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

• The plasma membrane is

selectively permeable

- allows some, but not all materials to cross

Outside the Cell

Water Oxygen Invaders CO 2 Wastes

Inside the Cell

Glucose Wastes

3.2 Cell Organelles

Cells have boundaries Structure of the Plasma Membrane

• Composed of a

phospholipid bilayer

3.2 Cell Organelles

Cells have boundaries Other 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 boundaries Other 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 C 6 H 12 O 6 + 6 O 2 = 6 CO 2 + 6 H 2 O + 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 6 CO 2 + 6 H 2 O + Light = C 6 H 12 O 6 + 6 O 2 and ribosomes

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

• Short, numerous hair-like

Flagella

• • projections Move in a wave-like motion Used for feeding and locomotion • Long projection • Moves in a whip-like motion • Used for locomotion