Cell Composition

1. Cell Composition

2. Botany 1010 September 9, 1999 Lecture #3

3. Composition of Living Things • All living things are composed of ? • The smallest unit of living matter is ? • The automatic tendency to maintain appropriate internal environment is called ? • Four characteristics of living things are ? • Biological growth occurs from the ?

4. Biological growth occurs from the ? Cells reproduce from a blue print called DNA, • Dioxy-ribo-nuclaeic Acid • Asexual reproduction: a copy of the blue print splits into 2 individual • Sexual reproduction: two parents blue prints combine to form a new individual • Metabolism is responsible for growth, maintenance, and reproduction

5. Evolutionary Change • Charles Darwin theorized that ? • These changes were selected because they ? • This Theory is referred to as ? • And occurs at the _____ level within a _______ ? • Various populations of different species (birds) that interact are communities

6. Species ? ? ? ? ? Population ? ? ? ? Properties of _____ are:

7. Chemical Cellular Multicullular Ecological Functional Biological Organisms can be organizedbased on differences in

8. Taxonometry is ? • K • P • C • O • F * G > S

9. How many Kingdoms of Life ?What are they?An organisms Scientific name is?

10. Reasoning • Using general principles or experience to infer more detailed predictions is ? • Using specific examples to draw a general conclusion ?

11. The scientific method? Is a process of critical review & skepticism • recognize a problem • make observations • developing an educated guess, a hypothesis • test your guess through experimentation • evaluate your results • have results peer reviewed

12. Guidelines for scientific thought • hypothesis consistent with what is known • hypothesis must be testable • the test must be repeatable • it must be falsifiable • IF berries are blue, • THEN they are blue berries • IF berries are NOT blue, • THEN they are NOT blue berries

13. Be Skeptical, Be Objective • Sources of ERROR • BIAS • ATYPICAL SAMPLE • Probability of ERROR (r^2) • ACCURACY • PRECISION • Theory: predictions made using the theory as a guide are consistently accurate and precise

14. Chemistry of Life Atoms: Molecules: composed of atoms held together by ionic or covalent bonds

15. ATOMS • Composed of Protons, Neutrons, and Electrons • Atomic Nucleus contains Protons and Neutrons • Neutrons and Protons have similar mass (weight) • Electrons have a very small mass and spin around the Atomic Nucleus • Atoms have equal number of protons (+) and electrons (-)

16. Elements • A substance that cannot be broken down into a simpler substance, and still maintains its characteristics • 92 naturally occurring elements • Latin / English names • Denoted by a two letter chemical symbol • Elements have a fixed number of protons • This number is an elements Atomic Number

17. H O N C Na P Hydrogen Oxygen Nitrogen Carbon Sodium Phosphorous Elements

18. 1H 8O 23/11 Na Hydrogen with 1 proton Oxygen with 8 protons Sodium 12 neutrons, 11 protons, and an atomic mass of 23 (11+12) Atomic Numbera subscriptwritten to the left of the Atomic Symbol

19. Molecules • Two atoms combine to form a molecule • 8O + 8O = O2 • Common notation O + O = O2, Oxygen Molecule Molecules and or Atoms combine in fixed ratio’s to form Compounds 2 H + 1 O = H2O, Water Molecule (compound)

20. Chemical Bonds Covalent • electrons are shared between atoms in a molecule or compound • Single bond: share one electron • (hardest to break apart) • Double bond: share two electrons • Triple bond: share three electrons • (easiest to break apart)

21. Covalent Bonds Nonpolar Covalent bonds • Atoms have equal attraction for electrons • O2, each Oxygen shares electrons equally Polar Covalent bonds • Atoms have different attraction (affinity) for shared electrons • H2O, Hydrogen atoms are electro-positive (2*-1) • Oxygen atoms are electro-negative (1*-2)

22. Ionic Bonds • Polar: Electrons from one atom are transferred to another • One atom gains an electron and becomes negatively charged (ANION) • The other atom looses an electron, thus there are more protons than electrons in the atom, causing a positive charge (CATION)

23. Ionic Compounds • Cations and Anions are held together by their opposite charges (mutual attraction) • Na (Sodium) donates electron (cation) • (positive charge = +1) • Cl (Chlorine) receives electron (anion) • (negative charge = -1) • NaCl, Ionic Compound called SALT

24. Ionic Compounds • It takes a great deal of energy to overcome the electrical attraction in solid substances that have ionic bonds • Ionic bonds dissolve easily (split apart) in water, WHY? • Hydrogen (+charge) attracts anion (Cl-) • Oxygen (-charge) attracts cation (Na+)

25. Water Chemical Properties • Water is an excellent SOLVENT • It easily dissolve ionic bonds • Process is called HYDRATION • Polar compounds are water loving Hydrophillic • Non Polar compounds are water hating Hydrophobic (oil & water don’t mix)

26. Water Properties • Unique biological solvent • Capable of dissolving other substances • … because it is polar, its electrons from one atom can be given to another atom/molec. • It is Cohesive: pulling other things with it • It is Adhesive: sticking to other surfaces Is Water important to biological processes ? … your body 70%; cells 80% of weight

27. Water Properties • Changes temperature more slowly than other substances • Specific Heat:temperature required to increase one gram of a substance one degree centigrade • High Heat of Vaporation: sweat cools us by getting rid of excess heat, evaporation • Salts dissociate in water and conduct electrical current (nerve impulses, etc.) as electrolytes

28. Water Properties • Acids ionize in water to yield hydrogen ions and an anion, (negative charge = -1) • Bases dissociate in water to produce hydrogen ions and a cation, (positive charge = +1) • The negative logarithm of the concentration of hydrogen ions are measured as pH • pH of water is 7.0