Cells

1. Cells

2. Bell Ringer • What did Robert Hooke observe with the use of a microscope? How did he describe what he saw? • What 3 components make up the cell theory? • Where is the DNA housed in a eukaryotic cell? • How do organelles in a cell compare to organs in the human body?

3. Learning Target • “I can” analyze the difference between a prokaryotic cell and a eukaryotic cell. • “I can” analyze the difference between a plant cell and an animal cell.

4. It’s a Rap • http://www.youtube.com/watch?v=-zafJKbMPA8

5. Discovery of the Cells • The discovery of the cell helped answer this question… • How do living things differ from non-living things? • Microscopes have made a huge impact on the study of biology. • Microscope observations of organisms led to the discovery of the basic characteristics common to all living things.

6. History • 1665, Robert Hooke observed a piece of cork under a microscope that only had the strength to magnify a specimen 30x. • Hooke observed many little boxes in the cork. • They reminded Hooke of small rooms that monks live in called “cells.” • Later, Hooke observed the same “little boxes” in the stem and roots of plants.

8. History Cont. • 10 years later a Dutch man by the name of Anton Van Leeuwenhoek used a more powerful microscope that could magnify specimens 300x. • He observed pond water and discovered many living creatures in the water that he named animalcules, which means “tiny animals.” • Thanks to Leeuwenhoek we now know these animalcules as single celled organisms(prokaryotes.)

9. History Cont. • It took over 150 years for scientists to fully appreciate the studies of Hooke and Leeuwenhoek. • Matthias Schleiden a German botanist, concluded that cells make up every part of a plant. • 1 year later Theodore Schwan a German zoologist, discovered that animals are also made up of cells.

10. History Cont. • Rudolph Virchow, a German physician, proposed that cells only come from the division of other cells. • All of the observations form Schleiden, Schwan, and Virchow helped form the Cell Theory.

11. Cell Theory • The cell theory is composed of the following 3 things. • 1. All living things are made up of one or more cells. • 2. Cells are the basic units of structure and function in an organism. • 3. All cells arise from existing cells.

12. Cell Shape • Cells vary greatly in size and shape. • A cells shape reflects the cells function. • There are at least 200 types of cells. • The human body is made up of about 100 trillion cells. • Larger cells often have shapes that increase the surface area available for exchange.

13. Cell Size • All substances that enter or leave a cell must pass through the surface of a cell. • As a cell gets larger, it takes up more nutrients and releases more waste. • Cell size is limited to by a cells surface area-to-volume ratio. • Cells with a greater surface area-to-volume ratio can exchange substances more efficiently. • Ex: lungs

14. Cell Organelles • Cell Membrane- is the cells outer boundary. • It acts as a barrier between the outside environment and the inside of the cell. • Cytoplasm- includes cytosol and almost all of the structures that are suspended in it. • Jelly like substance that is found in the inside of the cell. • Ribosome- is a cellular structure on which proteins are made. • Ribosomes are found all throughout the cytoplasm.

15. Prokaryotic Cell • Prokaryote is a single celled organism. • Ex: bacteria • Organization is very simple. DNA freely floats in the middle of the cell instead of being trapped in the nucleus. • Pro-No • The prokaryotic cell wall surrounds the cell membrane. The cell wall provides strength and structure to the cell. • Capsule- is a structure around the cell wall that enables prokaryotes to cling to surfaces, including, teeth, skin, and food. • Prokaryotic cells are thought to be 3.5 billion years old.

17. Prokaryotic Cell • Prokaryotic cells move around with the help of a flagella. • Flagella- Flagella are long projections composed of protein. They rotate due to a protein motor secured in the plasma membrane. • Prokaryotic cells also contain pili. • Pili- help bacteria stick to other cells. They are short “hair like” projections.

18. Eukaryotic Cell • Eukaryote is an organism made up of one or more cells. • Some live as single celled organisms. • Others are multicellular. • Because of their complex organization, eukaryotic cells can carry out more specialized functions that prokaryotic cells can not. • Eukaryotic cells first appeared 1.5 billion years ago

19. Eukaryotic • Eukaryotic cells contain an organelle called a nucleus that houses the DNA for the cell. • Eukaryotes have membrane bounded organelles. • Organelle- is a structure that carries out specific activities inside the cell. • Each organelle performs a distinct function. • Eukaryotic cells contain, cytoplasm, ribosomes, cell membrane, mitochondrion, Golgi apparatus, endoplasmic reticulum, centrioles, Lysosomes, nucleolus, and a nucleus.

21. Bell Ringer Prokaryotic vs. Eukaryotic • Compare and contrast a Eukaryotic and a Prokaryotic cell.

22. Bell Ringer • What 2 organelles prepare proteins for extracellular transport? • What is a central vacuole and where can it be found? • In the muscles there are tons of mitochondria, why is this?

23. Framework of the Cell • The cytoplasm of a Eukaryotic cell is packed with structures particular to the cell. • Cytoskeleton- helps the cell move, keep its shape, and organize its parts. • The cytoskeleton to the cell are like the bones to the body.

24. 3 types of Cytoskeleton • 1. Microfilaments- are long, thin fibers that are made of the protein actin. • They contract to pull the membrane in some places and expand to push it out in others. • 2. Microtubules- are, thick hollow fibers that are made of the protein tubulin. • Information molecules travel through these tubes to various places in the cell. • 3. Intermediate Fibers- are moderately thick and anchor organelles and enzymes to certain parts of the cell.

25. Directing Cellular Activity • Cellular activity depends on the proteins that the cell makes. • Instruction for making proteins is stored in the DNA. • In a Eukaryotic cell, DNA is packed into the nucleus. • This protects the DNA from other activity in the cell from getting lost or destroyed.

26. 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.

27. Nucleus • The nucleus is surrounded by a double membrane called the nuclear envelope. • The nuclear envelope has many nuclear pores. • Nuclear pores- are small channels that allow certain molecules to move in and out of the nucleus. • Nucleolus- located inside of the nucleus, this is where the ribosome parts are made. • Nucleolus nuclear pore cytoplasm Ribosome.

28. Ribosome • Ribosomes are made of RNA and many proteins. • Free Ribosomes- Float freely in the cytoplasm. • Their job is to make proteins that remain inside the cell, such as proteins that build new organelles or enzymes to speed up reactions. • Bound Ribosomes- are attached to the membrane of another organelle. • Their job is to make proteins that are exported from the cell.

29. Protein Processing • The proteins produced by cells have many uses. • Proteins that are sent outside the cell must remain separate from the cytoplasm. The cell does this with the help of a vesicle. • Vesicle- this is the site where proteins are packaged. It is a small, often spherical shaped sac that is formed by a membrane. • In a eukaryotic cell 2 organelles are responsible for modifying, packaging, and transporting proteins. • The Endoplasmic Reticulum and The Golgi Apparatus.

30. Endoplasmic Reticulum • Endoplasmic Reticulum (ER)- is a system of internal membranes that moves proteins and other substances through the cell. • The ER is connected to the outer membrane of the nuclear envelope.

31. Two Types of ER • Rough ER- ribosomes are attached to the surface of the ER. • Rough ER has a bumpy appearance. • 1.As proteins are made they cross the ER membrane, entering the ER. Then, the ER membrane pinches off to form vesicles around the protein. • Smooth ER- the rest of the ER is called smooth ER, with no attached ribosomes. • Smooth ER has a smooth appearance. • Smooth ER performs various functions such as making lipids and breaking down toxic substances.

32. Golgi Apparatus • Golgi Apparatus- is a set of flattened membrane-bound sacs. • Cell products enter one side of the Golgi Apparatus, which modifies, packs, and sorts them for distribution. • 2. Repackaging-The vesicles membrane fuses with the Golgi membrane. Inside the Golgi apparatus, enzymes modify the protein as they move through the organelle. • 3. As the vesicle membrane fused with the cell membrane, the completed proteins are released to the outside of the cell.

33. Storage and Maintenance • Vesicles play many roles in the cell. • Vesicles- help maintain homeostasis by storing and releasing various substances as cells need them. • Lysosome- is a vesicle that contains specific enzymes that break down large molecules. • These enzymes can digest food particles to provide nutrients for the cell. • They also help recycle materials in the cell by digesting old, damaged, or unused organelles.

34. Lysosomes • Lysosomes made by the Golgi Apparatus, prevent the enzyme from destroying the cell.

35. Central Vacuole • Central Vacuole- large membrane bound compartment found in plant cells. • Stores water, ions, nutrients and wastes. • It can also store toxins and pigments. • When the central vacuole fills up with water, it makes the cell rigid, allowing the plant to stand up right. • When the central vacuole loses water it causes it to wilt and the cell shrinks.

36. Other Vacuoles • Contractile Vacuole- Pumps excess water out of the cell. • This process controls the concentration of salts and other molecules and helps the cell maintain homeostasis. • Food Vacuole- forms when the cell membrane surrounds food particles outside the cell and pinches off to form a vesicle inside the cell.

37. Energy Production • Cells need a constant source of energy. • The energy needed for cellular function is produced by chemical reactions that occur in the mitochondria and chloroplasts. • Eukaryotic cells= mitochondria • Plant cells= chloroplasts • In both reactions ATP is produced. • ATP is the form of energy that fuels almost all cell processes.

38. Chloroplasts • Chloroplast- is an organelle that uses light energy to make sugar from carbon dioxide and water. • In the inner membranes of the chloroplasts is where the ATP producing chemical reactions take place.

39. Mitochondria • Mitochondrion- an organelle that uses energy from organic compounds to make ATP. • Cells that have a high energy requirement, such as muscle cells, will contain more mitochondria. • ATP producing enzymes are located on the inner membranes of the mitochondria.

40. Word Bank • Cell Membrane • Cytoplasm • Ribosome • Nucleus • Nuclear envelope • Rough ER • Smooth ER • Golgi Apparatus • Chloroplasts • Flagella • Pili • Capsule • Mitochondrion • Cell wall • Lysosome • Vacuole • DNA

41. Bell Ringer • I am like the assembly line for the cell because I assemble items that the cell needs • I am like the bricks for the cell because I give it structure • I am like the control center for the cell because I hold on the instructions of life • I am like the storage unit for the cell because I stored materials until they are needed • I am like a bakery for the cell because I only make proteins

42. Bell Ringer • An army is like a __________ because it protects the U.S.A from its enemies. • A light bulb is like a ________because it gives us energy. • A coach is like a _________ because he makes all the decisions for the team. • A postman is like a ______ because he sorts and packages items for people.

43. PLANT VS. ANIMAL • If a scientist viewed a plant cell and an animal cell under a microscope what could he or she expect to see? • On the poster that I pass out you need to list, define and tell how that particular organelle helps the cell function.

44. Bell Ringer • Get out your notebooks and study what we have covered so far in class. • If you weren’t here Thursday you need to have your project out on your desk and your questions that you completed in your notebook out.

45. Word Bank • Nucleus • Ribosomes • Endoplasmic Reticulum • Cell Membrane • Cell Wall • Lysosome • Vesicle • Cytoplasm • Golgi Apparatus • Nucleolus • DNA • Mitochondria • Chloroplasts • Nuclear Envelope • Vacuole

46. Diversity in Cells • Prokaryotic cells are always unicellular and limited in size. • Eukaryotes are often larger and can be either unicellular or multicellular. • Prokaryotic cells lack a nucleus and membrane bound organelles. • The different organelles and features of cells enable organisms to function in unique ways in different environments.

47. Diversity in Prokaryotes • Prokaryotes can vary in shape, the way that they obtain and use energy, the makeup of their cell walls, and their ability to move. • Prokaryotes contain • Flagella- long tail like structure that grows out of the cell, allows the cell to move. • Pili- are short hair-like projections that allow prokaryotes to attach to surfaces or to other cells.

48. Types of cells • The two types of Eukaryotic Cells are • Animal and Plant • Plant cells contain both cell walls and chloroplasts which Animal cells do not. • Plant and animal cells have highly specialized cells that form tissues and organs. • Tissue- a group of similar cells that perform the same function • Lung tissue • Leaf tissue

49. Types of cells • Organ- a collection of tissues that carry out a specialized function in the body. • Leaf • Lung • Organ System- a group of organs that work together to form body functions. • Circulatory System • Root System

50. Body Types • Multicellular Organisms- are composed of many individual, permanently associated cells that coordinate their activities. • Colonial Organisms- a collection of genetically identical cells that are permanently associated but in which little or no integration of cell activities occur.