DNA

So half way through an assignment and I'm stuck on one question. I think I may have missed a lesson but I am completely stumped.

3. Part of the sense strand of DNA molecule has the following code GCTTAC.
A. Draw a simple diagram to show the codes both strands of this DNA?
B. With the help of the diagrams show how this portion replicates.

I've tried to do some research looked in all my books but I can't make head nor tail of it. Any ones help would be much appreciated and a maybe an example pic.

Thank you

Reply 1

The Illuminati

Original post by kellyb124

I think A means pair them up so pair G with C and A with T sorta like:

G-C
C-G
T-A
T-A
A-T
C-G
( maybe include the number of hydrogen bonds too so three H bonds between G and C and two between A and T)

B I think it means describe semi-conservative replication. So include the role of DNA polymerase to break H bonds, how free nucleotides bind, the application of complementary base pairing rules and two double helices are formed with one strand from each coming from the original DNA helix.

Hope that helps

Reply 2

thegodofgod

Original post by The Illuminati

DNA Helicase breaks the H-bonds, right? :redface:

DNA Polymerase forms the H-bonds.

Reply 3

Revd. Mike

Original post by thegodofgod

DNA Polymerase forms the H-bonds.

Nope, polymerase copies the template strand to form a new strand. H-bonds between base pairs form spontaneously.

Reply 4

JJMick

You're all getting confused with DNA Polymerase and RNA Polymerase.

RNA Polymerase is used in transcription which is what you were describing above, but DNA Polymerase is used in PCR.

Reply 5

flowerscat

Hi

Have posted a link to the Scitable article on DNA replication here:

http://sciencebuz.com/a-level-topics/

Which might help answer your question....the pictures I think are really clear.

Original post by kellyb124

Reply 6

Akbar2k7

Original post by thegodofgod

DNA Helicase breaks the H-bonds, right? :redface:

DNA Polymerase forms the H-bonds.

Helicase DOES not unzip DNA it uncoils.

DNA polymerase forms Phospho-di-ester bonds as far as I know.

DNA unzips on heating. Hydrogen bonds break.

Similarly they form on temperature decrease spontaneously

(edited 12 years ago)

Reply 7

Revd. Mike

Original post by JJMick

You're all getting confused with DNA Polymerase and RNA Polymerase.

RNA Polymerase is used in transcription which is what you were describing above, but DNA Polymerase is used in PCR.

Not just in PCR, also in vivo DNA replication.

Reply 8

JJMick

Original post by Revd. Mike

Not just in PCR, also in vivo DNA replication.

Isn't that DNA Ligase that forms the bonds between the 'sticky ends' in in vivo gene cloning?

Reply 9

asaaal

Original post by JJMick

Isn't that DNA Ligase that forms the bonds between the 'sticky ends' in in vivo gene cloning?

DNA polymerase adds the nucleotides to the new DNA strand but DNA Ligase actually joins the two strands together :redface:

Reply 10

Revd. Mike

Original post by JJMick

Isn't that DNA Ligase that forms the bonds between the 'sticky ends' in in vivo gene cloning?

I wasn't actually talking about cloning, just DNA replication that occurs in S-phase of the cell cycle, for example. This is just where DNA is replicated.

In cloning, ligase is used to join cut strands of DNA together. This is a different process to the incorporation of nucleotides to a replicating strand.

Also, just make sure you're not mixing up your terms, in vivo vs. in vitro. :smile:

Reply 11

JJMick

Original post by Revd. Mike

Ah, I see what you mean now :smile:

I wasn't getting mixed up with my terms was I? In vivo gene cloning is where DNA Ligase is used after the use of restriction endonucleases etc.

Reply 12

Revd. Mike

Original post by JJMick

Ah, I see what you mean now :smile:

I wasn't getting mixed up with my terms was I? In vivo gene cloning is where DNA Ligase is used after the use of restriction endonucleases etc.

That part happens in vitro; the ligated DNA and vector then get put into the host organism.

Reply 13

JJMick

Original post by Revd. Mike

That part happens in vitro; the ligated DNA and vector then get put into the host organism.

It's still involved in the whole 'in vivo' gene cloning - the use of a plasmid vector is a living 'thing'. You know what I mean, it's not involved in PCR.

(edited 12 years ago)

Reply 14

Revd. Mike

Original post by JJMick

It's still involved in the whole 'in vivo' gene cloning - the use of a plasmid vector is a living 'thing'. You know what I mean, it's not involved in PCR.

The plasmid's definitely not a living thing, it's just a circle of DNA :tongue:

Reply 15

JJMick

Original post by Revd. Mike

The plasmid's definitely not a living thing, it's just a circle of DNA :tongue:

The use of it is technically 'in vivo' as it originates from a living thing. It can be argued both ways as I imagine test tubes would be used in the process.

Reply 16

alleycat393

Original post by JJMick

The use of it is technically 'in vivo' as it originates from a living thing. It can be argued both ways as I imagine test tubes would be used in the process.

In vitro (Latin: within glass) refers to studies in experimental biology that are conducted using components of an organism that have been isolated from their usual biological context in order to permit a more detailed or more convenient analysis than can be done with whole organisms. Colloquially, these experiments are commonly referred to as "test tube experiments". In contrast, the term in vivo refers to work that is conducted with living organisms in their normal, intact state, while ex vivo refers to studies on functional organs that have been removed from the intact organism.
Common examples of in vitro experiments include (a) cells derived from multicellular organisms (cell culture or tissue culture), (b) subcellular components (e.g. mitochondria or ribosomes), (c) Cellular or subcellular extracts (e.g. wheat germ or reticulocyte extracts), or (d) purified molecules in the test tube (often proteins, DNA, or RNA, either individually or in combination).