Molecular Genetics: DNA Replication Flashcards
DNA is __% this and __% this
50% genetics
50% protein
The nature of genetic material (5)
1.) DNA has to be able to replicate
2.) Stable (doesn’t change all the time)
3.) Contains information
4.) Transmit and control information in the cell
5.) Be able to change in a controlled way to enable survival of species by variations
Feulgen, what he discovered, and when
A scientist who created a stain which stains chromosomes to be able to see how they work
1912
Griffith, what he discovered, and when (7)
-1920
-2 forms of pneumonia bacteria
-S shape with shiny disks
-R shape with rough disks
-Injected mice with S they died
-Injected mice with R they lived
-If they heated the s cells then they lived
Conclusion of Griffiths expirment
The molecules the S cells released when killed could change living R cells into S cells. He called this transformation.
Avery-MacLeod-McCarty
Took Griffith’s experiment one step forward and figured out that it was DNA that caused the bacteria to turn into an infective form not protein
Hershey Chase experiment what and when (3)
-1852
-The tails on Bacteriophage touch a cell and they all glue onto it and the tail compresses into the cell and injects the DNA into the cell
-They died the Protein Sulfur red and the DNA Phosphorus green. They then looked to see if either colour was inside the cell after centrifugation.
Erwin Chargaff what and when (4)
-1950
-went through a bunch of different organisms
-Looked at the ratio of DNA AGCT foreach organism
-Chargaff’s ratios mean that CG pair together and AT pair together
Rosalind Franklin (2)
-taking crystals of DNA and taking x-rays of them
-characteristic pattern showing the structure of DNA was a double-helix
Watson and Crick what and when (4)
-1953
-Stole Franklins work
-built models of what DNA look like
-realized the pairs were the same size and were put together as a ladder
3 components of Nucleic acids
-Pentose Sugar (ribose of deoxyribose) made of Oxygen, Carbon, and Hydrogen
-Phosphate group
-Nucleotide base
What is the difference between ribose and deoxyribose?
Deoxyribose has a missing OH-
4 characteristics of nucleotides
-Have 4 bases (cytosine, guanine, thymine, and adenine)
-3 phosphate groups on the side
-ATP is one of the bases in DNA
-ADP has two phosphate groups
What’s on the bottom
two groups of nucleotide bases
purines and pyrimidines
Purines
Adenine and Guanine
Bigger structure
Pyrimidines
Cytosine, Thymine, Uracil
Smaller structure
How many bonds are on a GC pair
3 hydrogen bonds
How many bonds are on a AT pair
2 hydrogen bonds between them
1’ end
Where a base attaches
3’ end
-where the most important hydroxyl group is
-DNA can only build off this end
5’ end
Has an O group attached
5 characteristics of DNA
-Very stable
-Found in the Nucleus
-Only found outside the nucleus during replication, and in chloroplast and mitochondria
-Each cells contains all the genes for the organism
-Hard to break up
Meselson-Stahl (5)
-Proposed 3 models of DNA replication
-Semi-Conservative is the way replication works
-Each stand is pulled apart and then a new copy attaches to the other side
-They used E.coli and put it in N15 which is heavier and N14
-They crossed the N15 generation with N14 and did it multiple times and each time there was more N14 present than N15
6 proteins involved in DNA replication
helicase
topoisomerase
DNA polymerase I and III
DNA primase
ligase
single-stranding binding proteins
Helicase
unwinds DNA helix and puts stuff on it so the strand don’t glue back together
Topoisomerase
Relieves the overtwisting of the DNA ahead of the replication fork
DNA polymerase III
Assembles DNA chain on both sides
DNA polymerase I
Replaces the primer fragments with the correct DNA
ligase
Seals the nicks left between DNA where the RNA fragments used to be
single-stranding binding proteins
Stabilizes DNA in single-chain form
Okazaki fragments
The fragments of DNA placed in the lagging strand
Which way is DNA replicated
from the 3’–> 5’ end
What happens to the phosphate when DNA is being put together
When DNA is being put together the base being laid has 3 phosphates attaches. One stays and the other two push off and go to the 3’ end.
Proof reading
Depends on the ability of DNA polymerase to reverse and remove mismatched bases
What happens during the DNA repair mechanism
-Polymerase I recognizes the mispaired bases
-Remove a section of DNA with the mispaired, and replace it with a new section
The template strand is…
continuous
the new strand…
has nicks left in it
How does DNA replication explain cancer in older people
they have had more replications which means more time for replication errors to occur
Rolling circle replication (4)
1.) A donor cell duplicates with a recipient
2.) A strand of f-factor breaks and moves through a conjunction bridge
3.) DNA replication of the f-factor is continuous in the donor and discontinuous in the recipient
4.) One done they are completely identical copies
