reaction (catabolism):
AB A + B
• Synthesis reaction (anabolism):
A + B AB
• Exchange reaction (reversible):
AB A + B
KEY CONCEPT
• Reversible reactions seek equilibrium,
balancing opposing reaction rates
• Add or remove reactants:
– reaction rates adjust to reach a new
equilibrium
How do enzymes
control metabolism?
Activation Energy
• Chemical reactions in cells cannot start
without help
• Activation energy gets a reaction
started
Figure 2–7
How Enzymes Work
Figure 2–21
KEY CONCEPT
• Most chemical reactions that sustain
life cannot occur unless the right
enzymes are present
Organic and Inorganic
Molecules
• Organic:
– molecules based on carbon and hydrogen
• Inorganic:
– molecules not based on carbon and
hydrogen
Why is water so
important to life?
Properties of Water (1 of 2)
• Solubility:
– water’s ability to dissolve a solute to
make a solution
• Reactivity:
– most body chemistry uses or occurs in
water
Properties of Water (2 of 2)
• High heat capacity:
– water’s ability to absorb and retain heat
• Lubrication:
– to moisten and reduce friction
KEY CONCEPT
• Most of our body weight is water
• Water is the key structural and
functional component of cells and their
control mechanisms, the nucleic acids
Electrolytes
• Inorganic ions conduct electricity in
solution
• Electrolyte imbalance seriously
disturbs vital body functions
– Fluid balance
– Blood pressure
– Muscular contractions
pH
• pH:
– the concentration of hydrogen ions (H+) in
a solution
• Neutral pH:
– a balance of H+ and OH—
– pure water = 7.0
Acids and Bases
• Acid (acidic): pH lower than 7.0
– high H+ concentration,
low OH— concentration
• Base (basic): pH higher than 7.0
– low H+ concentration,
high OH— concentration
pH Scale
• Has an inverse relationship with H+
concentration:
– more H+ ions mean lower pH, less H+ ions
mean higher pH
Figure 2–9
KEY CONCEPT
• pH of body fluids measures free H+ ions
in solution
• Excess H+ ions (low pH):
– damages cells and tissues, alters proteins
– interferes with normal functions
• Excess OH— ions (high pH) also problem
• Normal blood pH – 7.35 to 7.45
• Incompatibile with life – 6.8 to 7.8
Acid and Alkaline
• Acidosis:
– excess H+ in body fluid (low pH)
– Loss of bicarbonate
– Blood level < 7.2
• Alkalosis:
– excess OH— in body fluid (high pH)
– Blood level > 7.5
Nucleic Acids
• Large organic molecules, found in the
nucleus, which store and process
information at the molecular level
• DNA and RNA
Deoxyribonucleic Acid (DNA)
• Deoxyribonucleic Acid (DNA)
–
–
–
–
Determines inherited characteristics
Directs protein synthesis
Controls enzyme production
Controls metabolism
• Ribonucleic Acid (RNA)
– Codes intermediate steps in protein
synthesis
KEY CONCEPT
• DNA in the cell nucleus contains the
information needed to construct all of
the proteins in the body
Nucleotides
• Building blocks of DNA
• Have 3 molecular parts:
– sugar (deoxyribose)
– phosphate group
– nitrogenous base (A, G, T, C)
DNA Bases
Figure 2–22b, c
Complementary Bases
• Complementary base pairs:
– purines pair with pyrimidines:
• DNA:
– adenine (A) and thymine (T)
– cytosine (C) and guanine (G)
• RNA:
– uracil (U) replaces thymine (T)
Nucleic Acids
• Long chains of
nucleotides form
RNA and DNA
• RNA and DNA
Figure 2–23
RNA and DNA
• RNA:
– Single strand
• DNA:
– Double helix
– Joined at bases by hydrogen bonds
Forms of RNA
• Messenger RNA (mRNA)
• Transfer RNA (tRNA)
• Ribosomal RNA (rRNA)
ADP and ATP
• Adenosine diphosphate (ADP):
– 2 phosphate groups
• di = 2
• Adenosine triphosphate (ATP):
– 3 phosphate groups
• tri = 3
– Energy for muscular contractions
KEY CONCEPT
• Body recycles/renews all chemical
components at intervals ranging from
minutes to years
• Metabolic turnover lets your body:
– Grow
– Change
– Adapt
SUMMARY (1 of 2)
• Atoms, molecules, and chemical bonds
control cellular physiology
• Metabolism and energy work within the
cell
• Importance of organic and inorganic
nutrients and metabolites
SUMMARY (2 of 2)
• Role of water and solubility in
metabolism and cell structure
• Chemistry of acids and bases, pH and
buffers
• Structure and function of
carbohydrates, lipids, proteins, and
nucleic acids