Organelle Structure and Function

Review Prokaryotes simple celled organisms

No nucleus

Eukaryotic cells multicellular organisms Nucleus organelles

Cytoskeleton Webs of proteins and fibers that make up a

skeleton for the cell. The cytoskeleton holds the cell together

and keeps the cell’s membrane from collapsing.

Consists of the microtubules, and microfilaments

Nucleus Functions of the cell are controlled by the

nucleus Nucleus surrounded by a double

membrane called the nuclear envelope. Nuclear membrane is made a two lipid

bilayers.

Nucleus The nucleus contains the DNA The nucleus contains the nucleolus. The nucleolus contains the RNA. RNA makes the proteins

Nucleus The hereditary information of a eukaryotic

cell is in the cell’s DNA, most of which is stored in the nucleus

Ribosomes Cells make proteins called ribosomes. Ribosomes are made of proteins and RNA. Ribosomes are found in the cytoplasm and

on the endoplasmic reticulum. Ribosomes are used to make new

organelles.

Endoplasmic Reticulum The endoplasmic reticulum or ER is an

extensive system of internal membranes that move proteins and other substances through the cell.

The ER is made of the lipid bilayer.

Rough Endoplasmic Reticulum The endoplasmic reticulum that is studded with

ribosomes is called rough ER. The rough ER help transport the proteins that are

made by its attached ribosomes. As each protein is made crosses the ER

membrane and enters the ER. The portion of the ER that contains the completed

protein then pinches off and forms a vesicles.

Vesicle A vesicle is a small membrane bound sac

that transports substances in cells. Because these proteins are enclosed inside

a vesicles, these proteins are kept separate from proteins that are produced by free ribosomes.

Smooth Endoplasmic Reticulum The rest of the ER is called the smooth ER

because it lacks ribosomes The smooth ER is used for making lipids

and breaking down toxic substances.

Golgi Appartatus Vesicles that contain newly made proteins move

through the cytoplasm into the golgi apparatus. The golgi apparatus is a set of flattened

membrane bound sacs that serves as the packaging and distribution center of the cell.

Enzymes inside the Golgi Apparatus modify the proteins that are received in the vesicles from the ER.

Golgi Apparatus The modified proteins are then put into

vesicles and bud from the surface of the Golgi Apparatus

Lysosomes Lysosomes are vesicles within the cell that

contain the cell’s digestive enzymes. Lysosomes destroy worn out cell parts, and

dead or dying cells.

Mitochondria A mitochondria or mitochondrion is an

organelle that harvests energy from organic compounds to make ATP, the main energy currency in cells.

Most ATP is made in the mitochondria. Cells that require large amounts of energy

like muscle cells have hundreds of mitochondria within the cell.

Mitochondria The outer membrane is smooth and the

inner membrane is greatly folded, to add its surface area.

In the mitochondrial matrix is where the chemical reactions take place in order to form the ATP necessary for the cells energy.

Mitochondria The mitochondria contain their own DNA. Mitochondria also have DNA and

ribosomes, and mitochondria make some of their own proteins.

This gives mitochondria the ability to replicate on its own.

Structure of Plant Cells All other organelles are in animal and plant

cells. Plants have three additional organelles:

Cell wall Chloroplasts Central vacuole

Cell Wall The cell membrane of a plant cell is

surrounded by a thick cell wall composed of carbohydrates, proteins, and cellulose.

The cell wall helps support and maintain the shape of the cell.

It protects the cell from damage, and connects it with adjacent cells.

Chloroplasts Plant cells contain one or more chloroplasts. Chloroplasts are organelles that use light energy

to make carbohydrates from carbon dioxide and water.

Chloroplasts along with mitochondria, supply much of the energy need to power the activities of the plant cell.

Chloroplast are equivalent to the mitochondria in animal cells.

Central Vacuole Much of the plant cell’s volume is take up by the

central vacuole. The central vacuole stores water and may contain

many substances, including ions, nutrients, and wastes.

When the central vacuole is full it makes the cell rigid.

The rigidity allows the plant to stand upright.