B6 Beyond the Microscope Flashcards
What is the typical size of a bacterial cell?
A few microns (thousandths of a mm)
What may a bacterial cell have? (6) What are their functions?
- flagellum (for movement)
- cell wall (to maintain shape and prevent it from bursting)
- bacterial DNA (to control the cell’s activities and replication of the cell)
- cell membrane (controls the movement of molecules in and out of the cell)
- cytoplasm (a jelly-like substance where most of he reactions within the cell occur)
- capsule (protection against antibiotics)
What are the four main shapes of bacteria?
- Spiral
- Spherical
- Rod
- Curved rods
Describe how bacteria reproduce by splitting in to 2?
Bacteria can reproduce very quickly. Bacteria divide in to 2 different cells and reproduce asexually. This process is known as binary fission.
How can bacteria:
- can survive on an enormous range of energy sources
- van exploit a very wide range of habitats
Because some bacteria can consume organic nutrient and other can make their own.
3 unusual places where bacteria can survive
- Human
- Hot springs
- Peat bogs
Describe aseptic techniques for culturing bacteria on an agar plate
- Make sure you don’t contaminate the plate
- Keep it free of microbe or sterile
What kingdom does yeast belong in?
Fungus
How yeast growth increases for every 10’c rise in temperature?
- It doubles until the optimum temperature is reached
Comparison of viruses with bacteria and fungi
- Viruses are much more smaller in comparison to bacteria and fungi
Describe the structure of a virus
- a protein coat
- surrounding a strand of genetic material
Limitations of viruses
- Can only reproduce in other living cells
- Can only attack specific cells
- May attack plant, bacterial or animal cells
Explain how viruses reproduce
- attaches itself to a host cell
- injects its genetic material in to host cell
- using the cell to make components of new viruses
- causing the host cell to split open releasing new virus
Describe methods of how bacteria can enter the body
- nose (airborne diseases)
- mouth (contaminated food or water)
- skin (insect bites, cuts, infected needles)
- reproductive organs (contact)
How does yeast reproduce?
Yeast cells reproduce in an asexual manner by a process called budding. The nucleus divides first, then a bulge forms on the side of the parent cell, which will develop into a new cell. (Binary fusion)
The optimum growth rate of yeast can be controlled in:
- availability of food
- temperature
- pH
- amount of waste products
What does bacteria cause?
- Cholera
- Food poisoning
What does virus cause?
- Chicken pox
- Influenza
What does fungus cause?
- athlete’s foot
Prevention of entry of microbes
- Skin (physical barrier, blood clots, washing)
- Stomach (acid kills bacteria)
- Respiratory system (cilia and mucus)
- Reproductive system (acidic urine kills many microbes)
Ways which allow the entry of microbes
- Contaminated food
- Contaminate water
- Contact
- Airborne diseases
How does a natural disaster increase transmission of disease?
- Broken sewage pipes
- Damaged water supplies
- Electricity supply cut off, hence food isn’t refrigerated
- Health services become over stretched, lack of supplies
- Many homeless, diseases can be easily transmitted
Define disease
Disease is a state in which the body is not healthy
What are the four stages of infectious diseases
- entry in to body
- rapid growth; the incubation period
- production of many toxin
- appearance of symptoms
Describe the germ theory (Louis Pasteur)
- Proved that decay was caused by micro-organisms
- He went on to explain microbes entering the body cause illness
- He later proposed that if we were to stop microbes entering the body, we would stop illness developing.
Describe the development of antiseptics. (Joseph Lister)
Antiseptics are solutions which kill microbes. Lister would spray his medical equipment with carbolic acid. This killed many microbes and reduced the number of postoperative infections.
Describe the discovery of Penicillin. (Alexander Fleming)
- He discovered that a mould called penicillin produced chemicals which killed bacteria.
- The fungus grew on one of his agar plates of bacteria. It caused an area where bacteria didn’t grow because the antibiotic would kill the bacteria, preventing the formation of bacteria.
How are viruses impacted by antibiotics?
- Viruses remain unaffected by antibiotics.
- This is because viruses do not feed and do not have a cell structure to damage.
How do strains of bacteria become resistant to antibiotics?
- A mutation occurs in some bacteria which gives them resistance to the antibiotics
- Treatment by the antibiotic kills the bacteria without such a mutation
- The bacteria with the resistance survive
- The surviving bacteria reproduce, passing the resistance gene on
- Eventually the whole population becomes resistant
How can the formation of resistant strain be avoided?
- Only prescribing antibiotics when required
- Completing the entire course
Place where bacteria is used
- Yoghurt making
- Cheese production
- Vinegar production
- Silage production
- Composting
Describe the process of making yoghurt
- Sterilisation of equipment
- Pasteurisation of milk
- Incubation of culture
- Sampling
- Addition of flavours, colouring and packaging
Purpose of Lactobacillus
- Breakdown of lactose in milk
- Production of lactic acid
What is fermentation?
Fermentation is the production of alcohol, beer and wine, by the breakdown of sugars by yeast in the absence of oxygen
Describe what is meant by pasteurisation and why it has to be done in the case of bottled beers
The product is heated and cooled quickly to kill any remaining microbes to give it a longer shelf life.
Word equation for fermentation
Glucose(sugar) —-> Ethanol (alcohol) + carbon dioxide
Some products can further be treated to increase the alcohol concentration to produce spirits.
T/F
True
Describe the main stages of brewing beer or wine
- Extracting sugar from source material
- Adding yeast, keeping it warm
- Preventing entry of any oxygen or other microorganisms
- Extracting the wine and beer (clarifying by a filtration process to purify)
- Pasteurising/Packaging
Explain how plants produce biomass
Photosynthesis produces the biomass within the plants, and this biomass can be directly or indirectly be used as biofuel.
Give examples of fuels from biomass
- Alcohol
- Wood
- Biogas
Describe different methods of transferring energy from biomass fuels
- burning fast growing trees
- fermenting biomass using bacteria or yeast
Advantages of using biofuels
- alternative source to fossil fuels
- no increase in greenhouse gas levels
- no particulates produced