Objectives 7.2 Cell Structure

1. Objectives 7.2Cell Structure -Describe the structure and function of the cell nucleus. -Describe the roles of the organelles. -Describe the function of the cell membrane.

2. Cell Organization • Many cellular structures act as if they are specialized organs. These structures are known as organelles or “little organs.”

3. The Nucleus • The nucleus is the control center of the cell. • The nucleus contains nearly all the cell’s DNA .

4. Vacuoles • Many cells contain structures called vacuoles that store water, salts, proteins and carbohydrates.

5. Lysosomes • Lysosomesare small organelles filled with digestive enzymes that function as the cell’s cleanup crew.

6. The Cytoskeleton • Eukaryotic cells are given their shape and internal organization by a network of protein filaments known as the cytoskeleton.

7. Centrioles • Centrioles are located near the nucleus and help to organize cell division. • Centrioles are not found in plant cells.

8. Ribosomes • Ribosomes produce proteins, some are found in the cytoplasm others are attached to the rough ER.

9. Endoplasmic Reticulum • The rough endoplasmic reticulum, or rough ER, is involved in the synthesis of proteins. • The smooth endoplasmic reticulum, orsmooth ER, has no ribosomes on its surface. The smooth ER is involved in the synthesis of membrane lipids and detoxification of drugs.

10. Golgi Apparatus • The Golgi apparatus modifies, sorts and packages proteins and other materials from the ER for storage in the cell or release outside the cell. It is like the UPS of the cell, where items are packaged and shipped.

11. Chloroplasts • Plants and other photosynthetic organisms contain chloroplasts. • Chloroplasts are the biological equivalents of solar panels. They capture the energy from sunlight and convert it into energy in a process called photosynthesis.

12. Mitochondria • Nearly all eukaryotic cells, including plants, contain mitochondria. • Mitochondria are the power house of the cell. They convert the chemical energy stored in food into ATP (ENERGY!). • The mitochondria is also unique because it has its own DNA, which came from the ovum, or egg, and therefore came directly from your MOM! 

13. Cellular Boundaries • Cells are surrounded by a barrier known as the cell membrane. • Many cells, including most prokaryotes, also produce a strong supporting layer around the membrane known as a cell wall.

14. Cell Walls • The main function of the cell wall is to provide support and protection for the cell. Prokaryotes, plants, algae, fungi have them. • Animal cells do not have cell walls.

15. Cell Membranes • All cells contain a cell membrane that regulates what enters and leaves the cell and also protects and supports the cell. • The composition of nearly all cell membranes is a double-layered sheet called a lipid bilayer. • The cell membrane is selectively permeable (only let’s certain things in).

16. The Lipid Bilayer • The fatty acid portions of such a lipid are hydrophobic, or “water-hating,” • while the opposite end of the molecule ishydrophilic, or “water-loving.”

17. True or False • Prokaryotic and eukaryotic cells are surrounded by a thin, flexible barrier called a cell membrane. _________________________ • Flagella made up of microtubules help organize cell division. _________________________ • Ribosomes that synthesize proteins are found on the smooth endoplasmic reticulum. _________________________ • Plant cells have chloroplasts but not mitochondria. _________________________

18. Answers • Prokaryotic and eukaryotic cells are surrounded by a thin, flexible barrier called a cell membrane.True • Flagella made up of microtubules help organize cell division. False, centrioles • Ribosomes that synthesize proteins are found on the smooth endoplasmic reticulum. False, rough • Plant cells have chloroplasts but not mitochondria.False, and