Hey there! Sign in to join this conversationNew here? Join for free
x Turn on thread page Beta
    • Thread Starter
    Offline

    0
    ReputationRep:
    hi
    im jus revising for the triple bilogy exam paper tomorrow and i got stuck on a few questions..can anyone help?

    Describe in a detail a method you could use to count the number of living bacteria in a sample of water..
    (is that the mthod using agar jelly??) :confused: :confused:

    decribe how large amounts of human growth hormone can be made from genetically engineered bacteria.

    help would really be appreciated
    cheers
    Offline

    15
    ReputationRep:
    (Original post by Dust)
    hi
    im jus revising for the triple bilogy exam paper tomorrow and i got stuck on a few questions..can anyone help?

    Describe in a detail a method you could use to count the number of living bacteria in a sample of water..
    (is that the mthod using agar jelly??) :confused: :confused:

    decribe how large amounts of human growth hormone can be made from genetically engineered bacteria.

    help would really be appreciated
    cheers
    triple biology. i did that a week ago. what board are you studying?
    • Thread Starter
    Offline

    0
    ReputationRep:
    edexcel...
    wat bout u?
    Offline

    15
    ReputationRep:
    i did AQA.
    • Thread Starter
    Offline

    0
    ReputationRep:
    (Original post by Dust)
    hi


    Describe in a detail a method you could use to count the number of living bacteria in a sample of water..
    (is that the mthod using agar jelly??) :confused: :confused:

    decribe how large amounts of human growth hormone can be made from genetically engineered bacteria.

    cheers

    cmon some1s gotta no!!
    Offline

    0
    ReputationRep:
    for the growth hormone, you 'cut' out the gene that codes for its manufacture using restriction endonucleases (specific enzymes) . You then cut open a bacterial plasmid, and insert the gene you cut out (into the plasmid), again joining it with enzymes. The plasmid is then replaced in a suitable bacterial cell, which can be cultured (so you have lots of them) and they will produce the hormone required.
    Offline

    0
    ReputationRep:
    Im not definite about the counting bacteria, but the only way i can think is to look at a small area of the sample under a microscope, count the number in that region, then multiply it by (total size/sample size) to give an approximation of the full number!
    Offline

    1
    ReputationRep:
    (Original post by Sapphira)
    Im not definite about the counting bacteria, but the only way i can think is to look at a small area of the sample under a microscope, count the number in that region, then multiply it by (total size/sample size) to give an approximation of the full number!
    I know they dilute it several times first. For example 1 part bacteria to 9 parts water will give 1 10th of the concentration it was originally, and doing that again will get one 100th. And then they can count and use that to work out how many in the original sample.
 
 
 
Poll
Are you going to a festival?

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Write a reply...
Reply
Hide
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.