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UW-Madison BIOLOGY 151 - The Cell Theory, Evolution, and Water

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BIO 151 1st Edition Lecture 2 Outline of Last Lecture 1. Species, Evolution, and Cells2. Are species stable?3. Does new life have to come from old life or spontaneous generation?4. What about cells? Outline of Current Lecture 1. What about cells?2. The Cell Theory (Mid 1800s)3. Why would species evolve?4. Is the theory of natural selection correct?5. Cells are mostly water6. Ions and ionic bonds7. Water propertiesCurrent Lecture The Cell Theory, Evolution, and Water -What about cells?:- invention of microscope- Robert Hooke (1655) called hollow pores in cork "cells" (like little rooms)- van Leeuwenhoek in 1600s found single-celled organisms which he called "animalcules"- one lens microscopeThe Cell Theory (Mid 1800s):- "Every animal appears as a sum of vital units (cells), each of which bears in itself the complete characteristics of life."- "omnis cellula e cellula" - Modern version - 1. All living organisms are made of cells (and the products of other cells). 2. All cells are produced by other cells.- Louis Pasteur (1860s)- boil broth (soup) - no cells- wait: cells appear (and it stinks)- seal the top: Needham (1745, sterile broth still generated life) vs. Spallanzani (no it didn't)- no spontaneous generation, or life needs air?These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.- Pasteur's experiment (1862)- all cells come from other cells (part 2 of the cell theory)-cells divide to produce new cellsWhy would species evolve?:- Darwin, Wallace and the theory of natural selection:1. There is variation of traits within the population of individuals that make up a species. 2. Those traits are heritable. 3. Certain traits allow better survival of individuals. Is the theory of natural selection correct?:- Why is there variation in traits?- Why are traits "heritable" and how heritable are they?- How do cells work and reproduce?- Where did cells come from?Cells are mostly water:1. Many chemicals dissolve in water.- Dissolved molecules can diffuse between parts of a cell - diffusion.- Covalent bonds are formed by sharing electrons between 2 atoms.- Want to fill outer valence shell.- Electronegativity - how much an atom attracts electrons.- Polar covalent bond - unequal electron sharing gives parts of molecules partial electric change - O and N like electrons more than H or C- H and C like electrons equallyIons and Ionic Bonds:- When atoms completely gain or lose electrons, they form ions-electrons not shared- ionic bond: attraction between plus and minus charge- polar molecules (and ions) can be attracted by hydrogen bonds-electrical attraction between positively and negatively charged ends-1/20th strength of a covalent bond- ions and polar molecules dissolve in water due to hydrogen bonding- water can ionize -H20 breaks into H+ and OH-pH = -log10[H+]-acids and bases (low vs. high pH)Water Properties:- water binds to charged or polarized molecules and surfaces - "adhesion" of water to hydrophilic molecules- water binds to water = "cohesion"- solid water (ice) molecules are packed less densely than liquid water molecules - ice floats in water- water requires higher heat input to increase temp. than many other substances - high specific heat- greater spacing between water molecules in ice- hydrogen bonding between


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UW-Madison BIOLOGY 151 - The Cell Theory, Evolution, and Water

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