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Section 2 Eukaryotic CellsChapter 4Bellringer
What are three differences between prokaryotic and eukaryotic cells?
Write your answer in your science journal.
Chapter 4What You Will Learn
• Eukaryotic cells have many parts--such as cell membranes, a nucleus, and ribosomes--in common.
• Plant cells and animal cells have some cell parts that are different.
Section 2 Eukaryotic Cells
Chapter 4Cell Wall
• Eukaryotic cells have many organelles in common to carry out important functions.
• Plants are eukaryotes that have some structures and organelles not seen in animal cells.
• Plant cells have a rigid structure that surrounds the cell membrane called the cell wall. Animal cells lack a cell wall.
Section 2 Eukaryotic Cells
Chapter 4Cell Membrane
• All cells have a cell membrane made up of proteins and phospholipids.
• A phospholipid has a water-loving, or hydrophillic, head and a water-fearing, or hydrophobic, tail.
• The phospholipids form a two-layer protective membrane.
Section 2 Eukaryotic Cells
Chapter 4Cell Membrane, continued
• The two-layer membrane makes it difficult for materials to pass into or out of the cell.
• Some materials, like nutrients and wastes, move through the membrane using protein passageways within the membrane.
Section 2 Eukaryotic Cells
Chapter 4Cytoskeleton
• The cytoskeleton is a web of proteins in the cytoplasm of some cells. It plays a key role in cell movement, shape, and division.
• Different cells have different shapes because of the arrangement of their cytoskeletons.
Section 2 Eukaryotic Cells
Chapter 4Nucleus
• All eukaryotic cells have a nucleus. The nucleus is the large organelle that contains the cell’s DNA.
• The DNA provides messages for making proteins. The messages are sent out of the nucleus through pores in the nucleus membrane.
• Some cells have a dark area within the nucleus called the nucleolus. Ribosome assembly begins here.
Section 2 Eukaryotic Cells
Chapter 4Ribosomes
• Ribosomes are small organelles that make proteins. There are more ribosomes than any other organelle in the cell.
• Because all cells need to make proteins, all cells have ribosomes.
• Unlike most organelles, ribosomes are not covered by a membrane.
Section 2 Eukaryotic Cells
Chapter 4Endoplasmic Reticulum
• The endoplasmic reticulum, or ER, is a system of folded membranes in which proteins, lipids, and other materials are made.
• Rough ER is covered with ribosomes that make proteins near the nucleus. Smooth ER lacks ribosomes.
Section 2 Eukaryotic Cells
Chapter 4Endoplasmic Reticulum, continued
• Smooth ER makes lipids and breaks down toxic materials. The ER also functions as a delivery system for the cell.
Section 2 Eukaryotic Cells
Chapter 4Mitochondria
• A mitochondrion is the main power source of a cell. Mitochondria are organelles in which sugar is broken down to release energy.
• Mitochondria have two membranes. The folded inner membrane of a mitochondrion is where ATP is made.
• ATP is the energy storing molecule used by the cell to carry out its functions.
Section 2 Eukaryotic Cells
Chapter 4Mitochondria, continued
• Most eukaryotic cells have mitochondria. They are unusual organelles in that they have their own DNA and divide on their own, like bacteria.
Section 2 Eukaryotic Cells
Chapter 4Chloroplasts
• Chloroplasts are organelles in which photosynthesis takes place. Plants, algae, and some prokaryotes have cells with chloroplasts.
• Chloroplasts are green because they contain chlorophyll, the pigment that traps the energy of sunlight.
• This energy is used to make sugar during photosynthesis.
Section 2 Eukaryotic Cells
Chapter 4Chloroplasts, continued
• Chloroplasts, like mitochondria, have their own DNA and two membranes. Photosynthesis takes place in the inner membrane.
Section 2 Eukaryotic Cells
Chapter 4Golgi Complex
• The Golgi complex packages and distributes proteins and lipids. The materials may be taken to other parts of the cell or may exit the cell.
• Materials may be modified in the Golgi complex to do different jobs before they are sent off.
• The Golgi complex pinches off portions of its membrane to create bubbles. The bubbles contain the materials to be transported.
Section 2 Eukaryotic Cells
Chapter 4Golgi Complex, continued
• The Golgi complex looks much like the smooth ER.
Section 2 Eukaryotic Cells
Chapter 4Cell Compartments
• The bubble that forms from the Gogi complex’s membrane is an example of a vesicle.
• A vesicle is a small sac that surrounds materials to be moved into or out of the cell. Vesicles also move materials within the cell.
• All eukaryotic cells have vesicles.
Section 2 Eukaryotic Cells
Chapter 4Lysosomes
• Lysosomes are vesicles that contain digestive enzymes. They carry out digestion inside a cell.
• Lysosomes destroy worn-out organelles, engulf foreign invaders, and get rid of wastes.
• Lysosomes are found mainly in animal cells.
Section 2 Eukaryotic Cells
Chapter 4Vacuoles
• A vacuole is another type of vesicle found in cells. They play an important role in plants.
• Vacuoles in plants and fungi may act like lysosomes. The large central vacuole in a plant cell stores water and other liquids.
• Some plants wilt when their large central vacuoles lose water.
Section 2 Eukaryotic Cells