Chapter+Four

Definition Worksheet #4: Chapter 4 Identify the major function of the following organelles and structures commonly found in cells. 1. Cell Membrane- Controls substances moving into and out of a cell. 2. Nucleus- Protects and controls access to DNA. 3. Nucleolus- A dense, irregularly shaped region where subunits of ribosomes are assembled from proteins and RNA. 4. Ribosomes- Structures on which proteins are built. 5. Rough Endoplasmic Reticulum- Modifies proteins made by ribosomes attached to it. 6. Smooth Endoplasmic Reticulum- Makes lipids, breaks down carbohydrates and fats and inactivates toxins. 7. Golgi Body (Apparatus)- Modifying new polypeptide chains, sorting, shipping proteins and lipids. 8. Vesicles- Transporting, storing, or digesting substances in a cell. 9. Lysosomes- Contain powerful digestive enzymes 10. Peroxisomes- Contain enzymes that digest fatty acids and amino acids. 11. Mitochondria- make ATP by sugar breakdown. 12. Centrioles- anchor for cytoskeleton, organize cytoskeletal elements. 13. Cytoskeleton: Microtubules- long, hollow cylinders that consist of subunits of the protein tubulin. 14. Cytoskeleton: Intermediate filaments- The most stabel part of a cell's cytoskeleton. 15. Cytoskeleton: Microfilaments- Are fibers that consist primarily of subunits of the globular protein actin. 16. Cilia- Whiplike structures that propel cells through fluid. 17. Flagella- Slender, cellular structures used for motion, longer than cilia. 18. Tight cell junctions- Links cells that line the surfaces and internal cavities of animals. 19. Adhering cell junctions- Anchor cells to each other and to extracellular matrix. 20. Gap (communicating) cell junctions- Opens channels that connect the cytoplasm of adjoining cells.

1. Four principles of the cell theory a. Every living organism consists of one or more cells b. The cell is the structural and functional unit of all organisms. A cell is the smallest unit of life, individually alive even as part of a multicelled organism. c. All living cells come from division of other, pre-existing cells. d. Cells contain hereditary material, which they pass to their offspring during division. 2. General Organization of a Cell: A. Most cells in the human body have the following three features: 1.**__Plasma__** __Membrane( Cell Membrane): What is the function of this__ membrane? **It seperates metobolic activites from events outside of the cell.** __ It has a__ phospholipid **bilayer** arrangement (like an Oreo cookie). The outer surface and inner surface has the phosphate heads that like water (are__**hydroliphic**__ __) while the middle of the two layers is made up of the fatty acid tails that__ __do not like water (are__ **hydrophobic** __).__ __2. **Nucleus** All eukaryotic cells have this organelle.__ __a. Please describe its features:__ __**Protects and controls access to DNA**__ __b. What is enclosed in the nucleus, necessary for reproduction?__ __**DNA**__
 * __ CHAPTER 4 __**** : Cell Structure and Function **

__3.__**Nucleoid** : the space inside the cell between the cell membrane and the nucleus. The space is filled with a semi-fluid liquid called the cytosol and numerous organelles that carry out specific functions. B. There are two types of cells that will be covered in this class: 1. __**Eukaryotic**___ __Cells: are those that have a clearly defined nucleus and numerous organelles. Animals and plants that are multicellular organisms have this type of cells.__ __2.__ __**Prokaryote**___ Cells: are those that do NOT have a nucleus (although they do have DNA) and NO organelles. An example would be Bacteria, that are unicellular (1 cell) organisms. C. Surface-to-volume ratio 1. If a cell is too __**small**____, there may not be enough space to hold all the organelles needed by the cell to survive.__ __2. If a cell is too__ **big**_, __the surface area may not be large enough to keep up with the increased volume, so parts of the cell may not get enough of the needed nutrients from the surrounding environment and will die. Also the cell may not be able to excrete (get rid of) waste products fast enough and the cell will die.__ __3. As a cell grows, the volume increases faster than the surface area.__ __a. The formula for Volume of a cell = length x width x height__ __b. The formula for Surface area of a cell = length x width__ __c. The volume (cm3) of a cell increases by a power of 3 (cubed) whereas the surface area (cm2) increases by a power of 2 (squared) so the volume increases faster than the surface area as a cell grows in size.__
 * Cell size || Sphere || Sphere || Sphere ||
 * Diameter (cm) || 2 || 3 || 6 ||
 * Surface area || 12.56 || **28.27** || **4** **// p //** **r 2= 113** ||
 * Volume || 4.3 || 14.14 || **4/3** ** p r3 = 113** ||
 * Surface-to-volume ratio || 3:1 || 2:1 || 1:1 ||

2. Introduction to Microscopes: A. __**Light**___ Microscope: 1. These were first used around the mid-1600’s 2. This type of microscope uses light to see the sample and lenses to magnify the image seen. 3. These have a maximum magnification of about__**200**__ times; beyond that level of magnification the image gets fuzzy or blurry. 4. These microscopes make it is possible to see plant and animal cells, the nucleus, and the largest of the organelles (mitochondria and chloroplasts) as well as most bacteria, but NOT viruses. 5. This type of microscope is the best choice for studying __living__ cells. B.__**Electron**__ Microscope: 1. These were first used around the mid-1950’s 2. This type of microscope uses a beam of electrons to create an image that is captured by receptors and stored on a monitor or computer screen. 3. These have a maximum magnification of about __**400**___ __times.__ __4. These microscopes make it possible to see even the smallest organelles, viruses and macromolecules like DNA and proteins.__ __5. A limitation to this type of microscope is that the sample must be frozen, and held in a vacuum. In other words the sample must be DEAD!__ __6. There are two types of electron microscopes:__ __a.__ __**Transmission**__ Electron Microscope: This microscope works by passing a stream of electrons through the slide and specimen to show __**smaller**__ __details of cell structure.__ b.**__Scanning__** Electron Microscope: This microscope works by passing a beam of electrons back and forth across the surface of a specimen coated with a very thin layer of metal. This microscope shows the __**surface**___details of cells, organisms and molecules, providing a three dimensional (3-D) image.

C. Match each description with the correct type of microscope.

2.__**C**__ scanning electron microscope 3. __**A**__ transmission electron microscope || A. || A narrow beam of electrons pass through a cell to form an image of internal structures. ||
 * 1. __**B**__ compound light microscope
 * ^  || B. || Glass lenses bend light rays to form an enlarged image of a specimen. ||
 * ^  || C. || A narrow beam of electrons moves back and forth across the surface of a specimen coated with a thin layer of metal creating an image of external structures. ||

D. Identify which type of microscope would best be used in each of the following situations.
 * 1.__**C**__ examining the fine structural details within cell organelles || A. compound light microscope ||
 * 2.**__A__** observing how a cell changes shape as it moves || B. scanning electron microscope ||
 * 3.__**B**__ studying the tiny bumps on the surface of a cell or virus || C. transmitting electron microscope ||
 * 4.__**A**__ filming changes in the nucleus as a cell prepares to divide ||  ||

3. Introduction to PROKARYOTIC Cells: (Bacteria) A. These cells are structurally the simplest cells known to exist. B. These cells lack a clearly defined, membrane bound nucleus; the DNA is simply found in an area called the **__nucleiod__**_ __region.__ __C. The CELL__ __**membrane**___ __(plasma membrane) is selectively permeable and regulates or monitors what gets into and out of the cell.__ __D. The CELL__ __**wall**___ __(seen in some of these cells) helps to maintain the shape of the cell and provides added protection.__ called a __**capsule**__ __that helps them attach and stick to surfaces.__ __F.__ __**Pili**__ __(singular: //pilus//) are short, hair-like extensions that help these cells cling to surfaces or in other words anchor bacteria to surfaces.__ __G.__ __**Flagella**___ are longer hair-like extensions used for movement.
 * 1) Many of these cells have a sticky, jellylike coating made of polysaccharides

4. Introduction to EUKARYOTIC Cells: A. These cells are structurally much more complex than prokaryotic cells. B. These cells have a clearly defined, membrane bound __**nucleus**__ that stores and protects the DNA. C. The CELL __**wall**___ (plasma membrane) is selectively permeable and regulates or monitors what gets into and out of the cell. D. These cells contain other membrane bound sacs called __**organelle**___, each with a specific structure and function. There are numerous benefits or advantages to having these structures in the cell. 1. Having separate organelles surrounded by their own membranes allows a cell to carry out very different activities at the same time. One organelle may be synthesizing (making) a protein while another organelle may be breaking down proteins. 2. Having organelles also greatly increases the membrane surface area, where chemical reactions frequently occur and allow the cell to maintain the needs of the cell while staying relatively small in size. Great summary of cell functions []

5. Please label the following on the picture of the eukaryotic cell: Nucleus, ribosome, rough endoplasmic reticulum, smooth endoplasmic reticulum, plasma membrane, golgi body, microtubules, mitochondrion, centrioles, lysosomes, cytoskeleton

commonnly found in Eukaryotic cells and a description of their primary functions: 1. Is called a plasma membrane because it is rather “fluid-like”, NOT rigid. 2. The membrane is described as being selectively permeable, which means it acts like a gatekeeper, controlling what enters and what exits the cell. B. **Nucleus**_: __generally found near center of the cell__ __1. Stores DNA (genetic information).__ __2. Is surrounded by a membrane similar to the cell membrane but it is a double__ __membrane, also known as the nuclear__ __**envelope**___, with small openings (nuclear pores) to allow small molecules to enter and leave easily. 3. It contains _**chromatin**, __which is a total collection of all the DNA molecules, unraveled into long strands and scattered throughout the nucleus with their associated proteins. Each individual strand of DNA is known as a__ __**chromasome**___ __(humans have 46, 23 from each parent) and it is normally not visible under a microscope unless the cell is preparing to undergo division.__ __4. It contains one or several darkened areas called__ a **nucleolus** _ (plural = //nucleoli// ) which is the location where RIBOSOMES are made. __1. What is the main function of the ribosome?__ __**Assemble polypeptide chains**__ __2. Where are free ribosomes located? What do they produce?__ __**In the cytoplasm suspended, they make proteins that will function in the cytoplasm.**__ __3. Where are “fixed” ribosomes located, and what do they produce?__ __**Bound to the rough ER, they make proteins that are exported from the cell.**__ 1.__**Rough**__ ER: a. is generally found near the nucleus (or continuous with it) and has what  appears to be many tiny dots (ribosomes) on the surface when viewed under a transmission electron microscope. b. the primary function is to begin to modify the protein structure (forming the 2o and 3o structures) and storing the protein made by the ribosomes c. this organelle begins the process of forming the proteins that will become part of the cell (plasma) membrane
 * 1) CELL MEMBRANE (__**Plasma**___ Membrane): outer surface of the cell
 * 1) **Ribosomes**: __seen as little dots throughout the cell__
 * 1) __**Endoplasmic**___ RETICULUM (ER): network of interconnected sacs (like a maze) that primarily function as “storage sheds”. There are two types:

2. **SMOOTH**_ER:  a. found anywhere in the cell, but does NOT have the dots (ribosomes) on the surface. b. synthesizes and stores lipids (fats) and then modifies them into fatty acids, phospholipids and steroids c. it makes the lipid molecules that become part of the cell membrane. d. in some cells, the smooth ER stores other substances: - calcium in muscle cells (for help in muscle contractions) - enzymes in liver cells (for detoxifying blood) E. TRANSPORT VESICLES: small round “sacs” scattered throughout the cell that are designed to move substances from one organelle to another (especially from the rER and sER to the Golgi Complex). F.**GOLGI** BODY (or COMPLEX or APPARATUS): a stack of flattened sacs (like plates) that are NOT connected to each other.  1. This organelle further modifies molecules produced in the rough and smooth endoplasmic reticulum. For example a protein or carbohydrate coat may be added to a lipid molecule, forming a lipoprotein or a glycolipid. 2. As the molecule is “improved”, it moves from one chamber to the next until it is finally released from the complex. G. SECRETORY VESICLES: these are similar to transport vesicles except the final destination is the cell membrane, so the contents can be released (secreted) from the cell, or the membrane of the vesicle can become part of the cell membrane. H.**LYSOSOMES** : these are similar to transport vesicles, but are generally larger in size and they stay inside the cell. These organelles contain enzymes for digesting macromolecules or destroying bacteria that enter the cell, or cell parts (damaged organelles) found within the cell. In a sense, they are like the cells “garbage disposal”. stay within the cell. They contain enzymes that break down **FATTY** acids, __**AMINO** acids and__ **HYDROGEN PEROXIDE**_(a toxic substance produced by the metabolism of some proteins and fatty acids). These organelles are found in a higher number in liver and kidney cells where their primary function is to break down **ALCOHOL** and other toxins (drugs).
 * 1) **PEROXISOMES**: these are also similar to transport vesicles, and they also

J.**MITOCHONDRION** __: a kidney bean shaped organelle with an inner chamber that has a large surface area by folding in on itself forming finger-like projections called cristae.__ __ 1. This organelle is the site of energy production.__ __as it converts glucose into **ATP**__. 3. There may be several of them depending on the energy demands of the cell. K. __: small “sacs” that store water or food substances. These are not so clearly visible in animal cells, however because plants can not relocate to find water, they tend to have a very large, central vacuole for water storage.__ __L. CYTOSKELETON: a network of protein fibers of various sizes, scattered throughout the cell cytoplasm.__ __1.**MICROFILAMENTS**__ __: these are the__ smallest __of the fibers and are typically found just under the surface of the cell membrane forming the cell cortex and reinforce the membrane. It helps with maintaining and changing the shape of a cell.__ __2.__ __**INTERMEDIATE** FILAMENTS: as the name implies are in between in size. These are scattered throughout the cytoplasm (like a net) and help to stabilize the cell as well as helping organelles remain in position (especially the nucleus).__ __3.__**MICROTUBLES** __: these are the__ largest __of the fibers and providing rigidity to the cell, and form “tracks” for organelles to follow as they move about inside the cell__ __M.__ **CILLA**_: long extensions from the cell membrane, generally few in number, that acts like a “tail” or “whip” and moves the cell in the surrounding area. The sperm cell is the only cell in the human that has this structure. N. _: short “hair-like” structures on the surface of the cell and are responsible for moving substances along the surface of the cell (out with old, in with new). The cells that line the respiratory tract and fallopian tubes (in women) have many of these structures. 7. Circle one of two possible answers given between the parentheses in each statement. 1. ( Protein Carbohydrate ) subunits form the basic components of microtubules. 2. ( Microtubules Microfilaments ) mechanically supports cell membrane and helps the cell change its shape. 3. Sperm and many other free-living cells use ( flagella cilia ) as whip-like tails for movement from one location to another. 4. The human respiratory tract is lined with beating ( flagella cilia ).

8. Review the various organelles by matching each phrase on the right with a structure from the list on the left. Answers can be used more than once and some require more than one answer.

B. Transport vesicle C. Secretory vesicle D. Smooth ER E. Lysosome F. Golgi apparatus G. Rough ER H. Fixed Ribosomes I. Free Ribosomes J. Peroxisomes K. Mitochondria || _D 1. Lipids are manufactured, modified or stored here _ 2. Forms the primary structure of a protein molecule that is probably going to be used by the cell A_ 3. Contains chromatin _E 4. Contain enzymes that break down large molecules or pathogens, or in other words carry out intracellular digestion _B 5. Carries secretions for export from cell _J 6. Breaks down drugs and alcohol in liver _ 7. Makes the phospholipid part of cell membranes _ A8. Cell control center _G 9. Numerous ribosomes on its surface give it its name _ 10. Performs the __final__ modifications of substances that will become part of the plasma membrane or other organelles, or be exported outside the cell _B 11. Deliver proteins, lipids and other substances from the ER to Golgi apparatus _B 12. Buds off from the Golgi apparatus and migrates to the cell membrane _ 13. Forms the primary structure of proteins that are probably going to be secreted from the cell _K 14. Acts like the “power plant” for the cell, producing large amounts of ATP _F 15. Takes in transport vesicles from the ER and performs the final modification of their contents _A 16. Surrounded by a double layer membrane with pores, often called an “envelope” ||
 * A. Nucleus

9. One more time, match each phrase with a structure from the list on the right. Answers can be used more than once and some require more than one answer.

2. _ Assembles and stores lipids in the cell 3. _ Stores and protects the DNA instructions for building polypeptide chains 4. _ Initiates protein modification following assembly of polypeptide chains 5. _ Location where proteins and lipids take on their final form 6. _ Process that transport substances out of the cell cytoplasm 7. _ Process that transports substances into the cell cytoplasm 8. _ Special vesicles budding from the Golgi body that contain enzymes that break down fatty acids and amino acids, forming hydrogen peroxide 9. _ Special vesicles budding from the Golgi body that become organelles of intracellular digestion 10. _ Transport unfinished proteins to the Golgi body for final modification 11. _ Transport finished cellular products to the plasma membrane for export from the cell 12. _ Sorts and packages lipids and proteins for transport to their proper destinations following modification 13. _ Transport unfinished lipids to the Golgi body for final modification || A. spaces within the smooth membranes of ER B. nucleus C. Golgi body D. vesicles budding from the Golgi body E. vesicles budding from the rough ER F. endocytosis with vesicles G. exocytosis with vesicles H. spaces within rough ER I. ribosomes in the cytoplasm J. vesicles budding from smooth ER K. lysosomes L. peroxisomes ||
 * 1. _ Assembles the primary structure of polypeptide chains

10. The ENDOMEMBRANE SYSTEM: Some of the organelles mentioned are closely connected to each other forming a “pathway” from the center of the cell to the surface for secreting products made within the cell, and replacing or expanding the cell membrane, or in some cases for creating storage areas for enzymes and molecules (lysosomes, peroxisomes and vacuoles). To be a member of this system, the structure __must__ have a membrane and must be part of the pathway; just having a membrane is not enough! A. Included in the endomembrane system, in their correct order from inside out: Smooth and Rough ENDOPLASMIC RETICULUM, TRANSPORT VESICLES, GOLGI COMPLEX, SECRETORY VESICLES, CELL MEMBRANE, (also the LYSOSOMES, PEROXISOMES and VACUOLES if they are not producing a substance to be released from the cell). B. Not included in the endomembrane system: RIBOSOMES (**because they do not have a membrane**) and MITOCHONDRIA (because it is not synthesizing or modifying a substance to be exported or used by the cell)

11. CELL JUNCTIONS: connections that hold cells in close proximity to each other __Where are these found in the body?__ **GASTROINTESTINAL TRACT** __B. **ADHERING**__ _ (Anchoring) JUNCTIONS: allows STRETCH between cells Where are these found in the body? **HEART MUSCLE** Where are these found in the body? 12. Choose the most appropriate description for each type of junction.
 * 1) **TIGHT**_ __JUNCTIONS: bind cells together forming a leak-proof barrier__
 * 1) **GAP**_ (Communicating) JUNCTIONS: cytoplasm of certain kinds of adjacent cells connect directly
 * HEART MUSCLE**

2. **B**_ gap or communicating junctions 3. **A**_ tight junctions || A. Link the cells of epithelial tissues lining the body’s outer surface, inner cavities, and organs to prevent substances from “leaking” between the cells. B. Link the cytoplasm of neighboring cells, forming an opening for cellular contents to move back and forth freely between the cells. C. Link the cells in tissues of the skin, heart, and other organs that are subject to stretching, holding them firmly together. ||
 * 1. **C**_ adhering or anchoring junctions


 * //Sample Test Questions for Chapter 4 and Lab #8://**

1. Which of the following clues would help you identify if a cell is a prokaryotic or eukaryotic cell?
 * 1) the presence of a rigid cell wall
 * 2) the cell contains DNA
 * 3) the cell carries out cellular metabolism
 * 4) the cell has a clearly defined nucleus
 * 5) all of the above

2. True or False : The nucleus has a single layered plama membrane.

3. Which of the following is //__not__// part of the endomembrane system?
 * 1) Ribosome
 * 2) Golgi apparatus (complex)
 * 3) Smooth Endoplasmic Reticulum
 * 4) Rough Endoplasmic Reticulum
 * 5) Mitochondria

4. Most of the protein used by a cell is produced in the
 * 1) Ribosomes
 * 2) Smooth endoplasmic reticulum
 * 3) Nucleus
 * 4) Mitochondria
 * 5) Golgi apparatus (complex)

5. Cellular organelles and structures seen in the cell can be divided into specific groups based on their functions. Which of the following is a function carried out by a cellular organelle or structure?
 * 1) manufacture large molecules from smaller fragments
 * 2) break down large molecules into smaller fragments
 * 3) produce ATP for energy
 * 4) allow for movement of the cell
 * 5) all of the above are functions performed by organelles

6. You would expect a cell with a large amount of smooth endoplasmic reticulum to
 * 1) make a lot of lipids
 * 2) move about actively in its surroundings
 * 3) secrete a lot of protein from the cell
 * 4) produce a large amount of ATP for energy

7. It is essential for the cells of the stomach to be tightly bound to each other, otherwise, HCl could leak from the inside of the stomach into the abdominal region. What type of cell junction would the stomach have? Most hormones are proteins that are secreted into the bloodstream to help activities in the body. Which of the following __best__ describes the correct order of organelles the hormone might pass through from its production to its exit from the cell? (not all structures are listed)
 * 1) anchoring (adhering) junctions
 * 2) tight junctions c. communicating or gap junctions
 * 1) rough ER, transport vesicle, Golgi apparatus, ribosomes, cell membrane
 * 2) smooth ER, ribosomes, transport vesicle, Golgi apparatus, lysosome, cell membrane
 * 3) ribosomes, rough ER, transport vesicle, Golgi apparatus, secretory vesicle, cell membrane
 * 4) ribosome, smooth ER, Golgi apparatus, transport vesicle, lysosome, cell membrane
 * 5) rough ER, ribosomes, Golgi apparatus, transport vesicle, cell membrane

8. The ribosomes are formed by the
 * 1) rough endoplasmic reticulum
 * 2) smooth endoplasmic reticulum
 * 3) Golgi apparatus
 * 4) Mitochondria
 * 5) Nucleoli

9. TRUE or FALSE: As a cell grows in size, the surface area increases at the same rate as the volume of the cell.

10. TRUE or FALSE: On a light microscope, the shortest ocular has the lowest (smallest) power of magnification.

11. A scientist wants to magnify a pollen grain 5000 times to better examine the organelles inside the cell. Which of the following microscopes would be best to use in this situation? 12. When working with a microscope, if the slide is moved to the right and away from you, how will the image viewed through the eye piece move? a. to the right and away from you b. to the left and away from you c. to the right and toward you d. to the left and toward you
 * 1) light microscope
 * 2) scanning electron microscope
 * 3) transmission electron microscope
 * 4) all of the above