Chapter 3 Section 1 Pg. 50
Robert Hooke English scientist Discovered cells in 1665
Anton van Leeuwenhoek Looked at water under a microscope. Found many living creatures and called them “animalcules” Today, we know that he saw organelles.
Characteristics of a Microscope Light Microscope- light passes through one or more lenses to produce an enlarged image of specimen. Electron Microscope- uses a beam of electrons rather than light. Magnification- ability to make an image appear larger than its actual size. Resolution- a measure of clarity of an image.
Compound Light Microscope Uses two lenses, the objective lens and the and the ocular lens (10X).
Electron Microscope Can magnify up to 200,000X. Electron beam and specimen must be placed in a vacuum chamber so that electrons in the beam will not bounce off of gas particles in the air.
Other Microscopes Scanning electron microscope- specimen is coated with thin layer of metal and electron beam bounces off of it. Scanning tunneling microscope- uses a needle like probe to measure differences in voltage cause by electrons that leak from the surface of the object being viewed.
Chapter 3 Section 2 Pg. 55
The Cell Theory Mattias Schleiden concluded that cells make up every part of the plant Theodor Schwann claimed that animals are also made up of cells Rudolph Virchow determined cells come from other cells. From these guys, we have formed THE CELL THEORY
The Cell Theory 1.All living things are made of one or more cells. 2.Cells are the basic unit of structure and function in organisms. 3.All cells arise from existing cells.
Cells must be small Smaller cells function more efficiently than large cells. 100 trillion cells in the human body. Surface area to volume ratio Substances do not have to travel far to reach the center of a small cell.
Common Features Cell membrane or plasma membrane Cytoplasm- cell interior Cytoskeleton- microscopic fibers Ribosomes- proteins are made on these. DNA-deoxyribonucleic acid
Prokaryotic Cells Single-celled organism that lacks a nucleus and other internal parts. Smallest and simplest type of cell. The genetic material is a single, circular molecule of DNA
Characteristics of Bacteria Prokaryotic Some do not need oxygen to survive DNA is suspended within the cell, usually in the center. They lack an internal supporting skeleton, so have to have strong cell wall. Some have a capsule (made of polysaccharides) which allows them to stick to things like teeth, skin, and food.
Characteristics of Bacteria Many have flagella, which are like tails that enable movement. Think of them as propellers
Eukaryotic Cells are Organized Eukaryote- organism that has a nucleus. Nucleus- houses the cell’s DNA. Organelle- a structure in the cell that carries out a specific function. Short hair-like structures called cilia protrude from the surface. Help propel through their environment OR help move things on the surface of the cell.
Eukaryotic Cells are Organized Cytoplasm- everything inside the cell, outside the nucleus. The “fluid” of the cell. Cytoskeleton- holds the cell together and keeps the membrane from collapsing or folding. Microtubules (larger) Microfilaments (smaller)
Cell Membrane as a Barrier Phospholipid Bilayer- polar heads and non-polar tails Inside repels water
Cell Membrane as a Barrier Proteins are embedded into the cell membrane. Marker Proteins Receptor Proteins Enzymes Transport Proteins
Chapter 3 Section 3 Pg. 61
Cell Organelles Nucleus is surrounded by a double membrane called the nuclear envelope. Nuclear pores are little channels or openings on the surface of the nuclear envelope. DNA is stored in the nucleus.
Cell Organelles Endoplasmic Reticulum (ER)- move proteins through the cell. Rough ER have ribosomes on them. Transports proteins made by the ribosomes. Smooth ER do not have ribosomes attached. Makes lipids. Vesicle- small, membrane bound sac that transports things in the cell. Golgi Apparatus-flattened sac that packages and distributes things in the cell. Lysosome- contain cell’s digestive enzyme. “death sentence” Copy steps on pg. 63 in notes.
Cell Organelles Mitochondria-gets energy from organic compounds to produce ATP for energy. Outer membrane Inner membrane
Plant Cell Differences Cell Wall- surrounds the cell membrane. Helps support and maintain cell shape. Chloroplasts- use light energy to make carbohydrates from CO2 and H20. This makes plants green. Central Vacuole- large, membrane bound space. It stores water and may contain other substances.