Deoxyribonucleic Acid [ DNA] Flashcards

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1
Q

Who discovered the specific ratios of : nitrogenous bases in DNA in 1951?

A

Erwin Chargaff

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2
Q

What does Chargaff’s rule state about : the nitrogenous bases in DNA?

A

The amount of adenine is equal to thymine, and guanine is equal to cytosine.

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3
Q

What is the ratio of total purines to total pyrimidines in DNA according to Chargaff’s rule?

A

1:1

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4
Q

Who conducted X-ray diffraction analysis of DNA that contributed to the understanding of its structure?

A

Maurice Wilkins and Rosalind Franklin

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5
Q

What structure did Wilkins and Franklin claim DNA had?

A

A duplex (double helix) molecule

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6
Q

What is the width of the DNA duplex?

A

2nm

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7
Q

What is the length of each turn of the:
DNA duplex?

A

3.4nm

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8
Q

Who proposed the Watson and Crick model of DNA in 1953?

A

Francis Crick and James Watson

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9
Q

What does the Watson and Crick model state about the structure of DNA?

A

DNA is made up of two polynucleotide chains attached by base pairs.

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10
Q

How are the two polynucleotide chains’
in DNA oriented?

A

They are opposite in direction
+
(antiparallel).

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11
Q

What is the direction of one of the polynucleotide chains in DNA?

A

5’ to 3’ downward

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12
Q

What is the direction of the other polynucleotide chain in DNA?

A

5’ to 3’ upward

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13
Q

What is the width of both polynucleotide chains in DNA?

A

2nm

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14
Q

What is the specificity of base pairing: in DNA?

A

Adenine pairs with thymine, and guanine pairs with cytosine.

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15
Q

How many hydrogen bonds are between guanine and cytosine?

A

Three hydrogen bonds

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16
Q

How many hydrogen bonds are between adenine and thymine?

A

Two hydrogen bonds

17
Q

How many base pairs are there in each turn of the DNA duplex?

A

10 base pairs

18
Q

What is the relationship between the two polynucleotide chains in DNA?

A

They are complementary to each other.

19
Q

Is there a restriction on the sequence of nucleotides in a DNA strand?

A

No, the sequence can vary in countless ways.

20
Q

What does the sequence of nucleotides in DNA specify?

A

It is specific for different species, organisms, and individuals.