1.8 - [Intro to] The structure of DNA & Nucleic Acid Flashcards
What does DNA stand for?
Deoxyribonucleic acid
True or False:
DNA strands form a double helix.
True
How are DNA strands held together?
Using hydrogen bonds
What is a nucleotide?
- It’s a monomer of DNA
- made up of 3 parts: phostphate group, deoxyribose sugar, and a nitrogen base
- these stack together to make a single strand of DNA
What is the “backbone of DNA”?
Phosphate and sugar bonded together
What is the bond called between phosphate and sugar?
phosphodiester bond
[phospho-di-ester]
What are the 2 groups of nitrogen bases?
Purines and Pyrimidines
Name the 2 purines
Adenine & Guanine
Name the 2 pyrimidines
Cytosine & Thymine
True or False:
For each nucleotide in DNA, the phosphate and deoxyribose sugar change.
False.
The phosphate and sugar DO NOT CHANGE
True or False:
The carbons in the sugars are numbered 1 to 5.
False.
They are numbered 1’ to 5’
[one prime to five prime]
True or False:
The carbons in the sugars are numbered 1 to 5.
False.
They are numbered 1’ to 5’
[one prime to five prime]
What is the difference between deoxyribose and ribose sugar (according to their diagrams)
Deoxyribose is missing an OH on C2’
Are Purines made of 1 or 2 carbon rings?
(Nitrogen bases)
Purines have 2 rings
Are Pyrimidines made of 1 or 2 carbon rings?
(Nitrogen bases)
Pyrimidines have 1 ring
Is thymine used in RNA or DNA?
Thymine is used in DNA only
What nitrogen bases does RNA use?
Adenine, guanine, cytosine, and uracil.
What is uracil?
- It’s a nitrogen base
- used in place of thymine in RNA
State the base pairing rules for nucleic acids
1) Purines can ONLY pair with pyrimidines
2) Bases only match if the SAME # OF HYDROGEN BONDS are made
What are the results of the base pairing rules?
What bases bonds with what? How many bonds do they make?
Adenine matches with Thymine. Form 2 hydrogen bonds
Guanine bonds with Cytosine. Form 3 hydrogen bonds
Single DNA strands have 3’ and 5’ ends. How can you tell which end is which?
If the oxygen in the sugar is pointing downwards (pentagon point facing down), it’s pointing towards the 5’ end.
What are the differences between DNA and RNA?
Hint: there are three
Sugars: DNA uses deoxyribose, RNA uses ribose
Strands: DNA is double stranded, RNA is single stranded
Bases: DNA uses thymine, RNA uses uracil
