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