2 - ICH - DNA Flashcards
What type of molecule is DNA?
Name it’s monomer?
Nucleic acid
Monomer = nucleotide
`What does DNA stand for?
Deoxyribonucleic acid
Name the 3 components of a nucleotide.
What are the differences for RNA and DNA?
Contains:
- Pentose sugar (deoxyribose for DNA and ribose for RNA)
- Phosphate group (from H3PO4)
- Nitrogenous organic base (DNA = Adenine, thymine, guanine, cytosine. RNA = Adenine, uracil, cytosine, guanine)
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Name the complementary base pairings?
Adenine - Thymine
Cytosine - Guanine
What is a:
Purine
Pyrimidine
Which bases are purines and which are pyrimidines in DNA?
Purine = Double ringed nitrogenous bases that form a part of a nucleotide
Pyrimidine = Single ringed nitrogenous bases that form a part of a nucleotide
DNA:
- Purines = A and G*
- Pyrimidines = C and T*
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Name the type of reaction and bond formed by the joining on nucleotides.
What do you use to hydrolyse it?
Condentation reaction
Phosphodiester bond
Nuclease
![](https://s3.amazonaws.com/brainscape-prod/system/cm/185/472/112/a_image_thumb.jpg?1463641856)
What are nucleic acids?
Polynucleotides made from monomers called nucleotides
How does a phosphodiester bond form?
H of the OH on carbon 3 of the pentose sugar in one nucleotide reacts with the OH in the phosphate group of the other nucleotide.
H2O is condensed.
![](https://s3.amazonaws.com/brainscape-prod/system/cm/189/421/141/a_image_thumb.jpg?1463641964)
Property of the phosphodiester bond?
The sugar phosphate bond is very strong and helps to maintain the sequence of nucleotides in the chain
The number of hydrogen bonds between:
- A-T
- C-G
- 2
- 3
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What direction do the chains of the polynucleotide run?
ANTIPARALLEL
One strand runs from 5’ → 3’ and the other 3’ → 5’
![](https://s3.amazonaws.com/brainscape-prod/system/cm/189/421/187/a_image_thumb.png?1463642263)
What is the structure of DNA often referred to as?
Double helix
What do these do in DNA replication?
DNA Helicase
DNA Ligase
DNA Polymerase
DNA Helicase = Enzyme that breaks hydrogen bonds holding the complementary base pairings together to unzip the 2 DNA strands.
DNA Ligase = Joins okazaki fragments of lagging strand together.
DNA Polymerase = Joins the nucleotide bases back together to form 2 new molecules of DNA which are identical to each othe and te original parent molecule.
Descibe an experiment to purify DNA
STRAWBERRIES!
- Break up a bit of strawberry in a test tube.
- Make a solution of detergent (washing up liquid), salt and distilled water. Add broken up cells to beaker containing detergent solution.
- Heat in hot water bath for 15 mins at 60°C. Detergent breaks down cell membranes, salt binds to DNA and causes it to clump together. Temperture denatures enzymes in cells.
- Place beaker in ice bath to cool. Filter the mixture into a new test tube.
- Add protease enzymes - This breaks down proteins in the mixture.
- Slowly dribble some cold ethanol down the side of the tube so a layer forms on top of the DNA-detergent mixture.
- Leave for a few minutes. DNA forms a white ppt (solid).
![](https://s3.amazonaws.com/brainscape-prod/system/cm/189/421/682/a_image_thumb.jpg?1463644630)
How does DNA replicate?
Semi conservatively = Half of the strands of the new daughter strands are from the parent strands