1. National 5 Biology
Cell Structure
Mr G Davidson

2. Cellular Structure
Cells are the living units from which all organisms are made.
Simple organisms have only one cell and are unicellular, e.g. bacteria.
Other organisms have many cells working together and are multicellular, e.g. humans.
Monday, September 17, 2018
Mr G Davidson

3. Animal Cell Structure Cell membrane Ribosome Nucleus Mitochondrion
Cytoplasm
Monday, September 17, 2018
Mr G Davidson

4. Animal Cell Structure Cell Structure Function Nucleus Cytoplasm
Controls cell activities and passes on information to the next generation
Cytoplasm
Site of all biochemical reactions
Cell membrane
Controls what enters and leaves the cell
Mitochondrion
Site of aerobic respiration
Ribosomes
Site of protein synthesis
Monday, September 17, 2018
Mr G Davidson

5. Plant Cell Structure Nucleus Ribosome Cell wall Cell membrane
Mitochondrion
Sap vacuole
Chloroplast
Cytoplasm
Monday, September 17, 2018
Mr G Davidson

6. Plant Cell Structure Cell Structure Function Chloroplast Cell wall
As well as the same structures found in animal cells,
the following structures are also found in plant cells only.
Cell Structure
Function
Chloroplast
Contains chlorophyll which traps light energy to be used in photosynthesis
Cell wall
Made of cellulose and supports the structure of the cell
Vacuole
Stores water and solutes as a solution called “cell sap”
Monday, September 17, 2018
Mr G Davidson

7. Fungal Cell Cell membrane Mitochondrion Cell wall Nucleus Cytoplasm
Vacuole
Cytoplasm
Monday, 17 September 2018
G Davidson

8. Fungal Cell Structure An example of a unicellular fungus is yeast.
It has structures in common with both animal and plant cells.
These structures carry out the same functions.
Monday, 17 September 2018
G Davidson

9. Bacterial Cell
Monday, 17 September 2018
G Davidson

10. Bacterial Cell Structure
Bacterial cells can be all different shapes.
The structures within the bacterial cell are much the same as animal cells.
The main difference is a lack of a nucleus.
Bacterial cells have plasmids which are circular rings of DNA as well as a large circular DNA.
The cell wall is different from a plant cell wall in that it is kind of slimy.
Monday, September 17, 2018
Mr G Davidson

11. Cell Sizes Cells cannot be seen without the aid of a microscope.
They are so small that we used units called micrometres(μm) or microns to measure them.
There are 1000 microns in 1 millimetre.
Monday, 17 September 2018
G Davidson

12. Cell Sizes
We can estimate the sizes of cells by knowing the diameter of the field of view.
e.g. if the field of view is 2mm which is 2000μm, and there are 8 cells stretching from one side to the other, then each cell must be 250μm. (2000/8)
Monday, 17 September 2018
G Davidson

13. Cell sizes Field of View This field of view is 1mm.
Estimate the size of each cell.
Answer – 62.5μm
Monday, 17 September 2018
G Davidson

14. Cell Sizes
We can magnify the size of the cells using the lenses on the microscope.
Total magnification = eyepiece x objective
e.g. if the objective lens is x20 and the eyepiece is x10, then the total magnification will be x200.
If we increase the magnification of the microscope the number of cells we see in the field of view decreases.
Monday, 17 September 2018
G Davidson