2: Structure of DNA and RNA Flashcards
State the 2 types of nucleic acid.
DNA and RNA
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.
- type of pentose sugar:
- RNA = ribose
- DNA = deoxyribose - possible bases:
- RNA = adenine, cytosine, guanine, uracil
- DNA = adenine, cytosine, guanine, thymine - 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
