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Questions and Answers
Mutations are a change in the DNA ______ sequence
Mutations are a change in the DNA ______ sequence
nucleotide
Mutations that produce changes in a single gene are known as ______ mutations
Mutations that produce changes in a single gene are known as ______ mutations
gene
Point mutations generally occur during ______
Point mutations generally occur during ______
replication
Chromosomal mutations can affect more than one ______
Chromosomal mutations can affect more than one ______
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The Latin word 'mutare' means 'to ______'
The Latin word 'mutare' means 'to ______'
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A mistake by DNA polymerase may cause a point ______.
A mistake by DNA polymerase may cause a point ______.
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Transposable elements can insert themselves into the sequence of a ______.
Transposable elements can insert themselves into the sequence of a ______.
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Depurination involves the removal of a ______ from the DNA.
Depurination involves the removal of a ______ from the DNA.
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Spontaneous changes in base structure are referred to as ______ shifts.
Spontaneous changes in base structure are referred to as ______ shifts.
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Chemical substances may cause changes in the structure of ______.
Chemical substances may cause changes in the structure of ______.
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Coli with a ts mutation may grow in the range 33-38°C but not in the range ______ °C
Coli with a ts mutation may grow in the range 33-38°C but not in the range ______ °C
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Chromosomal mutations can change the ______ of genes on chromosomes.
Chromosomal mutations can change the ______ of genes on chromosomes.
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There are four types of chromosomal mutations: deletion, ______, inversion, and translocation.
There are four types of chromosomal mutations: deletion, ______, inversion, and translocation.
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______ involves the loss of all or part of a chromosome.
______ involves the loss of all or part of a chromosome.
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A gene may be affected by a chromosomal rearrangement if the ______ occurred within the gene itself.
A gene may be affected by a chromosomal rearrangement if the ______ occurred within the gene itself.
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Movement to a heterochromatic region can create a ______ effect.
Movement to a heterochromatic region can create a ______ effect.
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Germ-line cells give rise to ______ such as eggs and sperm.
Germ-line cells give rise to ______ such as eggs and sperm.
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Induced mutations are caused by environmental ______ known to alter DNA.
Induced mutations are caused by environmental ______ known to alter DNA.
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A point mutation is a change in a single base ______
A point mutation is a change in a single base ______
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A transition is a change of a ______ to another pyrimidine or a purine to another purine.
A transition is a change of a ______ to another pyrimidine or a purine to another purine.
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Deletions or additions involve the alteration of short sequences of ______.
Deletions or additions involve the alteration of short sequences of ______.
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Silent mutations do not alter the ______ sequence.
Silent mutations do not alter the ______ sequence.
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Missense mutations do alter the amino acid ______.
Missense mutations do alter the amino acid ______.
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A nonsense mutation changes a codon to a ______ codon.
A nonsense mutation changes a codon to a ______ codon.
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Frameshift mutations involve the addition or deletion of nucleotides in multiples of ______.
Frameshift mutations involve the addition or deletion of nucleotides in multiples of ______.
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Up promoter mutations ______ transcription.
Up promoter mutations ______ transcription.
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A deleterious mutation lowers the chance of ______ and reproduction.
A deleterious mutation lowers the chance of ______ and reproduction.
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A conditional mutation affects the phenotype only under specific ______.
A conditional mutation affects the phenotype only under specific ______.
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Ionizing radiation includes X-rays and ______ rays
Ionizing radiation includes X-rays and ______ rays
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Nonionizing radiation includes ______ light
Nonionizing radiation includes ______ light
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Ionizing radiation can create chemically reactive molecules termed ______ radicals
Ionizing radiation can create chemically reactive molecules termed ______ radicals
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Direct repair involves an enzyme recognizing an incorrect alteration in DNA ______
Direct repair involves an enzyme recognizing an incorrect alteration in DNA ______
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Thymine dimers may cause ______ when the DNA strand is replicated
Thymine dimers may cause ______ when the DNA strand is replicated
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The mismatch repair system deals with base pair ______ in the DNA
The mismatch repair system deals with base pair ______ in the DNA
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Homologous recombination occurs at double-strand ______
Homologous recombination occurs at double-strand ______
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Base excision repair involves removing an abnormal base or ______
Base excision repair involves removing an abnormal base or ______
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Deamination involves the removal of an amino group from the ______ base.
Deamination involves the removal of an amino group from the ______ base.
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Deamination of 5-methylcytosine results in ______, a normal constituent of DNA.
Deamination of 5-methylcytosine results in ______, a normal constituent of DNA.
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Tautomeric shifts involve a temporary change in base ______.
Tautomeric shifts involve a temporary change in base ______.
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One example of a chemical mutagen is ______ acid, which deaminates bases.
One example of a chemical mutagen is ______ acid, which deaminates bases.
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Mutagens are usually classified as chemical or ______ mutagens.
Mutagens are usually classified as chemical or ______ mutagens.
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Base modifiers covalently modify the structure of a ______.
Base modifiers covalently modify the structure of a ______.
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Alkylating agents disrupt appropriate pairing by attaching ______ groups to bases.
Alkylating agents disrupt appropriate pairing by attaching ______ groups to bases.
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Intercalating agents distort the helical structure of ______.
Intercalating agents distort the helical structure of ______.
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5-bromouracil is a thymine ______ that can be incorporated into DNA.
5-bromouracil is a thymine ______ that can be incorporated into DNA.
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X-rays can cause base deletions and ______-strand breaks in DNA.
X-rays can cause base deletions and ______-strand breaks in DNA.
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Study Notes
Gene Mutation and DNA Repair
- Mutations are variations in DNA caused by mistakes during DNA copying, such as inserting the incorrect base or skipping a base.
- Mutations arise from the Latin word mutare, meaning "to change."
- Mutations are changes in the DNA nucleotide sequence, potentially causing heritable changes in genetic information.
- Organisms have evolved DNA repair mechanisms to counteract harmful mutations.
Types of Mutations
- Mutations are categorized as either gene mutations or chromosomal mutations.
- Gene mutations affect a single gene, while chromosomal mutations affect entire chromosomes.
Chromosomal Mutations
- Chromosomal changes involve alterations in chromosome structure or number, often impacting more than one gene.
Gene Mutations (Point Mutations)
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Point mutations affect one or a few nucleotides and occur at a single point in the DNA sequence.
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These mutations typically occur during DNA replication.
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A point mutation is a change in a single base pair involving a base substitution.
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A transition is a change of a pyrimidine (C or T) to another pyrimidine or a purine (A or G) to another purine.
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A transversion is a change of a pyrimidine to a purine or vice versa.
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Transitions are more common than transversions.
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Deletions or insertions of nucleotides can also cause a shift in the reading frame, affecting amino acid sequence.
Mutations in the Coding Sequence
- Silent mutations do not alter the amino acid sequence due to the degeneracy of the genetic code.
- Missense mutations alter the amino acid sequence, sometimes causing minimal impact, or potentially significant impact like in sickle-cell anemia.
- Nonsense mutations change a codon to a stop codon, resulting in a truncated polypeptide.
- Frameshift mutations occur when nucleotides are added or deleted in multiples of one or two, causing a shift in the reading frame and a change in the amino acid sequence downstream of the mutation.
Gene Mutations in Noncoding Sequences
- Mutations in noncoding sequences can alter gene expression.
- Promoter mutations can affect transcription rates.
- Mutations in splice junctions or 5' and 3' UTRs can affect mRNA stability and translation.
- Regulatory element/operator site mutations affect proper gene expression regulation.
Gene Mutations and Their Effects on Genotype and Phenotype
- Neutral mutations do not affect protein function.
- Deleterious mutations reduce the chances of survival and reproduction. Lethal mutations result in cell or organism death.
- Beneficial mutations enhance survival or reproductive success.
- Conditional mutations affect the phenotype only under specific environmental conditions.
Chromosomal Mutations
- Chromosomal mutations alter the number or structure of chromosomes, affecting gene location or copy number.
- Types of chromosomal mutations include: deletions, duplication, inversion and translocation.
- Deletion involves the loss of all or part of a chromosome, which is now unavailable for inheritance.
- Changes in chromosome structure can affect gene expression. This is called the position effect, and results from chromosomal rearrangement.
- Position effect results from movement to a position near regulatory sequences for a different gene and from movement to a heterochromatic region.
Mutations Can Occur in Germ-Line or Somatic Cells
- Geneticists categorize animal cells into germ-line (give rise to gametes) and somatic (all other cells) categories.
- Mutations in germ-line cells are found in the entire body of the organism, while mutations in somatic cells are restricted to a specific part, based on when the mutation occurred.
Causes of Mutation
- Mutations can be spontaneous, arising from abnormalities in cellular processes like errors in DNA replication, or induced, caused by environmental factors.
- Mutagens are agents that alter DNA structure.
- Spontaneous mutations arise due to three chemical changes: depurination, deamination and tautomeric shift.
- Induced mutations result from chemical and physical agents like ionizing radiation (X-rays, gamma rays) and nonionizing radiation (UV light).
- Different types of mutagens have different effects on DNA, which affect base pairing, nucleotide structure and can lead to mutations
DNA Repair
- Living organisms have multiple DNA repair systems to correct DNA alterations.
- DNA repair typically follows a multistep process: Detection of the irregularity. Removal of the damaged DNA. Synthesis of new normal DNA.
- Different types of DNA repair systems such as direct repair, nucleotide excision repair, mismatch repair, and recombination repair address different types of DNA damage.
Examples of Mutagens
- Nitrous acid, nitrogen mustard, and ethyl methanesulfonate are chemical mutagens that alter base structures.
- X-rays and UV light are physical mutagens that damage DNA structure.
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Description
This quiz covers the concepts of gene mutations and DNA repair mechanisms. Explore different types of mutations, including gene and chromosomal mutations, and understand their significance in genetic information. Test your knowledge on point mutations and their impact during DNA replication.
