Nucleic Acids and Nucleotide Structures
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Questions and Answers

What are the two types of nucleic acids?

  • DNA and RNA (correct)
  • DNA and cDNA
  • DNA and tRNA
  • RNA and mRNA

Which component of a nucleotide differs between DNA and RNA?

  • Pentose sugar (correct)
  • Nitrogens
  • Phosphate group
  • Nitrogenous base

What do nucleotides join together to form?

  • Lipids
  • Polypeptides
  • Proteins
  • Nucleic acids (correct)

What is released when two nucleotides join together?

<p>Pyrophosphate (C)</p> Signup and view all the answers

Which nitrogenous bases are found in nucleotides?

<p>Purines and pyrimidines (B)</p> Signup and view all the answers

Which sugar is present in RNA nucleotides?

<p>D-ribose (B)</p> Signup and view all the answers

What type of chemical reaction is transesterification?

<p>Exchange of alkoxy groups (C)</p> Signup and view all the answers

What is the role of pyrophosphate in the formation of nucleic acids?

<p>It releases energy during nucleotide bond formation (C)</p> Signup and view all the answers

What characterizes an ester bond?

<p>It is a covalent bond between an alcohol and a carboxylic acid. (A)</p> Signup and view all the answers

What is the role of oligonucleotides in molecular biology?

<p>They serve mainly as primers for DNA duplication and regulate gene expression. (B)</p> Signup and view all the answers

Which base pairing occurs in RNA?

<p>Adenine pairs with uracil. (D)</p> Signup and view all the answers

What is typical of polynucleotides?

<p>They are the longest polymers in the living world. (A)</p> Signup and view all the answers

How are base pairs in DNA primarily held together?

<p>By hydrogen bonds. (D)</p> Signup and view all the answers

Which nucleotide is not found in RNA?

<p>Thymine (C)</p> Signup and view all the answers

What happens during complementary base pairing in RNA?

<p>Adenine can pair with either uracil or thymine. (A)</p> Signup and view all the answers

Why is the attraction between base pairs in nucleic acids not as strong as covalent bonds?

<p>They are temporary interactions. (C)</p> Signup and view all the answers

What pairs with adenine in RNA?

<p>Uracil (A)</p> Signup and view all the answers

What is the process called when DNA is copied into RNA?

<p>Transcription (C)</p> Signup and view all the answers

What describes the complete set of DNA in a living organism?

<p>Genome (A)</p> Signup and view all the answers

Which of the following processes uses an existing strand as a template?

<p>DNA replication (C)</p> Signup and view all the answers

How many pairs of chromosomes does each somatic cell in the human body normally have?

<p>23 (D)</p> Signup and view all the answers

What are the sequences of DNA that are transcribed into RNA called?

<p>Genes (A)</p> Signup and view all the answers

What is the overall process of transcription and translation referred to as?

<p>Gene expression (A)</p> Signup and view all the answers

What structural feature is characteristic of DNA?

<p>Double helix (D)</p> Signup and view all the answers

Flashcards

Nucleic acids

Polymers that store, transmit, and use genetic information.

Nucleotide

The monomer of nucleic acids.

Nitrogenous base

Part of a nucleotide, either a pyrimidine or purine.

Pyrimidine

Six-membered single-ring nitrogenous base.

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Purine

Fused double-ring nitrogenous base.

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Phosphodiester linkage

Bond connecting nucleotides in nucleic acids (5' to 3').

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Nucleoside

Sugar and base, but no phosphate group.

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Transesterification

Exchange of alkoxy groups in a chemical reaction.

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Ester bond

A covalent bond formed between an alcohol and a carboxylic acid.

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Oligonucleotides

Short chains of nucleotides, typically with less than 20 monomers. Examples include primers in DNA replication and gene-regulating RNA molecules.

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Polynucleotides

Long chains of nucleotides, often referred to as nucleic acids. DNA and some RNA molecules are examples.

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Base pairing in DNA and RNA

Specific hydrogen bonding between complementary nitrogenous bases. In DNA, adenine (A) pairs with thymine (T), and cytosine (C) pairs with guanine (G). In RNA, adenine (A) pairs with uracil (U), and cytosine (C) pairs with guanine (G).

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Hydrogen bonding in nucleic acids

The force holding complementary bases together in DNA and RNA. It's weaker than a covalent bond, allowing for easy separation during DNA replication and transcription.

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RNA base pairing

Base pairing can occur within a single RNA molecule or between RNA and DNA. Adenine can pair with either uracil (RNA) or thymine (DNA).

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Why is RNA typically single-stranded?

While RNA can fold back on itself, it doesn't always form a double helix like DNA. This allows for more flexibility and diverse functions.

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What makes DNA and RNA different?

DNA contains thymine (T) and is typically double-stranded, while RNA contains uracil (U) and is usually single-stranded. Both use the same sugar-phosphate backbone.

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DNA Replication

The process by which DNA is copied exactly, using an existing strand as a template to create a new complementary strand through polymerization.

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Transcription

The process of copying a segment of DNA into RNA, using the DNA sequence as a template. This RNA molecule then carries genetic information.

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Translation

The process of using the sequence of the RNA molecule to determine the sequence of amino acids in a polypeptide chain. This is how genetic information is translated into proteins.

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Gene Expression

The overall process of transcription and translation, leading to the production of a protein from a gene.

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Genome

The complete set of DNA in a living organism. It contains all the genetic information necessary for an organism to function.

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Gene

A segment of DNA that is transcribed into RNA. It contains the information to make a specific protein.

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Somatic Cell

Any cell in a living organism other than a gamete (sex cell). They have 23 pairs of chromosomes.

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X Chromosome

One of the two sex chromosomes in humans, containing about 1,600 genes with various functions.

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Study Notes

Nucleic Acids

  • Nucleic acids are polymers for storing, transmitting, and using genetic information
  • Two main types: DNA (deoxyribonucleic acid) and RNA (ribonucleic acid)
  • Monomers are nucleotides

Nucleotide Components

  • Nitrogen-containing base (A nitrogenous base)
    • Pyrimidine: six-membered single-ring structure
      • Cytosine (C)
      • Thymine (T)
      • Uracil (U)
    • Purine: fused double-ring structure
      • Adenine (A)
      • Guanine (G)
  • Pentose sugar (five-carbon sugar)
    • Deoxyribose (in DNA)
    • Ribose (in RNA)
  • One to three phosphate groups

Nucleosides & Nucleotides

  • Nucleosides: pentose sugar + nitrogenous base (no phosphate)
  • Nucleotide monophosphates: nucleosides with one phosphate group.

Phosphodiester Linkages

  • Nucleotides join through phosphodiester linkages between the 5' and 3' carbons
  • Release pyrophosphate (2 phosphate groups) provides energy for the reaction.

Oligonucleotides and Polynucleotides

  • Oligonucleotides: short RNA molecules (about 20 nucleotides), function in DNA replication, gene expression
  • Polynucleotides: longer strands of RNA and DNA, DNA contains hundreds of millions of nucleotides; the largest polymers in living organisms

Base Pairing

  • Complementary base pairing occurs in DNA and RNA
  • DNA: A with T, C with G; RNA: A with U, C with G
  • Base pairing held together primarily by hydrogen bonds.

RNA Structure

  • Typically single-stranded
  • Can form base pairings within the same molecule or with DNA

DNA Structure

  • Double-stranded helix formed by two polynucleotide strands
  • Bases pair to hold strands together, (hydrogen bonds)
  • Key differences among DNA molecules are their different nucleotide bases

DNA Functions

  • DNA carries information, expressed through RNA in two ways:
    • Replication: Identical copies are made.
    • Transcription: DNA sequence is copied into RNA.
    • Translation: RNA sequence determines amino acid sequence in proteins, followed by gene expression.

Genes

  • Segments of DNA transcribed into RNA
  • The complete set of DNA in an organism is called its genome.
  • Not all DNA in a genome is used all the time.

Chromosomes

  • Structures containing genes.
  • Somatic cells normally have 23 pairs of chromosomes. (human)

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Nucleic Acids PDF

Description

Explore the fundamentals of nucleic acids, including DNA and RNA, and their monomers, nucleotides. Learn about the components of nucleotides, such as nitrogenous bases and pentose sugars, as well as the structural linkages that connect them. This quiz covers essential concepts in molecular biology and genetics.

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