Genetics help?

Question

1) List three main differences between DNA and RNA

2) Compare conservative, semiconservative, and dispersive modes of DNA replication.

3) Several temperature -sensitive mutant strains of E. coli display various characteristics. predict what enzymes or function is being affected by each mutation.
a) Newly synthesized DNA contains many mismatched base pairs.
b) Okazaki fragments accumulate, and DNA synthesis is never completed.
c) No initiation occurs.
d) Synthesis is very slow.
e) supercoiled strands are found to remain following replication , which is never completed.

4) define and indicate the significance of a) Okazaki fragments, DNA ligase and Primer RNA during DNA replication.

Answer 1

First off.....the poeple above are wrong.....except for looking at thoses links....but thats dumb...

1) DNA uses the deoxyribonucleic acid (Sugar)
DNa is double stranded in a double helix
DNA uses the base thymine

RNA uses just ribonucleic acid
RNA is single strnaded, usally just sright by itself
RNA uses Uricile instead of thymine


2) All can be comapired on this chart
http://www.niles-hs.k12.il.us/jacnau/chpt167.jpg

3)
a) DNA polymerase -They *proofread* the newly created DNA for errors...such as this...
b) DNA ligase - They bond the okazaki Fragments together with covelent bonds
c) RNA primers - The catalyse the begining of the newly formed DNA strand
d) Not sure abotu this, becasue....its not that big....but its possible because the RNA selection is hard. Its cold....i dunno
e) Signel Stranded Protiens?- I htink this becase these hold the DNA stable and opened during DNA replication. If the DNA is foudn to be supercoiled, its possible that these didnt hold it open properly.

4) Okazaki fragments are teh new complementary strands of DNA on the LAGGING strand. Since DNa replicates from teh 5' to 3' end, the one side will alway be fragmented. Without them, your DNA would be really screwed up on the laggging strand. Its important becae without it, you cant really get a newly synthesises complementary side for the semi conservative DNA

DNA ligase is an enzyme used to bond okazaki fragments together. Without them, one side of oen of the new semi conservative DNA would not be connected with teh phospodiester bonds throughout. It will have gaps.

RNA primer is an enzyme that joins the RNA nucleotides to teh DNA strand. They are usally about 10 nucleotides long, but they can be longer...much longer... This is important in DNA replication, becasue DNA polymearse canniot start teh first bonds of RNA nucleotides to the DNA. Without them, = DNA is slipt in half....wierd...
e)

Answer 2

1) Have a read of the wiki page comparing DNA with RNA

2) Have a read of the wiki page comparing the various modes of DNA replication

3) All of the above listed characteristics would inhibit protein synthesis or create mutant, often non-functioning proteins in the case of (a)
(a) DNA polymerase III
(b) DNA polymerase I, I guess
(c) DnaA, possibly helicase
(d) ?poor unwinding by helicase
(e) sounds like a DNA topoisomerase problem

4) Have a read of the wiki pages about Okazaki fragments, DNA ligase and primer RNA

Answer 3

Alot of these answers are found in the chapter or in a glossary...I know they are in my text book. Just read! Good luck.