Chapter 13 - DNA and Protein Synthesis Flashcards
I get that this is the first part of the first part of unit 6, but I don't feel like dealing with that presently
Go from smol to big - genome, nucleosome, chromosome, histone, gene, base pair, DNA
Genome is all genetic info
Genome is made of chromosomes are made up of nucleosomes are made of DNA around histones, DNA has genes in its segments and contains base pairs
Why did the scientists think proteins could be responsible for heredity?
Have great heterogeneity (diverse) and specificity of function
Also they didn’t know ship about nucleic acids
What is transformation according to Griffith?
Change in geno and pheno due to assimilation of external DNA by a cell
How did Griffith’s experiment prove there’s genetic material in living organisms?
He stuck some S bacteria into a rat with R bacteria and the R bacteria became S bacteria and he tried again with dead S bacteria and it was the same story so there was an inheritable thing that could be picked up
What is a bacteriophage?
Bacteria eating/infecting virus
How did Hershey and Chase label viral DNA protein in their experiment?
Radioactive isotope of sulfur to tag protein, radioactive isotope of phosphorus to tag DNA (bc chons chonp) so they could see what was being tracked and where it was
What were Hershey and Chase trying to find out in their experiment?
Is DNA hereditary material or protein?
What was the Hershey Chase experiment?
Added radioactivity tagged phages to cells to see whether DNA or Protein was incorporated (did 2 runs, added mix, blender to agitate and centrifuge, measured where radioactivity was (in liquid or pellet (cells were in pellet))
What led Hershey and Chase to conclude that DNA was in fact hereditary material (at least in some cells)?
It was incorporated into the cells while the protein (sulfur) stayed out and then the Ecoli released phages containing some radioactive phosphorus, so the DNA had an ongoing role
Who built the first model of DNA and shared the 1962 nobel prize for discovering its structure?
James Watson and Francis Crick
How did Rosalind Franklin and Maurice Wilkins contribute to the discovery of the double helix?
Rosalind Franklin made an X-Ray diffraction image of DNA, Maurice let Watson and Crick use her lab and supplied the image. Watson (or Crick?) looked at it and was like yeah, that looks pretty helical to me
What are nucleotides made of?
5-c sugar (deoxyribose), phosphate, nitrogenous base (which changes between nucleotides - A,T,C,G, sometimes U)
Why do A + T and G + C bind together, structure wise?
Purines must bond with pyrimidines, so if you think of “Cut The Pye” or “PURe As Gold”, you can’t have C+T or G+A. Otherwise, the structure of G and C are made to form 3 h bonds, while A and T only form 2.
What is a purine?
Nitrogen base. Has 2 rings. Pure as gold.
What is a pyrimidine?
Nitrogen base w/ 1 ring. Cut The Pye.
Which base is only found in RNA?
Uracil
If a fly has 23% A dna, what are the other percentages?
23% T, 100-46=54, 27% G 27% C
What does A stand for? (dna)
Adenine
What does T stand for? (dna)
Thymine
What does C stand for? (dna)
Cytosine
What does G stand for? (dna)
Guanine
What makes up the backbone of DNA?
Sugar and phosphate
What makes up the rungs of DNA?
Nitrogenous bases
How to tell A from C from G from T with a picture and no letters?
Pyrimidine or purine
how many bonds does it make
If you don’t see that look for a =O in C and G
How is the 5’ end different from the 3’ end?
5’ has 5th carbon and a phosphate group sticking out, 3’ end has the 3rd carbon and an OH group sticking out
What does it mean if DNA strands run antiparallel to each other?
They go in opposite directions
Describe the Meselson Stahl experiment
They cultured E-coli in a heavy nitrogen isotope then moved it to a lighter nitrogen isotope. Then, after the 1st round of replication, they took a sample and put it in a liquid and it all floated around the middle together. They then took a sample after the 2nd round of replication and put it in liquid and half floated and half sank.
How did Meselson and Stahl use the RESULTS OF THEIR EXPERIMENT to say that DNA replication is semi-conservative?
The DNA was all floating together in the 1st round of replication, so it wasn’t conservative (it would have split if conservative)
Then, it separated during the 2nd round, so it wasn’t dispersive (it would have stayed together if dispersive)
What does DNA semiconservativeness mean at the molecular level?
When DNA is replicated, it’s unzipped and the original strands are used as templates for the new strands, which get added to the old DNA and merge.
Why is prokaryote DNA replication different from Eukaryote DNA replication?
Prokaryote DNA has 1 origin of replication because the DNA is a loop, so no need for leading and lagging strand nonsense (maybe? it does go both ways) There are also no telomeres, because again, it is a circle. Eukaryotes have multiple origins of replication and replication bubbles that expand to meet up and form 2 daughter strands.
What is the origin of replication?
Place where DNA molecule replication starts and it consists of a specific sequence of nucleotides
What is the difference between the leading and lagging strands during DNA replication?
Leading runs 5’ to 3’ TOWARDS THE FORK (og 5’ is near the helicase)(new strand has 3’ near the helicase) and is made continuously, lagging runs 5’ to 3’ away from the fork and is made in segments
T or F: New nucleotides are added away from the center of the replication bubble
True
How is the lagging strand synthesized?
Added to in segments - primase does a little, then pol 3 does a little, then primase does a little more, and it continues because it can only go in the 5’ to 3’ direction ON THE NEW STRAND REMEMBER ANTIPARALLEL
The segments made by pol3 are called Okazaki fragments
What does primase do?
Adds RNA primer to the new strand of DNA because Pol3 will not add new nucleotides to the strand unless it’s there
What does Topoisomerase do?
relieves tension in the strand by cutting and reattaching because helicase is unwinding and otherwise it would get tangled
What does helicase do?
Unwinds the strand of DNA
What does DNA pol 1 do?
Removes the RNA primer and replaces it with DNA nucleotides
What does DNA pol 3 do?
Running 5’-3’, it adds nucleotides to the new strand as it’s being formed
What does DNA ligase do?
Seals up the Pol1 and pol3
How can DNA polymerase affect repair of DNA?
It can proofread each nucleotide against the template and replace it if it’s wrong
How does Ligase affect repair of DNA?
It can seal free ends of new dna to old dna to make the strand complete
What is mismatch repair?
When DNA is distorted, it’s detected and nuclease cuts out the damaged section, polymerase fills in the missing nucleotides, ligase seals it up
Why is there a short strand of DNA that can’t be repaired or replaced?
There’s no strand on the other end so primase doesn’t go so polymerase doesn’t go so it gets chopped off - overhangs look like damage =========——
What are telomeres and what do they do?
short sections of replicated meaningless dna - these prevent useful genes from getting chopped off/ eroded away
What does telomerase do?
Catalyzes lengthening of telomeres (not meant to go forever but it does in germ cells (I THINK) and cancer cells)
WHat is chromatin?
Uncondensed chromosome (DNA + protein)
Why is packing important in DNA?
Chromosomes can move throughout the cell more easily when packed than unpacked
What is genetic engineering?
Editing genes for practical uses
What is dna cloning?
Making lots of identical copies of specific segments of DNA
What is a plasmid and where does it come from?
Small circular bactewrial DNA molecules with very few genes
What do restriction enzymes do in bacteria?
They act as the bacteria’s immune system and cut up foreign DNA in the bacteria from other organisms/phages
How do scientists use restriction enzymes in genetic engineering?
Used to cut out DNA within a restriction site
What identifies a restriction site?
Palindrome nucleotide sequences
What is the purpose of electrophoresis?
Separate nucleic acids or proteins that differ in size or electrical charge
Which side of an electrophoresis is the DNA loaded into and why?
It’s loaded into the negative side because it’s negatively charged and travels to the positive side