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Chapter 4 Section 2 Eukaryotic Cells Bellringer What are three differences between prokaryotic and eukaryotic cells? Write your answer in your science journal.
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Chapter 4 Section 2 Eukaryotic Cells What 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.
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Chapter 4 Section 2 Eukaryotic Cells Cell 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.
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Chapter 4 Section 2 Eukaryotic Cells
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Chapter 4 Section 2 Eukaryotic Cells Cell 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.
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Cell Membrane, continued
Chapter 4 Section 2 Eukaryotic Cells Cell 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.
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Chapter 4 Section 2 Eukaryotic Cells
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Chapter 4 Section 2 Eukaryotic Cells Cytoskeleton 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.
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Chapter 4 Section 2 Eukaryotic Cells Nucleus 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.
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Chapter 4 Section 2 Eukaryotic Cells
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Chapter 4 Section 2 Eukaryotic Cells Ribosomes 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.
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Endoplasmic Reticulum
Chapter 4 Section 2 Eukaryotic Cells Endoplasmic 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.
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Endoplasmic Reticulum, continued
Chapter 4 Section 2 Eukaryotic Cells Endoplasmic Reticulum, continued Smooth ER makes lipids and breaks down toxic materials. The ER also functions as a delivery system for the cell.
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Chapter 4 Section 2 Eukaryotic Cells Mitochondria 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.
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Mitochondria, continued
Chapter 4 Section 2 Eukaryotic Cells Mitochondria, continued Most eukaryotic cells have mitochondria. They are unusual organelles in that they have their own DNA and divide on their own, like bacteria.
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Chapter 4 Section 2 Eukaryotic Cells Chloroplasts 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.
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Chloroplasts, continued
Chapter 4 Section 2 Eukaryotic Cells Chloroplasts, continued Chloroplasts, like mitochondria, have their own DNA and two membranes. Photosynthesis takes place in the inner membrane.
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Chapter 4 Section 2 Eukaryotic Cells Golgi 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.
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Golgi Complex, continued
Chapter 4 Section 2 Eukaryotic Cells Golgi Complex, continued The Golgi complex looks much like the smooth ER.
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Chapter 4 Section 2 Eukaryotic Cells Cell 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.
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Chapter 4 Section 2 Eukaryotic Cells Lysosomes 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.
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Chapter 4 Section 2 Eukaryotic Cells Vacuoles 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.
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Chapter 4 Section 2 Eukaryotic Cells
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