2. Conditions for the Origin of Life

4. Conditions for the Origin of Life A sequence of chemical reactions lead to life on Earth Sun and planets coalesced as result of a supernova On Earth, heavier materials sank to the core while lighter substances concentrated the surface Hydrogen, Oxygenand Carbon

5. Conditions (Cont.) Current Atmosphere: 78% N2 21% O2 Trace amounts of CO2, Primordial Atmosphere: Far more Hydrogen Far less Oxygen NH3, H2O, and CH4

6. CHON 4 common elements in living organisms Carbone, Hydrogen, Oxygen, and Nitrogen Some include 2 others Phosphorus and Sulfur P is crucial in DNA/RNA ; forms core of the phosphate groups in ATP/ADP S is used in the formation of some amino acids

7. Conditions (Cont.) Ocean Formation: High temperatures of Earth’s early crust continually evaporated water that had rained As the Earth cooled, rain water washed dissolved minerals to low areas creating lakes, seas, and oceans Volcanic explosions on land and in our oceans were the cause for accumulation of salts in our oceans

8. Stanley Miller Experiment Miller duplicated chemical conditions of early oceans and atmosphere and provided an energy source (electric spark) Found that the warm water and gasses when provided an energy source would continue to spark for about a week, forming organic compounds. Further experimentation supports Miller’s evidence by stating that amino acid that make up proteins form quite readily in this environment.

9. Cells Magnification needed to be seen Termed by Robert Hooke in 1665 Observed cork under magnification Cell Functional basic unit of life Hooke’s initial discovery led to differentiation in plant and animal cells Plant cells have a thick cell wall Animal cells have a thinner, more flexible plasma (cell) membrane

10. Cells Unicellular organisms carry out all necessary functions that support life within one cell without any help from other cells Multi-cellular organisms An organism consisting of many cells Cells have specific functions, and the aggregate of cells forms a complex organism

11. Cell Theory Termed by Matthias Shleiden and Theodor Schwann Cell Theory states: Cells are the fundamental units of life Cells are the smallest entities that can be called living All organisms are made up of one or more cells and new cells arise from pre-existing cells.

12. Cell Structure and Size Cells provide structure and form to the body by coming in a variety of shapes and sizes e.g., round, concave, rectangular, elongate, tapered, spherical, etc. Range from 5 – 50 microns Short for micrometer (10-3)

13. Cell Structure and Size Cell size: Restriction by ratio of surface area to volume Cells have a relationship with their surrounding medium and constantly absorb and release molecules. Cell volume increases much more rapidly in perspective with the surface area and cell may become too large to maintain a stable internal environment

14. Cytoplasm & Nucleoplasm Cytoplasm Everything within the plasma membrane except the nucleus Nucleoplasm Contents within the nuclear membrane

15. Cell Membrane Cell Membrane: Membrane surrounding the cytoplasm at the surface of the cell Contains various amounts of proteins and lipids Provides support, shape, strength, and regulates flow of materials Fluid-mosaic model Explains how molecules can move in and out of cell

16. Movement Thru Membrane Cells use 2 methods to keep a Chemical homeostasis or maintaining a constant internal environment. Passive transport Molecule movement occurs on its own without any energy input Active transport Cell expends energy to move molecules

17. Questions to think about There are 4 elements common to living things. Name them. What is a cell? How do plant and animal cells differ? What is the cell theory? What is a plasma (cell) membrane?

18. Exit Ticket Why are most cells small?