Cell Structure and Function

1. Cell Structure and Function

2. The Discovery of Cells • All living things are made up of one or more cells – from the tiniest bacterium to the largest whale. A _____ is the smallest unit that can carry on all of the processes of _____. • Before the seventeenth century, no one knew that cells existed. • Most cells are too _____ to be seen with the unaided _____. • Cells were not discovered until after the invention of the _____ in the early seventeenth century. • Cell Video (2:55)

3. The First Discoveries • One of the first microscopes was made by the Dutch drapery store owner _____ _____ _____. • With his hand-held microscope, Leeuwenhoek became the first person to observe and describe microscopic _____ and living _____.

4. The First Discoveries • In 1665, the English scientist _____ _____ used a microscope to examine a thin slice of _____ and described it as consisting of "a great many little boxes.”  • They reminded him of the small rooms in which _____ lived, so he called them "Cells.” He was the FIRST person to actually see ____.

5. The First Discoveries • In 1838, German botanist _____ _____ concluded that all _____ are composed of _____. • The next year, German zoologist _____ _____ reported that _____ are also made of _____.

6. The First Discoveries • In 1855, German physician _____ _____ stated that "THE ANIMAL ARISES ONLY FROM AN ANIMAL AND THE PLANT ONLY FROM A PLANT" or “_____ ONLY COME FROM OTHER _____.” •  His statement contradicted the idea that life could arise from nonliving matter, a.k.a., _____ _____.

7. The Cell Theory • The combined work of Schleiden, Schwann, and Virchow make up what is now known as the modern _____ _____. • The Cell Theory consists of THREE Principles: • A. All living organisms are composed of one or more _____. • B. Cells are the basic units of _____ and _____ in an organism. • C. Cells come only from reproduction of _____ _____. • Cell Overview (3:35) Review of Cell Theory (6:12)

8. Cell Diversity • Not all cells are alike.  Even cells within the same organism show enormous diversity in size, shape, and internal organization.  Your body contains over _____ different cell types.

9. Cell Shape • Cells come in a variety of specific shapes. • THE _____ OF A CELL DEPENDS ON ITS _____. • Notice how cells of the nervous system that carry information from your toes to your brain are long and threadlike. • Notice how blood cells are biconcave disks that can carry the optimum amount of _____. They are also flexible allowing them to squeeze through microscopic _____ _____.

10. Cell Size • A few types of cells are large enough to be seen by the unaided eye.  The female _____ _____is the largest cell in the human body and can be seen without the aid of a microscope. The male _____ _____ is the smallest. •  Most cells are visible only with a _____. • Cell Size and Scale

11. Why are cells so small?? • Cells are limited in size by the RATIO between their outer _____ _____ and their _____. • A SMALL CELL HAS MORE SURFACE AREA THAN A LARGE CELL FOR A GIVEN VOLUME OF CYTOPLASM.  This is important because the nutrients, oxygen, and other materials a cell requires must enter through its _____.  As a cell grows larger, at some point its surface area to volume _____ becomes too small to allow these materials to enter the cell quickly enough to meet the cell's need. • In other words, THE CELL'S _____ CAN ONLY CONTROL A CERTAIN AMOUNT OF LIVING, ACTIVE _____.

12. Prokaryotes and Eukaryotes • Cells fall into two broad categories depending whether or not they have a _____. • _____ - a large membrane-enclosed structure that contains the cell’s genetic material in the form of _____.

13. Prokaryotes • Generally smaller and less _____ than eukaryotic cells • Have genetic material not contained in a _____. • Carry out every activity associated with living things.

14. Eukaryotes • _____ and more complex than prokaryotic cells. • Contain dozens of structures and internal _____, many of which are highly specialized.

15. The Plasma or Cell Membrane (City Gate) • This _____ _____ membraneregulates what passes into and out of the cell. • All cells, from all organisms, are surrounded by a plasma membrane. • The cell membrane is a thin layer of _____, proteins, carbohydrates, and _____ groups that separate the cell's content from the world around it. • The cell membrane functions like a _____, controlling what enters and exits the cell.

16. The Plasma or Cell Membrane (City Gate) • Cell membranes are made mostly of _____ molecules. (phosphate + lipid) • Aphospholipid is a molecule that consists of two _____ (tails), and a _____ group (heads). • The phosphate head is _____ meaning "water-loving".   The phosphates will turn themselves toward _____ molecules. • The lipid tails are _____ meaning "water-fearing". The tails will turn themselves away from _____.

17. The Plasma or Cell Membrane (City Gate) • Cells are bathed in an _____, or watery, environment.  Since the inside of a cell is also an aqueous environment, both sides of the cell membrane are surrounded by _____ molecules.  These water molecules cause the phospholipids of the cell membrane to form two layers. • Cell membranes consist of two phospholipid layers called a _____ _____. • _____ phosphate heads face the watery fluids inside and outside the cell; _____ lipid tails are sandwiched inside the bilayer.

18. The Plasma or Cell Membrane (City Gate)

19. Membrane Proteins • A variety of _____ are embedded in the lipid bilayer. • Some proteins are attached to the surface of the cell membrane; these are called _____ _____, and are located on both internal and external surfaces. • The proteins that are embedded in the lipid bilayer are called _____ _____. •  Some integral proteins extend across the entire cell membrane and are exposed to both the inside of the cell and the exterior environment (_____ _____).

20. Membrane Proteins • These proteins help to _____ material into and out of the cell. • Integral proteins exposed to the cell's external environment often have _____ attached to them that serve as _____ badges that allow cells to recognize each other and may act as sites where viruses or chemical messengers such as hormones can _____. Membrane Video (1:26) Another One (1:23)

22. Desmosomes (Bridges) • They are cellular _____ that extend from the plasma _____. • They function in _____ cells together and are especially important in cells where shearing forces would easily tear them apart (muscle tissue, intestinal walls, epidermis).

23. Fluid Mosaic Model • Membranes are _____ and have the consistency of vegetable oil. • The lipids and proteins of the cell membrane are always in _____. • Proteins in and on the membrane form patterns, or _____. • Because the membrane is FLUID with a MOSAIC of proteins, scientists call the modern view of membrane structure the _____ _____ model.

24. Nucleus (City Hall) • The nucleus is often the most prominent structure within a eukaryotic cell. • The nucleus is the _____ _____ (brain) of the cell. • Most cells have a single nucleus; some cells have more than one. • The nucleus is surrounded by a double-layered membrane called the _____ _____. • The nuclear envelope is covered with many small _____ through which proteins and chemicals from the nucleus can pass.  

25. Nucleus (City Hall) • The nucleus contains _____. • The DNA is in the form of long strands called _____, which is a matrix of protein and DNA. • During _____ _____, chromatin strands coil and condense into thick structures called _____. • Most nuclei contain at least one _____ (plural, nucleoli). • The nucleolus synthesizes _____, WHICH BUILD PROTEINS. • When a cell prepares to reproduce, the nucleolus _____.

26. Nucleus (City Hall)

27. Centrioles • They are organelles that exist in pairs and are made of a _____ called tubulin. • They are usually located near the nucleus, which makes sense because they seem to assist in organizing cell division by moving _____ to opposite ends of the cell via fibers they produce called _____ fibers. • However, their main function is to produce the cell’s _____, cilia, and flagella. • They are not found in _____ cells.

28. Mitochondria (Power Plants) • Mitochondria are the sites of _____ reactions that transfer ____ from organic compounds to ATP.  Energy contained in food is released and converted to _____.  ATP is the molecule that nearly all cells use as their main source of _____. • Nickname: THE “_____” OF THE CELL. • Mitochondria are usually more numerous in cells that have a high _____ requirement like _____ cells.

29. Mitochondria (Power Plants) • Mitochondria are surrounded by TWO _____. • The outer membrane serves as a _____ between the mitochondria and the cytosol. • The inner membrane has many long folds, known as cristae (KRIS-tee).   The cristae greatly increase the _____ _____ of the inner membrane, providing more space for chemical reactions to occur, making the mitochondria more _____. • Mitochondria have their own _____ (from the ovum), and new mitochondria arise only when existing ones grow and divide.

30. Mitochondria (Power Plants)

31. Ribosomes (Factories) • Unlike most other organelles, ribosomes are NOT surrounded by a _____. • Ribosomes are the sites of _____ _____ in a cell. • They are the most numerous organelle in almost all cells. • Some are free in the cytoplasm; others line the membranes of _____ _____ _____.

32. Endoplasmic Reticulum (Streets) • The ER is a system of membranous tubules and sacs. • The ER functions primarily as an intracellular _____, a path along which _____ move from one part of the cell to another. • The amount of ER inside a cell varies, depending on the cell's activity. • Poisons, wastes, and other toxic chemicals are made harmless (detoxification). • ER is an extensive network of membranes that connect the nuclear envelope to the _____ _____.

33. Endoplasmic Reticulum (Streets) • Can be ROUGH or SMOOTH. • Rough ER is studded with _____ and it processes PROTEINS to be exported from the cell. • Smooth ERIS NOT covered with _____ and processes LIPIDS and CARBOHYDRATES. • The Smooth ER is involved in the synthesis of steroids in gland cells, the regulation of calcium levels in muscle cells, and the breakdown of toxic substances within _____ cells. Ro ugh Smoo t h

34. Golgi Apparatus (Post Office) • The Golgi apparatus is the processing, _____, and secreting organelle of the cell. • The Golgi is a system of _____ made of flattened sac-like structures. • Working closely with the ER, the Golgi modifies proteins for _____ by the cell. • Golgi also produces _____, which are transporting organelles.

35. Vesicles (UPS Trucks) • Cells contain several types of vesicles, which perform various roles; especially involved in _____ of materials. • Vesicles are small, spherically shaped sacs that are surrounded by a single _____ and are classified by their contents. • Vesicles often migrate to and merge with the _____ _____ to release their contents outside of the cell. The circular structures are vesicles that have been released from the Golgi.

36. Lysosomes (Street Cleaners) • Lysosomesare vesicles that contain _____ enzymes. • Lysosomes are vesicles that bud (break off) from the _____ apparatus. • They are the sites of “food” digestion in the cell. They can _____ _____ large molecules such as proteins, nucleic acids, carbohydrates, and lipids.

37. Lysosomes (Street Cleaners) • Some white blood cells use lysosomes to destroy _____. • Within a cell, lysosomes digest worn-out _____ and are also responsible for dissolving _____ when it is time for them to die, thereby maintaining an organism’s overall health. • Lysosomes are common in the cells of animals, fungi, and protists, but they are rare in _____ cells. Lysosome Video (1:00)

38. Cytoskeleton (Scaffolding) • Just as your body depends on your _____ to maintain its shape and size, a cell needs structures to maintain its shape and size. • In animal cells, an internal protein framework called the _____ maintains the shape of the cell. • The cytoskeleton (1) maintains the 3-D _____ of the cell, (2) participates in the _____ of organelles within the cytosol, and (3) helps the cell _____. • The cytoskeleton consists of threetypes of proteins: microtubules, microfilaments, and intermediate filaments.

39. Microtubules • Microtubules are HOLLOW TUBES like plumbing pipes. They are the largest strands of the _____. • Microtubules are made of a PROTEIN called _____. • Microtubules have three functions: • To maintain the _____ of the cell and hold organelles in place. • To serve as tracks for _____ and molecules to move along within the cell. • To form the centrioles.

40. Microfilaments • Microfilamentsare NOT HOLLOW and have a structure that resembles rope made of two twisted chains of protein called actin. • Microfilaments can _____, causing movement. • _____ cells are LOADED with microfilaments.

41. Cytoskeleton (Scaffolding)

42. Cilia and Flagella • Ciliaand flagella are organelles that extend from the surface of the cell, where they assist in _____ and food acquisition. • Ciliaare short _____ projections, while flagella are long _____ projections. • Unicellular organisms use cilia and flagella to move through _____. • In humans, cilia line parts of the upper _____ system, moving dust particles and _____ away from the lungs. This is why you should breathe through your _____, AND NEVER SMOKE! (The chemicals destroy cilia.)

43. Cilia and Flagella Bacterial cell with multiple flagella The ciliary escalator in upper respiratory tract Cilia/Flagella Video (3:12)

44. Plant Cell Organelles • One of the most important differences between plant and animal cells is the presence of a CELL _____ IN PLANT CELLS. • _____ such as mushrooms and yeast also have cell walls.  • A cell wall DOES NOT REPLACE the cell _____; cells with walls also have a cell membrane.  Plant cells are surrounded by a rigid cell wall that lies _____ the cell membrane. • The rigidity of cell walls helps _____ and _____ the plant. • Cell walls of plants contain a lot of _____, a complex carbohydrate.

45. The Cell Wall Cell wall Membrane Notice that the cell wall is MUCH thicker than the membrane.

46. Vacuole (Warehouse) • The vacuole is a large membrane-bound sac that takes up a large amount of _____ in most plant cells. • The vacuole serves as a _____ area, and may contain stored proteins, ions, waste, or other cell products. • Vacuoles of some plants contain _____. • Cells of animals and other organisms also may contain vacuoles, but they are much smaller and are usually involved in FOOD _____.

47. Vacuole (Warehouse)

48. Plastids • A third distinguishing feature of plant cells is the presence of structures called plastidsthat make or store _____. • They are surrounded by a double membrane and contain their own ______. • A common kind of plastid is the _____ (greenhouse),an organelle that uses _____ to covert _____ _____ AND _____ into SUGARS.  This process is called _____. • Chloroplasts are green because they contain _____, a pigment that ABSORBS THE _____ IN SUNLIGHT. 

49. Plastids • Other plastids called _____ store reddish-orange pigments that color fruits, vegetables, flowers, and autumn leaves. • Colorless plastids that store STARCH, LIPIDS, and PROTEINS are called _____ (bakery). They are found in the non-_____ parts of plants (mainly roots). Leucoplasts in potato cell

50. Plastids Chromoplasts in red pepper cell