AQA BIOL5 Biology Unit 5 Exam - 22nd June 2011

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Reply 1900

You just need to know that a primer is added, I don't think you need to know why. They probably know the end and begin of a DNA strand cos that's where the primers anneal and all that.

Thanks

Reply 1901

flowerscat

Original post by Tericon

For gene sequencing, how do you know what primers to add to the mixture if you don't know the sequence of bases?

This is why you cut your fragments with a restriction enzyme and insert the cut DNA into a vector with a known sequence. You can design the sequence of the primers based on the known vector sequence.

Reply 1902

feelbetter

Original post by angel1992

can someone explain the difference between a dna probe and primer? they both are the same things>> so cant one do the job of the other

DNA probes are labelled, either fluorescently or radioactively and are used to detect base sequences of DNA, a primer is added so a single stranded DNA to allow polymerase to add bases to make a double helix dna chain (i.e PCR reaction) in PCR it also helps prevent seperated strands from pairing up again

Reply 1903

empop92

do you need to know the specifics of how andenovirus is used in delivering gene to treat cystic fibrosis? or just that it can cause an immune response etc? cus i really don't want to learn all that if i don't have to :h:

Reply 1904

Abby :)

Can someone explain the whole antibitiotic resistance thing in identifying if Vectors have been taken up. o.O

I really really dont understand how the textbook explains it.
All i know is there is something involving tetracycling and acetyl or something
And if the vector is still apparent then it has taken the vector up?

-.- Hehe

Reply 1905

percy93

Original post by Sparkly-Star

*Chemo receptors
*Pressure receptors
*Influx of sodium ions
*Temperature
*Blood glucose conc.
*Menstrual cycle

I don't know about the other units haha! :p:

i think enzyme activity uses negative feedback.. it's somewhere in unit 1

Reply 1906

Sparkly-Star

Original post by Tericon

Thanks

BTW did the primers are added to start the DNA sequencing, whilst the DNA probes is labelled so it can be identified.

Reply 1907

RMS184

Question and answer time, helps me reivse!

1. Describe the role of tRNA in the process of translation.

Reply 1908

percy93

Original post by empop92

i think you should just remember that-
adenovirus can recover and cause infection
patient can develop immunity to it
might provoke an immune response
and obv just remember how they insert the gene- bang the gene into a bacterial cell, incorporate into epithelial cell, clone the cell, isolate bacterial cell and insert up the parents nose or something

Reply 1909

percy93

Original post by percy93

~patient! not parent! LOL

Reply 1910

Sparkly-Star

Do we need to know the method of genetic screening? :frown:

Reply 1911

KingMessi

Original post by RMS184

Question and answer time, helps me reivse!

1. Describe the role of tRNA in the process of translation.

tRNA carries a complementary anticodon sequence to the codon on mRNA. It therefore moves to a ribosome and with it carries an amino acid on its end chain. The next tRNA molecule with a complementary anticodon sequence binds to the codon on mRNA, and this tRNA molecule carries with it an amino acid. The two amino acids on the tRNA molecules bind by means of a peptide bond. The next tRNA molecule then carries the third anticodon sequence and the third amino acid, which joins to the other two by means of a peptide bond. Protein synthesis occurs in this way until tRNA reaches a codon that denotes a stop codon, at which point the tRNA, mRNA and ribosome all detach from one another and synthesis of the polypeptide is complete.

Reply 1912

Sparkly-Star

Sorry for re-post, do we need to know the method of genetic screening?

Reply 1913

BackDoorEntry

To get 3 marks for Quality of written comm in the essay, must you include an introduction and conclusion?

Reply 1914

angel1992

why does fsh need to be lowered by negative feedback in the first section of the oestrous cycle?

Reply 1915

KingMessi

Original post by Tericon

For gene sequencing, how do you know what primers to add to the mixture if you don't know the sequence of bases?

You don't use primers in DNA sequencing? :confused:

Reply 1916

percy93

Original post by angel1992

why does fsh need to be lowered by negative feedback in the first section of the oestrous cycle?

i think so that it doesn't overstimulate the follicles.. maybe... or maybe not.

Reply 1917

Sparkly-Star

Original post by KingMessi

You don't use primers in DNA sequencing? :confused:

You do, according to NT book.

Reply 1918

Carpet21

Original post by BackDoorEntry

To get 3 marks for Quality of written comm in the essay, must you include an introduction and conclusion?

Nope thankfully. :smile:

Reply 1919

Stirlo

Original post by Sparkly-Star

Sorry for re-post, do we need to know the method of genetic screening?

Yes I think we do. Basically the nucleotide sequence for a mutated gene is detemined using sequencing. A fragment of DNA with complimentary bases to this mutated gene is produced and radioactively labelled. This then undergoes PCR. A sample of DNA from the individdual being screened is isolated, this DNA is then split in single strands so that our complimentary probe can be attached if the mutated gene is present.

The probe and single target DNA strand is mixed, if the persons DNA has the mutation the probe will have joined to it;s complimentary sequence and will show up when an x-ray film is placed over it.