Bellringer

1. Section 2 Eukaryotic Cells Chapter 4 Bellringer What are three differences between prokaryotic and eukaryotic cells? Write your answer in your science journal.

2. Section 2 Eukaryotic Cells Chapter 4 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.

3. Section 2 Eukaryotic Cells Chapter 4 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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5. Section 2 Eukaryotic Cells Chapter 4 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.

6. Section 2 Eukaryotic Cells Chapter 4 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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8. Section 2 Eukaryotic Cells Chapter 4 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.

9. Section 2 Eukaryotic Cells Chapter 4 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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11. Section 2 Eukaryotic Cells Chapter 4 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.

12. Section 2 Eukaryotic Cells Chapter 4 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.

13. Section 2 Eukaryotic Cells Chapter 4 Endoplasmic Reticulum, continued • Smooth ER makes lipids and breaks down toxic materials. The ER also functions as a delivery system for the cell.

14. Section 2 Eukaryotic Cells Chapter 4 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.

15. Section 2 Eukaryotic Cells Chapter 4 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.

16. Section 2 Eukaryotic Cells Chapter 4 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.

17. Section 2 Eukaryotic Cells Chapter 4 Chloroplasts, continued • Chloroplasts, like mitochondria, have their own DNA and two membranes. Photosynthesis takes place in the inner membrane.

18. Section 2 Eukaryotic Cells Chapter 4 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.

19. Section 2 Eukaryotic Cells Chapter 4 Golgi Complex, continued • The Golgi complex looks much like the smooth ER.

20. Section 2 Eukaryotic Cells Chapter 4 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.

21. Section 2 Eukaryotic Cells Chapter 4 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.

22. Section 2 Eukaryotic Cells Chapter 4 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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