Transcript A View of a Cell

A View of a Cell
The Life Inside
The Cell Theory
Robert Hooke
Studies of cork cells
Nearly 200 years later…
Three Main Ideas of the Cell Theory
All organisms are composed of one or more cells
The cell is the basic unit of organization of
organisms
All cells come from preexisting cells
Cell Types
Prokaryotes
Mainly bacteria
No nucleus-single strand DNA within the cell
No membrane bound organelles
Contain cell wall
Eukaryotes
Plant and animal cells
Can be unicellular organisms such as algae and yeast
Clearly defined nucleus and organelles
Structure and Function
What does all that stuff do?
Cell (Plasma) Membrane
Definition
Separates the cell and its contents from the
surrounding environment
Function
“Gatekeeper”-controls what enters and
leaves the cell
Cell (Plasma) Membrane
Structure
Two phospholipid
layers (bilayer)
Phosphate headhydrophilic
Lipid tail-hydrophobic
Protein molecules-1/2
or all of way through
membrane
Carbohydrate chains
Cell Wall
Definition
Cell structure found in plants
Located outside of the plasma membrane
Function
Rigid barrier that gives the cell support and
protection
Structure
Carbohydrate-cellulose
Nucleus
Definition
“Brain” of the cell/control center
Function
Contains chromosomes
Nucleolus-makes ribosomes
Structure
Surrounded by nuclear envelope
Cytoplasm
Definition
Everything between the cell membrane and
the nucleus
Structure
Cytosol-jellylike material, mostly water
Organelles-“mini-organs” of the cell
Ribosomes
Function
Manufactures enzymes and other proteins
Structure
Organelle found in the nucleus, free in
cytoplasm, or in the lining of the endoplasmic
reticulum
Endoplasmic Reticulum
(ER)
Function
Transports and processes
materials through the cell
Structure
Network of membranes
that connects nuclear
membrane to cell
membrane
“accordion folded”
smooth and rough ER
Golgi Apparatus
Function
Responsible for packaging and secreting of
cell products
Further modifies proteins
Structure
Flattened tubes
Vacuoles (animal cells)
Function
Temporary storage of materials, such as
food, enzymes and other materials needed by
the cell
Structure
Many small vacuoles in animal cells
Lysosomes
Function
Garbage collector”
Digest excess or worn
out organelles,
engulfed viruses and
bacteria
Structure
Small sacs inside
cytoplasm, can fuse
with vacuoles and
release enzymes
Mitochondria
Function
“Powerhouse of the cell”
Cellular respiration takes
place here to create energy
for the cell
Structure
Outer membrane and
highly folded inner
membrane to allow for a
large surface area in a
small space
Plastids-Chloroplasts
Function
Captures sunlight and coverts it into food
using CO2 and H2O (photosynthesis)
Structure
Appear green because they contain
chlorophyll, a pigment that absorbs the
energy in sunlight
Plastids-Vacuoles (plant)
Function
Stores water, proteins,
sugar, etc
Some store pigments
which give plants their
color
Structure
Large membrane
bound sac
Cilia and Flagella
Function
Allow cell to move-important in unicellular
organisms
Structure
Cilia-many short hair-like projections that
move in a wave motion
Flagella-longer projections that use a whiplike motion
Cytoskeleton
Function
A constantly changing structure that provides
a framework and support for the cell
Structure
Composed of tiny rods and filaments, within
the cytoplasm
All pictures from
http://www.biology4kids.com