10.1 - Nucleotides Flashcards
What are nucleotides made up of?
- Pentose sugar
- Base (nitrogenous bases)
- Phosphate group (negatively charged)
Elements in nucleotides?
- Phosphorus
- Nitrogen
- Carbon
- Oxygen
- Hydrogen
Draw a diagram of a single nucleotide
…
What do nucleotides do?
Used to form DNA and RNA
Differences between general structure of nucleotides in DNA and RNA?
Sugar in DNA: deoxyribose
Sugar in RNA: ribose
Base in DNA: Thymine used
Base in RNA: Thymine not used. Replaced by uracil.
Difference between deoxyribose and ribose sugar?
Deoxyribose sugar has one less oxygen atom
Bases in DNA:
- Adenine
- Thymine
- Cytosine
- Guanine
Which bases have a double ring structure?
- Adenine
- Guanine
What are bases with double ring structure called?
Purines
What are bases with a single ring structure called?
Pyrimidines
What bases have a single ring structure?
- Thymine
- Cytosine
Where does reaction occur to form polynucleotide?
Between phosphate group (on 5th carbon) of one nucleotide and the hydroxyl group (on carbon 3 of pentose sugar) of the other.
Name of bond between two nucleotides?
Phosphodiester bond
What type of reaction forms a phosphodiester bond?
Condensation (as water is produced).
Two nucleotides joined by phosphodiester bond?
dinucleotide
Examples of polynucleotides?
RNA and DNA
Other name for polynucleotides?
Nucleic acids
About the phosphate group?
Inorganic molecule that is acidic and slightly negatively charged
About the nitrogenous base?
Complex organic molecule containing two or more carbon rings in structure as well as nitrogen.
Role of phosphodiester bonds?
Form a strong, long sugar-phosphate ‘backbone’ with a base attached to each sugar.
Structure of DNA:
Two strands of polynucleotides coiled into helix. Known as DNA double-helix.
How are the two strands of double helix joined together?
Hydrogen bonds between bases.
How do bases join?
Base on one strand is complementary to bases on the other strand
Result of pyrimidine bases linking with Purine bases?
The distance between sugar-phosphate backbone is constant. Result in parallel nucleotide chains.
How are the two polynucleotide strands in DNA antiparallel?
Run in opposite directions.
How do polynucleotide strands run in opposite directions?
On the left, the carbon 5 is at the top and carbon 3 (-OH) is at the bottom.
On the right, the carbon 3 (-OH)is at the top and the carbon 5 is at the bottom.
Guanine and Cytosine hydrogen bonds?
Form 3 hydrogen bonds
Adenine and Thymine hydrogen bonds?
Form 2 hydrogen bonds
What is the result of complementary bases?
Proportion of Adenine to Thymine is always the same.
Proportion of Guanine to Cytosine is always the same.
Can calculate proportions of different nucleotides.
20% of the nucleotides in a sample of DNA contain base guanine. What are the proportions of the other bases?
Guanine: 20%
Cytosine: 20%
Thymine: 30%
Adenine: 30%
What does pairing between bases allow for?
copied and transcribed - key properties of heredity.
Where is DNA found?
Chromosomes in the nucleus
Where is RNA found?
Cytoplasm
Role of RNA?
In protein synthesis
Difference between length of DNA and RNA?
DNA: long molecule
RNA: relatively short molecule
Difference between structure of DNA and RNA?
RNA: One polynucleotide strand
DNA: Two polynucleotide strands in double helix
What happens to RNA molecules after protein synthesis?
Degraded in cytoplasm - the phosphodiester bonds are hydrolysed in the cytoplasm. RNA nucleotides released and reused.
Bonding of uracil to adenine?
2 hydrogen bonds
