Chapter 7.3, The Cell's Interior and Organelle Structure and

Function

The Foundation of the Cell Just like a house, if you took away all the

furniture, appliances, sheet rock, trim, electrical, plumbing, insulation and all the accessory components of a house, you would be left with a basic skeletal structure and a foundation.

Similarly, a cell's foundation starts with the Cytoplasm and the Cytoskeleton

The Cytoplasm and the Cytoskeleton

Function of the Cytoplasm and the Cytoskeleton In prokaryotes, metabolic activities take place

directly in the cytoplasm. In eukaryotes, the cytoplasm holds all the

organelles in place that perform all the metabolic activities.

Some other functions of the cytoskeleton and cytoplasm include transportation of substances, and cell division, but their main role is to support the cell and the organelles.

The Nucleus and DNA (The Boss)

One way to understand the cell is to use an analogy of a factory, or a school, or a sports team.

The nucleus of the cell is like a factory's manager, or a school's principal, or a sports team's captain or coach.

The Nucleus contains the cell's DNA, which is the blueprint or instructions for all of the cell's activities.

Everything a cell does is directed by the DNA.

The Nucleus and DNA (The Boss)

Ribosomes (The Producers) Almost our entire body is made up of proteins. Ribosomes are non-membrane bound

organelles that manufacture proteins. Ribosomes are the only organelle found in both

prokaryotes and eukaryotes. Ribosomes are made in the Nucleolus. The

nucleolus is found in the center of the nucleus. In our analogy, ribosomes would be the

workers, the students in a school, or the players of a sport’s team.

Ribosomes

The Endoplasmic Reticulum (The Facilitators or Helpers) There are two types of Endoplasmic Reticulum. ER is a system of folded sacs and channels. Rough ER is called rough because it is covered with

ribosomes. Smooth ER is without ribosomes. ER transports and assists the ribosomes in the

production of proteins. ER could be the assembly line of a factory, the

teachers and staff of a school, or the assistant coaches of a sports team.

ER, the Facilitators

Golgi Apparatus (Golgi bodies) (The Inspectors and Shippers) Once the proteins are manufactured and

assembled, they are taken to the final inspection and packaging center; the Golgi Apparatus.

The Golgi Apparatus is a flattened stack of membranes that modify, sort, and package proteins.

The Golgi Apparatus could be inspectors and shippers at a factory, the counselors at school, or the officials and scorekeepers at a game.

The Golgi Apparatus (The Inspectors and Shippers)

The Vacuole (Storage Facility or Warehouse) Vacuoles are temporary storage facilities in

cells for things like enzymes and waste. Vacuoles are mostly found in plant cells and

rarely found in animal cells. In a factory this could be the warehouse, in a

school this could be the supply room, and for a team this could be the locker room.

The Vacoule (Storage Facility or Warehouse)

Lysosomes (The Clean-Up Crew) Lysosomes are organelles that contain enzymes

that break down food, waste and worn out organelles.

Lysosomes also help break down bacteria and viruses.

In our factory, school, and sports team analogies, our lysosomes could be represented by our building custodians. A very important, but underappreciated job. Next time you see a custodian, be sure to thank them for the hard work they do. If it wasn't for them, we would work in a filthy environment.

Lysosomes (The Clean-Up Crew)

The Mitochondria (The Power) None of the other jobs could be performed

without an energy source. The Mitochondria are the energy source (ATP)

that fuels all the activities of the cell. In a factory, the mitochondria could be a

generator or some type of an electrical source. In a school it could be the lunch room, or

perhaps the electricity supplying the computers and all the technology in a school.

For a sports team it could be the fans cheering.

The Mitochondria (The Power)

The Chloroplasts(Alternative Energy) Chloroplasts are organelles that can harness

energy from the sun just like solar panels Inside the chloroplasts are small flat disk-

shaped structures called thylakoids that convert light from the sun into usable energy.

The thylakoids contain a special pigment called chlorophyll that traps the sunlight.

Chloroplasts are only found in plants, some protists and bacteria, but not animal cells.

Chloroplasts (Alternative Energy)

Cell Wall (Plant Skeletons) The Cell Wall is another structure found only in

plants, fungi, protists, and bacteria. Animals have no cell walls. For plants, the cell wall is what gives the plant

support and structure. Plants don't have a skeleton like animals, so

the cell wall made of tough fibrous cellulose holds up the entire plant structure.

Giant redwoods and sequoias stand up several stories high under the force of cell walls.

Cell Walls (Plant Skeletons)

Cilia and Flagella (Transportation)

Cilia and Flagella are the transportation devices. They can be found on both prokaryotic cells and

eukaryotic cells. Their primary function is locomotion. Cilia are little hair-like structures that beat back

and forth like little paddles. Flagella are long tail-like structures that move

around like a whip or a propeller. In our analogy these could be cars or buses.

Cilia and Flagella (Transportation)

In Summary Cytoplasm and

Cytoskeleton – The Foundation

Nucleus – The Boss Ribosomes – The

Producers ER – The Facilitators Golgi Apparatus – The

Inspectors and Shippers Vacuole – Storage Facility

or Warehouse

Lysosomes – The Clean-Up Crew

Mitochondria – The Power source

Chloroplasts – Alternative Energy

Cell Wall – Plant Skeletons

Cilia and Flagella - Transportation