3.3.1 | Introduction to eukaryotes (1 day) |
3.3.2 | Eukaryotic cell membrane (1 day) |
3.3.3 | Plant and Animal Cell Organelles (1-2 days) Organelles shared by plant and animal cells Organelles found only in animal cells Organelles found only in plant cells Other structures found only in plant cells |
3.3.4 | Specific cell processes and organelles (1-2 days) 3.3.4 a Formative quiz: eukaryotic cell structures and functions |
3.3.5 | Additional activities for Lesson 3.3 (1-4 days depending upon what is used) |
Lesson 3.3 Eukaryotic cells suggested answer key
Quick quiz: eukaryotic structures and functions KEY
1. Diagram of a typical eukaryotic cell, showing subcellular components. Organelles: (1) nucleolus (2) nucleus (3)ribosome (4) vesicle (5) rough endoplasmic reticulum (ER) (6) Golgi apparatus (7) cytoskeleton (8) smooth ER (9) mitochondria (10) vacuole (11) cytoplasm (12) lysosome (13) centrioles within centrosome (14) virus particle shown to approximate scale
2. The diagram is of an animal cell based on shape, organelles present, cell wall not present, chloroplasts not present, centrioles present.
3. Self-directed students can use their eukaryotic cell structure chart (from section 3.3.2) to check their answers
4. a. Reduction in the number of mitochondria should result in a reduction in the total production of ATP, if everything else remains the same in the cell. This loss of ATP may be detrimental to future cell functioning.
b. An increase in the number of Golgi apparatus may decrease the time required to modify, package, and sort the proteins and lipids of the cell, if everything else remained the same.
c. An increase in the number of chloroplasts will result in an increase in the amount of light collected for the process of photosynthesis. Since photosynthesis takes place in chloroplasts, an increase in number of chloroplast should also increase the amount of photosynthesis taking place in the cell. This, then, would increase the amount of sugar that would be created, some of which may then be stored as starch within the cell. The increase in the number of mitochondria should increase the number of ATP molecules available to the cell.
d. If a plant cell were unable to create a vacuole, that would suggest it was also unable to create vesicles. Vacuoles are created from fusing many vesicles together. In a situation like this, a cell would have a very difficult time functioning, if at all, since vesicles are used for a variety of essential cell functions.
5.a. A significant increase in the production of proteins would suggest an increase occurred in the number of ribosomes being used for protein synthesis or that the actual number of ribosomes increased in the cell.
b. Knowing that vesicles within the cell help with the repair of the cell membrane, a membrane that can no longer be repaired would suggest that a problem existed with vesicle formation, or with the Golgi apparatus, or with the production of phospholipids by the endoplasmic reticulum of the cell.
c. If the plant cell vacuole contains mostly water, a large decrease in its capacity would suggest that the water has moved out. This could occur if the plant cell was placed into a salt solution. If the plant cell vacuole contains starch, a significant decrease in its volume would suggest the cell is in need of nutrients for energy production. Possibly the plant cell has not been able to photosynthesize due to lack of enough light intensity at the proper light wavelengths, or it is under some other environmental stress.
d. If vesicles are no longer produced in a cell, then there is a problem with the Golgi apparatus, since that organelle secretes vesicles as part of its function within the cell. If this continues for an extended period of time, the cell will die.
e. If proteins are not labeled, there is a problem in the rough endoplasmic reticulum of the cell, as labeling occurs there. Such an event would limit cell functioning as protein labels are essentially the “address” to which they need to be sent.
Additional activities for Lesson 3.3:
These activities should be incorporated into the lesson at the discretion of the instructor.
While some instructors may wish to place the Study of Cells lab activity at the beginning of the lesson, others may wish to place it after 3.3.3 is completed. The length of this activity may allow it to be broken into smaller sections that could then be inserted into the lesson at more convenient points. It is imperative that instructors provide a complete pre-lab, including lab safety protocols, prior to doing this activity
The same is true of the cell coloring/identification sheets. It may be to the student’s advantage to work concurrently on the animal and plant cell coloring sheets while working through 3.3.2 and 3.3.3. In some cases, instructors may opt to use these coloring sheets as a form of assessment or review.
The cell analogy activity could be used as a form of formative assessment/additional practice or as part of a summative assessment.
The review/reinforcement links may be used as individual or small group review tools.
The Study of Cells general lab safety concerns
This document is meant as a guide to lab safety concerns for this particular activity. It is not intended to be the ONLY safety information to be presented to students. Instructors are responsible for providing adequate preparatory information to their students prior to engaging in any laboratory activity.
As in all laboratory activities, materials from the lab are not to be consumed by students or removed from the laboratory. In addition, food or beverages students may have are not allowed in the laboratory.
If students have allergies to any of the materials used in this activity, they should not participate in it. They can be given data from the lab for analysis.
Any accidents must be reported immediately to the instructor.
Hands should be thoroughly washed prior to leaving lab and washed during the activity if needed.
Part A: Cork cells
If you opt to have students cut their own cork sample, you need to demonstrate how to do it safely.
Some instructors may prefer to have pre-sliced cork samples available for students to use, eliminating the need for razor blades.
Proper disposal of materials and cleaning of slides and cover slips needs to be addressed.
Part B: Human epithelial cells
Students are to prepare a slide only with their own cheek cells.
Flat sided toothpicks work well for this activity and instructors should demonstrate how to safely collect cheek cells, without abrading the inside of the cheek.
Toothpicks must be thrown away into the garbage.
MSDS information regarding the correct usage and risks associated with the usage of methylene blue must be read by the instructor and communicated to the students. Proper personal lab safety equipment must be available to be used by students.
Proper disposal of materials and cleaning of slides and cover slips needs to be addressed.
Part C: Plant epidermal cells
Instructors may opt to provide students with chunks of onion, rather than having the students cut an onion.
Remind students to avoid touching their face or eyes once they have handled the onion. Students should wash their hands after they have touched the onion.
Consider the room ventilation, as a small area with many cut onions can
cause tearing of the eyes
Consider demonstrating how to peel the thin membrane layer required for this activity. Some students may attempt to view a chunk of onion.
MSDS information regarding the correct usage and risks associated with the usage of iodine must be read by the instructor and communicated to the students. Proper personal lab safety equipment must be available to be used by students.
Proper disposal of materials and cleaning of slides and cover slips needs to be addressed.
Part D: Cells of Anacharis (elodea) leaf
Review how to create a wet mount.
Proper disposal of materials and cleaning of slides and cover slips needs to be addressed.
Part E: Potato cells
If you opt to have students cut their own potato slice, you need to demonstrate how to do it safely.
Some instructors may prefer to have pre-sliced potato samples available for students to use, eliminating the need for razor blades.
MSDS information regarding the correct usage and risks associated with the usage of iodine must be read by the instructor and communicated to the students.
Proper disposal of materials and cleaning of slides and cover slips needs to be addressed.
Part F: Cells of tomato pulp and skin
Consider demonstrating what amount of pulp and skin should be collected by students for this activity.
Proper disposal of materials and cleaning of slides and cover slips needs to be addressed.
Part G: Cells of a beet
If you opt to have students cut their own beet slice, you need to demonstrate how to do it safely. Be sure students know that beet juice may stain their fingers and other materials. They should wash their hands once they are done with collecting their specimen.
Some instructors may prefer to have pre-sliced beet samples available for students to use, eliminating the need for razor blades.
Proper disposal of materials and cleaning of slides and cover slips needs to be addressed.
Part H: Specialized animal cells
Substitute prepared slides as needed.
Students may need to be reminded to avoid touching the objective lens to the surface of the coverslip, as they focus the microscope.
Advise students in terms of what needs to be done if a slide breaks, including its disposal.