Ultrastructure of cells 1.2

Eukaryote cells are larger than prokaryote cells and they have a more compartmentalised structure since endosymbiosis lead to the creation of organelles. There are two basic types which student need to be able to draw, eukaryote and prokaryote cells. In this topic students also learn how to recognise organelles in cells and to suggest cell functions depending upon cell structure.


Key words

Learn and test your biological vocabulary for 6.1 digestion and absorption using these flashards 

Clean sweep - quick revision through the whole topic

These slides summarise the essential understanding and skills in this topic. 
They contain short explanations in text and images - good revision for all students.

Read the slides and look up any words or details you find difficult to understand.

Know the tricky details - for grade 7

These slides cover difficult parts of this topic - important if you are aiming for a high grade.
If grade 5 is your target, then save time, move on, study this information later, once you have revised the other topics.

Skills and applications

How to draw a eukaryote animal cell diagram quickly in an exam -  video tutorial

How to draw a eukaryote animal cell in an exam. from David Faure on Vimeo.

How to identify organelles in electron microscope images and to explain how the structures relate to the cell's function.

Interpreting electron microscope images from David Faure on Vimeo.

This video help students to identify organelles and to make the link between cell structure and function.

Revision summary list for topic 1.2 Ultrastucture of cells

  • Know and be able to draw the simple structure of Prokaryote cells
  • Know and draw the compartmentalised structure of Eukaryotic cells.
  • Understand that the resolving power of electron microscopes is between 10µm and 1nm
  • whereas light microscopes resolve details between 1mm and 1µm.

Skills and applications

  • Ability to identify organelles from microscope images of cells.
  • Ability to explain how the composition of organelles will be different in cells with different functions,
    (eg. goblet cells which make mucus and palisade mesophyll cells which do photosynthesis).
  • Explain how the structure of prokaryotes allows them to divide by binary fission. 

Revision mindmap

This diagram summaries the main sections of topic 1.2 Cell ultrastructure.
Test if you can draw your own list or concept map from memory.

Review questions

This self marking multiple choice quiz contains questions covering the skills outlined in the image above:
A quiz of multiple choice questions for ultrastructure of cells topic 1.2

1

The image below shows three structures as seen in an electron microscope.

Which of the structures are prokaryote cells?

Students are expected to be able to recognise and draw the simple structure of Prokaryote cells.

There is no compartmentation in prokaryote cells, and as membranes can be seen in structure B (a mitochondrion) it is not a prokaryote.

2

The electron microscope below shows three organelles found in an animal cell.

What is the name of the organelles?

Know how to idenfity the organelles in eukaryotes and draw their compartmentalised structure.
A mitochondrion (pleural = mitochondria) has an outer membrane and inner membrane folded into long thing 'flaps' called cristae.

3

The electron microscope below shows an organelle found in both animal and plant cells.



What is the name of the organelle?

Know how to idenfity the organelles in eukaryotes and draw their compartmentalised structure.
The rER has parallel membranes covered in dots, which are ribosomes, used for making proteins, for secretion from the cell.

4

The electron microscope below shows a ciliated epithelial cell from the lungs.

What is the name of the organelle labelled X?

The nucleus is the largest organelle in the cell. You can often see black speckled chromatin in it, and sometimes black patches.
5

The electron microscope below shows an organelle found in eukaryote cells.

What is the name of the organelle?

Chloroplasts are distinctive because they have stacks of membranes inside, called grana, which hold the chlorophyll that absorbs light.

6

What are the structures labelled X and Y likely to be in this electron microscope image?

Students are expected to be able to identify organelles from microscope images of cells. The nucleus is distinctive because it is about 10µm in size, and it has black dots in it, chromatin, and sometimes one or more dark patches within the nuclear membrane. It also has a double membrane, not often easily visible.

7

If you found a eukaryote cell in an electron microscope image, and it contained a lot of rER, Golgi apparatus and many darkly stained vesicles, what do you think the function of the cell is most likely to be?

Student are expected to explain how the composition of organelles will be different in cells with different functions,

(eg. goblet cells which make mucus (a protien) will contain lots of rER and vesicles of musus, and palisade mesophyll cells which do photosynthesis will contain lots of chloroplasts)

8

Why is it that prokaryotes can divide by the simple process of binary fission, but eukaryotes have to divide by the more complex process of mitosis?

To explain how the structure of prokaryotes allows them to divide by binary fission you could mention:

  • Prokaryotes have a single chromosome, eukaryotes have multiple chromosomes
  • Prokaryotes have no nuclear membrane, which eukaryotes have.
9

This electron microscope shows a group of prokaryotes.

What structures are most likely to be found inside these cells?

Skill: you should know how to draw prokaryotic cells (with a cell wall, plasma membrane, cytoplasm, pili, flagella, 70s ribosomes and nucleoid.) and eukaryotic cells (free 80s ribosomes, rough endoplasmic reticulum (rER), lysosome, Golgi apparatus, mitochondrion and nucleus)

10

The electron microscope image below shows a cell.

What are the organelles shown by the labels X & Y?

If you look closely at X, it points to the cell wall, outside the plasma membrane, it is close to the plasma membrane, but not touching the chloroplast.

The pale area below Y is the vacuole.

Organelle Y is a mitochondrion, you can tell this by its size, and the presence of membranes inside.

11

How does compartmentalisation by their internal membranes benefit eukaryotic cells?

Eukaryote cells (approx. 100µm in diameter) are much larger than prokaryote cells (approx 1µm) and so the concentration of reactants in the cytoplasm would be more dilute if all the metabolism happened in the cytoplasm.

Specialist organelles, like mitochondria keep the enzymes for aerobic respiration in one place, which increases their concentration, and increases the rate of reactions.

12

What is the term used to describe the smallest distance which two objects can be seen as separate objects in a microscope?

The resolving power, or resolution, is the ability to separate objects, to produce separate images of two objects.

Total Score:

Revision fun activities

Try this matching flashcards game.
If you can't see the content below, please click this link Ultrastructure of cells Quizlet matching game

Alternatively this is an Arcade game to practise the basics.

If you can't see the content below, please click this link to the Classtools Arcade game "Ultrastructure of cells"