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| Question | Answer |
| What are the two types of organism? | Prokaryotic and Eukaryotic |
| What are prokaryotic and eukaryotic organisms made up of? | Prokaryotic organisms are made up of prokaryotic cells (They're single-celled organisms). Eukaryotic organism are made up of eukaryotic cells. |
| What type of cell is a eukaryotic cell and what cells does it include? | It's a complex cell, which includes all animal and plant cells. |
| What type of cell is a prokaryotic cell and what cells does it include? | It's a smaller, simpler cell and the main example of a prokaryotic cell is bacteria. |
| What 6 organelles make up a prokaryotic cell and describe what they are made of (for some) and their functions? | 1) Plasma Membrane - which is made of mainly lipids and proteins. It controls the movement of substances into and out of the cell. 2) A cell wall - It supports the cell. The cell wall is made of a polymer called peptidoglycan. 3) Plasmids - Which are small loops of DNA that aren't part of the chromosome. They contain genes for things like antibiotic resistance, and can be passed between bacteria, (they are not always present in bacteria). 4) DNA - in a bacterium it floats free in the cytoplasm. It is circular DNA, which is present as one coiled-up strand. 5) Capsule - not all bacteria have this. It is made up of secreted slime, and it helps to protect the bacteria from attack be cells of the immune system. 6) Flagellum (1) or Flagella (2+) - not all bacteria have one. It is a long, hair-like structure that rotates to make the bacteria move. |
| What type of organism is a cholera bacterium? | A Prokaryotic Organism |
| What does a cholera bacterium produce? | A toxin. |
| What does the toxin that cholera bacterium produce, do? | It causes chloride ion protein channels in the plasma membranes of the small intestine epithelial cells to open. Therefore, the choride ions move into the small intestine lumen, this lowers the water potential of the lumen. Water then moves out of the blood, across the epithelial cells, and into the small intestine lumen by osmosis. The massive increase in water secretion into the intestine lumen leads to really, really, really bad diarrhoea, which causes the body to become extremely dehydrated. |
| What can be used to treat diarrhoeal diseases? | Oral Rehydration Solutions |
| What do oral rehydration solutions do? | They replace the fluid which has been lost due to the diarrhoea, in a way that is viable for all countries (as not everywhere in the world has access to drips - which is the fastest way to rehydrate). |
| Explain how Oral Rehydration Solutions work? | It is a drink that contains large amounts of salts (such as sodium ions and chloride ions) and sugars (such as glucose and sucrose) dissolved in water. The sodium ions are included to increase glucose absorption (sodium and glucose are co-transported into the epithelial cells of the small intestine). Getting the concentration of the ORS right is essential for effective treatment. ORS' are very cheap treatment and the people administrating it don't require much training. This makes it a great way to treat diarrhoeal diseases in developing countries (where they are a huge problem). |
| What are scientists doing for ORS'? | They are researching and developing new, improved ORS', as they are so important in the treatment of diarrhoeal diseases. |
| What problems do scientists developing ORS' have to overcome? | The ORS' must be put into use to show that they are more effective than the the old ones, and to show that they are safe. This has to be done by clinical testing on humans, but there are ethical issues with this. Ethical Issues: 1) Diarrhoeal diseases mostly affect children, so many trials involve children. Parents decide whether their child takes part (the child doesn't make their own decision) - some people think this is unethical. Scientists believe that the treatment must be trialled on children to show that it is effective against a disease that mainly affects children. 2) Clinical trials usually involve a blind trial. This is where some people will get the new treatment and some people will get the old treatment, but the patients wont know what treatment they have had to keep the test fair. Some people think this is unethical as people have the right to chose what treatment they want to have. 3) When a new ORS is first trialled, there's no way of knowing whether it'll be better than the current ORS - which means there is a risk of the patient dying when the original and better treatment was available. |
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