Download Ch. 3: “Cell Structure” Section 3: “Cell Organelles” Describe the role

Ch. 3: “Cell Structure”
Section 3: “Cell Organelles”
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Describe the role of the nucleus in cell activities.
Analyze the role of internal membranes in protein production.
Summarize the importance of mitochondria in eukaryotic cells.
Identify three structure in plant cells that are absent from animal cells.
The Nucleus
• The nucleus is an internal compartment that houses the cell’s DNA. Most functions of a eukaryotic cell
are controlled by the cell’s nucleus.
• The nucleus is surrounded by a double membrane called the nuclear envelope.
• Scattered over the surface of the nuclear envelope are many small channels called nuclear pores.
• Ribosomal proteins and RNA are made in the nucleus.
• Ribosomes are partially assembled in a region of the nucleus called the nucleolus.
Ribosomes and the Endoplasmic Reticulum
• Ribosomes are the cellular structures on which proteins are made.
• The Endoplasmic Reticulum or ER is an extensive system of internal membranes that move proteins
and other substances through the cell.
• The part of the ER with attached ribosomes is called the rough ER.
• The rough ER helps transport proteins that are made by the attached ribosomes.
• New proteins enter the ER.
• The portion of the ER that contains the completed protein pinches off to form a vesicle.
• A vesicle is a small, membrane-bound sac that transports substances in cells.
• The ER moves proteins and other substances within eukaryotic cells.
Packaging and Distribution of Proteins
• Vesicles that contain newly made proteins move through the cytoplasm from the ER to an organelle
called the Golgi apparatus.
• The Golgi apparatus is a set of flattened, membrane-bound sacs that serve as the packaging and
distribution center of the cell.
Mitochondria
• Mitochondria are organelles that harvest energy from organic compounds to make ATP.
• ATP is the main energy currency of cells. Most ATP is made inside the mitochondria.
• Mitochondria have two membranes. The outer membrane is smooth. The inner membrane is greatly
folded, and has a large surface area.
• Mitochondria have their own DNA. Mitochondria reproduce independently of the cell. Mitochondrial
DNA is similar to the DNA of prokaryotic cells.
• Mitochondria are thought to be descendants of primitive prokaryotes.
• Mitochondria have an inner and an outer membrane.
Structures of Plant Cells
Plants have three unique structures that are not found in animal cells:
1. Cell Wall
• The cell membrane of plant cells is surrounded by a thick cell wall, composed of proteins and
carbohydrates.
• The cell wall
• helps support and maintain the shape of the cell
• protects the cell from damage
• connects the cell with adjacent cells
2. 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 needed to power the activities of
plant cells.
• Chloroplasts, like mitochondria, have their own DNA and reproduce independently of the plant cell.
• Chloroplasts, like mitochondria, are thought to be descendants of ancient prokaryotes.
3. Central Vacuole
• Most of a plant cell’s volume is taken up by a large, membrane-bound space called the central vacuole.
• The central vacuole stores water and may contain ions, nutrients, and wastes.
Summary of Organelles