Biology help, DNA replication?

Question

1. Between which types of compounds in a double-stranded DNA molecule must ht bonds break before replication take place?
a. phosphate base
b. sugar-phosphate
c. adenine-thymine
d. sugar-base

2. to which organelles does messenger RNA attach?
a. chloroplasts
b. ribosomes
c. mitochondria
d. lysosomes

3. the coded info in a DNA molecule directly determines the formation of____
a. polysaccharides
b. lipids
c. monosaccharides
d. polypeptides

4. if the code for an amino acid is ATG on the DNA molecule, this code on the transfer RNA molecule may be written as
a. ATG
b. CTG
c. AUG
d. CTA

errghh... i dont like DNA stuff, so if you can explain how you got the answers itd help me out alot!! thankss :]

Answer 1

1.c-strands must be split so nucleotides are on outside to be used as a template for replication
2.b-translation of mrna occurs at ribosomes
3d-dna transcripts to mrna which translates to amino acids(polypeptides)
4c-dna complements rna which then complements trna, trna and dna should be identical accept uracil instead of thymine on rna
just stuff that you have to memorize

Answer 2

1. Answer: Adenine-Thymine. These are hydrogen bonds holding the 2 strainds of DNA together. They must be broken for replication to occur.
2. Ribosomes. Ribosomes take the mRNA and translate it into an Amino acid sequence which eventually becomes the protein.
3. Polypeptides. Peptide is another word for Amino acid. basically, the word means "multi-Amino Acid" which is what proteins are made of.
4. AUG. This is the only answer that makes sense, because RNA never uses a T, it uses U instead in its base pairs.

Hope this helps. Message or e-mail me if you need more help

Answer 3

1. C
--There's no such thing as a phosphate base in DNA, just nitrogen bases.
--The sugar-phosphate bonds are on the sides of the DNA ladder, and replication needs the ladder to unzip down the midde.
--AT go together (letters with straight lines) and CG go together (letters with curves)
--No good reason to separate the bases from the sugars. You need to have the bases unzip from the opposite bases.

2. B -- Ribosomes are the places where proteins are made.

3. D -- DNA has the code for how to build the proteins. Proteins are also called polypeptides.

4. C -- DNA is transcribed into mRNA.
DNA's ATG is matched by mRNA's UAC. (RNA has U, not T)
mRNA's UAC is matched by tRNA's AUC.

Answer 4

Ok 1) c, DNA is double stranded, replicates in the nucleus and both strands are templates 2) c, Proteins need to attach to help unravel the DNA, RNA comes later and it doesn't fold over 3) b, because its a double helix not single, no ion channels involved and ribose doesnt help replication.