2: Structure of DNA and RNA Flashcards Preview

IB Biology SL > 2: Structure of DNA and RNA > Flashcards

Flashcards in 2: Structure of DNA and RNA Deck (12):
1

State the 2 types of nucleic acid.

DNA and RNA

2

What are the polymers DNA and RNA composed of?

subunits called nucleotides

3

Name all the parts of a nucleotide.

- pentose sugar
- phosphate group
- base

4

Sketch and label a nucleotide. (p28)

-

5

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

6

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

7

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

8

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

antiparallel - they run alongside each other but in opposite directions

9

Where do hydrogen bonds form in a DNA molecule?

between the bases of two strands

10

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

11

Who discovered the structure of DNA?

Watson and Crick

12

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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