Page 1 of 2: Chargaff's rule

kumar123 · Credits: 6047 My Scrapbook

This was discussed before but I couldnt find that post anywhere
Chargaff's rule is-
A+G=T+C
A/T= G/C
A=T=G=C
A+T=G+C
Ans given is 2
Is it 1??

ramyark31 · Credits: 128 My Scrapbook

I REMEMBER reading in one of the question banks as in dna A=T G=C ---called as chargaff's rule ....correct me if wrong

contagious · Credits: 818 My Scrapbook

the answer should be 2 only yaar

BRAVO · Credits: 46206 My Scrapbook

i agree

fibroma · Credits: 329 My Scrapbook

one is also correct

decembermist · Credits: 41372 My Scrapbook

ans is A)

decembermist · Credits: 41372 My Scrapbook

Chargaff's Rule" Total Pyrimidines (C+T) = Total Purines (A+G) in DNA

A + G = C + T

mdali007 · Credits: 5833 My Scrapbook

Chargaff's Rule states that total purines equals

total pyrimidines.

In dsDNA (or dsRNA) (ds = double stranded)

% A = % T (% U)

% G = % C

% purines = % pyrimidines

% A + % G = % T (% U) + % C

In other words 1 is definately the correct

answer !!!!

MockTurtle · Credits: 5627 My Scrapbook

Total purines(A+G)=Total pyrimidines(T+C)
which means that among 100 parts of DNA,50 will be accounted for by A+G and 50 by T+C So
A+G=T+C (STEP 1)
Taking this equation 1 step further,in 50 parts of DNA,25 will be accounted for by A and 25 by its complementary nucleotide T (The same holds for G and C)
So,
A(25 fractions) =T(25 fractions) =G(25 fractions) =C(25 fractions)

So,A=G=T=C

I'D GO FOR OPTION C

mdali007 · Credits: 5833 My Scrapbook

MockTurtle when you took it to the next level you

also took it out of the limitations of the Chargaff's

rule .. no doubt you may be right but it doesn't

comply to Chargaff's rule anymore ... I still say

that the answer is definately 1 and hold my

stance !!!

MockTurtle · Credits: 5627 My Scrapbook

Chargaff's Law Of Base Pairing..as far as i remember it.Or am i wrong on this one?

MockTurtle · Credits: 5627 My Scrapbook

I wont go into much details about this..Chargaffs Rule is an elementary thing about which nothing much needs to be discussed.If u still think i'm in the wrong,look up the book..talk with some biochem pg's..heck,look up the internet even.Just for samplers i'm copy-pasting the material from one of the educational web sites on the net.Read it up
DNA is a double stranded helix

Once biologists determined that DNA was the genetic information, the race was on to find how the structure of DNA could account for its role in heredity.

In 1953, Watson and Crick (got Nobel in 1962) used X-ray crystallography data supplied by Maurice Wilkins and Rosalind Franklin to determine the structure of DNA.

- in X-ray crystalography , X-rays are passed through a DNA crystal and the defracted X-rays are collected and used to infer the structure of the atoms in the crystal.

Watson and Crick used the crystallography evidence, plus the known structure of nucleotides and their covalent bonding, to construct wire models. In 1953 they announced that DNA was a double helix.

"Fig 10.3 shows the double helix. It is made of two polynucleotide strands twisted around each other. Specific base pairing in the form of H-bonding between bases keeps strands together and give DNA its shape. Strands are in antiparallel configuration.

in complementary base pairing, A pairs with T, and G pairs with C.

this explains Chargaffs rules, which indicated that regardless of where DNA comes from, the number of A’s = T’s, and number of G’s = C’s

The DNA double helix structure is correlated with its function. The sequence of nucleotides encodes information. The change in sequence via mutations is the raw material for evolution. The fact that DNA is double stranded and there’s complementary base pairing also allows for precise replication of the DNA molecule, as is required in heredity."
I would have posted the name of this (reliable) site but rxpg rules bar me from doing so.

U can always do a google search though.

mdali007 · Credits: 5833 My Scrapbook

you took the words right out of my mouth ...

"Chargaffs Rule is an elementary thing about which

nothing much needs to be discussed" ... thanks

and sorry if i offended you in anyway ....

MockTurtle · Credits: 5627 My Scrapbook

No man,no question of bein offended at all..And sorry if i sounded abusive.Must be the weather

eamstar · Credits: 115 My Scrapbook

hello
this is my first time posting so pls excuse me if i'm wrong in any way
i would like to give an example
in a certain fragment of ds-dna of 100 bases
a=30
so complementary base t=30
then g=c=20 each
the rule is a+g=t+c
as we can see a=g=t=c doesnt always hold good
coming to option 2 a/t= g/c =1 and similarly we can say a/g= t/c etc
those r all derivations
from the merit of it option 2 is also right
but to b precise the rule per se is a+g=t+c
so the answer is a+g=t+c

MockTurtle · Credits: 5627 My Scrapbook

Yes...i think im wrong...

MockTurtle · Credits: 5627 My Scrapbook

Well..this is a maze,isnt it?If u say A+T=G+C then definitely A=T=G=C.. and if A+T does not equal G+ C, then the other doesnt hold either.
Crazy,huh?

contagious · Credits: 818 My Scrapbook

so i think both options 1 n 2 r right but the first seems to be more correct

ok guys???
did i get it right?

eamstar · Credits: 115 My Scrapbook

well mockturtle i donno what to say
ok leave the apparently complex chargaff's rule just consider
2+5=7 and also 3+4=7
but its not like 2=3=4=5 right?

u got it right contagious

ok if there is still more to b discussed then let the replies come
thank u

contagious · Credits: 818 My Scrapbook

thanks eamstar

strange id yaar???

is it i am star types or eamstar

		Sign In New User? Sign Up Sign in to access your control panel and messenger!