2: Structure of DNA and RNA Flashcards Preview

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Flashcards in 2: Structure of DNA and RNA Deck (12):

State the 2 types of nucleic acid.



What are the polymers DNA and RNA composed of?

subunits called nucleotides


Name all the parts of a nucleotide.

- pentose sugar
- phosphate group
- base


Sketch and label a nucleotide. (p28)



State the differences between DNA and RNA nucleotides.

1. type of pentose sugar:
- RNA = ribose
- DNA = deoxyribose

2. possible bases:
- RNA = adenine, cytosine, guanine, uracil
- DNA = adenine, cytosine, guanine, thymine

3. number of strands:
- RNA usually has one strand
- DNA usually has two strands


Sketch and label the structure of DNA. (p28)

- remember to draw 4 base pairings showing bonds between (8 nucleotides in total):
1. A-T
2. G-C
3. T-A
4. C-G

rest is on p28


How are nucleotides linked in DNA and RNA?

by covalent bonds between the pentose sugar of one nucleotide and the phosphate of the next one


Describe the arrangement of the two strands in a DNA molecule?

antiparallel - they run alongside each other but in opposite directions


Where do hydrogen bonds form in a DNA molecule?

between the bases of two strands


Describe a DNA molecule.

- 2 antiparallel strands, wound to form double helix
- hydrogen bonds between strands
- DNA polymer strand made up of nucleotide subunits
- nucleotides made of: deoxyribose (pentose sugar), phosphate group, and a base
- possible bases: adenine, guanine, thymine, cytosine
- complementary base pairs: A-T, G-C
- covalent bonds link nucleotides


Who discovered the structure of DNA?

Watson and Crick


How did they convince others that they had found the structure of DNA?

by building a model:
- all bond lengths to scale
- all bond angles were correct
- used cardboard shapes to represent bases and found that A-T and C-G base pairs could be formed, with h-bonds linking bases

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