Radiobiology (mutation)
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Questions and Answers

What role do triplets of bases play in genetic coding?

Triplets of bases code for specific amino acids, which are essential for protein synthesis.

How does DNA control enzyme production in a cell?

DNA sequences dictate which enzymes are produced, affecting the cellular reactions and structures.

What distinguishes a mutation in germ cells from a mutation in somatic cells?

Mutations in germ cells can be passed to offspring, while mutations in somatic cells may affect the individual but are not inherited.

What is the impact of a deletion mutation on the reading frame of a gene?

<p>A deletion mutation alters the reading frame, potentially changing the entire sequence of amino acids downstream.</p> Signup and view all the answers

Explain the concept of silent mutations and their significance.

<p>Silent mutations are changes in DNA that do not alter the phenotype of the organism.</p> Signup and view all the answers

What is the primary function of DNA in living organisms?

<p>DNA controls all the chemical changes that occur in cells.</p> Signup and view all the answers

Which sugar is found in DNA, and how does it differ from ribose?

<p>The sugar in DNA is deoxyribose, which lacks one oxygen atom compared to ribose.</p> Signup and view all the answers

Name the four organic bases found in DNA.

<p>The four organic bases in DNA are Adenine (A), Thymine (T), Cytosine (C), and Guanine (G).</p> Signup and view all the answers

What are the components of a nucleotide in DNA?

<p>A nucleotide in DNA is made up of deoxyribose, a phosphate group, and an organic base.</p> Signup and view all the answers

How do low-energy electrons affect DNA strands?

<p>Low-energy electrons can break a DNA strand by forming transient molecular anions.</p> Signup and view all the answers

What roles do the phosphate group and deoxyribose play in the structure of DNA?

<p>The phosphate group and deoxyribose form the backbone of the DNA molecule.</p> Signup and view all the answers

Explain the consequence of bond dissociation in DNA due to transient molecular anions.

<p>Bond dissociation can lead to the breakdown of the DNA structure, potentially causing mutations.</p> Signup and view all the answers

What type of molecular damage is predominantly caused by radiation?

<p>Indirect damage, primarily through the generation of OH radicals and electrons.</p> Signup and view all the answers

What is the typical range of the mean free path for Low Energy Electrons (LEEs)?

<p>0.1 to 10 nm.</p> Signup and view all the answers

Describe the structure of DNA in terms of nucleotides.

<p>DNA is composed of millions of nucleotides joined in a long chain forming a double strand.</p> Signup and view all the answers

How are the two strands of DNA held together?

<p>They are held together by chemical bonds between complementary bases.</p> Signup and view all the answers

Explain the bonding specificity between Adenine and Thymine.

<p>Adenine and Thymine bond due to their favorable configuration, which allows for hydrogen bridge formation.</p> Signup and view all the answers

What base pairs with Cytosine in DNA, and why?

<p>Guanine pairs with Cytosine due to specific hydrogen bonding capabilities.</p> Signup and view all the answers

What components make up the sugar-phosphate backbone of DNA?

<p>The sugar and phosphate groups of nucleotides form the backbone.</p> Signup and view all the answers

What is clustered damage in DNA, and how can it occur?

<p>Clustered damage refers to multiple simultaneous damages within a localized area of DNA, often caused by LEEs.</p> Signup and view all the answers

Why is indirect damage more prevalent in radiation damage mechanisms?

<p>Indirect damage is more prevalent because radiation interacts with water molecules, producing reactive species like OH radicals.</p> Signup and view all the answers

What role do hydroxyl radicals play in radiation damage to DNA?

<p>Hydroxyl radicals contribute to DNA damage by breaking chemical bonds or altering bases.</p> Signup and view all the answers

Flashcards

DNA

Deoxyribonucleic acid; a chemical substance found in cell nuclei that controls cellular processes and organism traits.

Nucleotide

The building block of DNA, composed of a sugar (deoxyribose), a phosphate group, and a nitrogenous base.

Deoxyribose

A five-carbon sugar that forms part of a DNA nucleotide.

Nitrogenous base

An organic molecule (adenine, thymine, cytosine, or guanine) that is part of a DNA nucleotide and crucial for DNA's base pairing.

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DNA molecule

A large molecule composed of repeating nucleotide units, forming a long chain that carries the genetic code.

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DNA function

Controls cellular processes and dictates the organism's characteristics.

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Components of a Nucleotide

Sugar (deoxyribose), phosphate group, and a nitrogenous base.

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Genetic Code

The sequence of bases in DNA that determines the order of amino acids in proteins.

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Triplet Code

A group of three consecutive bases in DNA that codes for a specific amino acid.

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Point Mutation

A change in a single base in DNA.

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Insertion Mutation

The addition of one or more bases to a DNA sequence.

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Deletion Mutation

The removal of one or more bases from a DNA sequence.

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DNA structure

DNA is a double helix formed by nucleotides joined in a long chain.

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Nucleotide composition

Nucleotides consist of a sugar-phosphate backbone and bases.

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Base pairing

Adenine pairs with Thymine, and Cytosine pairs with Guanine.

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Double-stranded DNA

DNA is made of two strands, held together by base pairing.

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Radiation damage (indirect)

Radiation damages DNA mostly through the generation of free radicals, not directly.

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Mean free path (LEEs)

The average distance traveled by charged particles before interacting with DNA.

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Clustered damage

When radiation causes multiple breaks in the DNA molecule near each other.

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Electron-induced damage

Damage to DNA caused by high-energy electrons.

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Transient Anions

Short-lived negatively charged ions formed during radiation damage.

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Joined nucleotides

Individual nucleotides linked together to form DNA chains.

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Study Notes

DNA Structure

  • DNA stands for deoxyribose nucleic acid
  • It's a chemical substance found in the nucleus of all living cells
  • DNA controls chemical changes within cells
  • DNA dictates the formation of different cell types (e.g., muscle, blood, nerve)
  • DNA directs the development of various organisms (e.g., buttercup, giraffe, human)
  • DNA is a large molecule comprised of a chain of subunits
  • These subunits are called nucleotides
  • Each nucleotide consists of a sugar called deoxyribose, a phosphate group (-POâ‚„), and an organic base

DNA Bases

  • The most common organic bases are
    • Adenine (A)
    • Thymine (T)
    • Cytosine (C)
    • Guanine (G)

Nucleotides

  • Deoxyribose, phosphate, and one of the bases form a nucleotide
  • Nucleotides join to create a DNA molecule

DNA Pairing

  • DNA is typically a double-stranded molecule
  • Sugar-phosphate chains are arranged on the outside of the molecule
  • Strands are held together by chemical bonds between bases

Base Pairing

  • Adenine (A) pairs with Thymine (T)
  • Cytosine (C) pairs with Guanine (G)
  • These pairings are crucial for DNA's structure and function

DNA and Genes

  • A sequence of bases in DNA makes a gene
  • Genes code for complete proteins
  • Genes can have thousands of bases

Point Mutations

  • A point mutation is a change in a single base within a DNA sequence
  • This change can lead to a missense or nonsense mutation
  • Missense mutations result in a change in an amino acid in the polypeptide chain possibly leading to a malfunctioning protein
  • Nonsense mutations result in a stop codon, interrupting the protein sequence

Insertion and Deletion Mutations

  • An insertion mutation occurs when an extra base is added into the DNA sequence
  • A deletion mutation happens when a base is removed to the DNA sequence
  • Both shift the reading frame and can change the amino acids coded for within the protein

DNA and Enzymes

  • Proteins make cell structures
  • Proteins also create enzymes
  • DNA controls the production of enzymes
  • Enzymes direct biological reactions within the cell, controlling the cell's structure and function
  • DNA controls cell function via protein (enzyme) synthesis

Classification of Mutations

  • Silent mutations: DNA changes that do not affect the organism's phenotype
  • Germ cell mutations: Occur in reproductive cells (sperm or egg) and are passed on to offspring
  • Somatic mutations: Occur in body cells, and may result in diseases such as cancer

Other

  • Radiation damage to DNA is often indirect
  • Radiation may cause DNA strand breakage
  • Certain amino acids are more radiosensitive than others

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Mutations 4th Lecture PDF

Description

This quiz covers the essential aspects of DNA, including its structure, nucleotides, and the role it plays in controlling cell types and organism development. Test your understanding of DNA structure and its fundamental components like bases and pairing.

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