3.1 Our understanding of the cell grew as microscope quality improved.

Cell Theory Mainly Schleiden, Schwann, Virchow All organisms are made of cells All existing cells are produced by other cells The cell is the most basic unit of life.

General Cell Characteristics Tend to be microscopic Enclosed in a membrane Filled with cytoplasm

Types of cells Prokaryotic No nucleus No membrane bound organelles Like bacteria Eukaryotic Nucleus Membrane bound organelles Like not bacteria

3.2 Cells have an internal structure

Cytoskeleton Support and shape Position and transport organelles Strength Assists in cell division Cell movement

Nucleus Stores genetic information Control center of the cell

Endoplasmic Reticulum Transport Rough: has ribosomes for processing proteins Smooth: no ribosomes, process lipids and carbohydrates

Ribosomes Made of rRNA Form proteins

Golgi apparatus Golgi bodies Packaging and shipping

Vesicles Membrane bound sacks Storage

Mitochondria Energy

Vacuoles Like little warehouses Storage

Lysosomes Waste disposal Digest material

Centrioles Tubes in centrosomes Help in mitosis Form cilia and flagella

Plant cell parts Chloroplasts: where photosynthesis occurs Have a cell wall of cellulose for support

3.3 Cell membrane

Functions Enclose cell like a fence does Controls passage of stuff like a fence does

Structure Phospholipid bilayer Proteins, carbohydrates, and lipids may be imbedded in the membrane The fluid mosaic model

Selectively permeable Lets some stuff in, keeps other stuff out. Kinda like a fence does

Receptors A substance can bind to its receptor Causes an action on the other side of the membrane

3.4 Stuff can move across cell membranes

Transport Passive: just happens Active: requires energy

Passive transport Diffusion: stuff diffuses from regions of high concentration to regions of low concentration Osmosis: diffusion of water

Three types of solutions Hypotonic: Lower concentration Water moves out of cell Hypertonic Higher concentration Water moves out of cell Isotonic Same concentration No net movement of water

Examples

Facilitated diffusion Some molecules can only diffuse through transport proteins. Facilitated diffusion is diffusion through transport proteins. Revolving door

3.5 Some transport requires energy

Active transport Requires energy Goes against a gradient

Types Pumps Endocytosis: takes material into the cell Pinocytosis: cell drinking Phagocytosis: cell eating Exocytosis: expels material from the cell