Nucleic acids Flashcards

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1
Q

Bases in DNA

A

adenine, guanine, cytosine, thymine

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2
Q

Bases in RNA

A

adenine, guanine, cytosine , uracil

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3
Q

Difference in base pairing in nucleic acids

A

Adenine - thymine or uracil form 2 hydrogen bonds between them

Guanine - cytosine form 3 hydrogen bonds between them

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4
Q

Differences between DNA and RNA

A

In DNA, two long polynucleotide chains form a double helix, whereas in RNA is consists of one single helix short polynucleotide chain

RNA has uracil as a nitrogenous base rather than thymine

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5
Q

What does semi conservative DNA replication mean and why is it important

A

One strand of one of the new DNA chain is from the original DNA, and the other is a newly synthesised strand

it ensures that the genetic code remains identical between generations of cells

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6
Q

Whole process of semi-conservative replication

A
  • DNA helicase will unzip the original DNA strand by breaking the H bonds between all the bases leaving two separate template strands
  • New free DNA nucleotides will attach to the exposed bases on the template strands by complementary base pairing
  • DNA polymerase will join adjacent nucleotides 5’-3’ to form phosphodiester bonds on the new strand of nucleotides
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7
Q

Why is DNA antiparallel

A

as the sugar phosphate backbone runs 3’-5’ up one strand and 3’-5’ down the other strand

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8
Q

What is the meselson-stahl experiment

A

Its evidence for semi-conservative replication

Added DNA of E coli in two separate test tubes in and grew them in 14n and 15n nitrogen isotopes.

then allowed DNA to replicate one generation to allow nitrogen isotopes to be incorporated into the DNA

then took a sample from each test tube and grew them together and allowed one generation of replication

then took all three tubes and spun in a centrifuge to allow DNA to form bands

14n showed a band at the high point

15n showed a band at a lower point

14n+15n showed a band in between, suggesting that the replication was semi conservative as both isotopes of nitrogen were incorporated into the DNA

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9
Q

Structure of ATP

A

Adenine, ribose and 3 phosphates

adenosine triphosphate

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10
Q

what is ATP broken into and how

A

ADP + Pi

its hydrolysed using the enzyme ATP hydrolase

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11
Q

How is ATP synthesised

A

ADP + Pi = ATP

Condensation reaction to form a bond between to inorganic phosphates using the enzyme ATP synthase

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12
Q

Adaptation of ATP (x2)

A
  • it can be rapidly resynthesized after it has been broken down so can be recycled to be used in various functions in the body
  • the inorganic phosphate can phosphorylate other compounds to make them more reactive
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13
Q

Properties of ATP (x4)

A

-Releases small amounts of energy at a time to prevent cell death by heat as energy can be wasted through heat

  • cannot leave the cell that it is synthesised in, so is constantly available for use in respiration
  • it is an immediate source of energy as hydrolysis of ATP involves only 1 step
  • Is soluble
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