B6 Bacteria

HideShow resource information
  • Created by: Qiao-Chu
  • Created on: 10-04-13 08:50

Bacterial Cells

Smaller and simpler than animal cells

Have cell wall to keep shape and prevent bursting

Strand of DNA in cytoplasm controlling cell activities and replication

Several small loops of DNA called plasmids

Flagellum (tail) to help move

Can come in rods, curved rods, spheres and spirals

Consume wide range of organic nutrients - provides energy

Some bacteria provide own nutrients

Can survive in almost any habitat e.g. air, soil, water, human, food

Cell wall, cytoplasm, DNA strand, flagellum, plasmid, cell membrane

1 of 4

Asexual Reproduction

Bacteria are clones of each other

Reproduce by process of binary fission

Reproduce very quickly

Disease-causing bacteria can reproduce and cause disease before body has chance to react

Reproduce faster when in warmth and good supply of nutrients

Important to store food carefully

Fridges slow down bateria's reproduction because cold so wouldn't spoil quickly

2 of 4

Aseptic Technique for Culturing Bacteria

Culture means to grow bacteria on an agar plate - Petri dish containing agar jelly

Bacteria can be transferred to plate from sample using wire inoculation loop

Must use aseptic technique to protect from infection and agar being contaminated by other microbes

Wear gloves and keep long hair tied back

Sterilise equipment before and after - pass inoculation loop through Bunsen burner flame to kill unwanted bacteria

Sealing dish after bacteria transferred

Disposing cultures safely after use - pressure sterilising in an autoclave

3 of 4

Bacteria in Use (Yoghurt)

Equipment sterilised to kill unwanted microorganisms

Milk pasteurised (heated to 72 degrees Celsius for 15 seconds) again to kill unwanted microorganisms, then cooled

Starter culture of Lactobacillus bacteria added, mixture incubated (heated to 40 degrees Celsius) in a vessel called fermenter

Bacteria breaks down lactose sugar in milk to lactic acid causing milk to clot and solidify

Sample taken to make sure consistency is correct then flavours and colours added then yoghurt packed

Bacteria also used to make cheese, vinegar, silage (animal feed) and compost

4 of 4


No comments have yet been made

Similar Biology resources:

See all Biology resources »See all Microbes and disease resources »