Biology Chapter 9.3 Flashcards

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Questions and Answers

Describe the structure of a nucleotide.

The nucleotide is the repeating structural unit of both DNA and RNA. A nucleotide has three components: at least one phosphate group, a pentose sugar, and a nitrogenous base.

Compare the structure of nucleotides found in DNA versus RNA.

Nucleotides vary in the sugar and nitrogenous base. DNA contains deoxyribose and the bases adenine, thymine, cytosine, and guanine. RNA contains ribose and the bases adenine, uracil, cytosine, and guanine.

What are the building blocks of a nucleotide?

A sugar (ribose or deoxyribose), a nitrogenous base, and a phosphate group.

What are purines?

Purines are a class of double-ring nitrogenous bases found in nucleotides, which include adenine (A) and guanine (G). Signup and view all the answers

What are pyrimidines?

Pyrimidines are a class of single-ring nitrogenous bases found in nucleotides, which include thymine (T), cytosine (C), and uracil (U). Signup and view all the answers

What chemical group is found at the 3' end of a DNA strand?

A hydroxyl group. Signup and view all the answers

What chemical group is found at the 5' end of a DNA strand?

A phosphate group. Signup and view all the answers

Which of the following could be the components of a single nucleotide found in DNA? (Select all that apply)

Deoxyribose, adenine, and thymine Signup and view all the answers

A key difference between the nucleotides found in DNA versus RNA is that:

Both b and c are correct. Signup and view all the answers

Uracil is associated with DNA nucleotides.

False Signup and view all the answers

Chemically, how does ribose differ from deoxyribose?

Ribose has an -OH group on the 2' carbon, while deoxyribose has an -H on the 2' carbon. Signup and view all the answers

In a nucleotide, what functional groups are attached to the 5' carbon and the 3' carbon?

5' is attached to a phosphate group, and 3' is attached to an -OH group. Signup and view all the answers

What does 1', 2', 3', etc. mean with respect to ribose and deoxyribose?

These prime notations indicate carbon atoms in the sugar molecules, distinguishing them from the base numbering. Signup and view all the answers

Distinguish between AMP, ADP, and ATP.

AMP contains one phosphate; ADP contains two phosphates; ATP contains three phosphates. Signup and view all the answers

Study Notes

Nucleotide Structure

Nucleotides are the basic building blocks of DNA and RNA.
Each nucleotide consists of three components: a phosphate group, a pentose sugar, and a nitrogenous base.

Differences in Nucleotide Structure Between DNA and RNA

DNA nucleotides contain deoxyribose sugar, whereas RNA nucleotides contain ribose sugar.
Four bases are involved:
- DNA includes adenine (A), guanine (G), cytosine (C), and thymine (T).
- RNA includes adenine (A), guanine (G), cytosine (C), and uracil (U).
Purines (A, G) have a double-ring structure; pyrimidines (T, C, U) have a single-ring structure.

Nucleotide Composition and Properties

A nucleotide consists of:
- A phosphate attached to the 5' carbon of the sugar, forming a phosphodiester bond.
- A nitrogenous base attached to the 1' carbon.
- An important hydroxyl (-OH) group at the 3' carbon allows for linkage with adjacent nucleotides.

Types of Bases

Purines: Include adenine (A) and guanine (G); characterized by double-ring structures.
Pyrimidines: Include thymine (T), cytosine (C), and uracil (U); characterized by single-ring structures.

Nucleosides and Nucleotide Derivatives

Nucleosides consist of a sugar and a base, without a phosphate.
AMP (adenosine monophosphate) has one phosphate group.
ADP (adenosine diphosphate) has two phosphate groups.
ATP (adenosine triphosphate) has three phosphate groups.

Sugar Structure

Deoxyribose has a hydrogen atom (-H) at the 2' carbon, while ribose has a hydroxyl group (-OH) at the 2' carbon.

Covalent Linkages in Nucleic Acids

Nucleotides link together by covalent bonds formed between the 5' phosphate of one and the 3' hydroxyl of another, resulting in a sugar-phosphate backbone.

Nucleotide Differences and Functions

The chemical structure changes between DNA and RNA affect stability: DNA is stable due to deoxyribose, while RNA is more reactive because of ribose.
Functional groups:
- 5' carbon has a phosphate group.
- 3' carbon has a hydroxyl (-OH) group.

Cellular Components

The difference between AMP, ADP, and ATP lies in the number of phosphate groups attached (mono-, di-, and triphosphate, respectively).

Functional Importance

The structure and functional groups of nucleotides play critical roles in their function during processes like DNA replication and RNA transcription.

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Description

This quiz focuses on the structure of nucleotides, highlighting their roles in both DNA and RNA. It includes definitions and comparisons of nucleotides to enhance understanding of molecular biology concepts.