DNA as genetic material

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What is a nucleoside?
nucleotide without phosphate group. just the nucleobase, and five carbon sugar
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what is a nucleotide?
ribose/deoxyribose sugar, nitrogenous base and at least 1 phosphate grou;
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What is a polynucleotide?
bipolymer of 13+ nucleotide monomers covalently bonded in a chain.
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what is nucleic acid?
one/two polynucleotide chains. eg DNA or RNA
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Distinguish between the bases.
See page.
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Outline Griffiths experiment.
Strain S made mice die. Strain R didn't. If S was heat-killed then the mouse lived. If S heat-killed and R together then mouse died. Found Heat stable transforming component that changed R to S.
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Outline the Avery experiment.
Experiment 1 the S+R strain was treated with tripsin (protein breakdown) the mouse dies. Experiment 2 the S+R strain was treated with DNase. the mouse lived. This concluded that the transforming principle was DNA.
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Outline the Hershey-chase experiment
1. the bacteriophage had a sulfur labelled protein capsule. NO sulfur was found in the cell it infected. 2. The bacteriophage had a phosphorous labelled core. Phosphorous was detected inside the cell it infected. Shows it must be DNA.
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What is the length of the human genome in each cell?
1.8m
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What is the role of topoisomerase in replication?
Topoisomerase 1 relaxes super coil caused by torsion energy of unwinding. Topoisomerase 2 (gyrase) cuts and reseals DNA strands to relieve supercoil.
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Lagging strand
Thought that you get lots of okasaki fragments build in the right direction that are made together. Instead it is found the lagging strand is looped and the DNA is now replicated in the correct direction.
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function od DNA pol3, b-protein sliding clamp, SSb, and DNA pol1
DNA pol3-synthesises new strands, DNA pol 1-at junction of okasaki fragments replaces primer with DNA. sliding clamp-attaches DNA pol 3 to DNA. SSB (single strand binding protein) stops helix and keeps parent strands single.
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RNA primers, DNA helicase, Primase and DNA ligase
RNA primers-single regions of DNA already with W+C pairing , DNA helicase-unwind strand (also topoisomerases) Primase- makes RNA primers. DNA ligase-joins the two fragments made by pol1 and 3 together.
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What if an error occurs?
Pol 1 +3 have an 3-5' exonuclease activity which stops reverses , removes incorrect base and adds a new correct base. They work as a different angle is formed with an non-wc base pairing.
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Other cards in this set

Card 2

Front

what is a nucleotide?

Back

ribose/deoxyribose sugar, nitrogenous base and at least 1 phosphate grou;

Card 3

Front

What is a polynucleotide?

Back

Preview of the front of card 3

Card 4

Front

what is nucleic acid?

Back

Preview of the front of card 4

Card 5

Front

Distinguish between the bases.

Back

Preview of the front of card 5
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