Nucleic Acids Flashcards

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Questions and Answers

Draw a nucleotide and label the three main parts.

Nucleotide consists of a base, a deoxyribose sugar, and a phosphate.

Which of the following represent purine and pyrimidine nucleotides?

Pyrimidine: A & G

Purine: C & T

Pyrimidine: C & T (correct)

Purine: A & G (correct)

Explain why the pairing of one purine with one pyrimidine is important to the shape of a DNA molecule.

It maintains a constant distance between the deoxyribose backbones.

Define 'complementary base pairing.'

A base in one strand forms specific hydrogen bonds with another base in the opposite strand. Signup and view all the answers

Explain the difference between a nucleotide and a 'base.'

A base is one of the nitrogenous bases; a nucleotide is composed of a base, a sugar, and a phosphate. Signup and view all the answers

Explain how the structure of DNA is important to its function as an information storage molecule.

DNA stores genetic information and consists of two spiraling backbones with bases running between them. Signup and view all the answers

List three structural differences between DNA and RNA.

<ol> <li>DNA contains thymine while RNA contains uracil. 2. DNA has deoxyribose; RNA has ribose. 3. DNA is double-stranded; RNA is single-stranded.</li> </ol> Signup and view all the answers

Describe the importance of phosphodiester bonds and hydrogen bonds to the structure of DNA and RNA molecules.

Hydrogen bonds stabilize the DNA structure, while phosphodiester bonds link nucleotides. Signup and view all the answers

Calculate the percentage of each of the nucleotides in a DNA molecule if the percentage of one of the nucleotides is known.

If T is 28%, then A is also 28%. Signup and view all the answers

Describe how a phosphodiester bond is formed between two nucleotides.

The phosphate group is linked to the 5' carbon of one nucleotide and the 3' carbon of the next nucleotide. Signup and view all the answers

Predict the effect of increasing temperature on the structure of DNA and RNA molecules.

DNA unwinds, hydrogen bonds break, and it turns into single strands (denaturation). Signup and view all the answers

Explain how the structure of DNA makes it possible for a cell to make exact copies of its chromosomes quickly and with very few errors.

Complementary base pairing allows each strand to serve as a template for the other during replication. Signup and view all the answers

Explain why the two strands in a DNA molecule are described as antiparallel to each other.

The strands run in different directions: one 3' to 5' and the other 5' to 3'. Signup and view all the answers

Study Notes

Nucleotides and Their Structure

A nucleotide consists of three main components: a nitrogenous base, a deoxyribose sugar, and a phosphate group.
Purine nucleotides include adenine (A) and guanine (G); pyrimidine nucleotides consist of cytosine (C) and thymine (T).

Importance of Base Pairing

Pairing one purine with one pyrimidine maintains a consistent distance of three carbon rings between deoxyribose backbones, critical for the DNA structure.
"Complementary base pairing" refers to specific hydrogen bonds that form between bases across the two strands of DNA.

Nucleotides vs. Bases

The term "base" specifically refers to one of the nitrogenous bases (A, G, C, T).
One nucleotide is made up of a base, a sugar, and a phosphate; there are four types of nucleotides corresponding to four nitrogenous bases.

DNA Structure and Function

DNA stores genetic information via its double helix structure, consisting of two intertwined backbones and base pairs.
Bases are linked by hydrogen bonds, creating "bridges" between the strands that stabilize the entire structure.

Structural Differences Between DNA and RNA

DNA features adenine, thymine, guanine, and cytosine as bases, while RNA replaces thymine with uracil (U).
DNA contains deoxyribose sugar; RNA contains ribose sugar.
DNA is double-stranded; RNA exists as a single strand.

Bonds in Nucleic Acids

Hydrogen bonds stabilize DNA structure, holding complementary nucleotide bases together.
Phosphodiester bonds connect nucleotides in both DNA and RNA, forming the backbone of these nucleic acid molecules.

Calculating Nucleotide Percentages

If one percentage of a nucleotide is known, the percentage can be calculated for complementary nucleotides; e.g., if T is 28%, then A is also 28%.

Formation of Phosphodiester Bonds

A phosphodiester bond is created when a phosphate group links the 5' carbon of one nucleotide to the 3' carbon of another, forming a 3'-5' phosphodiester bridge.

Effects of Temperature on Nucleic Acids

Increasing temperature leads to DNA unwinding and the breaking of hydrogen bonds, resulting in denaturation and formation of single strands.

DNA Replication Mechanism

DNA replication occurs before cell division, with each strand serving as a template for creating a complementary strand, ensuring accuracy and fidelity of genetic information.

Antiparallel Nature of DNA Strands

DNA strands run in opposite directions (3' to 5' and 5' to 3'), facilitating stable hydrogen bonding between complementary bases, critical for the double helix formation.

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Description

Test your knowledge of nucleic acids with these flashcards that cover the structure of nucleotides and their importance in DNA. Learn about purines and pyrimidines and their role in maintaining the DNA structure. Perfect for biology students studying genetics and molecular biology.