A DNA strand has the following bases: TAC GAT. What is the COMPLEMENTARY strand of DNA?

Question

I'm confused by the word "complementary", I don't know whether to use thymine for adenine or uracil (think thats the correct u-word spelling). Help greatly appreciated!

Answer 1

DNA is a double helical molecule. this is formed due to complementary base pairing between the 2 strands of dna molecule.
DNA as u now is a polymer of nucleotides.
each nucleotide has sugar + phosphate + nitrogenous base.

nitrogenuos bases are A, T, G, C.


now complementary base pairing is between one purine and one pyrimidine.
purines are A, G.
pyrimides are T, C.

ADENINE (A) forms 2 bonds with thymine(T)
cytosine (C) forms 3 bonds with guanine (G)

this is due to there molecular structures which u can read in any basic biochemistry book.

i hope u have an idea about the word "complementary".....

now the sequence u have asked the complementary sequence will be:
ATG CTA

NOTE:nucleotide sequences (DNA or RNA) are always written by indicating the direction in which they are to be read and no spaces are required between codons.

example : for ur sequence, it can be written as

5' TACGAT 3'
3' ATGCTA 5'


NOW about URACIL:
its is not present in DNA
it is present in RNA in the place of thymine.

actually, the pyrimidine base, cytosine, spontaneously deaminates to give uracil.

Special repair mechanisms occur within the cell to replace uracil in DNA. However, if uracil was also a part of DNA structure, repair systems would not bo able to differentiate between natural uracil and uracil spontaneously formed from cytosine and therefore, would replace all uracil present.

now u'll think that what abt RNA?
remember that DNA is the hereditary material and any change in its base sequence means life and death for the organism. RNA, on the other hand is constantly being made and degraded based on dna sequences. therefore, any error in it is not long-lasting....


i hope things are much clear to u now....

Answer 2

1. double helix 2. James Watson and Francis Crick 3. sugar, phosphate, and a base 4. The original DNA molecule is unzipped 5. the brain (not sure on this one) 6. making proteins as dictated by the DNA (I think) 7. when DNA is copied to mRNA which can leave the nucleus 8. RNA has the base uracil and DNA has thymine 9. the three mRNA bases that code for an amino acid 10. the three bases on a tRNA that match up with mRNA 11. protein (I think) 12. cancer 13. DNA replication 14. chromosomes line up 15. TAG GCA ATA CAT GGT 16. UAG GCA AUA CAU GGU 17. haven't done this experiment 18. Deoxyribonucleic Acid 19. thymine 20. prophase, metaphase, anaphase, telophase, cytokinesis

Answer 3

Complementary Base Sequence

Answer 4

Second answer is *almost* right!

DNA has directionality and the DNA strands in a duplex run opposite directions (anti-parallel). When you write a DNA sequence you always write it from the 5' end to the 3' end. So your sequence is:

5'-TAC GAT-3'

If we write down the matching bases the sequence running the *opposite direction* is:

3'-ATG CTA-5'

Since you always write DNA 5' to 3', you have to write the sequence in reverse order like this:

5'-ATC GTA-3'

So the complementary sequence is ATC GTA. Does that make sense?

Answer 5

Complementary just means the other side of the DNA that matches. It's the other half of the DNA puzzle. In DNA ALWAYS use thymine. Uracil is only in RNA.

The complementary strand for TAC GAT is ATG CTA.
In DNA, match round letters together (CG) and straight-lined letters together (AT).

When you make RNA, and you use uracil, then match AU (AUstralia), and round letters (CG). Just memory tricks.

Answer 6

Yes, Uracil is the correct spelling, however Uracil is not found in DNA, it is actually found in RNA. So what they mean by the complement is to include the counterpart and NOT the RNA strand. In other words, the second DNA strand. Since A binds to T and G binds to C, the compliment of that sequence is ATG CTA.