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Cell Structure and Function. 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 _____.

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the discovery of cells
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)
the first discoveries
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 _____.
the first discoveries1
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 ____.
the first discoveries2
The First Discoveries
  • In 1838, German botanist _____ _____ concluded that all _____ are composed of _____.
  • The next year, German zoologist _____ _____ reported that _____ are also made of _____.
the first discoveries3
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., _____ _____.
the cell theory
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)

cell diversity
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.
cell shape
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 _____ _____.
cell size
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
why are cells so small
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.
prokaryotes and eukaryotes
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 _____.
  • Generally smaller and less _____ than eukaryotic cells
  • Have genetic material not contained in a _____.
  • Carry out every activity associated with living things.
  • _____ and more complex than prokaryotic cells.
  • Contain dozens of structures and internal _____, many of which are highly specialized.
the plasma or cell membrane city gate
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.
the plasma or cell membrane city gate1
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 _____.
the plasma or cell membrane city gate2
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.
membrane proteins
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 (_____ _____).
membrane proteins1
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)

desmosomes bridges
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).
fluid mosaic model
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.
nucleus city hall
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.  
nucleus city hall1
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 _____.
  • 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.
mitochondria power plants
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.
mitochondria power plants1
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.
ribosomes factories
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 _____ _____ _____.
endoplasmic reticulum streets
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 _____ _____.
endoplasmic reticulum streets1
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

golgi apparatus post office
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.
vesicles ups trucks
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.

lysosomes street cleaners
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.
lysosomes street cleaners1
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)

cytoskeleton scaffolding
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.
  • 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.
  • 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.
cilia and flagella
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.)
cilia and flagella1
Cilia and Flagella

Bacterial cell with multiple flagella

The ciliary escalator in upper

respiratory tract

Cilia/Flagella Video (3:12)

plant cell organelles
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.
the cell wall
The Cell Wall

Cell wall


Notice that the cell wall is MUCH thicker than the membrane.

vacuole warehouse
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 _____.
  • 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. 
  • 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


Chromoplasts in red pepper cell