B4 - Microbes
- Created by: Naomi
- Created on: 20-01-13 21:38
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- Microbes
- Bacteria
- Bacteria have certain features that allow them to survive, these include:
- A cell wall to maintain shape and stop it from bursting
- A flagella for movement
- DNA to control the cells activities and replication of the cell
- 3 different shapes:
- Bacilla (rod shape)
- Cocci (spherical)
- Spirilla (spiral)
- Reproduce asexually by splitting into 2. They clone themselves
- Called binary fission
- Bacteria are very successful in terms of numbers because:
- They can survive on an enormous range of different energy sources
- They can live in a wide range of habitats
- Some live by taking in organic nutrients, others can make their own food
- Reproduce very quickly
- Bacteria have certain features that allow them to survive, these include:
- Viruses
- Not living cells, but made up of a protein coat surrounding a strand of genetic material
- They can only reproduce in other living cells
- 1. They attach themselves to a host cell
- 2. Inject its genetic material into the cell
- 3. Use the cell to make components of the new virus
- 4. Cause the host cell to split open and die to release the virus
- 3. Use the cell to make components of the new virus
- 2. Inject its genetic material into the cell
- 1. They attach themselves to a host cell
- Yeast
- Yeast is a single celled fungus that is grown for many functions
- Its growth rate can be altered by:
- Changing temperature
- The growth rate doubles for every 10 degree rise in temperature until the optimum
- Changing pH
- Changing food availability
- Removing waste products
- Changing temperature
- Fermentation
- The process of fermentation in yeast involves anaerobic respiration
- glucose ---> ethanol+carbon dioxide
- When yeast is used in brweing it soon uses up all the oxygen in the container by respiring aerobically. This allows the number of cells to increase rapidly
- The conditions are kept anaerobic so that alcohol is made
- The process of patturisation is brweing ot kill harmful microbes. The liquid is kept at an elevated temperature for a predetermined time
- The alcohol concentration produced by brewing is limited . This is because high concentrations of alcohol kills yeast cells
- The process of fermentation in yeast involves anaerobic respiration
- Yoghurt making
- 1. All the equipment is stepilised using aseptic techniques
- 2, The milk is pasteurised by heating it to 78 degrees
- 3. The milk is cooled down and is incubated with a culture of bacteria
- The milk has to be cooled so that the bacteria isn't killed when it is added
- The bacteria that is added is called lactobacillus
- It causes the breakdown of lactose in milk into lactic acid, which makes the yoghurt taste acidic
- 3. The milk is cooled down and is incubated with a culture of bacteria
- 2, The milk is pasteurised by heating it to 78 degrees
- 1. All the equipment is stepilised using aseptic techniques
- Disease transmission
- Disease causing microorganisms can be passed on in a number of different ways
- Some microbes, such as salmonella, are spread in food
- They can be prevented from spreading by correct food hygiene
- Some, such as cholera, may be spread in water
- They can be prevented by correct water treatment
- Other microbes need direct contact
- They can be prevented from spreading by barrier methods
- Many microbes, such as those that cause flu are spread in airbourne droplets
- They can be stopped from spreading by correct use of tissues and isolation of patients
- Some microbes, such as salmonella, are spread in food
- There are four stages in an infectious disease
- 1. The microbe enters the body
- 2. It reproduces many times without causing symptoms. This is called the incubation period
- 3. The microbes cause the production of many toxins
- 4. These toxins cause symptoms
- 3. The microbes cause the production of many toxins
- 2. It reproduces many times without causing symptoms. This is called the incubation period
- 1. The microbe enters the body
- Disease causing microorganisms can be passed on in a number of different ways
- Treatment of disease
- Many scientists have made important discoveries that have helped prevent microbes from causing disease
- Louis Pasteur
- Helped prove germ theory of disease by realising that microbes from the air could make food go bad
- Joseph Lister
- Invented the first antiseptic
- Antiseptics are used outside of the body to kill microbes and prevent their entry
- Work on most microbes
- Antiseptics are used outside of the body to kill microbes and prevent their entry
- Invented the first antiseptic
- Sir Alexander Fleming
- Discovered the first antibiotic penicillin, which is made from a fungus
- Antibiotics are used inside the body to kill microbes
- Have no affect on viruses
- Antibiotics are used inside the body to kill microbes
- Discovered the first antibiotic penicillin, which is made from a fungus
- Louis Pasteur
- Problems are occuring because some bacteria are developing resistance to antibiotics
- This resistance appears in bacterium by a mutation
- Because bacteria can the survive and reproduce the resistance is spread by natural selection
- To try and prevent spreading, docator take various steps
- They only prescribe antibiotics when really necessary
- They advise patients to finish the dose so partially resistant bacteria are killed
- To try and prevent spreading, docator take various steps
- Because bacteria can the survive and reproduce the resistance is spread by natural selection
- This resistance appears in bacterium by a mutation
- Many scientists have made important discoveries that have helped prevent microbes from causing disease
- Bacteria
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