1. Cell Structure Ms. Hughes Bio I

2. Introduction to Cells All life forms on our planet are made up of cells. From the cells in our body to the cells in an elephants gut. All of these cells have the same chemical machinery.

3. The Discovery of Cells Most cells are too small to be seen with the naked eye. Microscope observations of organisms led to the discovery of the basic characteristics common to all living things.

4. Scientists Robert Hook – 1 st discovery ◦ English scientist ◦ 1665 ◦ Cork under a crude microscope Theodore Schwann – 2 nd discovery ◦ German zoologist ◦ Animals are also made of cells ◦ 1858 Rudolph Virchow ◦ German physician ◦ 1859 ◦ Cells come only from the division of existing cells  Cell theory

5. Cell Theory All living things are made up of one or more cells. Cells are the basic units of structure and function in organisms. All cells arise from existing cells.

6. Looking at Cells Cells vary greatly in size and shape. ◦ Square, long, spherical, triangular, oval ◦ Over 2 feet long less that 1 millimeter A cell’s shape reflects the cell’s function. SHAPE DETERMINES FUNCTION!!!

7. Cell size and shape Cell size is limited by a cell’s surface area-to- volume ratio. Cells with greater surface area-to-volume ratios can exchange substances more efficiently. A cell may grow large in one or two dimensions but remain small in oth ers.

8. Cell Features All cells have a cell membrane, cytoplasm, ribosomes, and DNA. cell membrane is the cell’s outer boundary. It acts as a barrier between the outside environment and the inside of the cell. Cytoplasm includes the fluid and almost all of the structures suspended within the fluid. Ribosome cellular structure on which proteins are made. DNA genetic material that provides instructions for making proteins, regulates cellular activities and enables cells to reproduce.

9. Prokaryote Read aloud at the bottom of 154.

10. Eukaryote Read silently on page 155.

11. Activity Compare and contrast prokaryotes and eukaryotes. Homework: write a diary/journal entry as if you are the first person to discover cells. You also have discovered prokaryotes and eukaryotes. Explain how you knew they were different when you discovered them.

12. Inside the Eukaryotic Cell The Framework of the Cell ◦ The cytoskeleton is a web of protein fibers, found in eukaryotic cells. ◦ The cytoskeleton supports the cell in much the same way that bones support your body. ◦ The cytoskeleton helps the cell move, keep its shape and organize its parts.  Microfilaments - smallest  Microtubules - largest  Intermediate filaments -medium

13. Directing Cellular Activity DNA instructions are copied as RNA messages, which leave the nucleus. In the cytoplasm, ribosomes use the RNA messages to assemble proteins.

14. Nucleus The nucleus is surrounded by a double membrane called the nuclear envelope. Nucleolus – region of the nucleus that contains the majority of the DNA/chromosomes. BRAIN

15. Ribosomes Made of RNA and many proteins Make proteins Some are bound and some are free Ribosomes can switch back and forth from free to bound FACTORY

16. Protein Processing Vesicle – a small, often spherical-shaped sac that is formed by a membrane. In eukaryotic cell, two structures are mainly responsible for modifying, packaging and transporting proteins for use outside the cell. The endoplasmic reticulum and the Golgi apparatus are organelles that prepare proteins for extracellular export.

17. Endoplasmic Reticulum A system of internal membranes that moves proteins and other substances through the cell. The membrane of the ER is connected to the outer membrane of the nuclear envelope. Rough ER – ribosomes are attached and proteins are transported through the ER. Smooth ER – enzymes perform various function such as making lipids and breaking down toxic substances. TRANSPORT SYSTEM

18. Golgi Apparatus Set of flattened membrane-bound sacs. Cell products enter one side of the Gogli apparatus, which modifies, sorts and packages them for distribution. Repackaging – partner 1 pg 158 Exporting – partner 2 pg 158

19. Activity Get with your partner and make sure that you understand the important information for each of the functions of the Golgi Apparatus. Homework: create 5 questions about the golgi apparatus for another group to answer.

20. Storage and Maintenance Vesicles help maintain homeostasis by storing and releasing various substances as the cell needs them. Lysosome Central Vacuole Other Vacuole

21. Lysosome A lysosome is a vesicle that contains specific enzymes that break down large molecules. The digest food particles to provide nutrients for the cell. They also help recycle materials in the cell digesting old, damaged or unused organelles.

22. Vacuoles Vacuoles Central Vacuole ◦ Many plant cells contain a large membrane bound compartment called the central vacuole. ◦ This large vacuole stores water, ions, nutrients and wastes. Other vacuoles ◦ Some protists have contractile vacuoles which pump excess water out of the cell.

23. Energy Production The energy for cellular functions is produced by chemical reactions that occur in the mitochondria and chloroplasts.

24. Chloroplast Organelle that uses light energy to make sugar from carbon dioxide and water. Contain chlorophyll a pigment that turns the plant green Only found in plants

25. Mitochondria An organelle that uses energy from organic compounds to make ATP. Some ATP is made in the cytosol most of a cell’s ATP is made inside mitochondria.

26. Activity Compare organelles to place in a city. Outside activity Homework: compare all of the organelles to an item in your home. Explain your comparison.

27. Diversity in Cells Prokaryotes are always unicellular and limited in size. Eukaryotes are often larger and can be either unicellular or multicellular. The different organelles and features of cells enable organisms to function in unique ways in different environments.

28. Diversity in Prokaryotes Flagella – long whip like tails that rotate quickly to move an organism through its environment. Pili – short, thick outgrowths that allow prokaryotes to attach to surfaces or to other cells.

29. Activity Diversity in Eukaryotes Read the paragraph on page 163 and write down what you already knew, what you learned and what you would like to learn more about.

30. Get with a partner and go over what you wrote down.

31. Levels of organization Plants and animals have many highly specialized cells that are arranged into tissues, organs, and organ systems. Tissue – organ – organ system

32. Tissue – a distinct group of cells that have similar structures and functions. Organs – different tissues, with specialized structures that have a specific function. Organ system – various organs that carry out a major function and work together to accomplish this goal.

33. Activity Map out circulatory

34. Body Types A multicellular organism is composed of many individual, permanently associated cells that coordinate their activities.

35. Cell Groups Some unicellular organisms can thrive independently but others live in groups. Cells that live as a connected group but do not need each other for survival are considered colonial organisms.

36. Multicellularity Only occurs in eukaryotes such as the organisms on page 166. Some protists, fungi, and all plants and animals have a multicellular body. Most multicellular organisms begin as a single cell and grow into a multicellular organism such as a chicken from an egg.

37. Hierarchy Heart Cell

38. Homework Write a story as if you are part of an multicellular organism and explain how you as a cell are part of this organism using the hierarchy we just learned.