2.1 DNA Structure And Replication Flashcards
Components of deoxyribonucleotide vs ribonucleotide (3)
1) deoxyribose vs. ribose (pentose) sugar
2) nitrogenous base (ATCG vs. AUCG)
3) phosphate group
Pentose sugars occur as ____ forms
Ring
In nucleic acids, the 5’ carbon of the pentose sugar is linked to the ________ ____ in an ____ bond
Phosphate group; ester
In nucleic acids, the 1’ carbon of the pentose sugar is linked to the ___________ ____ in an _________ bond.
Nitrogenous base; glycosidic
Difference in structure of deoxyribose VS ribose
At the 2’ carbon, deoxyribose has a hydrogen atom, instead of a hydroxyl group like in ribose
Properties pentose sugars confer on the nucleotide (2):
1) Provides OH groups that contribute to its hydrophilicity
2) Allows for the addition of nucleotides due to a free 3’ OH group
Explain why there is a difference in structure between RNA and DNA (hint: helix)
RNA is a less tightly coiled helix as DNA, as the partial neg. charge of the -OH grp in ribose repels the neg. charge of the phosphate
S->Property of RNA
As RNA exists as a less tightly coiled helix, it is more susceptible to chemical and enzyme degradation
2 types of nitrogenous bases
Purines (AG)
Pyrimidines (CT/U)
Structure of purines (hint: rings)
Have a 6 membered (nitrogen-containing) ring fused to a 5 membered ring
Structure of pyrimidines (hint: ring)
Have a 6-membered ring
Pure As Gold
Purines — Adenine, Guanine
Pyrimidines are CUT from purines
Pyrimidines — cytosine, uracil, thymine
— one ring
Thymine: the meTHYl is MINE
Add. Methyl substituent at C5
Nucleoside =
pentose sugar + nitrogenous base
Glycosidic bond: the __’ carbon of the pentose is linked to the nitrogenous base via a __________ ______.
1; condensation reaction
Nucleotide =
Nucleoside + phosphate grp
A ________ bond is formed between the _’ carbon of the pentose and the ________ _____, in a __________ _______.
Phosphoester; 5; phosphate group; condensation reaction
dATP
deoxyadenosine triphosphate
GMP
guanosine monophosphate
The _’ phosphate group of one nucleotide and the _’ hydroxyl group of the other is joined in a ___________ bond via _________.
5, 3, phosphodiester, condensation
Phosphodiester bonds between 5’ phosphate and 3’ hydroxyl group of nucleotides form a ________, ________, sugar-phosphate backbone.
Linear, unbranched
Role of phosphodiester bonds (2)
1) They confer strength and stability to the polynucleotide chain, as they are strong covalent bonds
2) prevents breakage of chain during DNA replication
5’ end of DNA/RNA chain:
Free 5’ carbon carrying a phosphate group