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Introduction to the lesson
So far in this chapter, we have mostly studied the difference between animal cells and plant cells. However, there is an even more fundamental difference between eukaryotic cells (which includes both animal cells and plant cells) and prokaryotic cells (bacteria). In this lesson we will explore these two different types of cell. We will also look at viruses and determine where they fit in -- are they living creatures or not? This is another very important section which will be tested in the exam so make sure that you know it well.
The difference between prokaryotic cells and eukaryotic cells
Read the section under the heading "Two fundamentally different types of cell" in your text book (p.21-22).Learning Activity 1
Answer the following questions in your exercise book.
- Answer Question 1.6 on p. 21.
- Copy and complete the following table, comparing prokaryotic and eukaryotic cells. A few examples are provided for you.
| prokaryotic cells | eukaryotic cells | |
|---|---|---|
| unicellular/multicellular | unicellular | multicellular |
| nucleus | ||
| membrane bound organelles | ||
| DNA (description) | naked | associated with protein, forming chromosomes |
| ribosomes | slightly smaller: 70S (about 20nm in diameter) | slightly larger: 80S (about 25nm in diameter) |
| cytoplasm | ||
| motility | ||
| cell division | ||
| reproduction | ||
| metabolic pathways |
Endosymbiosis
Learning Activity 2
Answer the following question in your exercise book.
- In your own words, explain what is meant by the term “endosymbiosis”. What evidence is there to support this idea?
Viruses
Read the section under the heading "Viruses" in your text book (p.21-22).
Learning Activity 3
Answer the following questions in your exercise book.
- Why are viruses parasitic?
- Describe the structure of a virus.
- Draw and label the diagram of a virus (see Fig. 1.31 on p.22).
Definitions and review
Definitions
- Prokaryote
- Eukaryote
- Protocist
Mindmap
Add this section to your chapter one mindmap.