1. Year 8 Science Seaview High School
Cells
Year 8 Science
Seaview High School

2. What do we already know? Onion skin cells X40 X100 Cheek cells X40

3. What do we already know? Mag: x100 If we are not careful, air
bubbles can form when
the cover slip is lowered.
These are of little interest.
Focus on drawing the cells.
Onion skin cell 14/5/2015
This diagram shows a sample of
onion skin cells. The dark circles
are the nucleus and the lines are
the cell walls.

4. How big is a single cell?

5. Types of microscope

6. Types of microscope

7. Electron microscope images
Bacteria
Psuedomonas aeruginosa

8. More images

9. So, what are cells? Building blocks that make up all living things.
Living things (organisms) can be made up of one cell (unicellular) or many cells (multicellular).
The cells themselves are made up of smaller structures. We will discuss these tomorrow.
Organisms can be classified (sorted out) based on the type of cells they are made of.

10. How big are these cells? Differs between organisms.
Multicellular organisms can have different sized cells within them.
In most cases, too small to see without a microscope.
Why so small?
Being small helps to get things in and out.
If they were big, this would take longer and cells couldn’t react quickly enough to stay healthy.

11. The nucleus
The first types of organisms to appear on Earth were the prokaryotes.
Prokaryotes do not contain a defined nucleus or other defined structures.
Billions of years later, the eukaryotes appeared.
Eukaryotic cells have a defined nucleus and contain other structures (organelles).
Members of the kingdoms animalia, plantae, protista and fungi are all eukaryotes.

12. The eukaryotic cell

13. The prokaryotic cell

14. What do we all share? Most cells are similar to the eukaryotic cell.
They have a membrane that contains fluid called cytosol and other smaller structures called organelles.
This is where the chemical processes that support life occur. These processes are called ‘metabolism’.

15. All on their own
While multicellular organisms (like us) have lots of cells to share the workload, single-celled organisms have only one cell to do it all.

16. Single celled amoeba

17. The five kingdoms Animalia (animals) Plantae (plants)
Fungi (mushrooms,
yeast, mold)
Protista (algae)
Monera (bacteria)

18. A classification key

19. What is the benefit of being a multicellular organism?
Many different types of cells that do different jobs.
Different structure; specialised to do the required job.

20. Specialised cells in the human body
Red blood cell
Skin cells
Nerve cell
Adipose cell
(fat storage)
Sperm cell
Bone cell
Muscle cell
Lung epithelial cells
Egg cell

21. Quiz time! 1) what do all living things have in common?
2) What is the difference between a prokaryotic cell and a eukaryotic cell?
3) What are the 5 kingdoms? Which one of these contains the prokaryotes?
4) Why are there 5 kingdoms and not just plants and animals?
5) Which unit of measurement do we need to measure most cells?