Chapter 7 Cell Structure and Function

7.1 The Discovery of Cells  Robert Hooke –Discovered 1 st cell –Observed dead cork cells –Named the cell: basic unit of living organisms

Anton van Leeuwenhoek Looked at & described the 1 st living cell

The Cell Theory  Matthias Schleiden & Thomas Schwann –Schleiden  Botanist –Schwann  Zoologist  Developed the cell theory: 1.All life forms are made from one or more cells. 2.Cells only arise from pre-existing cells. 3.The cell is the smallest form of life.

Two basic cell types: 1.Prokaryote oBefore a nucleus (NO Nucleus) oSingle-celled 2.Eukaryote oHas a nucleus oUnicellular or multicellular oContained organelles (membrane bound structures)

Which one is a prokaryotic cell? Is B. a plant or an animal cell? A. B.

7-2 Eukaryotic Cell Structure  Contain Organelles which means “little organs”.  Each cell contains Cytoplasm which holds all of the organelles.

Nucleus: Control center of the cell Contains DNA Has a nuclear envelope & Nucleolus

Ribosomes: make proteins most numerous organelle in the cell Found on and off of ER

Endoplasmic Reticulum : Two types of ER: Smooth (no ribosomes) Rough (has ribosomes) Smooth makes and transports lipids Rough transports proteins

Golgi Apparatus: Stores and packages chemicals

Lysosome: “Stomach of the cell” Vacuole that contains digestive enzymes

Mitochondria: “Powerhouse of the cell”

Chloroplast: Capture sunlight and convert it into chemical energy in a process called photosynthesis

7-3 Cell Boundaries  All cells are surrounded by a cell membrane (also called a plasma membrane).  Some cells are surrounded by a cell wall (especially plant cells).  Both serve as a boundary between the cell and its environment.  The Cell membrane is semi-permeable.

The Plasma Membrane FUNCTIONS: 1)Controls what enters and leaves the cell (maintaining homeostasis with selective permeability) 2)Protects the cell  Also the cell wall’s main function!!

PM continued…  PM is made of a bilayer of phospholipids!!  Two ends to a phospholipid: –Hydrophilic –Hydrophobic  Two types: –Saturated –Unsaturated

Fluid Mosaic Model (PG. 182)

Random movement of Molecules  Robert Brown – Brownian Motion  Molecules are in a constant state of motion –Gas = fast movement –Liquid = medium movement –Solid = slow movement  Molecules move from high concentrations to low concentrations because of a concentration gradient.

Diffusion Through Cell Boundaries  Diffusion: the movement of particles from and area of high concentration to low concentration  Osmosis is the diffusion of water

Diffusion

Three types of solutions (Pg. 186) 1)Isotonic: concentrations on both sides of the plasma membrane are equal  No net movement 2)Hypertonic: concentration of dissolved substances outside the cell are higher than inside  Water moves out  Cell Shrinks 3)Hypotonic: concentration of dissolved substances inside the cell are higher than outside  Water moves in  Cell Swells

Two types of transport  Passive Transport  Move with the concentration gradient  NO energy required 1.Simple Diffusion 2.Osmosis 3.Facilitated Diffusion  Active Transport  Move against the concentration gradient  Energy REQUIRED 1.Endocytosis a)Pinocytosis (drinking) b)Receptor- mediated endocytosis c)Phagocytosis (Eating) 2.Exocytosis