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    can anybody Define Genetic code?

    thanks
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    right, can anyone tell me the ratios i need to know for genetics, i can remember dihibrid crosses should be 9:3:3:1 , if not it must be because of epipstasis, any others..
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    (Original post by greenford)
    can anybody Define Genetic code?

    thanks
    The Genetic code is the set of rules by which information encoded in DNA or RNA is translated into proteins by living cells. The code defines a mapping between tri-nucleotide sequences, called codons, and amino acids
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    (Original post by rebeccalouise_92)
    right, can anyone tell me the ratios i need to know for genetics, i can remember dihibrid crosses should be 9:3:3:1 , if not it must be because of epipstasis, any others..
    Unlinked genes - 9: 3: 3:1

    Recessive - 9: 3:4

    Donminant - 12: 3:1 or 13: 3

    Complemntry action - 9:7
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    The plant hormones auxins seem very undecided as to what they want to do.

    -A high concentration of auxins inhibit growth in roots. However auxins can be used as rooting hormones as they make a cutting grow roots.

    -A low concentration of auxins leads to leaf loss but a high concentration of auxins causes fruit to drop.

    Correct me if I'm wrong but some of that stuff seems to conflict. Do you get different types of auxins or something?
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    (Original post by thecookiem0nster)
    PCR only works on short strands. The fragments are too long for PCR, so you need BACs and in vivo gene cloning
    omg thanks!!!
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    In the golden rice example do we need to remember the name of the gene and bacteria?
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    do you think we need to learn examples of epistasis anyone?
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    (Original post by CoventryCity)
    In the golden rice example do we need to remember the name of the gene and bacteria?
    The specification just says: "Outline the process involved in the genetic engineering of "Golden Rice"

    OCR usually give marks for detail like names, especially if its AVP

    So I would learn them just to be on the safe side.

    Photoene synthase from a daffodil

    Crt1 from a bacterium

    And Lycopene synthase is already present in the endosperm
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    (Original post by rebeccalouise_92)
    do you think we need to learn examples of epistasis anyone?
    The spec only says describe, so I dont think we need to know them.

    But if you still want to learn one, then in the june 2010 f215 they had a question on drosophila eye colour, which is an epistatic relationship involving 3 loci (i think)
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    Need to go over module 1, Definitions, Past papers all by 12.30 tomorrow!
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    Teacher just emailed and said make sure you revise this for you're synoptic revision:

    - focus on photosynthesis and respiration as it links in to ecology
    - Also, check through your organelles and nerve impulses.
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    (Original post by greenford)
    can anybody Define Genetic code?

    thanks
    Its the sequence of nucleotide bases which codes for the construction of a protein/ polypeptide.
    It has some key features;
    It is a triplet code; 3 nucleotide bases code for one amino acid.
    It is a degenerate code, all amino acid except methionine have more than one code.
    It is widespread, but not universal
    Some codes don't correspond to an amino acid but indicate stop at the end of a polypeptide chain.
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    (Original post by rebeccalouise_92)
    do you think we need to learn examples of epistasis anyone?
    No but you need to understand how it works, cuz u may be given information and you have to draw a genetic daigram etc.
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    Conservation questions gets on my nerves. I'm praying and hoping there won't be muck questions on it.
    Oh and a tip, if you do not have enough conservation questions you can use conservation questions from AS
    And also do all questions on the textbook.
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    (Original post by greenford)
    can anybody Define Genetic code?

    thanks
    Genetic code is a set of bases on DNA that contains the instructions for the formation of a polypeptide. It has many characteristics-

    - triplet code- a set of 3 bases code for one amino acid
    - degenerate- each amino acid has more than one code bar one
    - some are 'stop codons' signifying the end of the polypeptide chain.
    - widespread but not universal as most codons code for the same amino acid in all organisms, however this is not always the case.

    Hope this helps
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    So whose actually feeling prepared for this exam?
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    What do we need to know about cyclic AMP, apart from it activates proteins by altering its 3D structure...? Anything elsee??
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    (Original post by greenford)
    So whose actually feeling prepared for this exam?
    HAHA! unless you have seen the paper already or know everything inside out...NOBODY! let us hope it is a paper with low grade boundaries
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    please could somone outline the points about NERVIUS SYSTEM its the only topic i feel very weak at. help!!

    also just as a general question; has there ever been a time when u have WORKED VERY HARD and put it a lot of effort into revising and still get a grade with which u were disappointed? or does hard work always pay off?
 
 
 
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