Unit 1 – Living Cells Topic 2 – Microbes! Types of Microbes Controlling the growth of microbes Microbes in industry

Controlling the growth of microbes LEARNING OUTCOMES Name 2 characteristics about how microbes grow and reproduce State what antibiotics do State what antifungals do State what antivirals do

Think / Pair / Share You have seen microbes grow on agar dishes These dishes have now been destroyed What would happen to the microbes if we left them in the incubator? Why do you think we should control how microbes grow? How do you think we can do control the growth of microbes?

Microbial Growth Microbes, such as bacteria and yeast, have many characteristics that help them to reproduce, such as being able to reproduce asexually and grow rapidly. http://www.youtube.com/watch?v=gEwzDydciWc

Controlling the growth of Microbes 1 Microbes need a suitable temperature to reproduce. Placing microbes in cold temperatures (fridge) slow down the growth of microbes. Placing microbes in very hot temperatures (oven) can destroy microbes.

Controlling the growth of Microbes 2 Special chemicals can be used to PREVENT the microbes from growing any further. These chemicals can be found in: cleaning products such as bleach or disinfectant or in medicinal products like: AntiBiotics are used to treat Bacterial infections (bacteria) AntiVirals are used to treat Viral infections (viruses) AntiFungals are used to treat Fungal infections (fungi)

Alexander Fleming (1881 –1955) The Discovery of Penicillin and Antibiotics VIDEO (2.20 mins) http://www.youtube.com/watch?v=tMPY-zf8X94

Alexander Fleming (1881 –1955) we now call them antibiotics. Alexander Fleming accidentally discovered penicillin (an antibiotic) He was throwing out old mouldy bacterial cultures when he noticed that they had clear areas around the mould He concluded that the mould was secreting a chemical that was killing the bacteria He isolated the chemical The mould was called Penicillium so he called the substance penicillin Fleming’s discovery led to the discovery of many similar substances we now call them antibiotics.

Antibiotic Disk Bacteria can be grown all over nutrient agar in a petri dish Then an antibiotic can be added. Antibiotics stop bacteria from growing. Antibiotic NO bacteria growing Bacteria growing

Clear zone (NO bacteria growing) Diameter of clear zone

Antibiotic Multi-disks We can use SEVERAL antibiotics to see which one is more effective at stopping the growth of bacteria.

Antibiotic Multi-disks Aim: To investigate… Measurements to be made: Which antibiotic is more effective at stopping the growth of bacteria The diameter of the clear zone, in cm, using a ruler

Antibiotic Multi-disks Results: Conclusion: (answer your aim and link in your results)

Antibiotic Multi-disks Results: Conclusion: Antibiotic Diameter of CLEAR ZONE (cm) P S TE C E G Antibiotic ____ was the most effective at stopping the growth of the bacteria because it had the ______ clear zone.

Controlling the growth of microbes LEARNING OUTCOMES Name 2 characteristics about how microbes grow and reproduce State what antibiotics do State what antifungals do State what antivirals do

Controlling the growth of microbes LEARNING OUTCOMES Explain what is meant by ‘resistant’ bacteria Explain what is meant by ‘sensitive’ bacteria

Resistant Vs Sensitive bacteria Region of bacterial growth (Bacteria is resistant here) Not all antibiotics are as effective as each other. What is the best antibiotic? What are the worst antibiotics? ‘best’ and ‘worst’ are not scientific terms. Instead we can use ‘resistant’ and ‘sensitive’ Region of no bacterial growth (Bacteria is sensitive here)

Resistant Vs Sensitive bacteria If bacteria is prevented from growing it is said to be sensitive to the antibiotic And if the bacteria is not affected it is said to resistant to the antibiotic. From the antibiotic multi disk diagram, the bacteria is resistant to antibiotics _______ And the bacteria is sensitive to antibiotics _______ P and E G, S, C and TE

Antibiotics / destroyed / resistant / over-use Resistant Bacteria Resistant bacteria are not killed by antibiotics. This is because the bacteria are too ‘strong’ to be destroyed. More and more bacteria are becoming resistant to antibiotics. The main reason is because we over-use them! Antibiotics / destroyed / resistant / over-use

Controlling the growth of microbes LEARNING OUTCOMES Explain what is meant by ‘resistant’ bacteria Explain what is meant by ‘sensitive’ bacteria