Organization of Life

• Cell• Tissue

• Organ

• Organ System

• Organism

Cells

• All living organisms on Earth are divided in pieces called cells.

• There are smaller pieces to cells that include proteins and organelles.

• Cells hold all of the biological equipment necessary to keep an organism alive and successful on Earth.

Organelles

• Means “little organ”

• Small parts of the cell

• Each with their own special job in the cell

Examples of Organelles

• Nucleus• Rough Endoplasmic

Reticulum (ER)• Smooth ER• Ribosomes• Golgi apparatus

• Cell Membrane• Cytoskeleton• Mitochondria• Lysosomes

Plants Only:• Chloroplast• Vacuoles• Cell Wall

Prokaryote

• Unicellular organism

• Lack membrane bound organelles

• No nucleus

• Ex: bacteria

Eukaryote

• Unicellular or Multi-cellular organism

• Contain a true nucleus and membrane bound organelles

• Ex: yeast, plants and animals

Nucleus• The nucleus is the

brain of the cell. • Contains the

genetic material – DNA. (Code for making proteins)

• Not all organisms have a nucleus.

Nucleus (yellow)

Nucleus

• The nucleolus is a small section of the nucleus. (usually in the center)

• The nuclear membrane is a thin membrane around the nucleus.

Cell Membrane• Also called the plasma membrane

• The boundary between the cell and its environment.

1

Protein

Cell Membrane

• It’s Function: Protection of the cell– Keeps bad things from coming in– Allows needed materials in– Keeps good things in– Allows wastes out

• This is called selective permeability – allows some molecules to pass through while keeping others out.

2

Cell Membrane• The cell membrane allows the cell to

maintain homeostasis. – Homeostasis- the ability of an organism to

maintain equilibrium and survive.

3

Cell Membrane Structure• Made of 2 phospholipids back

to back. • The membrane is NOT water

soluble.

One phospholipid

Bilayer of the Membrane

4

Head

Tail

Cell Wall

• Surrounds a plant cell

• Inflexible compared to cell membrane

• Provides support and protection

• Permeable to all molecules

Cell Wall

Cell Wall

Cell Cell MembraneMembrane

Inside of Cell

All plant cells have BOTH a cell wall and a cell membrane

• Jelly-like fluid that fills a cell

• All organelles are suspended in the cytoplasm

Cytoplasm

Cytoskeleton

• Scaffolding or skeleton structure in the cytoplasm

• Maintains cell shape, protects the cell, & enables the cell to move

Endoplasmic Reticulum (ER)

• Interconnected tubes & vesicles

• Responsible for:– Protein transport– Production & storage of biomolecules

• Usually found near the nucleus

Endoplasmic Reticulum (ER)

• Smooth ER– Has no Ribosomes

• Rough ER– Has ribosomes on the

surface

Ribosomes

• Location of protein production in the cell.• Small structure made of RNA and protein

that is NOT membrane bound (no membrane).

• Use the “recipe” written on DNA to make proteins.

*Remember: DNA can’t leave the

nucleus so RNA is the messenger.

Ribosomes

Attached to the

ER (Endoplasmic

Reticulum)

Can be free

floating in

cytoplasm

Or

Golgi Body

• Function is to modify, sort and package biomolecules for use inside or outside the cell.

• Think of the Golgi Body as a post office.

Lysosomes

• Contain digestive enzymes

• They digest excess or worn out organelles, food particles and invaders (virus & bacteria)

Mitochondria• Found in both plants and animals.

• Location of cellular respiration.

• Energy converter … converts sugars/food into energy (ATP) for the cell

Chloroplast• Found only in plants.

• Location of Photosynthesis.

• Full of chlorophyll a green pigment.

Vacuole

• Membrane bound sac

• Storage for food, water & waste– Small in animals– Larger in plants

Multiple Cells

– Stained to show the difference between the nucleus (green) and the membrane (red)

Red Blood Cells

Nerve Cell

White Blood Cell & BacteriaWhite Blood Cell & Bacteria

Red Blood Cells flowing through blood vessels

Brain Cancer Cell

Organisms• Simple Organisms:

– Are unicellular– Very basic– Growth is restricted

• Complex Organisms: – Are multi-cellular– Can be basic or

complex– Have the ability to grow

Salmonella typhimurium invading human cells

Cells Alive!• Size?

– http://www.cellsalive.com/howbig.htm

• Cell Animation– http://www.cellsalive.com/cells/3dcell.htm

Resources• Wikipedia

• Cells Alive!

• Biology4Kids.com