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 Two Basic Cell Types (p173)(p173)

Prokaryotes Prokaryotes （原核生物（原核生物 ):):

Cells that do not contain any Cells that do not contain any

membrane-membrane- bound organellesbound organelles

Most unicellular (one cell) organisms;Most unicellular (one cell) organisms;

bacteria bacteria

Two Basic Cell Types Two Basic Cell Types (p173)(p173)

Eukaryotes (Eukaryotes (真核生物 )::

Cells that do contain membrane-Cells that do contain membrane-

bound organellesbound organelles

Most multicellular (many cells) Most multicellular (many cells)

organisms;organisms; plants, animals, etc. plants, animals, etc.

Some unicellular organism too; algaeSome unicellular organism too; algae

Prokaryote Vs. Prokaryote Vs. EukaryoteEukaryote

Prokaryote Eukaryote

No membrane-bound organelles

Membrane-bound organelles

No nucleus Nucleus

Small (0.001-0.01 mm) Large (0.01-0.1mm)

Small Ribosomes Large 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 cellSmooth ER- no ribosomesRough ER- ribosomes

Transportation CenterGolgi 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 waterIn 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 organismsChlorophyll- 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 CellsOrganelle Plants only Animals only Both

Plasma Membrane

X

Cell Wall X

Nucleus X

Ribosomes X

Endoplasmic Reticulum

X

Gogi Apparatus X

Lysosome X

Vacuole (large) (small) X

Centrioles X

Mitochondria X

Chloroplasts X

Tour of an Animal Cell

Tour of an Plant Cell

P 192

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