Lab 2 Cell Structure and Cell Membrane
CONTENT 1) Cell Membrane Diffusion Rate Passive Transport Osmosis and Dialysis 2) Cell Structure Prokaryotic Cells Eukaryotic Cells 3) Cell Reproduction Cell Cycle Mitosis Cytokinesis 4) Chromosome Structure 5) Online Onion Root Tip Mitosis	What Do I Need To Hand In For This Lab? Sketches Red Blood Cell in Isotonic Solution Red Blood Cell in Hypotonic Solution Red Blood Cell in Hypertonic Solution Prokaryote Cell Eukaryote Cell Stages of Cell Cycle Mitosis Stages Cytokinesis Chromosome Tables / Charts / Graphs Data Table for Diffusion of Different Molecular Weights Table of Osmotic Potential and Time Graph of Osmotic Potential vs Time Graph of Osmotic Change vs Time (Osmotic Rate) Table of Dialysis Tests Chart of Summary of Events During Phases of Mitosis Chart of % time in different phases of the cell cycle Questions Diffusion Questions 1-4 Passive Transport Questions 1-3 Osmosis Questions 1-7 Dialysis Questions 1-6 Cell Structure Questions 1-3 Mitosis Questions 1-3 Cover Page Lab 2 Cover Page

1) Cell Membrane

Movement of Materials Through Cell Membranes

Click Here to View an Animation on How the Cell Membrane Interacts With the Surrounding Fluids
      CELL MEMBRANE INTERACTION

Click Here to View an Animation on Membrane Fluidity
      MEMBRANE FLUIDITY

Click Here to View an Animation on the Cell Membrane
      CELL MEMBRANE

Click Here to View another Animation on the Cell Membrane
      CELL MEMBRANE 2

To perform their functions, cells must maintain homeostasis in spite of an ever changing environment. In order to maintain homeostasis, the cell membrane regulates the movement of substances into and out of the cell, preventing the flow of some substances while allowing others to pass through easily. The membrane is said to be selectively permeable, because not all substances penetrate the cell membrane the same.

The external and internal environments of a cell are water solutions of dissolved molecules and ions. Movement of these molecules and ions in the solutions and through the cell membranes is by diffusion. Molecules and ions move from regions in which their concentration is high to regions in which it is lower by kinetic energy until they become distributed throughout the cell. When salt dissolves in a glass of water, the sodium and chlorine ions of which it is composed become equally distributed in the water.

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PASSIVE TRANSPORT

Passive diffusion (Passive Transport) is the random motions of the solute and solvent molecules and requires no added energy.

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ACTIVE TRANSPORT

Active transport is a type of diffusion in which dissolved particles move against a concentration gradient. This type of diffusion does require an energy input. For example, human red blood cells have almost 30 times more potassium than does blood plasma. 

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OSMOSIS

A special case of diffusion that occurs in living systems is osmosis. Osmosis is the diffusion of water molecules through a selectively permeable membrane from a region in which they are more highly concentrated to a region in which their concentration is lower. 

Both diffusion and osmosis result from the kinetic activity of molecules or ions. They are affected by a number of factors, such as temperature, the molecular weight of the diffusing substance, and the lipoid solubility of the solute.  In this experiment, you will examine some of the factors regulating these processes.

There are three experiments to perform for this portion of the lab.

1) Diffusion Rate
2) Passive Transport
3) Osmosis and Dialysis

In order to access the Cell Membrane Virtual Lab you will need to use the links supplied for each of the individual experiments. Instructions for performing each of the three experiments are given in the Lab.

CELL MEMBRANE VIRTUAL LAB

EXPERIMENT # 1 Diffusion Rate

Diffusion is a process of equalization which involves movement of molecules from an area of high concentration to an area of low concentration. This exercise investigates diffusion as it applies to movement of particles in a semi-solid material called agar. Molecules are in a constant state of motion. The motion of these molecules are influenced by many factors.

Factors Influencing Diffusion
1) Kinetic Energy
Kinetic energy is the driving force which causes the molecules to move
2) Nature of the environment
The agar environment we will be using is a semisolid material through which we will   measure the rate of diffusion of substances with different molecular size
3) Size of the molecules
Smaller molecules move faster than larger molecules

Click Here to View an Animation on Diffusion
        DIFFUSION

**If the link above does not work you can try the link given below
DIFFUSION EXPERIMENT

 

If you have any problems accessing or downloading this virtual lab you can try this alternate link

 

ALTERNATE VIRTUAL DIFFUSION EXPERIMENT

You will need to supply the following in your lab report for this diffusion experiment #1

1) Data Table for Diffusion of Different Molecular Weights

2) Answers to Diffusion Questions 1-4

TABLE 1
Click Here to Access

TABLE FOR DIFFUSION OF DIFFERENT MOLECULAR WEIGHTS (WORD)

TABLE FOR DIFFUSION OF DIFFERENT MOLECULAR WEIGHTS (PDF)

QUESTIONS
DIFFUSION QUESTIONS
1) What are the three things which influence the movement of molecules and particles?  
2) In agar, what size of molecules move the fastest?
3) Which dye, the methylene blue or the potassium permanganate, diffused at the fastest rate?
4) Why did one dye diffuse faster than the other?

Click Here for a MS WORD version of the questions

Click Here for a PDF version of the questions

1)Isotonic solutions which produce a normal shaped cell
Hypotonic solutions which causes cells to swell2)
Hypertonic solutions which causes the cell to shrink

**The blood which we will be using in this experiment is human blood. If you become exposed in any way to the blood you must immediately notify your instructor. He will probably tell you to restart your computer so that you do not become infected with a disease like a virus.

Click Here to View an Animation on Passive Transport Diffusion
        PASSIVE TRANSPORT DIFFUSION

Click Here to View an Animation on Passive Transport Facilitated Diffusion
        PASSIVE TRANSPORT FACILITATED DIFFUSION

SKETCH 1, 2, 3
**You will need to supply the following in your lab report for this experiment #2

1) S1)1ketch of red blood cell in isotonic solution
2)
2) Sketch of red blood cell in hypotonic solution
3) Sketch of red blood cell in hypertonic solution
4) Answers to Passive Transport Questions 1-3

QUESTIONS
PASSIVE TRANSPORT QUESTIONS
1) Describe the appearance of red blood cells in an isotonic solution
2) Describe the appearance of red blood cells in a hypotonic solution
3) Describe the appearance of red blood cells in a hypertonic solution

Click Here for a MS WORD version of the questions

Click Here for a PDF version of the questions

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EXPERIMENT #3 Osmosis and Dialysis

There are two parts to this experiment #3. PART 1 will consider OSMOSIS and PART 2 will consider DIALYSIS.

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VIRTUAL LAB

In order to access the OSMOSIS AND DIALYSIS  EXPERIMENT you will need to use the link supplied to the left.

**If the link above does not work you can try the link given below
OSMOSIS AND DIALYSIS EXPERIMENT

If you have any problems accessing or downloading this virtual lab you can try this alternate link

ALTERNATE OSMOSIS AND DIALYSIS EXPERIMENT

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PART 1 OSMOSIS

Osmosis is the diffusion of water through a selectively permeable membrane. Water will generally move quite freely through the cell membrane by diffusion. Osmotic movement of water occurs when the solute (non-penetrating) concentrations differ between the opposing sides of the cell membrane. A difference in solute (non-penetrating) concentrations means there is a difference in water concentrations and water will move from the region of higher concentration to a region of lower concentration. For example, water osmotically moves into a cell when the fluid outside the cell has more water (less solutes) than the fluid inside the cell. In this case, as water moves into the cell, it swells as the water pressure inside the cell increases.

The device you will be using to collect data for the experiments is an osmometer. This is a device used to measure osmotic force

**When you are finished with PART 1 of experiment # 3, be sure that you include the following with your lab report.

1) Table of Osomotic Potential and Time
2) Graph of Osmotic Potential vs Time
3) Graph of Osmotic Change vs Time (Osmotic Rate)
4) Answers to Osmosis Questions 1-7

TABLE 2
Click Here to Access

TABLE OF OSMOTIC POTENTIAL AND TIME (WORD)

TABLE OF OSMOTIC POTENTIAL AND TIME (PDF)

GRAPH 1
Click Here to Access

GRAPH OF OSMOTIC POTENTIAL AND TIME (WORD)

GRAPH OF OSMOTIC POTENTIAL AND TIME (PDF)

GRAPH 2
Click Here to Access

GRAPH OF OSMOTIC CHANGE AND TIME (WORD)

GRAPH OF OSMOTIC CHANGE AND TIME (PDF)

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QUESTIONS
OSMOSIS QUESTIONS
1) Over the 90 minute period, what distance did the column of sugar move?
2) Which term is used to describe the tonicity of the distilled water? (Hypotonic or Hypertonic)
3) Explain why the sugar solution rises in the thistle tube over time.
4) Explain why the diffusion rate of water changed over the 90 minute period of time.  
5) We began the experiment by pouring a 20% sucrose solution into the thistle tube. Describe what the makeup of the sucrose solution probably is after the 90 minute period. (more or less than 20%).
6) Describe why this change in sucrose % has changed.
7) From the knowledge you have gained, explain why it is not a good idea to drink salt water when you are thirsty.

Click Here for a MS WORD version of the questions

Click Here for a PDF version of the questions

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Click Here to View an Animation on Osmosis
     OSMOSIS

Click Here to View Another Animation on Osmosis
     OSMOSIS 2

Click Here to View a Different Animation on Osmosis
     OSMOSIS 3

Click Here to View an Animated Discussion on Osmosis
     OSMOSIS DISCUSSION

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PART 2 DIALYSIS

Dialysis is the separation of solutes according to their size by diffusion through a permeable membrane. Depending upon the molecular pore size of the membrane, solutes will either diffuse across the membrane or be restricted by their size. In our experiment the solute molecules always move from the stronger concentration (hypertonic) to the weaker (hypotonic). Dialysis involves the movement of some, but not all, of the dissolved substances in a solution. The substance that moves has small molecules, so these can pass through the pores in the membrane, but other substances, with larger molecules, cannot escape. This process occurs normally in the kidney. Substances with small molecules, such as salts, glucose and urea, continuously pass out of the blood through a membrane under pressure, but useful substances are later reabsorbed. Waste substances are then excreted as urine.

In this exercise you will measure diffusion of small molecules through dialysis tubing, an example of a semi permeable membrane. The movement of a solute through a semi permeable membrane is called dialysis. The size of the minute pores in the dialysis tubing determines which substance can pass through the membrane. A solution of glucose and starch will be placed inside a bag of dialysis tubing. Distilled water will be placed in a beaker, outside the dialysis bag. The dialysis bag with the starch glucose solution will be inserted into the beaker of distilled water. After 30 minutes have passed, the solution inside the dialysis tubing and the solution in the beaker will be tested for glucose and starch. The presence of glucose will be tested with glucose test strips. The presence of starch will be tested with Lugol's solution (iodine potassium iodide).

TABLE 3
**When you are finished with Part 2 of experiment # 3, be sure that you include the following with your lab report.

1) Table of Dialysis Tests
2) Answers to Dialysis Questions (1-6)

Click Here to Access the Table

TABLE OF DIALYSIS TESTS (WORD)

TABLE OF DIALYSIS TESTS (PDF)

QUESTIONS
DIALYSIS QUESTIONS
1) Considering tonicity, how would you describe the relative tonicities of the:
           a) dialysis bag solution
           b) beaker solution?
2) By analyzing the differences between the tonicities of the solutions in the bag and the beaker, where should water diffuse to?
           a) into the bag
           b) into the beaker
3) Did starch diffuse from the bag? Why or why not?
4) Did glucose diffuse from the bag? Why or why not?
5) Did osmosis occur during this experiment? Why or why not?
6) Did dialysis occur during this experiment? Why or why not?

Click Here for a MS WORD version of the questions

Click Here for a PDF version of the questions

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2) Cell Structure

There is diversity in the form and function of cells that make up living organisms. Single cells, such as Amoeba, can be free-living organisms able to exist independently. Some cells live in a loosely organized colony of similar cells that move from place to place. Others are fixed as part of the tissues of higher plants and animals and depend on integrated activities with other cells.
Cells vary in size. Many bacteria are roughly 1 micrometer long, which is equal to 10-6 meter. The yolk of an ostrich egg, also a single cell, is the size of a small orange. Cells have special functions, such as the transport of oxygen and carbon dioxide by red blood cells. Other cells have different specialties. Whatever the cells form and function, the cell is recognized as the basic unit of living matter, containing all those properties and processes that are collectively called life. Click Here to View a movie of an Amoeba Moving        AMOEBA MOVING	Figure 2.2 Amoeba
Click the play button to view the movie to the right showing an amoeba moving about. An alternative view for this animation is given below: http://www.youtube.com/watch?v=7pR7TNzJ_pA

Biologists recognize two basic types of cells. 1) Eukaryotic cells (Greek karyon means kernel or nucleus, eu means good or true) have a well-defined nucleus, which is separated by a membrane from the rest of the cell in which the organelles are found. Examples include protozoa and the cells of fungi, plants, and animals.
2) Prokaryotic cells, as exemplified by bacteria and cyanobacteria, lack a nuclear membrane and cytoplasmic organelles. The cyanobacteria (blue-green algae) have a well-developed photosynthetic apparatus that is similar to the components of the chloroplasts of higher plant cells. The differences between prokaryotic and eukaryotic cells are evident, but they do have several characteristics in common.  They both are surrounded by a cell (plasma) membrane that is similar in structure, though functionally different. The cell membrane of prokaryotic cells is the site of energy-yielding reactions that take place inside the eukaryotic cell mitochondria.	Figure 2.3 Sperm and Egg
Click the play button to view the movie to the right on live sperm cells. An alternative view for this animation is given below: http://www.youtube.com/watch?v=vvnEsOaKxuw&feature=related

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Prokaryotic Cells Flesispiria rappini First described as "Flexispira rappini", this bacterium was subsequently determined to be closely related to Helicobacter spp (causes stomach ulcers). Note the spiral configuration of organisms cell wall, and the presence of bipolar multiple flagella. SKETCH 4 **Utilizing the electron micrographs, images provided in this lab and your text book, sketch a representative prokaryote cell and identify the following: Cell wall, DNA region, Cytoplasm

Figure 2.5 Gram-negative "Flexispira rappini" bacteria, magnified 6976 X

Figure 2.6 Light microscopic image 400 X. Brucella spp., gram-negative coccobacilli

Figure 2.7 Light microscopic image 1000 X. Brucella spp., gram-negative coccobacilli

Figure 2.8 Diagram of Eschirichia coli (Electron micrograph)

Figure 2.9 Light microscope (430X) reveals bacteria adhering to vaginal epithelial cells

Click the play button to view the movie to the right discussing bacteria which are Prokaryotes. An alternative view for this animation is given below: http://www.youtube.com/watch?v=J6akNYlkehY

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Eukaryotic Cells   Generalized Cell Eukaryotic cells differ from prokaryotic cells primarily in the association of their DNA with proteins and the organization of this complex into large structures called chromosomes. A cells group of chromosomes is surrounded by the nuclear envelope, a membrane that separates these contents of the nucleus from the cytoplasm.	Figure 2.10 Generalized Eukaryotic Cell
Click the play button to view the movie to the right which take you on a view of a Eukaryotic cell. An alternative view for this animation is given below: http://www.youtube.com/watch?v=u54bRpbSOgs&feature=related     Click the play button to view the movie to the right which compares Eukaryotic and Prokaryotic cells. An alternative view for this animation is given below: http://www.youtube.com/watch?v=yWy4o_UfZ4A&feature=related     SKETCH 5 **Using the images of the microscopic slides in this lab and text book, sketch a typical eukaryotic cell and identify the following: Cell membrane, Cytoplasm, Endoplasmic reticulum, Nucleus, Nucleolus, Golgi body, Nuclear envelope, Mitochondria, Lysosome, Ribosomes
You can use the links below to study cell structure in more detail INTERACTIVE CELL 1 INTERACTIVE CELL 2 CELL ORGANELLE IDENTIFICATION ANIMAL CELL ORGANELLES

Figure 2.11 Animal Cell Model

Figure 2.12 TEM of Animal Cell

Figure 2.13 TEM of white blood cells. Note the nucleus of the cell.

Figure 2.14 Blood Cells. The image above is of a scanning electron microscope. One can see red blood cells, several white blood cells including lymphocytes, a monocyte, a neutrophil, and many small disc-shaped platelets.

QUESTIONS CELL STRUCTURE QUESTIONS 1) Is the cell in this electron micrograph to the right prokaryotic or eukaryotic? 2) What structural differences did you observe between prokaryotic and eukaryotic cells? 3) Observe the electron micrograph below a) Is the cell prokaryotic or eukaryotic? b) Identify the labeled structures. (A, B, C)

Click Here for a MS WORD version of the questions

Click Here for a PDF version of the questions

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3) Cell Reproduction

A typical multicellular organism begins life as a zygote, which is formed from the union of a sperm and an egg. The egg and sperm, though unequal in size, give an equal number of chromosomes to the zygote. Each gamete contributes the haploid number (half) of the total number of chromosomes. The zygote, therefore, contains a diploid number (full) of chromosomes (a haploid set from each parent). For example, the diploid complement of the human zygote is 46 chromosomes. The haploid complement of the egg and sperm is 23 chromosomes. The reduction from the diploid number to the haploid number is brought about by a type of cell division called meiosis, which occurs in the formation of the gametes. After fertilization, the zygote gives rise to all the cells that make up the organism by repeated cell divisions, called mitosis.

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The Cell Cycle

The series of events that comprises the life span of an actively dividing cell is termed the cell cycle. The cell cycle involves an interphase during which the cell outwardly appears dormant, and an M phase (for mitosis), during which the cell is actively dividing. 

For convenience, the process of mitosis is divided into four distinct stages: prophase, metaphase, anaphase, and telophase. The replication of deoxyribonucleic acid (DNA) and the synthesis of ribonucleic acid (RNA) and proteins that are essential for mitosis occur during interphase. Note in the images below that the replication of DNA occurs during a period of interphase called the S (for synthesis) phase. The doubling of DNA during the S phase provides a full complement of DNA for the daughter cells that will result from the next mitotic division. During interphase, there are also two phases called G (for gap) phases.

The G1 phase preceding DNA replication is the period between the end of one mitotic division and the beginning of the S phase of the next division. It is during G1 that a cell may begin a pathway that leads to differentiation, rather than continue the cell cycle. During the G2 phase, the structures directly involved with mitosis, such as the spindle fibers, are assembled. The combination of G1, S, G2, and M phases makes up the cell, or mitotic, cycle.  The mitotic process usually occupies only 10% of the total time taken by the cell cycle. It is important to learn to distinguish among the several parts of mitosis. The organization of DNA strands into chromosomes and the separation of the chromosomes are termed karyokinesis. Division of the cell body is termed cytokinesis.  SKETCH 6 **Using images in your text book and this lab as a resource, construct a cell cycle image that would include identifying the following stages of the cell cycle: G1 phase, S phase, G2 phase, M phase

Figure 2.15 Cell Cycle Click Here to View an Animation on the Cell Cycle CELL CYCLE

Click the play button to view the movie to the right showing animations of the cell cycle. An alternative view for this animation is given below: http://www.youtube.com/watch?v=O3_PNiLWBjY

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Mitosis
Mitosis is one stage of the cell cycle in which the nucleus divides and the replicated chromosomes separate and migrate to opposite sides of the cell.

 

Click the play button to view the movie to the right reviewing the stages of mitosis. An alternative view for this animation is given below: http://www.youtube.com/watch?v=VlN7K1-9QB0

 

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TABLE 3
**Construct a table which summarizes the events at each stage of mitosis. Use the link below to access the Summary Table

TABLE OF SUMMARY OF EVENTS IN MITOSIS (word)

 

TABLE OF SUMMARY OF EVENTS IN MITOSIS (pdf)

 

SKETCH 7
**From the images below, sketch each of the stages of mitosis and label as: Interphase, Prophase, Metaphase, Anaphase, Telophase

 

Use this link to view an animation of Mitosis
             MITOSIS 1

Use this link to view another animation of Mitosis
             MITOSIS 2
 

Use this link to view a different animation of Mitosis
             MITOSIS 3

 

Use this link to view a different animation of Mitosis
             MITOSIS 4

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Mitosis in animal cells can be observed in the images presented below. The images are from a prepared slide of salamander skin.  

Interphase Interphase cells are characterized by a distinct nucleus bounded by a nuclear membrane. The nucleolus may or may not be identifiable. Immediately adjacent to the nuclear envelope is a cytoplasmic organelle referred to as the centrosome, which contains the centrioles.   INTERPHASE ANIMATION

Prophase Karyokinesis begins with prophase. During prophase  two pairs of structures called centrioles are organized with in the centrosome. They begin to move apart, migrating around the nucleus toward opposite poles of the cell. Spindle fibers radiate from each pair of centrioles like spokes on a wheel. The centrioles will continue to migrate until they lie at opposite poles of the cell. The spindle fibers are arranged so as to attach to the condensing DNA which are now referred to as chromosomes. PROPHASE ANIMATION

Metaphase During metaphase, the chromosomes migrate toward the central region of the cell. The chromosomes are maneuvered into position by the spindle fibers that are attached to the kinetochore (middle) of each chromosome. METAPHASE ANIMATION 1   METAPHASE ANIMATION 2

Anaphase Anaphase begins when the pairs of chromatids are pulled apart by the spindle fibers and become daughter chromosomes. The process continues as the chromatids are pulled toward the poles of the cell. When the chromosomes reach the poles, telophase begins.   ANAPHASE ANIMATION

Telophase During telophase, the spindle fibers disappear, two daughter nuclei are organized and the new nuclear membranes are formed. In late telophase, the cytoplasm becomes deeply furrowed, or pinched in between the two nuclei, and cytokinesis takes place. This results in two daughter cells having equivalent nuclear contents and equal amounts of cytoplasm.   TELOPHASE ANIMATION

Figure 2.16 Stages of Mitosis

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Cytokinesis A major event in cell division is the separation of the two new individual cells. Cytokinesis takes place by furrowing. To visualize how furrowing takes place, imagine wrapping a string around a balloon and slowly tightening the string until the balloon has been pinched in two. In life, the animal cell is pinched in two, forming two individual cells, each with a single nucleus.	Figure 2.17 Cytokinesis
Click the play button to view the movie to the right discussing the process of cytokinesis. An alternative view for this animation is given below: http://www.youtube.com/watch?v=KE2VI7tDL1k

SKETCH 8 **Based on the images in your text book and this lab and the images you have viewed on cell mitosis, construct a sketch of Cytokinesis and identify the following: Cell furrow, Daughter cells   Click Here to View an Animation on Cytokinesis      CYTOKINESIS

Figure 2.18 Cytokinesis

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QUESTIONS
MITOSIS QUESTIONS

1) If the chromosome number of a typical cell is 16 before Mitosis, what is the chromosome number of each newly formed nucleus after nuclear division has taken place? 2) Why must the DNA be duplicated during the S phase of the cell cycle, prior to mitosis? 3) Observe the sketches to the right and below labeled A-E and identify the stage of mitosis in each.

A

B

C

D

E

Click Here for a MS WORD version of the questions

Click Here for a PDF version of the questions

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4) Chromosome Structure

Chromosomes are condensed versions of the DNA molecule. Chromosomes consist of a pair of chromatids with very similar DNA patterns and a central point of attachment of the chromatids, called the centromere.

SKETCH 9 **Using the images in this lab and your text book, sketch an image of the chromosome and identify the following: Chromatid, Centromere, Chromosome Use this link to view an animation giving more information on Chromosomes CHROMOSOMES Use this link to view an animation detailing chromosome structure CHROMOSOME STRUCTURE

Figure 2.19 Chromosome

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5) Online Onion Root Tip Mitosis
 

Growth in an organism is carefully controlled by regulating the cell cycle. In plants, the roots continue to grow as they search for water and nutrients. These regions of growth are good for studying the cell cycle because at any given time, you can find cells that are undergoing mitosis. In order to examine cells in the tip of an onion root, a thin slice of the root is placed onto a microscope slide and stained so the chromosomes will be visible. Use the link given above to access a virtual study on root tip mitosis. The cells you'll be looking at in this activity were photographed with a light microscope and then digitized so you can see them on the computer. Although slicing the onion root captures many cells in different phases of the cell cycle, keep in mind that the cell cycle is a continuous process. Scientists have divided the process into 5 phases, each characterized by important events, but these divisions are still arbitrary.   In this activity, you will be presented with cells from the tip of an onion root. You will classify each cell based on what phase it is in. At the end you will count up the cells found in each phase and use those numbers to predict how much time a dividing cell spends in each phase.

Figure 2.20 Events of Mitosis

VIRTUAL LAB In order to perform this lab you will need to have a good knowledge of the stages of mitosis. You will be identifying images of cells and recording what stage they are in. A summary of the phases is given above. This information should help you. The data collecting can be recorded on a data table you can access from the links below. You will need to link as directed below to another website in order to perform the exercise. Use this link to start this portion of the lab. ONLINE MITOSIS LAB An alternative link is as follows: http://www.biology.arizona.edu/cell_bio/activities/cell_cycle/cell_cycle.html

TABLE 4 **You will need to record your results in the table referred to below. TABLE FOR MITOSIS LAB (WORD) TABLE FOR MITOSIS LAB (PDF)

Figure 2.21 Cells in the tip of an Onion Root

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END LAB 2

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