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Introduction to the lesson
In Lesson 1.3 we began to look at the structure of an animal cell as seen through a light microscope. However, as we have seen in Lesson 1.4 and 1.5, the light microscope cannot show all the organelles of a cell. In this lesson we will look at the organelles of an animal cell as seen through an electron microscope. Take note: you need to know the ultrastructure of cells very well for the exam. You will be required to give the function and size of the organelles as well as be able to draw them and recognize drawings of them. This lesson is, therefore, extremely important so make sure that you go through it thoroughly and learn all the organelles.
Ultrastructure of an animal cell
Read the section under the heading "Ultrastructure of an animal cell" in your text book (p.13-19).
Learning Activity 1
Answer the following questions in your exercise book.
- Make summary notes of the following structures and organelles of an animal cell seen by the electronic microscope, giving the size and function of each (illustrate your notes):
- Nucleus
- Endoplasmic reticulum
- Ribosomes
- Golgi apparatus
- Lysosomes
- Mitochondria
- Cell surface membrane
- Microvilli
- Microtubules and microtubule organising centres (MTOCs)
- Centrioles and centrosomes
- What is ATP and ADP?
- Where is ATP produced in animal cells?
- What is the role of ATP in the animal cell?
- Describe the endosymbiont theory
- What size ribosomes exist in the cytoplasm of a cell?
- What size ribosomes are found in mitochondria?
- List the organelles of an animal cell in size order from the largest to the smallest.
- Draw the ultrastructure of a typical animal cell as seen with an electronic microscope.
- Compare your drawing of an animal cell under a light microscope with your drawing of an animal cell seen with an electronic microscope. What is similar? What is different? Which one shows more detail? Why?
- Answer Question 1.4 on p.14
Definitions and review
Definitions
- Ultrastructure
- Nuclear envelope
- Nuclear pores
- Nucleolus
- Smooth ER
- Rough ER
- Ribosomes
- Golgi vesicles
- Lysosomes
- Cristae
- Endosymbiont theory
- Trilaminar appearance
- Microvilli (sing. microvillus)
- Epithelial cells
- Microtubules
Mindmap
Add this section your chapter one mindmap. (Make sure that you have a brief description of the function and size of each organelle. You might want to add illustrations of the organelles as well.)