Biology CP Name______
Unit 3 Cellular BiologyPart 3C Structure and Function
(NOTE: Included in this unit: History of the Microscope and Cells and Microscope Use)
The Cell Theory states: Textbook p. 190
1. All living things are made up of cells.
2. Cells are the basic unit of structure and function in living cells.
3. New cells are produced from existing cells
Even with the wide variety of cellular size, shape and function, the structure of all cells is remarkably similar.
Despite their differences, all cells, at some point, contain *___DNA______the molecule that carries biological information. In addition all cells are surrounded by a thin, flexible barrier called a *cell membrane.
PROKARYOTIC and EUKARYOTIC CELLS Textbook p. 193
Cells fall into two broad categories depending on whether they contain a *nucleus______.
The nucleus (plural-nuclei) can be described as a large membrane enclosed structure that contains genetic material in the form of DNA and cntrols many of the cell’s activities.
Eukaryotes are cells that *___enclose their DNA in nuclei______.
Prokaryotes are cells that *____ do not enclose their DNA in nuclei ______.
Prokaryotic cells are generally *______smaller______and *_____simpler______than eukaryotic cells. Despite their simplicity, prokaryotes carry out every activity associated with living things. The organisms we call ______bacteria______are prokaryotes.
Eukaryotic cells are generally *______larger______and *____more complex______than prokaryotic cells. Eukaryotes display great variety. Some, like the protists, live solitary lives as *_____unicellular______organisms. Others form large ______multicellular______organisms (ex. Plants, animals and fungi).
*Differences and Similarities Between Prokaryotic and Eukaryotic Cell Types
*to fill this table in, see pages 206-207. (+ present, -- absent)
Cell Characteristic / Prokaryotic Cell / Eukaryotic Cellouter cell membrane / + / +
cytoplasm-cellular fluid / + / +
ribosomes-structures which form proteins / + smaller / + larger
nucleus / - / +
chromosomes (DNA or RNA) / + / +
membrane bound organelles / - / +
cells carry out life processes / + / +
average size of cells / 1-10 mm / 2-1,000mm
time of evolution / 3.5 billion years ago / 1.5 billion years ago
Found in these Domains / Archaea and Bacteria / Eukarya
general shape of the cell / spherical, rod shaped, spiral / wide variety of shapes depending on function
Let’s explore the size and scale of cells:
http://learn.genetics.utah.edu/content/begin/cells/scale/
http://learn.genetics.utah.edu/content/cells/scale/
CELL ORGANIZATION: Textbook Lesson 7.2 p.196-207
It’s easy to divide the Eukaryotic cell into two major parts: the * ___nucleus______and the *__cytoplasm______. The *__cytoplasm______is the portion of the cell outside the nucleus. ___Prokaryotic____cells have cytoplasm, too, even though they do not have a nucleus.
The cytoplasm contains an aqueous (water-based) solution (also called the Cytosol).
The Cytoplasm looks just like “empty space” in diagrams, but it’s not!
The cytoplasm is a dynamic and active part of the cell. The cell’s metabolism (the sum of all chemical reactions in the cell), transport of materials throughout the cell and the activities associated with each organelle all occur in the cytoplasm.
We will consider each major structures of eukaryotic plant and animal cells (some of which are found in prokaryotic cells) one by one.
Because these structures act like specialized organs, they are called *__organelles______, literally “little organs”.
ANALOGY: In some respects the living cell can be compared to a modern factory. Organelles of the cell can be compared to the specialized machines and assembly lines of the factory. Cells, like factories follow instructions and produce products. This analogy works so well, we can use it to help us understand how cells work. As you learn about the cell, think about the comparisons.
A. NUCLEUS
Like the main office in a factory, the nucleus is the ______control center______of the cell.
Structure of the Nucleus:
1. The nucleus contains: *_nearly all the cell’s DNA and, with it , the coded instructions for making proteins and other important molecules______.
Note: Prokaryotic cells lack a nucleus, but they do have *______DNA______that contains the same kinds of instructions.
2. The nucleus is surrounded by a double membrane that is also called the nuclear envelope. The nuclear envelope is semi permeable:
a) Covered with small nuclear pores (openings).
b) the nuclear pores keep DNA within the nucleus but allow smaller molecules like RNA and proteins out.
3. *__Chromosomes____, which carry the cell’s genetic information, are also found in the nucleus. Most of the time, it is spread throughout the nucleus in the form of *_chromatin____ (a complex of DNA bound to proteins), but when a cell divides this condenses into *__chromosomes___ which can be seen under a microscope.
3. The nucleus usually contains one or more nucleoli (nucleolus is singular) which are areas composed of sections of condensed DNA and proteins (they look dark when viewed through the microscope). The nucleolus is where *______the assembly of ribosomes begins______.
B. VACUOLES, VESICLES, LYSOSOMES, AND THE CYTOSKELETON
These organelles represent the cellular factory’s _storage space__, __cleanup crew__, and_support structures___.
VACUOLES and VESICLES
Vacuoles and vesicles are places for the cell to store things!
Vacuoles and vesicles are both found in cytoplasm of all eukaryotic cells. They are sac-like membrane-enclosed structures (compartments).
The function of vacuoles is to: *store materials like water, salts, proteins, and carbohydrates
Plant cells typically have one large central vacuole filled with *_liquid__. The pressure of the central vacuole in these cells increases their *__rigidity____, making it possible for plants to support heavy structures, such as *____leaves____ and flowers.
Vacuoles are also found in some unicellular organisms and some animals. For example, paramecium (a freshwater protist) contains a specialized vacuole called a *______contractile vacuole______that contracts rhythmically to pumps excess water out of the cell. Some organisms form “food vacuoles” through endocytosis or release waste particles by exocytosis.
Nearly all eukaryotic cells contain smaller membrane-enclosed structures called *_____vesicles______which store and move materials between cell organelles, as well as to and from the cell surface.
LYSOSOMES
Lysosomes are the ______clean up crew______, they take care of “junk” removal!
Lysosomes are small organelles (membrane-bound sacs) filled with *____enzymes______. They are found in the cytoplasm of all animal cells, but are rare in plant cells. (Plant cells store their digestive enzymes in the large, central water vacuole instead).
Lysosomes break down * lipids, carbohydrates, and proteins into small molecules that can be used by the rest of the cell _____
Lysosomes are also involved in breaking down * organelles that have outlived their usefulness
***Lysosomes form compartments that maintain the correct pH for the enzymes of hydrolysis, while at the same time protecting the cell from the digestive enzymes that might break down necessary cell parts.***
Lysosomes are formed by the Golgi apparatus.
.
CYTOSKELETON
The cytoskeleton provides movement and support. It is like the __steel______or cement beams and __columns____ that hold up the factory walls and roof.
Eukaryotic cells are given their shape and internal organization by a network of *__protein_____ filaments known as the *__cytoskeleton______.
Certain parts of the cytoskeleton also help *____transport____ materials between different parts of the cell, much like the *___conveyor belts____ that carry materials from one part of a factory to another.
Some cytoskeletal components may also be involved in moving the entire cell as in *_cell flagella___ and *____cilia_____.
The cytoskeleton helps* the cell maintain its shape and is also involved in movement
The cytoskeleton is mostly made up of two different types of protein filaments:
1. Microfilaments are * threadlike structures made up of a protein called actin
Form a tough flexible framework that supports the cell and help cells move.
2. Microtubules are * hollow structures made up of proteins called tubulins
In many cells, microtubules play critical roles in maintaining cell shape. They are also important in cell division.
In animal cells, organelles called *___centrioles____ (which help organize cell division) are also formed from tubulins.
Microtubules also help build projections from the cell surface:
*_cilia (plural) _- (shorter, more numerous) *_flagella (plural)_- (longer, fewer)
cilium (singular) flagellum (singular)
C. ORGANELLES THAT BUILD PROTEINS: RIBOSOMES, ENDOPLASMIC RETICULUM, AND the GOLGI APPARATUS
RIBOSOMES
Each ribosome is like a _small machine_____ in a factory, turning out proteins on orders that come from its DNA “___boss____”!
Ribosomes are found in both prokaryotic and eukaryotic cells, though in prokaryotic cells the ribosomes are smaller and simpler.
Ribosomes are: * small particles of RNA and protein
Ribosomes produce * proteins by following coded instructions that come from DNA
Ribosomes are made by the NUCLEOLUS.
Ribosomes can be found attached to the rough ER or or floating free in cytoplasm.
ENDOPLASMIC RETICULUM
The endoplasmic reticulum is like the _conveyor__ ___belt______on an assembly line!
The Endoplasmic Reticulum (ER) is where * lipid components of the cell membrane are assembled, along with proteins and other materials that are exported from the cell
The ER is found in the cytoplasm of all eukaryotic cells.
Rough Endoplasmic Reticulum: The portion of the ER involved in the synthesis of proteins is called the *rough Endoplasmic Reticulum. It is given this name because of the *___ribosomes_____ found on its surface. Newly made proteins leave these ribosomes and are inserted into the rough ER, where they may be chemically *_modified___.
Proteins made on the rough ER include those that will be released, or *______secreted____ , from the cell as well as many *______membrane_____ proteins and proteins destined for *___lysosomes_____and other specialized locations within the cell. Cells which produce large amounts of protein for export have large amounts of Rough ER.
Other cellular proteins are made on “* free “ ribosomes, which are not attached to membranes.
Smooth Endoplasmic Reticulum: Ribosomes *___are not______found on the surface of the smooth ER. In many cells, the smooth ER contains collections of *____enzymes_____ that perform specialized tasks, including the synthesis of *______membrane lipids____ and the *_detoxification______of drugs. *___Liver_____cells, which play a key role in detoxifying drugs, often contain large amounts of smooth ER.
GOLGI BODIES OR GOLGI APPARATUS
The Golgi apparatus directs customization and packaging/shipping!
In eukaryotic cells, proteins produced in the rough ER move next into an organelle called the Golgi apparatus which appears like a stack of *____flattened membranes______.
As proteins leave the rough ER, molecular “*______address tags____” get them to the right destination as they are bundled into tiny *____vesicles______that bud from the ER and carry them to the Golgi.
The Golgi apparatus *_modifies, sorts and packages proteins and other materials from the endoplasmic reticulumfor storage in the cellor release outside the cell.
From the Golgi, proteins are “shipped” to their final destination inside or outside the cell.
D. ORGANELLES THAT CAPTURE AND RELEASE ENERGY
CHLOROPLAST
Chloroplasts are the biological equivalent of _solar_ _power__plants; site of Photosynthesis!
Chloroplasts are located in the cytoplasm of eukaryotic autotrophs such as plants and some other organisms.
***Each chloroplast contains its own unique DNA, proteins and ribosomes; can self-replicate.***
Function: Chloroplasts capture*energy from sunlight and convert it into food that contains chemical energy in a process called photosynthesis.
Read pages 230-233 (Lesson 8.2 in the text) for information on chloroplasts and photosynthesis.
Plants gather the sun’s energy with light-absorbing molecules called *_pigments____.
Plants’ principal pigment is *____chlorophyll_ which appears green to our eyes because it does not absorb light well in the green region of the spectrum.
The chloroplast contains saclike photosynthetic membranes called *____thylakoids______which are interconnected and arranged in stacks known as *grana______(singular: granum). Pigments such as chlorophyll are located in the thylakoid membranes. The fluid portion of the chloroplast, outside of the thylakoids, is known as the *____stroma___.
Photosynthesis uses the energy of sunlight to:* convert water and carbon dioxide (reactants) into high-energy sugars and oxygen
Plants then use the sugars to produce complex carbohydrates such as *_starches___, and to provide energy for the synthesis of other compounds, including *_proteins____ and *___lipids_____.
Write the overall equation for photosynthesis :
In symbols:* 6 CO2 + 6H2O __ C6H12O6 + 6O2
In words:* Carbon dioxide + water sugar + oxygen
Although the equation for photosynthesis looks simple, there are many steps to get from the reactants to the final products. In fact, photosynthesis actually involves two sets of reactions which work together to capture the energy of sunlight and transform it into energy-rich compounds such as carbohydrates.:
*_Light-dependent_ reactions (Calvin cycle) require the direct involvement of light and light-absorbing pigments. These reactions take place within the thylakoid membranes. Uses water and produces oxygen.
*__ Light-independent __ reactions use carbon dioxide but do not need light and complete the process of photosynthesis by producing carbon-containing sugars and other carbohydrates. These reactions take place outside the thylakoids in the stroma.
*Think about it:
Do you think all plant parts contain chlorophyll? Explain. *__No, only those cells that receive sunlight produce chlorophyll, it would not be efficient to produce chlorophyll in other cells______
Some prokaryotic bacteria are photosynthetic. Do they contain chloroplasts?*______No, they do not have membrane-bound organells.
MITOCHONDRIA Textbook Lesson 7.2 p. 202
Mitochondria are like the _____power______plants______of the cell!
Mitochondria are located in the cytoplasm of all eukaryotic cells
(In humans, nearly all of our mitochondria come from the cytoplasm of the egg cell (mother)).
Function: Mitochondria convert * the chemical energy stored in food into compounds that are more convenient for the cell to use.
Structure:
Each mitochondrion contains its own unique DNA, proteins and ribosomes; can self-replicate.
Has an outer membrane which encloses a fluid (“matrix”) and a highly folded inner membrane (“cristae”).
**Mitochondria convert chemical energy stored in food into a form that can be used easily by the cell. This form is called ATP.**