Eukaryotic and Prokaryotic Cells Practice

Neuron Adaptation: Neurons are well suited for their function because they possess long axons and dendrites, allowing them to pass electrical messages over long distances throughout the body.
Microscopy Technique:
- Coarse Focusing Wheel: Used to roughly focus on a specimen by bringing it into the initial view.
- Fine Focusing Wheel: Used to focus the image more sharply for detailed observation.
Aerobic Respiration: The word equation for aerobic respiration is:
- $Glucose + Oxygen \rightarrow Carbon\,Dioxide + Water$
Energy in Respiration: It is scientifically incorrect to say that energy is "made" during respiration. According to the laws of physics, energy cannot be created or destroyed; instead, energy is released during the process of respiration.
Plant-Specific Organelles: The organelles found exclusively in plant cells (and not animal cells) include:
- Chloroplasts
- Cell wall
- Vacuole

To Know:
- Classify organisms as eukaryotes and prokaryotes.
- Compare the structural and functional differences between eukaryotic and prokaryotic cells.
- Justify why prokaryotes lack mitochondria.
Learning Objective: To evaluate the structural and functional differences between eukaryotic and prokaryotic cells.

Classification: Eukaryotic cells include all plant and animal cells.
Size: They are generally larger, typically measuring between $10-100\,\mu m$ in size.
Genetic Material: Eukaryotic cells contain their genetic material (DNA) enclosed within a nucleus.
Internal Structure:
- Membrane-bound Organelles: Organelles in eukaryotic cells are contained within membranes.
- Mitochondria: Present; these are the sites of aerobic respiration.
- Ribosomes: Present; these are the sites of protein synthesis.
- Cytoplasm: The jelly-like substance where chemical reactions occur.
- Cell Membrane: Controls the passage of substances into and out of the cell.

Classification: Bacterial cells are the primary example of prokaryotes.
Size: They are much smaller than eukaryotic cells, typically measuring between $1-10\,\mu m$ in size.
Genetic Material: Prokaryotic cells do not have a nucleus. Instead, their DNA is kept in a large loop or in small rings called plasmids.
Internal Structure:
- Lack of Membrane-bound Organelles: They do not contain a nucleus or other membrane-bound organelles like mitochondria or chloroplasts.
- Respiration: While they do not have mitochondria, they still respire; this process occurs in the cytoplasm.
- Ribosomes: Present; they serve as the site of protein synthesis.
- Physical Boundaries: They possess a cytoplasm, a cell wall, and a cell membrane.

Question 1: Eukaryotic cells are bigger than prokaryotic cells. (Answer: True)
Question 2: Prokaryotic cells contain their genetic information in a nucleus. (Answer: False)
Question 3: Bacteria are prokaryotic cells. (Answer: True)
Question 4: Plant cells are prokaryotic cells. (Answer: False)
Question 5: Eukaryotic cells can contain mitochondria to provide energy through aerobic respiration. (Answer: True)

Organism: Euglena (a unicellular organism).
Observed Features: Flagellum, stigma, reservoir, nucleus, nucleolus, chloroplast, contractile vacuole.
Classification Decision: Euglena is a eukaryotic cell.
Justification: Despite being unicellular, it contains a nucleus and membrane-bound organelles such as chloroplasts and a contractile vacuole, which are defining characteristics of eukaryotes.

Misconception Alert: "Is this correct? Prokaryotic cells do not contain mitochondria because they do not respire."
- Correction: This is incorrect. While prokaryotes lack mitochondria, they still perform respiration; the reactions simply take place in the cytoplasm rather than a specialized organelle.
Drill Questions & Answers:
1. Where is the genetic material in eukaryotic cells found? Enclosed within the nucleus.
2. Where is the genetic material in prokaryotic cells found? Floating freely in the cytoplasm (as a loop or plasmids).
3. Which type of cell contains membrane-bound organelles? Eukaryotic cells.
4. What type of cell is a Salmonella bacterium? Prokaryote.
5. What is the function of ribosomes in both cells? Ribosomes make proteins for the cell (protein synthesis).
6. Which type of cell is larger? Eukaryote.
7. Where does aerobic respiration take place in a eukaryotic cell? Mitochondria.
8. Difference between bacterial and animal cells: A bacterial cell has a cell wall, no nucleus, no mitochondria, and contains plasmids; its genetic material is not enclosed in a nuclear membrane.
9. Organelles absent in prokaryotes (besides nucleus): Chloroplasts and mitochondria.

How to 'Describe':
- Use bullet points for clarity.
- Cover enough points to fully address the prompt.
- Use scientific keywords.
- "Say what you see" if interpreting a diagram or graph.
How to 'Compare':
- Provide both similarities and differences.
- Write paired statements that address the same feature for both subjects.
- Use the linking term "whereas" to connect statements (e.g., "Prokaryotic cells do not have a nucleus, whereas eukaryotic cells do").

Which of these is an example of a prokaryotic cell?
- A. Animal cell
- B. Plant cell
- C. Bacterial cell (Correct Answer)
What is the relative size of eukaryotic cells and prokaryotic cells?
- A. Prokaryotic cells are larger than eukaryotic cells
- B. Eukaryotic cells are larger than prokaryotic cells (Correct Answer)
- C. Prokaryotic cells and eukaryotic cells are roughly the same size
What is the difference between eukaryotic and prokaryotic cells?
- A. Eukaryotic cells contain DNA within a nucleus, prokaryotic cells contain DNA in loops and plasmids (Correct Answer)
- B. Eukaryotic cells contain DNA in loops and plasmids, prokaryotic cells contain DNA within a nucleus
- C. Prokaryotic cells contain mitochondria to provide them with energy