DNA Structures and Base Pairing

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Which of the following is a correct statement about nucleotides?

Nucleotides are composed of a sugar group, a phosphate group, and a nitrogenous base. (correct)

Pyrimidines are always found in the sugar-phosphate backbone of a nucleotide.

The formation of a nucleotide involves the removal of water during bonding of the base and sugar.

Nucleotides contain either adenine or cytosine as the nitrogenous base.

Which nitrogenous base is a pyrimidine in DNA?

Uracil

Adenine

Cytosine (correct)

Guanine

Why are purines called such in the context of nucleic acids?

Due to their single carbon ring structure.

Purines form phosphodiester bonds in the sugar-phosphate backbone.

Because they contain 4 nitrogen atoms and two carbon rings. (correct)

Purines are only found in RNA molecules.

Which type of organic compound is present in both purines and pyrimidines?

Heterocyclic aromatic compounds Signup and view all the answers

What process occurs when a nucleotide is formed by bonding a base to a sugar molecule?

Condensation reaction Signup and view all the answers

In DNA, which bases pair together based on complementary hydrogen bonding?

Adenine-Thymine and Guanine-Cytosine Signup and view all the answers

What type of bond is formed between two nucleotides to create a polynucleotide strand?

Covalent phosphodiester bond Signup and view all the answers

How do purines and pyrimidines join together in DNA structure?

By forming hydrogen bonds Signup and view all the answers

Which part of the sugar molecule determines the direction of the DNA strand?

Deoxyribose ring carbons Signup and view all the answers

What is the term used to describe the rigid structure formed by the covalent bonds between sugars and phosphates in DNA?

Backbone Signup and view all the answers

In a double helix structure, what causes two nucleic acid chains to join together?

Hydrogen bonds Signup and view all the answers

Which end of a DNA strand is referred to as the '3’ end' based on its sugar composition?

'Free' third carbon end Signup and view all the answers

What is the reason behind DNA strands being complementary?

The hydrogen bonding between nucleotides Signup and view all the answers

Why does the phosphate/ribose backbone of DNA orient itself outward?

Because it is hydrophilic Signup and view all the answers

How many hydrogen bonds form between Adenine and Thymine in DNA base pairing?

2 Signup and view all the answers

In the double helix structure of DNA, what allows for the most stable energy configuration?

The correct pitch between strands Signup and view all the answers

How many base pairs typically rotate per turn in the stable double helix arrangement of DNA?

10 - 15 Signup and view all the answers

What makes RNA different from DNA in terms of nucleotide composition?

Presence of ribose sugar and uracil base Signup and view all the answers