Chapter 7 A view of the cell

The History of the Cell Theory (p 172) Compound Light microscopes Invented by Anton van Leeuwenhoek 1500 x Electron microscopes Scanning electron microscope (SEM, 扫描电镜 ) Surface of 3D objects Transmission electron microscope (TEM, 透射电镜 ) Inside a cell Scanning Tunneling microscope (STM) Viewing atoms

The History of the Cell Theory (p172) Robert Hooke- first to use the word “cells” The cell theory (P 172) 1. All organisms are composed of one or more cells. 2. The cell is the basic unit of structure and organization of organisms. 3. All cells come from preexisting cells.

Two Basic Cell Types (p173) Prokaryotes （原核生物 ): Cells that do not contain any membrane-bound organelles Cells that do not contain any membrane-bound organelles Most unicellular (one cell) organisms; bacteria

Two Basic Cell Types (p173) Eukaryotes (: Eukaryotes ( 真核生物 ): Cells that do contain membrane- bound organelles Cells that do contain membrane- bound organelles Most multicellular (many cells) organisms; plants, animals, etc. Some unicellular organism too; algae

Prokaryote Vs. Eukaryote ProkaryoteEukaryote No membrane-bound organelles Membrane-bound organelles No nucleusNucleus Small ( mm)Large ( mm) Small RibosomesLarge Ribosomes Small, normally circular DNA Large, chromosome DNA

Maintaining a Homeostasis (p175) Homeostasis- stable state of a healthy functioning cell Plasma Membrane- “guard” of the cell; first step towards homeostasis Selective permeability ( 选择透过性 )- a process in which a membrane allows some molecules to pass through while keeping others out. Transport proteins- special tunnels or doors that only let in specific molecules

Structure of the Plasma Membrane (p177) Phospholipids- hydrophilic heads and hydrophobic tails make a double layered wall Cholesterol- help keep membrane fluid and stable Carbohydrates- used in cell communication

Structure of the Plasma Membrane

Fluid Mosaic Model

Cell Organelles Organelles- “tiny organs” inside the cell have a specific job to maintain homeostasis Some are in all cells; membrane Some are only found in either animal or plant cells

Cellular Boundaries (p179) Animal Cell: Plasma membrane Plant Cell: Plasma membrane and Cell wall (cellulose)

The Nucleus ( 细胞核 ) (p180) The “brain” of the cell; contains DNA (Chromatin)

Making proteins! Ribosomes- take copy of DNA’s information (mRNA) and use it as a guide to create proteins Endoplasmic Reticulum- site of chemical reactions inside cell Smooth ER- no ribosomes Rough ER- ribosomes

Transportation Center Golgi Apparatus- puts proteins into small membrane-bound packages called vesicles which are sent out and around the cell Vacuoles- storage compartments for food, enzymes, etc. In plant cells- they are very large and hold lots of water In animal cells- very small

Vacuoles

Cellular Digestion Lysosomes- sacs of digestive enzymes that break down old organelles, food, and viruses/bacteria

Making Energy in Plant Cells (p184) Chloroplasts- perform photosynthesis to make energy from sunlight in planets and some unicellular organisms Chlorophyll- chemical that absorbs all wavelengths of sunlight, expect green

Making Energy in Animal Cells (p185) Mitochondria- “power house” of the cell; produces ATP(energy unit for cells) by breaking down sugars and other organic compounds (cellular respiration)

Organelles for Support (p 185) Cytoplasm- clear gel-like fluid inside cells; help holds organelles in place Cytoskeleton- “Bones” of the cell; crossing rods, filaments, and tubes, that hold the cells shape. Also act at a “railroad” system to move things around the cell

The Cytoskeleton

Organelles for Support (p187) Centrosome- move chromosomes during cell division in animal cells

Locomotion (p187) Flagella- long, wipe-like tail that pushes and rolls the cell Cilia- short, hair-like paddles that push the cell along

Animal Cells Vs. Plant Cells OrganellePlants onlyAnimals onlyBoth Plasma Membrane X Cell WallX NucleusX RibosomesX Endoplasmic Reticulum X Gogi ApparatusX LysosomeX Vacuole(large)(small)X CentriolesX MitochondriaX ChloroplastsX

Tour of an Animal Cell

Tour of an Plant Cell

P 192

Homework Ch. 7 workbook pages (Due Friday) Cell labeling practice sheet