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 environmentFunction

“Gatekeeper”-controls what enters and leaves the cell

Cell (Plasma) Membrane

Structure Two phospholipid

layers (bilayer) Phosphate head-

hydrophilic 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 protectionStructure

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 nucleusStructure

Cytosol-jellylike material, mostly water Organelles-“mini-organs” of the cell

Ribosomes

Function Manufactures enzymes and other

proteinsStructure

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 organismsStructure

Cilia-many short hair-like projections that move in a wave motion

Flagella-longer projections that use a whip-like 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 fromhttp://www.biology4kids.com