1. Structure & Function of Cells
Living Cells
Structure & Function of Cells
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.
Tuesday, December 04, 2018
Mr G Davidson

3. Animal Cell Structure Cell membrane Nucleus Cytoplasm
Tuesday, December 04, 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
Tuesday, December 04, 2018
Mr G Davidson

5. Plant Cell Structure Nucleus Cell wall Cell membrane Cytoplasm Vacuole
Chloroplast
Cytoplasm
Tuesday, December 04, 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”
Tuesday, December 04, 2018
Mr G Davidson

7. Cellular Structure Cells are too small to be seen with the naked eye.
We use a light microscope to study cells.
Stains are often used to make certain parts of the cells more visible, e.g.
Methylene blue is often used to stain animal cells
Iodine solution is often used to stain plant cells.
Tuesday, December 04, 2018
Mr G Davidson

8. Microbial Cells A microbe is a microscopic unicellular organism.
Microbes are found almost everywhere that life can exist.
Microbes exist in huge numbers.
They can usually reproduce very quickly.
Tuesday, December 04, 2018
Mr G Davidson

9. Microbial Cells
Some can cause disease and some can cause things to rot (decompose).
Others are useful, e.g. bread-making, wine-making, recycling, etc..
There are different types of microbe, e.g. bacteria, yeast, etc.
Tuesday, December 04, 2018
Mr G Davidson

10. Yeast Yeast is a unicellular fungus. Yeast cells are not mobile.
Yeast can be used to change sugar into alcohol and carbon dioxide in a process called fermentation.
Yeast +
Sugar
Alcohol +
Carbon dioxide
Tuesday, December 04, 2018
Mr G Davidson

11. Uses of Yeast
Humans have made use of yeast for thousands of years for such things as:
Baking
Wine making
Brewing
Tuesday, December 04, 2018
Mr G Davidson

12. Baking Alcohol Yeast + + Dough Carbon + dioxide Sugar When the dough
is cooked the
alcohol evaporates
Alcohol
Yeast + +
Dough
Carbon
dioxide +
Sugar
Carbon dioxide
makes the
dough rise
Tuesday, December 04, 2018
Mr G Davidson

13. Wine Making Alcohol Yeast + + Sugar from Carbon fruits dioxide
Alcohol used to
make wines &
spirits for drinking
Alcohol
Yeast +
Alcohol can also
be used as an
alternative fuel +
Sugar
from
fruits
Carbon
dioxide
Carbon dioxide
is released as
a waste product
Tuesday, December 04, 2018
Mr G Davidson

14. Brewing Yeast Alcohol + Malted + barley Carbon + dioxide Hops
Alcohol used to
make beers
Yeast
Alcohol
Starch in
barley
changed
to sugar +
Alcohol can also
be used as an
alternative fuel
Malted
barley +
Carbon
dioxide +
Used to
add
flavour
Hops
Carbon dioxide
is released as
a waste product
Tuesday, December 04, 2018
Mr G Davidson

15. Bacteria
Bacteria are useful for some things as well, such as making yoghurt.
Bacteria feed on a sugar found in milk called lactose.
This sugar is converted to lactic acid by the bacteria.
It is the lactic acid which turns the milk into yoghurt.
Tuesday, December 04, 2018
Mr G Davidson

16. Antibiotics
Antibiotics are substances which prevent the growth of bacteria.
Penicillin was the first antibiotic and it was discovered by Alexander Fleming in 1928.
He was growing bacteria and discovered that a fungus has contaminated his plates and that no bacteria were growing near the fungus.
Tuesday, December 04, 2018
Mr G Davidson

17. Alexander Fleming
Tuesday, December 04, 2018
Mr G Davidson

18. Antibiotics Bacteria are less sensitive to this antibiotic
resistant to
this antibiotic
“Clear area”
indicates no
bacterial growth
Bacteria
Tuesday, December 04, 2018
Mr G Davidson

19. Antibiotics
Many other antibiotics have now been discovered and they are produced by fungi.
Bacteria which cannot grow near an antibiotic are said to be sensitive to the antibiotic.
Tuesday, December 04, 2018
Mr G Davidson

20. Antibiotics
Bacteria which do grow near an antibiotic are said to be resistant to the antibiotic.
A wide range of antibiotics are, therefore, required to combat the wide range of bacteria that exist.
There are effectively 2 groups of antibiotics:
Narrow-spectrum antibiotics which are useful against a few specific species of bacteria.
Wide-spectrum antibiotics which are useful against a wide range of species of bacteria.
Tuesday, December 04, 2018
Mr G Davidson