Nucleic Acids Flashcards
What are the 3 components of nucleic acids
- Phosphate group
- Pentose sugar
- Nitrogenous base
What does the backbone of a DNA molecule consist of?
- Phosphate group
- Deoxyribose sugar
What bonds are present between bases?
Hydrogen bonds
What bonds are present between the sugar and phosphatgroup?
Phosphodiester bonds
How are phosphodiester bonds broken?
Hydrolysis
How does DNA and RNA differ?
- DNA has the base thymine and RNA has uracil
- Ribose has an oxygen atom and deoxyribose doesn’t
- DNA contains the sugared deoxyribose and RNA contains ribose
- DNA is double stranded and RNA is single stranded
What are the 2 groups of nucleotides?
- Purines
- Pyrimidines
What are purines?
- Adenine and guanine
- Contain double carbon ring structures (hexagon and pentagon)
- Made up of carbon and nitrogen
What are pyrimidines?
- Thymine and cytosine
- Contain a single carbon ring structure (hexagon)
- Made up of carbon and nitrogen
How many hydrogen bonds are present between adenine and thymine (purines)?
2
Complementary base pairing
How many hydrogen bonds are present between cytosine and guanine (pyrimidines)?
3
Complementary base pairing
What’s a nucleoside?
Same as a nucleotide but doesn’t have a phosphate group
What is a monomer?
An individual (nearly identical) unit that acts as a building block for large biological molecules
What is a polymer?
A large molecule made up many small monomers in a chain
Who discovered the double helical structure of DNA?
James Watson and Francis Crick
What is Erwin Chargaff’s rule?
The % A = T and the % C= G
Describe the order of nucleotides
- 5’ to 3’
- Strands are anti-parallel
What is meant by 6’ and 3’ end of a nucleotide?
The 5’ end is the phosphate group and the 3’ end is the hydroxyl group of the sugar
Is the helix usually right-handed or left-handed?
Right-handed
Does the helix spiral clockwise or anti-clockwise?
Clockwise
How many bases are there per twist?
10
How big is one big complete turn in the helix?
3.4nm
What are the 2 asymmetrical grooves on the outside of the high handed helix called?
- Major groove
- Minor groove
What can bind to these grooves to interact with a particular sequence of bases
Proteins
What is the predominant form of DNA secondary structures in living cells ?
B-DNA
What other double believes can form under certain in vitro conditions?
A-DNA and Z-DNA
How long is human nuclear DNA?
2m
What are the 4 significant RNA molecules?
- rRNA
- tRNA
- mRNA
- siRNA
What is a gene?
A section of DNA that contains the complete sequence of DNA to code for an entire protein
