Cells In this section we will examine in depth many aspects of the fundemental structure for life, THE CELL

Topics on Cells Introduction and History of Cell Theory Basic Cell Structure General Shared Characteristics Similarities and Differences between Prokaryote and Eurayote cells Principle organelles and their functions Processes of Cellular Control Enzymes Review Genetic Material Structure and Function of DNA and RNA Control of Transcription and Translation

Topics on Cells Proteins Cellular Reproduction Duplication and Synthesis Transcription and Translation Cellular Reproduction Cell Cycle Mitosis Meiosis

Topics on Cells Cellular Energy Cellular Transportation ATP Aerobic v. Anaerobic respiration Alcohol and Lactic Acid Fermentation Photosynthesis Cellular Transportation Osmosis Simple Diffusion Facilitated Diffusion

Introduction and History of Cell Theory Predictions were made early about cells that have become the basis for modern cell theory. Rudolf Virchow wrote “Every animal appears as a sume of vital units, each of which bears in itself the complete characteristics of life” he went on to say “All cells come from cells”

Introduction and History of Cell Theory Modern cell theory has three principles Every living organism is made up of one or more cells. The smallest living organism are single cells, and cells are the functional units of multicellular organisms. All cells arise from preexisting cells.

Introduction and History of Cell Theory Though cells vary dramatically in their structure and function, from the simple Streptococcus bacteria cell to the trillions of cells that exist in your body right now there are common characteristics between them.

General Shared Characteristics Molecular Components Proteins Amino acids Lipids Carbohydrates Sugars Nucleotides DNA RNA

General Shared Characteristics Structural Components Plasma membrane Cytoplasm Ribosomes

General Shared Characteristics Metabolism Extracts evergy and nutrients from the environment Uses energy and nutrients to build, repair and replace cellular parts

General Shared Characteristics Plasma Membrane It isolates the cell’s contents from the external environment. It regulates the flow of materials into and out of the cell, for example, acquiring nutrients and expelling wastes. It allows interaction with other cells

General Shared Characteristics DNA is used as Hereditary Blueprint Each cell has genetic material The genetic material is deoxyribonucleic acid (DNA) In eukaryotic cells (plants, animals, fungi, and protists) this DNA is contained within a separate membrane-bound structure called the nucleus. In prokaryotic cells (bacteria and archaeans) the DNA although localized to a particular region within the cell is not separated by membranes from the rest of the cell’s interior

General Shared Characteristics All Cells contain Cytoplasm Cytoplasm consists of all the material inside the plasma membrane and outside the DNA-containing region It contains water, salts, and an assortment of organic molecules Most metabolic activities occur here

General Shared Characteristics All Cells Obtain Energy and Nutrients from their environment Due to their complexity cells must continously acquire and expend energy At some point this energy has come from the sun

General Shared Characteristics Cell Function Limits Cell Size Cells are small, between 1 and 100 micrometer (millionths fo a meter) Since Hooke first identified cells in 1665 technology has allowed us to learn more and more Why do you think cells are so small? Why are large organisms made up of small units rather than one giant cell?

Cell Size Comparison Just to emphasis how small a cell is think of this. I am 1.91m tall my cells are 0.0001-0.000001m in diameter. If you increase each of our sizes equally till the cell was my size I would be between 19.1 and 1910 Km tall. That is half way across the United States.

General Shared Characteristics Now back to why cells are so small. The answer to this relates to diffusion or movement of molecules into and out of the cell The larger the cell is the longer nutrients take to get to the center. In a 20 cm cell it would take 200 days for oxygen to get to the center. Secondly as cells get larger their volume increases faster than their surface area. Triple a cells radius and it becomes 27 times greater involume but 9 times greater in surface area (remember pie?) Thus more need for exchange but less space to do it in