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Chapter 16 and 17 DNA Replication And Translation and Transcription (DNA,…
Chapter 16 and 17 DNA Replication And Translation and Transcription
DNA
Eukaryotic/Prokaryotic:DNA Replication
Eukaryotic DNA
Circular Chromosomes
Could result into two daughter DNA molecules
Parental strands separate = a replication bubble with two forks
Prokarkyotic DNA
Linear Chromosomes
Bubbles fuse and synthesis of the daughter strands complete (From opposite side of the the bubbles.
Bubbles expand as replication proceeds in both directions
Structure of the DNA
Under Microscope
Nitrobgenous Base
5'>3' and 3'>5'
Sugar-phosphate backbone
Phosphate group-DNA nucleotide
Double Helix; presence of two strands
"Ladder Style" -Pairing
The nitrogenous Bases Pair
Cytosine>Guanine(C>G)
Guanine>Cytosine(G>C)
Adenine>Thymine(A>T)
Thymine> Adenine (T>A)
DNA Replication Definition:
End of Replication Bubble is a replication fork. A Y shaped region where the parental strands of DNA are being unwound.
Primase-sythesize an RNA primer at 5' ending leadingstrand and at 5' end of each Okazaki fragment of laging strand
Helicases-enzyme that untwist the double helix at the replication forks, separating the two parental strands and making them available as template strands.
Single-Strand binding protein-stabilize the unwound parental strands
Topoisomerase-Relieves oeverwinding strain ahead of replication forks by brekaing swiveling and rejoining DNA strands
DNA pol 1- Removes RNA nucleotides of primer from 5' end and replaces them with DNA nucleotide added to 3' end of adjacent fragment
DNA pol 3-Using parental DNA as template, synthesize new DNA strand by adding nucleotide to an RNA primer or a pre-existing DNA strand.
DNA ligase-Joins Okazaki fragments of laging strand; on leading strand, joins 3' end of the DNA that replaces primer to rest of leading strand DNA.
Process of Creating New Strands of DNA
nucleotide chain that = during the DNA synthesis Chain is called Primer
Primer is created in the RNA primase
DNA Strands will start from the 3' end of the RNA primer
DNA Polymerase
Type of Enzyme: they need primer and DNA template strand along which complementary DNA
Prokaryote: Have several Polymerase
DNA polymarase 1
DNA polymerase 3
Eukaryotes
11 different DNA polymerase
ATP Vs. dATP
Difference in Sugar
dATP-Ribose
ATP-Adenosine Triphosphate
DNA polymerase catalyzes the addition of the addition of a nucleotide to the 3' end of a grwoing strand, with the release of two phosphates.
only add to the free 3' end of a primer or growing DNA strand, never to the 5' end
Mutation Vs. Repair and Telomere
Repair
mismatch repair
remove and replace incorrectly paired nucleotide that have resulted from the replication errors.
nucleotide excision repair
repair due to the ultraviolet; removes the damaged part; DNA polymerase fills the removed section; DNA ligase makes new strands
Why do DNA need to be repair
They can be subjected to potential harmful chemical and physical agents such as X-rays.
Mutation
A change in the nucleotide sequence of an organism's DNA or in the DNA or RNA virus
Telomere
Tolemeres
Noncoding sequence
do not contain genes;
they postpone erosion of genes near the ends of chromosomes
ttaggg
Leading and Laging strands
Antiparallel
Double helix is Antiparallel
opposite direction to each other like two sided of a street.
effect on how replication occur
Leading Strands
only one primer is need fro DNA poll 3 to synthesize the entire leading strand.
1) After RNA primer is made, DNA pol 3 starts to synthesize the leading strand.
2) The leading strand is elongated continuously in the 5'>3' direction as the fork progresses.
Laging Strands
synthesized discontinously as a series of segments "Okazaki Fragments
can't be started until enough template has been expose at the replication fork.
Transcription Vs. Translation
occur in all organism
Transcription
Synthesis of RNA using information in the DNA
Transcription at a Eukaryota promoter
mRNA which carries a genetic message from the DNA to the protein sytnthesizing machinery of the cell.
Promoter-start of the trancription process
2)
Elongation
-the polymerase moves downstream, unwinding the DNA and elongating the RNA transcript 5'>3'. which reform the double helix. thymine change to uracil during the transcription process
3)
Termination
-Eventually the RNA transcript is released, and the polymerase detaches from the DNA.
1)
Initiation
-after the RNA polymerase bind to the promoter the DNA strands unwind and polymease initiates RNA synthesis at the start point on the template strand. (Create bubbles)-RNA polymerease
DNA>RNA>Protein
passing Genetic material: RNA polymerase ensure that DNA don't mutate, making the DNA passed down and making sure that it''s not damage
Translation
Synthesis of a polypeptide using the information in the mRNA
Site=Ribosomes
Change in languange-nucleotide sequence of an mRNA molecule into the amino acids sequence of a polypeptide
