A level Biology: Post your doubts here!

[My Name]

Please explain... how are 4 tRNA molecules needed? (A)View attachment 59851

The answer is A since each tRNA molecule is specific to one amino acid.
As mentioned in the question there are 4 kinds of amino acids thus 4 tRNA molecules needed.

 

[mohmed ahmed soliman]

outbreeding / inbreeding hybridization help in them notes or anything

 

[My Name]

outbreeding / inbreeding hybridization help in them notes or anything

I didn't make/don't have any notes for this yet.
You can check the book http://www.gceguide.com/Books/Cambridge International AS and A Level Biology Coursebook.pdf

 

[mohmed ahmed soliman]

p41 june 2014 help in part b of q 2
i found this in examiner report
t was rare to find a candidate who clearly described DNA sequencing, rather than just an application of electrophoresis. A correct description of automated Sanger sequencing needed to refer to modified PCR using chain-terminating dideoxynucleotides, followed by electrophretic separation of the different length DNA copies, plus the use of a laser scanner to detect the fluorescently tagged dideoxynucleotides.
in er
(total) DNA / genome, cut into fragments ; by restriction enzymes ; DNA, denatured / made single stranded ; ref. primers / (modified) PCR ; ref. dideoxynucleotides / chain termination ; DNA / Taq, polymerase ; copies of different lengths produced ; electrophoresis ; A description detection, of fluorescence / by laser scanner ; sequence of, bases / nucleotides, read (by computer)

 

[My Name]

View attachment 59869
p41 june 2014 help in part b of q 2
i found this in examiner report
t was rare to find a candidate who clearly described DNA sequencing, rather than just an application of electrophoresis. A correct description of automated Sanger sequencing needed to refer to modified PCR using chain-terminating dideoxynucleotides, followed by electrophretic separation of the different length DNA copies, plus the use of a laser scanner to detect the fluorescently tagged dideoxynucleotides.
in er
(total) DNA / genome, cut into fragments ; by restriction enzymes ; DNA, denatured / made single stranded ; ref. primers / (modified) PCR ; ref. dideoxynucleotides / chain termination ; DNA / Taq, polymerase ; copies of different lengths produced ; electrophoresis ; A description detection, of fluorescence / by laser scanner ; sequence of, bases / nucleotides, read (by computer)

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[mohmed ahmed soliman]

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What do you need help in?

m j p41 2014 q2
what is sanger proceess why they ask about it in pp if it is not in sy
we only took microarray
how do they ask about SANGER PROCESS

 

[My Name]

m j p41 2014 q2
what is sanger proceess why they ask about it in pp if it is not in sy
we only took microarray
how do they ask about SANGER PROCESS

Oh I can't help you then.Sorry.

 

[Midnight dream]

m j p41 2014 q2
what is sanger proceess why they ask about it in pp if it is not in sy
we only took microarray
how do they ask about SANGER PROCESS

I don't know if it is still in syllabus or not. I think it is actullay.
Well DNA sequencing is the process of determining the precise order of nucleotides within a DNA molecule .To determine the exact sequence of DNA , We take 4 test tubes and in each test tube take a specific dideoxynucleotide i.e Adenine in one while cytosine in other and so on..
Dideoxynucleotides are chain-elongating inhibitors of DNA polymerase.
Sanger sequencing is a method of DNA sequencing based on the selective incorporation of chain-terminating dideoxynucleotides by DNA polymerase during in vitro DNA replication.

Watch the vid. you ll get the idea really easily.
Hope it helps.

 

[mohmed ahmed soliman]

With reference to any named species of plant or animal, explain why this species is considered
to be endangered and outline the reasons that have caused it to become endangered. [8]
[Total: 15]
10 (a) Describe the action of penicillin on bacteria. [8]
are they still in syllabus

 

[My Name]

I don't know if it is still in syllabus or not. I think it is actullay.
Well DNA sequencing is the process of determining the precise order of nucleotides within a DNA molecule .To determine the exact sequence of DNA , We take 4 test tubes and in each test tube take a specific dideoxynucleotide i.e Adenine in one while cytosine in other and so on..
Dideoxynucleotides are chain-elongating inhibitors of DNA polymerase.
Sanger sequencing is a method of DNA sequencing based on the selective incorporation of chain-terminating dideoxynucleotides by DNA polymerase during in vitro DNA replication.

Watch the vid. you ll get the idea really easily.
Hope it helps.

Thanks!

 

[mohmed ahmed soliman]

I don't know if it is still in syllabus or not. I think it is actullay.
Well DNA sequencing is the process of determining the precise order of nucleotides within a DNA molecule .To determine the exact sequence of DNA , We take 4 test tubes and in each test tube take a specific dideoxynucleotide i.e Adenine in one while cytosine in other and so on..
Dideoxynucleotides are chain-elongating inhibitors of DNA polymerase.
Sanger sequencing is a method of DNA sequencing based on the selective incorporation of chain-terminating dideoxynucleotides by DNA polymerase during in vitro DNA replication.

Watch the vid. you ll get the idea really easily.
Hope it helps.

may u help me to write an answer for this q
m j p41 2014 q2

 

[ashcull14]

detail of reproductive isolation
its quite precise in mary jones and it doesnt include some of the MS points
please HELP

 

[ashcull14]

may u help me to write an answer for this q
m j p41 2014 q2

Q2(a) Cross pollination occurs between two parents rather than a single parent.Both parents are not closely related so out breeding takes place.Therefore,a greater variety of alleles are present as both parents have different genotypes .since these are passed onto the offspring new alleles are formed in it.
b)DNA is cut into pieces using a restriction enzyme and is denatured to a single strand.DNA polymerase has to form a complementary strand to it.thus it is initiated by a primer that attaches to the start of the DNA chain and continues to add nucleotides along the strand and DNA forms complementary pairs to frm copies of different lenghts.DNA fragments are ready for electrophoresis to make them visible .They are transferred onto an absorbent paper on top of the gel across an elctric field.DNA probes carrying flourescent stains that show up in UV light .The sequences of base is interpreted by the computer

 

[ashcull14]

 

[mohmed ahmed soliman]

help to calculate t test value

 

[Shah34]

Hello guys
Can u plz explain ??
Bio practical paper

 

[mohmed ahmed soliman]

View attachment 59903

which year maybe we have to say that rubisco catalyses co2 and rubp reaction ,co2 fixation
becasue in ms we have collision between co2 and enzyme above the confusing point
i think we should say that in C more co2 is there to be fixed . more co2 collide with rubp so more enzyme substrate complex forms
this reaction is catalysed by rubisco
by the way its AVP so u can anything but related and valid not only this confusing point

 

[My Name]

Hello guys
Can u plz explain ??
Bio practical paper

The picture isn't clear.
Can you mention the which paper it is?

 

[mohmed ahmed soliman]

rubiso

View attachment 59903

rubisco active site is complementary to substrates co2 and rubp

 

[Shah34]

The picture isn't clear.
Can you mention the which paper it is?

9700/32/MJ/14