AQA BIOL5 Biology Unit 5 Exam - 22nd June 2011

Reply 120

T.M 27

*subscribes* btw cobra2k10 - you are officially a life saver :biggrin:

Reply 121

tehsponge

11

Original post by arvin_infinity

Im doing AQA and there is no Sanger method! Weve got chain termination method

instead..dunno if theyre the same :confused:

ohh description is the same tho ...

CGP just doesnt make any sense to me atm..
Here is CGP example : There is a image of electrophoresis in gene sequencing , in which there is a T nucleotide (Not fragment!!?) at the bottom of the gel near +ve electrode

Thanks for reply

I'm doing AQA as well. We use the Nelson Thornes textbook, and the Sanger method is in there. Dunno, maybe the syllabus doesn't specify a certain technique, it might just be the one Nelson Thornes uses.

I just did some Googling, the Sanger method is the chain termination method. The names are synonymous I think.

I just looked at the CGP diagram and now I'm confused too :lolwut:

I'll look through both books and try get my head around it, then get back to you...

Reply 122

tehsponge

11

Original post by Mie Peson

Thanks for your reply. I know how the method works. I'm just confused at the last part where you number the fragments in the rectangular thing for electrophoresis. By assigning them numbers and seeing how much each fragment travels, sequence is determined depending under which base column the fragments are. My question was whether this is the sequence of the original sample DNA or is it the sequence that is complementary to sample DNA. It has to be either one of them as the sequence is only single stranded :confused:

The ones on the electrophoresis gel would be complementary to the template strand. You can then determine what the template strand was from that.

Reply 123

tehsponge

11

Original post by arvin_infinity

Here is CGP example : There is a image of electrophoresis in gene sequencing , in which there is a T nucleotide (Not fragment!!?) at the bottom of the gel near +ve electrode

Thanks for reply

Okay, I read through both books again. Its named a T nucleotide, because its only one base long. So in this case the A terminator (because A is complementary to T) was the first nucleotide to join on.

The next one (if we're looking at the same diagram) is another T, but this time it has TWO nucleotides in it, so two bases. This time the A terminator attached to the second T base in the sequence.

In the 3rd one (3 bases/nucleotides long), the sequence ends with a C, so the terminator is G. You keep doing this until you've reached the end of the gel, and then you have your original template sequence.

Basically the first one on the gel will always just be 1 nucleotide. Then as you go along, they become larger DNA fragments.

Its a pretty confusing technique, if you want me to try and explain it better just let me know :smile:

Reply 124

skygirl999

6

Hi

I have a question on SiRNA? (Its under the 'regulation of transcription and translation section')
Within the Nelson Thornes textbook it says 'SiRNA is small sections of double-stranded RNA'. However all the sources I have consulted say that RNA is a single stranded polynucleotide molecule. How comes mRNA and tRNA are single stranded molecules, but SiRNA is a double stranded molecule?

Reply 125

tehsponge

11

Original post by skygirl999

Hi

I have a question on SiRNA? (Its under the 'regulation of transcription and translation section')
Within the Nelson Thornes textbook it says 'SiRNA is small sections of double-stranded RNA'. However all the sources I have consulted say that RNA is a single stranded polynucleotide molecule. How comes mRNA and tRNA are single stranded molecules, but SiRNA is a double stranded molecule?

I asked one of my friends that same question and they said that double stranded RNA is made in the lab. I'm not sure if thats true though. I just Googled it and found this:
"Double-stranded RNA (or dsRNA) is RNA with two complementary strands, similar to the DNA found contained by all "higher" cell. dsRNA forms the genetic material of some virus. In eukaryotes, it acts as a trigger to initiate the process of RNA interference and is present as an intermediate step within the formation of siRNAs (small interfering RNAs)."

So the dsRNA must be taken from viruses.
We don't actually have to know why siRNA is double stranded, it just is.

Reply 126

-jessica

Revision? We haven't even finished learning everything yet! We still have a good chapter or two to go.

Reply 127

Mie Peson

[QUOTE=tehsponge;31191

894]The ones on the electrophoresis gel would be complementary to the template strand. You can then determine what the template strand was from that.

Thanks,i get it now

Reply 128

arvin_infinity

3

Original post by tehsponge

Okay, I read through both books again. Its named a T nucleotide, because its only one base long. So in this case the A terminator (because A is complementary to T) was the first nucleotide to join on.

The next one (if we're looking at the same diagram) is another T, but this time it has TWO nucleotides in it, so two bases. This time the A terminator attached to the second T base in the sequence.

In the 3rd one (3 bases/nucleotides long), the sequence ends with a C, so the terminator is G. You keep doing this until you've reached the end of the gel, and then you have your original template sequence.

Basically the first one on the gel will always just be 1 nucleotide. Then as you go along, they become larger DNA fragments.

Its a pretty confusing technique, if you want me to try and explain it better just let me know :smile:

Makes more sense now..thanks..So DNA fragment at the bottom only contain one

nucleotide. Number of nucleotide increases as we go up the gel.

Bear in mind that , TTC is only a primer in which there is no modified nucleotide added .

I mean modified nucleotide are added after after 3!

Dont want to make it more complicated but couldnt figure out how we know which

primer to use , if

DNA sequence is unknown. :confused:

(edited 12 years ago)

Reply 129

tehsponge

11

Original post by arvin_infinity

Makes more sense now..thanks..So DNA fragment at the bottom only contain one

nucleotide. Number of nucleotide increases as we go up the gel.

Bear in mind that , TTC is only a primer in which there is no modified nucleotide added .

I mean modified nucleotide are added after after 3!

Dont want to make it more complicated but couldnt figure out how we know which

primer to use , if

DNA sequence is unknown. :confused:

Well, the number of nucleotides in a DNA fragment will be largest near the positive end of the gel, since they move slower. The smallest fragments will be near the negative end.

I guess they use a load of different primers? I'm not sure...

Reply 130

T.M 27

Original post by cobra2k10

Hiya fellow biologists :biggrin:

!! Below are a few past synoptic essay titles that have been asked:

•

Carbon dioxide may affect organisms directly or indirectly. Describe and explain these effects.

•

The causes of disease in humans.

•

The part played by the movement of substances across cell membranes in the functioning of different organs and organ systems.

•

The part played by enzymes in the functioning of different cells, tissues and organs.

•

Movements inside cells.

•

Transfers through ecosystems.

•

The transfer of substances containing carbon between organisms

•

Cells are easy to distinguish by their shape. How are the shapes of cells related to their function?

•

The transfer of substances containing carbon between organisms and between organisms and the environment.

•

Humans and microorganisms.

•

The biological importance of plants to humans.

•

The importance of hydrogen bonds in living organisms.

•

How nitrogen-containing substances are made available to and are used by living organisms.

•

Carbon dioxide in organisms and ecosystems

•

Why offspring produced by the same parents are different in appearance

•

Polymers have different structures. They also have different functions. Describe how the structures of different polymers are related to their nctions.

•

Describe how nitrogen-containing substances are taken into, and metabolised in, animals and plants.

•

Heat and many different substances are transferred within the body and between the body and the environment. Explain how surface area is linked to this transfer.

•

Inorganic ions include those of sodium, phosphorus and hydrogen. Describe how these and other inorganic ions are used in living organisms.

•

Bacteria affect the lives of humans and other organisms in many ways. Apart from causing disease, describe how bacteria may affect the lives of humans and other organisms.

•

Negative feedback in living organisms.

•

Mean temperatures are rising in many parts of the world. The rising temperatures may result in physiological and ecological effects on living organisms. Describe and explain these effects.

•

The transfer of energy between different organisms and between these organisms and their environment.

•

Ways in which different species of organisms differ from each other.

•

The process of osmosis and its importance to living organisms.

•

Energy transfers which take place inside living organisms.

•

How carbon dioxide gets from a respiring cell to the lumen of an alveolus in the lungs.

•

How an amino acid gets from protein in a person’s food to becoming part of a human protein in that person.

•

How the structure of proteins is related to their functions.

•

The causes of variation and its biological importance.

•

The structure and functions of carbohydrates.

•

Cycles in biology.

•

How bacteria affect human lives.

•

The biological importance of water.

•

The movement of substances within living organisms.

•

The different ways in which organisms use ATP.

•

How the structure of cells is related to their function

.

omg thank you SOO much! any chance you could tell us where you got these from so we can find the mark schemes? thanks again! :biggrin:

Reply 131

Flux_Pav

hey guys

just need to confirm something on sanger method
in the bill indge book, it finds out the base sequence of a gene that has not been studied before
firstly, why is the single stranded DNA cloned into a vector?
so you end up with fragments that have complementary bases to the template strand with the last base being a dideoxynucleotide. But, when you interpret the autoradiograph, the base sequence of the harmful gene must be COMPLEMENTARY to the newly synthesized strand. so why does the book say that the first base of the harmful gene is adenine because the added base is dDNA?

Reply 132

User544981

10

hi
can anyone help me with this essay question

gene technology is the greatest development in biology since Edward Jenner 'invented' vaccination. Discuss

i know i shud write bout dna and stuff but i dont know how to write it

what woud anyone suggest for this essay question
can anyone help plz

Reply 133

skygirl999

6

Original post by tehsponge

I asked one of my friends that same question and they said that double stranded RNA is made in the lab. I'm not sure if thats true though. I just Googled it and found this:
"Double-stranded RNA (or dsRNA) is RNA with two complementary strands, similar to the DNA found contained by all "higher" cell. dsRNA forms the genetic material of some virus. In eukaryotes, it acts as a trigger to initiate the process of RNA interference and is present as an intermediate step within the formation of siRNAs (small interfering RNAs)."

So the dsRNA must be taken from viruses.
We don't actually have to know why siRNA is double stranded, it just is.

Hmm, ok, thank you for trying to help. I always like to understand things though, even if it is not strictly on the mark scheme. I will ask my teacher at school and see if he can explain why it is :smile:

Thanks again.

Reply 134

INeedToRevise

8

BIOL5 Past paper questions with markschemes
http://www.mediafire.com/file/ynzizznywym/Unit%205%20-%20Biology.rar

Reply 135

INeedToRevise

8

Biol5 past paper questions with markschemes:
http://www.mediafire.com/file/ynzizznywym/Unit%205%20-%20Biology.rar

Reply 136

chemicalguy

3

Original post by cobra2k10

Hiya fellow biologists :biggrin:

!! Below are a few past synoptic essay titles that have been asked:

•

Carbon dioxide may affect organisms directly or indirectly. Describe and explain these effects.

•

The causes of disease in humans.

•

The part played by the movement of substances across cell membranes in the functioning of different organs and organ systems.

•

The part played by enzymes in the functioning of different cells, tissues and organs.

•

Movements inside cells.

•

Transfers through ecosystems.

•

The transfer of substances containing carbon between organisms

•

Cells are easy to distinguish by their shape. How are the shapes of cells related to their function?

•

The transfer of substances containing carbon between organisms and between organisms and the environment.

•

Humans and microorganisms.

•

The biological importance of plants to humans.

•

The importance of hydrogen bonds in living organisms.

•

How nitrogen-containing substances are made available to and are used by living organisms.

•

Carbon dioxide in organisms and ecosystems

•

Why offspring produced by the same parents are different in appearance

•

Polymers have different structures. They also have different functions. Describe how the structures of different polymers are related to their nctions.

•

Describe how nitrogen-containing substances are taken into, and metabolised in, animals and plants.

•

Heat and many different substances are transferred within the body and between the body and the environment. Explain how surface area is linked to this transfer.

•

Inorganic ions include those of sodium, phosphorus and hydrogen. Describe how these and other inorganic ions are used in living organisms.

•

Bacteria affect the lives of humans and other organisms in many ways. Apart from causing disease, describe how bacteria may affect the lives of humans and other organisms.

•

Negative feedback in living organisms.

•

Mean temperatures are rising in many parts of the world. The rising temperatures may result in physiological and ecological effects on living organisms. Describe and explain these effects.

•

The transfer of energy between different organisms and between these organisms and their environment.

•

Ways in which different species of organisms differ from each other.

•

The process of osmosis and its importance to living organisms.

•

Energy transfers which take place inside living organisms.

•

How carbon dioxide gets from a respiring cell to the lumen of an alveolus in the lungs.

•

How an amino acid gets from protein in a person’s food to becoming part of a human protein in that person.

•

How the structure of proteins is related to their functions.

•

The causes of variation and its biological importance.

•

The structure and functions of carbohydrates.

•

Cycles in biology.

•

How bacteria affect human lives.

•

The biological importance of water.

•

The movement of substances within living organisms.

•

The different ways in which organisms use ATP.

•

How the structure of cells is related to their function

.

These came from my site here at http://writingthesynopticessay.co.uk

I've also done a list of suggested titles to prepare:
?Lipids in health and disease.
?Genes and diversity.
?The ways in which different organisms become adapted to their environments.
?Coordination within organisms and between organisms and their environments.
?Discuss how scientists collect, analyse and interpret biological data.
?A space probe brought back samples of life-forms from a hot, dry planet with low atmospheric oxygen but high carbon dioxide concentrations. Describe the adaptations these life-forms would have in order to survive these conditions.
?The physiological impact of lifestyle on health.
?The impact of human activities on the diversity of animals and plants.
?Receptors and coordination.
?The pathways of synthesis of carbohydrates from atmospheric carbon dioxide.
?Proteins such as insulin, FSH or an anti-influenza antibody are made in cells that are remote from their target tissues. Describe how one of these is synthesised and exerts an effect elsewhere.
?Perform a critical analysis of methods used to collect biological data.
?Stem cells research offers a great number of potential benefits to humans. It also comes with many down sides. Write a balanced account of the ways in which stem cells could and should be used to benefit humans.
?Discuss the benefits and drawbacks of gene cloning technologies.

You can get a free essay on this site too here

Reply 137

Flux_Pav

is there anywhere else where we can get free A grade sample essays for this synoptic paper?