Cells 9/25/09

A Brief History Robert Hooke – In 1664, he saw the 1 st cell and named it a cell (cork); used a microscope Anton van Leeuwenhoek – 1 st person to observe living cells; refined lenses to magnify images Schleiden, Schwann, and Virchow – made up cell theory.

Cell Theory 1. All living things are made up of cells 2. Only cells can make cells. 3. Cells are the basic units of structure and function in an organism. Two types of cells – Prokaryotes – cell that lacks membrane-bound organelles. No nucleus. Primitive – ex. Bacteria – Eukaryotes – cell that has organelles protected by membranes. More complex. Endosymbiotic theory Evidence to support the idea that prokaryote cells developed 1 st and eukaryote cells resulted when prokaryotic cells ingested each other.

Prokaryotic cells lack a nucleus and membrane-bound organelles. – All cells share certain characteristics. Cells tend to be microscopic. All cells are enclosed by a membrane. All cells are filled with cytoplasm. All cells contain genetic information (DNA). Bacterium (colored SEM; magnification 8800x) cell membrane cytoplasm

Types of Eukaryotic Cells Plant – has cell wall, large vacuole, plastids (ex. Chloroplast), no centrioles Animal – no cell wall, small vacuole, centrioles, no plastids

Eukaryotic cells have a nucleus and membrane- bound organelles.

Eukaryotic Membranes Parts of Cell --- organelle – “little organ” Plasma or cell membrane – outer membrane. Phospholipid (P+O+fat) Cell wall – outer membrane of plants. Made up of cellulose (we can’t digest)

Nucleus – control center of cell. a. nuclear membrane – outside edge of nucleus. b. nucleolus – makes ribosomal RNA c. chromosomes – contains genetic material (DNA) d. nucleoplasm – fluid inside nucleus. Used to protect organelles within nucleus. Eukaryotic Nucleus

What differences do you notice between the cells? Cell WallNo cell Wall Rigid shapeRound shape Large VacuoleSmall Vacuole Green Color! Lacks chloroplast (plastids) No centriolesCentrioles

Cell membranes are composed of two phospholipid layers. 1. Phospholipid bilayer. 2. Other molecules embedded in the membrane. 3. The fluid mosaic model describes movement in membrane. cell membrane protein cholesterol protein carbohydrate chain protein channel

Fluid Mosaic Model 1. The phospholipid bilayer behaves like a fluid more than it behaves like a solid – Like a boat on an ocean! 2. The mosaic consists of lipids and proteins in the cell membrane constantly changing.

Membrane Proteins Integral protein – any protein embedded into the membrane Transmembrane proteins – extend across the plasma membrane Peripheral proteins – aid in conformational changes Video!

Organelles in Plant and Animal Cells 9/28/09

Cytoplasm – clear fluid inside cell. Acts as shock- absorber to protect contents of cell. Endoplasmic reticulum (ER) – channels used for transporting things within cell (highway system). a. smooth ER – contains no ribosomes b. rough ER – contains ribosomes. Used for transporting molecules needed in protein making. Ribosomes – makes proteins Golgi body or apparatus – packages and “labels” proteins and lipids sent to different parts of the cell.

Golgi Apparatus Ribosomes Rough ER Smooth ER

Smooth ER function – detoxification of drugs and poisons, production of steroid hormones, release of calcium

Mitochondria - “powerhouse of cell” – makes energy by cellular respiration. Has many folds called cristae that increases the surface area.

Vacuole – storage area for food, water and waste. Larger in plant cells.

Lysosomes – “suicide sac” – contains enzymes used to digest foreign materials and sometimes the cell itself.

Microtubules (bigger) and microfilaments (smaller) - used for structural support – called cytoskeleton. Microtubule Organization in PlantsMicrofilament Arrangement in Bundles

Centrioles – only in animal cells. Used during cell reproduction.

Cilia ( hair –like projections) & flagella (long tail-like whip) – structures some cells have for cell movement. Protist CiliateE. Coli bacterium with flagella

Plant cells have cell walls that provide rigid support.

Chloroplasts – convert solar energy to chemical energy. – plastids that hold chlorophyll (green pigment used for making food in plants)