3.2 Cell Organelles

KEY CONCEPT Eukaryotic cells share many similarities.

3.2 Cell Organelles

Cells have boundaries

The Plasma Membrane

• Forms a boundary

between a cell and the

outside environment

• Controls the passage of

materials into and out of

the cell

• Helps to maintain

homeostasis

3.2 Cell Organelles

Cells have boundaries

Water

Inside the Cell

Outside the Cell

Oxygen

Wastes

CO2

Glucose

WastesInvaders

• The plasma membrane is selectively permeable

- allows some, but not all materials to cross

3.2 Cell Organelles

Cells have boundaries

Structure of the Plasma Membrane

• Composed of a phospholipid bilayer

3.2 Cell Organelles

Cells have boundariesOther components in the Plasma Membrane

Proteins

• some span the entire membrane and help materials cross

• others are found on the inner and outer surface – anchoring

3.2 Cell Organelles

Cells have boundariesOther components in the Plasma Membrane

• Cholesterol – strengthen the membrane

• Carbohydrates – cell identification

3.2 Cell Organelles

Cells have boundaries

• The Plasma membrane is referred as the fluid mosaic model

*Fluid - flexible

*Mosaic - pattern

3.2 Cell Organelles

Cells have boundaries

The Cell Wall• A rigid structure located

just outside of the plasma

membrane

• Found in plants, fungi, most

bacteria, and some protists

• Provides protection and

support

• It is not selectively permeable

• In plants, it is composed of

cellulose

3.2 Cell Organelles

Cells have an internal structure.

The Cytoskeleton

- A network of protein fibers that crisscross the entire cell

- Three types of fibers

a) Microtubules

b) Intermediate filaments

c) Microfilaments

3.2 Cell Organelles

Cells have an internal structure.• The cytoskeleton has many functions.

– supports and shapes cell– helps position and transport organelles– provides strength– assists in cell division– aids in cell movement

3.2 Cell Organelles

Cells have an internal structure.

The Cytoplasm

-Fills the space between the nucleus and cell membrane

-Consists of organelles and cytosol(mostly water)

3.2 Cell Organelles

Several organelles are involved in making and processing proteins.

The Nucleus

• Storehouse of DNA

• Surrounded by a nuclear

membrane

• Nuclear pores allow large

molecules to pass

between the nucleus and

the cytoplasm

• The nucleolus is where

ribosomes are produced

3.2 Cell Organelles

Several organelles are involved in making and processing proteins.

The Endoplasmic Reticulum

• An interconnected network of folded membranes

• Important in synthesis and transport of cellular materials

• Two types – Rough ER and Smooth ER

3.2 Cell Organelles

Several organelles are involved in making and processing proteins.

Rough Endoplasmic Reticulum

• Has ribosomes attached

• Proteins are made by the

ribosomes on the

surface, and then

move inside the rough ER

to be packaged into a

vesicle

• The vesicle then takes

the protein to the Golgi

Apparatus

3.2 Cell Organelles

Several organelles are involved in making and processing proteins.

Ribosomes

• The site of protein

synthesis

• Can be found attached

to Rough ER or free in

the cytoplasm

3.2 Cell Organelles

Several organelles are involved in making and processing proteins.

Smooth Endoplasmic Reticulum

• No ribosomes attached

• Produces lipids

• Detoxification of drugs

and poisons

3.2 Cell Organelles

Several organelles are involved in making and processing proteins.

The Golgi Apparatus

• Closely layered stacks

of membrane – enclosed

spaces

• Modifies, packages, and

transports proteins

• The vesicles can then

be stored, transported,

or secreted

3.2 Cell Organelles

Some organelles transform energy in the cell

Mitochondria

• Bean shaped organelle

with a double membrane

• Produces ATP through

cellular respiration

• The cell uses the ATP for

energy

• Mitochondria have their

own ribosomes and DNA

C6H12O6 + 6 O2 = 6 CO2 + 6 H2O + ATP

3.2 Cell Organelles

Some organelles transform energy in the cell

The Chloroplast

• Organelles that carry out

photosynthesis

• Found in plant cells

• Has two membranes

• Contains chlorophyll

which absorbs light and

gives plants their green

color

• Also have their own DNA

and ribosomes6 CO2 + 6 H2O + Light = C6H12O6 + 6 O2

3.2 Cell Organelles

Other organelles have various functions.

Vacuoles

• A membrane bound sac used for storage

Ex – water, food molecules, and enzymes

• Plant cells have

one large vacuole

• Animal cells have

many small vacuoles

3.2 Cell Organelles

Other organelles have various functions.

The Lysosome• Membrane bound organelle

that contains digestive

enzymes

• Digests worn out organelles,

food particles, and engulfed

viruses or bacteria

• Numerous in animal cells

• Their presence in plant cells

is still questioned by some

scientists

3.2 Cell Organelles

Other organelles have various functions.

Centrosome and Centrioles

• The centrosome is a small

region of the cytoplasm that

produces microtubules

• In animals, it contains a pair

of centrioles

• Centrioles help DNA divide

during cell division

3.2 Cell Organelles

Other organelles have various functions.

Cilia Flagella• Short, numerous hair-like

projections

• Move in a wave-like motion

• Used for feeding and

locomotion

• Long projection

• Moves in a whip-like motion

• Used for locomotion