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Each level of biological organization has emergent properties
Biological organization is based on a hierarchy of structural levels
BIOLOGY 22 LECTURE
I.B. Chemical Basis of Life
Ms. Heidie L. Frisco Department of Biology November 2009
OUTLINE I. The Chemical Context of Life II. Water and the Fitness of the Environment III. Carbon and the Molecular Diversity of
Life IV. The Structure and Function of
Macromolecules A. Carbohydrates B. Lipids C. Proteins D. Nucleic Acids E. Vitamins and Minerals*
LEARNING OBJECTIVES
1. Torecognizethecontributionofphysicalmatterinthestructureoflivingthings
2. Toreviewhowanimals,orlivingthingsingeneral,areorganizedinthesubcellularlevel
3. Toenumeratetheinorganic&organicmoleculesthatmakeuplivingthings
At the end of the lecture, the students should be able to:
THE CHEMISTRY OF LIFE
Matter consists of chemical elements & compounds
Matter anything that takes up space and has mass
Life requires about 25 chemical elements
117 elements (as of January 2007) 25 of 94 natural elements CHON 96% of living matter
P,S,Ca,K,trace elements 4% of an organisms weight
GROUP ASSIGNMENT: Indicate the importance of the above minerals to human health.
Pica
A craving for nonfood substances
geophagia pagophagia
ATOMS AND MOLECULES
Atoms unit of matter - each element is made up of atoms Structure determines the
behavior of an element
Atoms combine by chemical bonding to form molecules
Covalent Bonds - sharing of a pair of valence electrons by two atoms - Non-polar and Polar Covalent Bonds
Atoms combine by chemical bonding to form molecules
Ionic Bonds - attraction between cations and anions - SALTS
Weak chemical bonds play important roles in the
chemistry of life
Brain
Nasal cavity
Odorant
Odorant receptors
Plasma membrane
Odorant
Cilia
Chemoreceptor
Epithelial cell
Bone
Olfactory bulb
Mucus
Weak chemical bonds play important roles in the chemistry of life
Ionic Bonds
Hydrogen Bond - occurs when H
covalently bonded to one electronegative atom is also attracted to another electronegative atom
Van der Waals Interactions
A molecules biological function is related to its shape
A molecule has a characteristic size and shape
Molecular shape basis for how most molecules of life recognize and respond to one another
Chemical reactions change the composition of matter
Chemical reactions the making and breaking of chemical bonds - leading to changes in the composition of matter
WATER AND THE FITNESS OF THE ENVIRONMENT
EFFECTS OF WATERS POLARITY
EFFECTS OF WATERS POLARITY
Properties of Water:
1. Waters cohesive property
2. Ability to stabilize temperature
3. Expansion upon freezing
4. Versatility as a solvent
Organisms depend on the cohesion of water molecules
Cohesion Adhesion
Surface Tension
Water contributes to Earths habitability by moderating temperatures
Waters high specific heat - Specific Heat: amount of heat
that must be absorbed or lost for 1g of that substance to change its temperature by 10C
- 1 cal/g/0C
Waters high heat of vaporization
- Heat of Vaporization: quantity of heat a liquid must absorb for 1g of it to be converted from the liquid to gaseous state
- 1g:580cal - Evaporative cooling
Oceans and lakes dont freeze solid because ice floats
Water is a very versatile solvent
Organisms are sensitive to changes in pH
CARBON AND THE MOLECULAR DIVERSITY OF
LIFE
Carbon atoms are the most versatile building blocks of molecules
Electron distribution
Variation in carbon skeletons contributes to the diversity of organic molecules
Functional groups also contribute to the diversity of life