Second Half F24: Lecture Slides 74 - 89 Flashcards
What is RNA?
Ribonucleic Acid
What is DNA?
Deoxyribonucleic Acid
What are Nucleic Acids?
Linear polymers made by connecting nucleotides via phosphodiester bonds.
What is the repeating unit called?
Nucleotide
What does a nucleotide consist of?
Sugar, Base and a Phosphate Group
What are the “sugars” linked together by?
The phosphates from the backbone of nucleic acid - “sugar-phosphate backbone”
What does RNA contain?
D-ribose
What does DNA contain?
An unusual sugar, D-2 deoxyribose where the -OH of carbon 2 is replaced by -H
What form do both sugars occur in?
B-furanose
What two parent compounds are the nitrogenous bases derivatives of?
Pyrimidines and Purines
Which bases are the Pyrimidines?
Cytosine (C) found in both DNA and RNA
Thymine (T) in DNA and Uracil (U) in RNA
What are tautomeric forms?
Isomers that differ by the shift of a H atom and a double bond.
What does the OH group undergo?
Keto/Enol Tautomerism
What does the NH2 group undergo?
Amino/Imino Tautomerism
What are Purines?
A Fused (joined together), bicyclic (two rings) heterocycle
What are the Two Purine Bases in RNA and DNA?
Adenine and Guanine
What does a Nitrogenous Base and Sugar Produce?
A nucleoside
How is a nucleoside formed?
A base is joined to the sugar through a glycosidic bond
What is a nucleoside a special type of?
A glycoside found in nucleic acids.
What is the glycosidic bond sometimes called?
A glycosidic bond to designate the C-N linkage
What links to the anomeric carbon of ribose/deoxyribose?
The NH at position 9 of purines and the NH at position 1 of pyrimidines
What are Nucleotides?
A base + sugar + phosphate
How does a nucleotide compare to a nucleoside?
A nucleotide is a phosphorylated nucleoside.
How is a phosphodiester linkage formed?
A phosphate group bridges between the 5’ OH of one nucleotide unit and the 3’ OH of another
*Same for both DNA and RNA
What does each linear nucleic acid strand have?
A specific 5’end (lacks a nucleotide at the 5’ position) and a 3’ end (lacking a nucleotide at the 3’ position)
What are the phosphate groups at pH 7?
Completely ionized and negatively charged at ph 7
What way are nucleotide sequences written from?
5’ to 3’
What does the 2’ hydroxyl of RNA (absent from DNA) act as?
A nucleophile in an intramolecular displacement, breaking the phosphodiester linkage.
