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Flashcards in B6 Deck (46):

Define: bacteria

• Microscopic single-celled organisms
• Smaller & simpler than animal and plant cells
• Largest bacteria is only a few microns long


How do bacteria cells differ from plant and animal cells?

• Simpler
• Don't have a 'true' nucleus, mitochondria, chloroplasts or a vacuole


What do bacteria cells have?

• A flagellum (whip-like tail) for movement
• Have a cell wall to maintain shape and stop the bacterium from absorbing water and bursting
• Have bacterial DNA for cell replication and to control the cell's activities


How can a bacterial cells be classified?

By it's shape
- spherical
- spiral
- rod
- curved rod


Where do bacteria source their food/energy?

• Some bacteria fees on organic nutrients
• Some bacteria make their own food in a similar way to plants


As bacteria can use so many different types of nutrients and energy, they're extremely adaptable meaning they can...

• Survive in by variety if different habitats such as:
- hot springs
- acid peat bogs
- inside humans


How do bacteria reproduce? What is this called?

• They reproduced asexually by splitting in two
• This is called binary fission


What do bacteria need to reproduce rapidly?
How are they produced commercially?

• The right conditions
• They can be grown commercially on a large scale in tanks called fermenters


Bacteria grow and reproduce quickly which can mean..?

• Diseases spread quickly as conditions inside the human body are ideal for bacterial growth (warm, moist, food available)
• Food can become contaminated by bacteria and toxic waste produced by bacteria as they feed. Food spoils very quickly.


What is a virus?

• Not living cells
• Can only reproduce in other living cell
• Attack specific cells and can infect plant, bacteria or animals cells.
• Much caller than bacteria or fungi


Describe the three stages of how a virus attacks a living cell.

1. The virus attaches to a host cells and injects it's genetic material into the cell
2. It uses the cells to make components for a new virus
3. The host cell splits up to release the virus


What is yeast and how does it reproduce?

• A single-celled fungus
• They reproduce asexually by 'budding'


What do yeast require to reproduce quickly?

• Lots of sugar
• Optimum temperature and pH
• The removal of waste products, such as alcohol, which poison hone yeast


Describe the process of 'budding'

• Chromosomes are copied and new nucleus is made
• The new cell 'buds' off the parent


Describe trends between temperature and yeast growth.

• The growth rate of yeast doubles with every 10° rise in temperature
• Increasing the temperature increases the rate of growth
• However, above 40° the yeast enzymes become denatures and slows the growth rate


What is the aseptic technique? + Give advantages of this method.

• Growing and transferring bacteria
• Without contamination
• Without any loss of microbes to the surroundings


Describe the stages of the aseptic technique.

1. Sterile agar plates prepared with nutrient agar (containing food and water microbes needed for growth)
2. Use a sterile swab to wipe across the area you wish to test for microbes
3. Quickly, lift just a corner of the agar plate (just enough to wipe the swab across the surface of the agar)
4. Swiftly replace the lid and seal it down
5. Incubate in warm place, after 24 hours colonies of bacteria will become visible. Do not re-open.


Why is it important to using the aseptic technique when handling bacteria?

• Ensures no unexpected harmful bacteria are grown in large amounts which could make people ill
• Safeguards people from being exposed to pathogenic microbes


What is a pathogen? Give examples.

• Pathogens are microorganisms that cause disease. Some bacteria are pathogens. Viruses and fungi can also be pathogens.


When will you begin to feel symptoms due to a pathogen producing toxins?

• Pathogens reproduce very quickly once inside the body
• This is know as the incubation period and initially there might not be symptoms
• As they multiply, the pathogens begin to produce toxins, which start to produce symptoms such as fever


How might pathogens enter the body? (4 points)

1. Airborne microorganisms enter through your nose
2. Microorganisms in contaminated food enter thought the mouth
3. Microorganisms can also be injected into the skin e.g. Insect bites, infected needles & wounds
4. Microorganisms can be passed on through the reproductive organs during sex


What illnesses does bacteria cause & how is it transmitted?

• Cholera + Food poisoning
• Contaminated water


What illnesses do virus' cause and how are they transferred?

• Influenza --> airborne droplets
• Chickenpox --> direct contact/ airborne droplets


What illness does fungi cause and how is it transferred?

• Athlete's foot
• Direct contact


Why do diseases spread quickly after natural disasters?

• Sewage systems and water supplies can be damages and therefore drinking water becomes contaminated
• Electrical supplies can be damaged so fridges/freezers stop working causing food to go off more quickly
• Energy supply disruptes, hard to cook food properl
• Hospitals and medical centres destroyed
• Roads and infrastructure damaged, sick p/injured harder to reach


What theory did Louis Pasteur come up with in the 1860's?

• Showed that microorganisms were in the air and were the cause of food decay - not the air itself which people had thought at the time
• This led to the Germ Theory of Disease which explained that microorganisms, passed from one person to another, caused many diseases


How was the concept of antiseptics discovered and by whom?

• 1865 by Lister
• Realised spraying wounds with carbolic acid prevented wound infections
• Carbolic acid is an antiseptic as it kills bacteria
• Antiseptics are still used today to kill bacteria in wounds on the skin, preventing the spread of disease.


How and when did Fleming discover penicillin as an antibiotic?

• 1928
• When so e of his bacterial culture plates got contaminated with penicillin mould he noticed that the mould killed the surrounding bacteria
• He used the mould to make the first antibiotic


How do bacteria develop a resistance to antibiotics?

• Through natural selection
• One bacterium may survive the antibiotic treatment due to genetic change
• The bacterium will then rapidly multiply, producing millions of antibiotic resistant bacterial cells
•This leads to an infection resistant to antibiotics


Name five useful types of bacteria.

• compost
• silage (winter feed for cattle)
• vinegar
• cheese
• yoghurt


Describe the stages do making yoghurt?

1. Equipment is sterilised using steam to kill any pathogens
2. Raw milk is heated to 80° to kill bacteria, the quickly cooled (pasteurisation)
3. A live bacterial culture is added to the warm milk. The mixture is incubated for several hours
4. The bacteria reproduce and feed on lactose sugar in the milk, producing lactic acid, which gives a sharp taste to the yoghurt and thickens and preserves it.
5. Manufacturer samples the yoghurt for consistency and flavour
6. Flavours and colours may be added before packaging


What bacteria feed on the lactose sugar in milk and give the yoghurt it's taste and texture? HT

• lactobacillus


What type of respiration is fermentation yeast?

• Anaerobic


What is the useful product of fermentation?

• Alcohol


What happens in the process of fermentation?

• Sugars are broken down by yeast in the absence of oxygen to produce the alcohol


What gives an alcoholic drink it's taste/flavour when added to the fermented yeast and sugar?

• fruits
• seeds


Give the word and symbol equation for fermentation.

Glucose ---> ethanol + carbon dioxide
C6H12O6 ---> 2C2H5OH + 2CO2


What do yeast cells feed on?

• sugars


How does yeast respire?

• It can respire with aerobically or anaerobically to release energy from sugar


What type of respiration do brewers desire when producing alcohol and why?

• Anaerobic respiration as alcohol is a by-product


How is beer pasteurised? Why is this done?

• By heating it to 72° for 15 seconds, then cooling quickly
• Kills harmful microorganisms but doesn't affect the taste much
• This needs to be done to bottled beers to prevent spoilage microbes


What factor affects how strong a beer can brewed?

• Some strains of yeast can tolerate higher concentrations of alcohol so they can be used to brew stronger beers


What is distillation?

• Distillation of alcoholic drinks makes the alcohol more concentrated and is used to produce spirits
• As it produces very strong alcoholic drinks, distillation can only be done on licensed premises, it's a commercial process


What are the two stages of distillation?

• The liquid is heated to evaporate the alcohol
• The concentrated alcohol is trapped and cooled (condensed) back into a liquid


What is biomass?

• Plants grow new plant tissues by using some glucose from photosynthesis to produce starch and cellulose
• This new material is biomass


Give example of biomass

• Fast growing trees - e.g. Pine burned to release energy
• manure or other waste - broken down by bacteria or yeast in a fermenter to release methane (biogas) which can be used to power electricity generators
• Sugar cane - broken down by yeast in a fermenter to produce alcohol