Lecture 1 - Nucleotides and DNA Flashcards Preview

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Flashcards in Lecture 1 - Nucleotides and DNA Deck (79)
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1

What are the 3 parts of a nucleotide?

1. Purine or pyrimidine base
2. Pentose sugar
3. Phosphate group

2

What forms the backbone of DNA?

Phosphoester linkages between phosphate groups and sugars

3

Order of DNA?

5' => 3'

4

How to differentiate between purines and pyrimidines?

Longer name = smaller structure

5

2 purines?

1. Adenine
2. Guanine

6

3 pyrimidines?

1. Cytosine
2. Thymine (DNA)
3. Uracil (RNA)

7

On what part of nucleotides do mutations happen most often on?

Base

8

What is a nucleoside?

Base + sugar

9

What is a nucleotide?

Base + sugar + phosphate

10

What are deoxyribonucleotides?

Nucleotides with β-2′-deoxy-D-ribofuranose (without a 2' (-OH) group)

11

What are deoxyribonucleotides used for?

DNA

12

What are ribonucleotides used for?

RNA

13

Order of DNA synthesis?

5' => 3'

14

How many H bonds between A and T?

2

15

How many H bonds between C and G?

3

16

Why is the antiparallel structure of DNA more thermodynamically favorable/stable?

Because it orients the H bonds in a linear manner, in which they are the strongest

17

How was the DNA structure discovered?

By X-ray showing the diffraction pattern of DNA: spots forming a cross in the center denote a helical structure and heavy bands at the left and right arise from the recurring bases

18

Periodicity of the helical structure? What does it represent?

34 angstroms (36 in solution) = periodicity of the stacking of the bases

19

Which noncovalent bond is the strongest in the presence of water?

Van der Waals

20

If the H bonds contribute so significantly to the stability of DNA, then what must be true about the interior of the helix?

Water is excluded

21

What does the 5' end of DNA/RNA lack?

A nucleotide at the 5′ position

22

What does the 3' end of DNA/RNA lack?

A nucleotide at the 3′ position

23

Is the backbone of DNA/RNA polar?

YES, VERY

24

What is the sugar of RNA? How does it exist in solution?

β-D-ribofuranose: the straight-chain (aldehyde) and ring (β-furanose) forms of free ribose are in equilibrium (99% ring form)

25

What happens to DNA when put in solution?

B to A form

26

What is semi-conservation replication of DNA?

The preexisting or "parent" strands become separated, and each is the template for biosynthesis of a complementary "daughter" strand

27

What are the 3 forms of DNA? Most common one? Least common one?

1. A
2. B (most common)
3. Z (least common)

28

Helical sense of A form DNA?

Right handed

29

Helical sense of B form DNA?

Right handed

30

Helical sense of Z form DNA?

Left handed