2The Discovery of CellsAll 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)
3The First DiscoveriesOne 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 _____.
4The First DiscoveriesIn 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 ____.
5The First DiscoveriesIn 1838, German botanist _____ _____ concluded that all _____ are composed of _____.The next year, German zoologist _____ _____ reported that _____ are also made of _____.
6The First DiscoveriesIn 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., _____ _____.
7The Cell Theory Cell Overview (3:35) Review of Cell Theory (6:12) 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)
8Cell DiversityNot 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.
9Cell 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 _____ _____.
10Cell Size Cell Size and Scale 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
11Why 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 _____.
12Prokaryotes 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 _____.
13Prokaryotes Generally smaller and less _____ than eukaryotic cells Have genetic material not contained in a _____.Carry out every activity associated with living things.
14Eukaryotes _____ and more complex than prokaryotic cells. Contain dozens of structures and internal _____, many of which are highly specialized.
15The Plasma or Cell Membrane (City Gate) This _____ _____ membrane regulates 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.
16The Plasma or Cell Membrane (City Gate) Cell membranes are made mostly of _____ molecules. (phosphate + lipid)A phospholipid 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 _____.
17The 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.
19Membrane ProteinsA 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 (_____ _____).
20Membrane Proteins Membrane Video (1:26) Another One (1:23) 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)
22Desmosomes (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).
23Fluid Mosaic ModelMembranes 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.
24Nucleus (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.
25Nucleus (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 _____.
27CentriolesThey 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.
28Mitochondria (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.
29Mitochondria (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.
31Ribosomes (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 _____ _____ _____.
32Endoplasmic 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 _____ _____.
33Endoplasmic Reticulum (Streets) Can be ROUGH or SMOOTH.Rough ER is studded with _____ and it processes PROTEINS to be exported from the cell.Smooth ER IS 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 ughSmoo t h
34Golgi 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.
35Vesicles (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.
36Lysosomes (Street Cleaners) Lysosomes are 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.
37Lysosomes (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)
38Cytoskeleton (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 three types of proteins: microtubules, microfilaments, and intermediate filaments.
39MicrotubulesMicrotubules 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.
40MicrofilamentsMicrofilaments are 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.
42Cilia and FlagellaCilia and flagella are organelles that extend from the surface of the cell, where they assist in _____ and food acquisition.Cilia are 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.)
43The ciliary escalator in upper Cilia and FlagellaBacterial cell with multiple flagellaThe ciliary escalator in upperrespiratory tractCilia/Flagella Video (3:12)
44Plant Cell OrganellesOne 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.
45The Cell Wall Cell wall Membrane Notice that the cell wall is MUCH thicker than the membrane.
46Vacuole (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 _____.
48PlastidsA third distinguishing feature of plant cells is the presence of structures called plastids that 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.
49PlastidsOther 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