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OCR Biology F215 Control, Genomes and Environment Fri 15 June 2012

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Reply 980
Original post by Lomas
Can anyone explain why you would use Replica plating, genetic engineering etc and the difference between them please

I understand the process of each but I'm sometimes unsure why you would use one and not the other, e.g- in a exam question which one they are asking you to explain.


Well genetic engineering is used to engineer a specific gene (e.g. gene for insulin) into a section of dna (plasmid) which can then be taken up by bacteria from where the bacteria are grown to produce the insulin...

Replica plating is used to identify which bacteria have taken up the recombinant plasmid (plasmid which has combined with insulin gene). Some bacteria wouldn't have taken up a plasmid and some would have taken up a plasmid that is non-recombinant (so the plasmid just reseals in the presence of dna ligase); the bacteria we want are the ones that have taken up the recombinant plasmid and these bacteria are transgenic and can be identified using replica plating.


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Reply 981
Compare the two processes of gene cloning by explaining the advantages of each.

Processes = In vitro (PCR) + In vivo
Reply 982
Okay, a small peice of tissue is taken from the shoot tip, called an explant. It is then placed in a growth medium.

The cells in the explant tissue divides forming a group of undifferentiated cells, called callus.

Individual Callus cells are removed and placed in a culture medium containing shoot growth hormones.

After leaving the plant the grow, the shoots are removed and transferred to another growth medium containing root growth hormones, for example auxins.

The grown plants are then planted in soil to grow more before it is planted outside.

:smile: bam!

Explain how meiosis can lead to genetic variation?

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Original post by ds4143
Okay, a small peice of tissue is taken from the shoot tip, called an explant. It is then placed in a growth medium.

The cells in the explant tissue divides forming a group of undifferentiated cells, called callus.

Individual Callus cells are removed and placed in a culture medium containing shoot growth hormones.

After leaving the plant the grow, the shoots are removed and transferred to another growth medium containing root growth hormones, for example auxins.

The grown plants are then planted in soil to grow more before it is planted outside.

:smile: bam!

Explain how meiosis can lead to genetic variation?

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well done :wink: but you will lose 1 mark i think cause you had to mention they are transferred to greenhouse to allow them to acclimatise and then they are planted outside.

Crossing over which takes place in anaphase 1 and allows a length of DNA chromatid to be swapped with another.
Independent assortment such as reassortment of chromosomes and is in metaphase 1
Mutation is random
fertilisation
Reply 984
Original post by otrivine
well done :wink: but you will lose 1 mark i think cause you had to mention they are transferred to greenhouse to allow them to acclimatise and then they are planted outside.

Crossing over which takes place in anaphase 1 and allows a length of DNA chromatid to be swapped with another.
Independent assortment such as reassortment of chromosomes and is in metaphase 1
Mutation is random
fertilisation


Crossing over takes place at Prophase I during Meiosis I where chromatids break off at the chiasmata and can reattach to non-sister chromatids in the same bivalent. You can also say the independent assortment of the sister chromatids occurs during Metaphase II. Otherwise your correct, just remember crossing over = prophase I.


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Original post by Sparkzz
Crossing over takes place at Prophase I during Meiosis I where chromatids break off at the chiasmata and can reattach to non-sister chromatids in the same bivalent. You can also say the independent assortment of the sister chromatids occurs during Metaphase II. Otherwise your correct, just remember crossing over = prophase I.


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sorry meant prophase hey do u want to revise please ? from chapter 1 to chapter 2 uptio genomes?
Reply 986
Original post by otrivine
sorry meant prophase hey do u want to revise please ? from chapter 1 to chapter 2 uptio genomes?


Ok, i will give u a set of questions, however slow replies so i apologise in advance!!

1) Name three advantages of Immobilising enzymes (3 marks)
2) What is a clone? (2 marks)
3) Define vegetative propagation. (1 mark)
4) Define hemizygous (2 marks)
5) Why can't males inherit sex-linked conditions from their fathers? (2 marks)

10 marks.


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Original post by Sparkzz
Ok, i will give u a set of questions, however slow replies so i apologise in advance!!

1) Name three advantages of Immobilising enzymes (3 marks)
2) What is a clone? (2 marks)
3) Define vegetative propagation. (1 mark)
4) Define hemizygous (2 marks)
5) Why can't males inherit sex-linked conditions from their fathers? (2 marks)

10 marks.


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1) enzyme molecules do not mix freely with substrate so Purification costs are low
The enzyme molecules are more stable as they are proteceted by the enzyme matrix and enzymes are available for reuse.
2)its to produce genetically identical daughter cells and are same as their parent cells .mitosis
3)Refers to the individual producing new structures and these grow to a new individual but they are genetically the same
3)you mean homozygous right ?
4) Because of different chromosomes X on the male, heterozygous alleles, different gene loci
Reply 988
Ohh yes I remember that now, thanks!

And thats good! except for the prophase thing sparkzz already mentioned...and additional info, independent assortment also happens at metaphase II :smile:

Got a question for me :biggrin:?

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Original post by ds4143
Ohh yes I remember that now, thanks!

And thats good! except for the prophase thing sparkzz already mentioned...and additional info, independent assortment also happens at metaphase II :smile:

Got a question for me :biggrin:?

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thanks :wink: where did you go ? answer faster :biggrin:

ok
Describe the process of electrophoresis (4)
Reply 990
Original post by otrivine
1) enzyme molecules do not mix freely with substrate so Purification costs are low
The enzyme molecules are more stable as they are proteceted by the enzyme matrix and enzymes are available for reuse.
2)its to produce genetically identical daughter cells and are same as their parent cells .mitosis
3)Refers to the individual producing new structures and these grow to a new individual but they are genetically the same
3)you mean homozygous right ?
4) Because of different chromosomes X on the male, heterozygous alleles, different gene loci


1) yes correct
2) yes correct
3) yes correct
4) hemizygous is when one allele is responsible for the characteristic. check page 24.
5) because the x chromosome is is inherited from the mother. therefore males only inherit the y chromosome from their father.


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Original post by Sparkzz
1) yes correct
2) yes correct
3) yes correct
4) hemizygous is when one allele is responsible for the characteristic. check page 24.
5) because the x chromosome is is inherited from the mother. therefore males only inherit the y chromosome from their father.


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in my book page 24 is on F214?????????
are u using a different book cause in the ocr does not mention !?
more please :wink:
ok let me give you some as well so did i get 7/10 ?
1)Suggest Name 2 ways to treat sickle cell and what amino acid is replaced (3)
2)what do you understand by the term Restriction enzyme (1)
Reply 992
1. Inexpensive as separation of the enzyme-substrate complex from the mixture is not needed. The enzyme becomes much more stable, therefore reducing the chances of it becoming denatured. Also it can be reused

2. An organism that is genetically identical to the organism that has been used to produce the clone. For example Binary fission, bacteria cells dividing asexually producing clones.

3. Is when a structure is taken from another organism and used to grow into another individual organism. -genetically identical to parent cells.

4. Hemizygous...Im not sure is it something to do with having one allele and not the other :/?

5. Because males ummm im not sure lol




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I hate this paper. This is the one paper that's gonna decide whether I'll be going to university. Does anyone have a inkling to what topics may come up by looking at past papers? I heard that everything on the spec has to be covered over 3 years of exams?
Reply 994
Anyone can post any material besides past papers and answers please
Reply 995
Original post by otrivine
thanks :wink: where did you go ? answer faster :biggrin:

ok
Describe the process of electrophoresis (4)


Sorry! I didnt realise you replied
Okay umm DNA is mixed with restriction enzymes which cut them into bits. It is also mixed with radioactive markers.
The sample are placed into wells at the negative side of the gel.
Gel with samples inside wells is place in a solution and an electric current is passed through.
Because dna is negatively charged it moves towards the positive electrode. The different lengths of dna samples moves at different speeds...shorter ones travel faster than longer ones.
The radioactive markers help us see where the dna samples has reached.

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Original post by ds4143
Sorry! I didnt realise you replied
Okay umm DNA is mixed with restriction enzymes which cut them into bits. It is also mixed with radioactive markers.
The sample are placed into wells at the negative side of the gel.
Gel with samples inside wells is place in a solution and an electric current is passed through.
Because dna is negatively charged it moves towards the positive electrode. The different lengths of dna samples moves at different speeds...shorter ones travel faster than longer ones.
The radioactive markers help us see where the dna samples has reached.

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yep yep 4/4
Reply 997
Original post by katie.lou
You need to know that the H zone gets shorter, as do the I bands. the Z lines pull towards each other. Then you just need to know the role of ATP (the ratchet mechanism) and role of calcium ions (to attach to troponin which moves trypomyosin). That's obviously shortened but they're the main things I think :smile:


Thank you!! :biggrin: Appreciate it :smile:
Reply 998
Original post by otrivine
yep yep 4/4


Woo, okay
Name the different parts of the lac operon (3) and what each of them do (3)


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Original post by ds4143
Woo, okay
Name the different parts of the lac operon (3) and what each of them do (3)


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do you mean the binding sites?

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