Lecture Notes

Lecture Notes - Lecture 1 : 3/29/10 Building Blocks of Life...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Lecture 1 : 3/29/10 Building Blocks of Life INTRODUCTION TO CELLS The cell is life’s fundamental unit o Smallest form of life Eukaryotic cell Prokaryotic cell All life forms are made from one or more cells o Mitosis Scientific study of cells o Discovery science: describe observations o Hypothesis-based science: propose and test explanations o Better understanding of nature o Biotechnology applications ATOMS & BONDS Element: cannot be broken down into other substances o 25/92 natural elements are essential for life o 4 elements make up 96% of living matter Carbon Nitrogen Oxygen Hydrogen o Elements combine to form chemical bonds and compounds Atom: Smallest unit of matter that retains the properties of an element o Protons o Neutrons o Electrons Valence: bonding capacity, determined by the unpaired valence elections in outermost shell Covalent bond: sharing of electrons between elements • Single • Double • Polar • Nonpolar Ionic bond: transfer of electrons between atoms Hydrogen bond: H shared between polar molecules • F, O, N • Partial +/- charges between polar molecules o Molecule: Elements held together by covalent bonds o Compound: fixed ratio of 2 or more elements o Van Der Waals: Slight interactions between nonpolar covalent molecules WATER Most important molecule for life on Earth Life began in water and evolved here for 3 billion years before spreading to land Our cells are 70-95% water, we can only survive for 1 week without water Water is polar molecule attracted to itself. This is the critical factor for all of water’s most important properties Properties of Water: o Cohesion: Water molecules stay close together due to hydrogen bonding o High specific heat: A great deal of energy is required to break H-bonds to release/vaporize individual molecules o Evaporative cooling: water molecules with highest energy leave water reservoir as vapor, lowering the T of remaining liquid o Ice floats: Solid water is 1-% less dense than liquid form. This unusual feature results in crystal-like matrix of water molecules in ice. Insulates water underneath o Excellent solvent: dissolves polar and nonpolar substances and salts ACIDS & BASES Dissociation of water results in ions Pure water has equal concentrations: [H+] =[OH-] Pure water is NEUTRAL or ph=7 pH Scale o measures level of acidity o pH = -log[H+] o Acid: Increases [H+] or reduces pH o Base: Reduces [H+] or increases pH BUFFERS Compound that prevents sudden change in pH Critical for most cells to maintain pH 6-8 Lecture 2 : 3/31/10 Macromolecules I REVIEW Water has a covalent bond : sharing electrons o It is a molecule CHEMISTRY OF CARBON (C) Whereas water is the universal medium for life, C makes up the majority of the cell’s structures The C in our bodies ultimately derives from the action of plants. Plants harness the power of sunlight to convert CO 2 into Carbon-based macromolecules...
View Full Document

This note was uploaded on 03/05/2012 for the course BILD 1 taught by Professor Boulanger during the Spring '08 term at UCSD.

Page1 / 13

Lecture Notes - Lecture 1 : 3/29/10 Building Blocks of Life...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online