Genetics: Exam 3
Which of these are examples of mutagens? -5-Bromouracil -2-Aminopurine -Cytosine -Nitrous acid -Nitrogen mustard -Adenine -Guanine
-5-Bromouracil -2-Aminopurine -Nitrous Acid -Nitrogen Mustard
Which of the following are examples of base pair mismatches? -Cytosine on parent strand and Adenine on daughter strand -Adenine on parent strand and Cytosine on daughter strand -Adenine on parent strand and Thymine on daughter strand -Cytosine on parent strand and Thymine on daughter strand -Cytosine on parent strand and Guanine on daughter strand
-Cytosine on parent strand and Adenine on daughter strand -Adenine on parent strand and Cytosine on daughter strand -Cytosine on parent strand and Thymine on daughter strand
Which of the following can be categorized under induced mutations? -Depurination -Environmenta -UV light -Ethylmethanesulfate -Natural processes -Deamination -Can result in point mutations -DNA polymerase errors -Radiation
-Environmental -Ethyl methanesulfate -UV light -Radiation -Can result in point mutations
A benign tumor is
A localized growth with a precancerous genetic change
A mutagen is an
Agent that causes mutations
A method for obtaining fetal cells in a sample of the fluid surrounding the fetus is called
Amniocentesis
Match the life stage to the type of screening that would be used to detect a genetic disease: Fetus
Amniocentesis and karyotyping to detect chromosomal abnormalities
A mutation in one gene that reverses the effects of a mutation in a different gene is _______________
An intergenic suppressor
Certain compounds have a structure similar to normal DNA bases and can be incorporated into daughter strands during DNA replication. These compounds are called base _________________
Analogs
What is the inheritance pattern when a trait occurs with the same frequence in both sexes and an affected offspring can have two unaffected parents?
Autosomal recessive
Physical mutagens include
Both X-rays and UV light
The region where two chromosome pieces break and re-attach to the other chromosome pieces is called a chromosomal ________________
Breakpoint
Nucleotide excision repair (NER) is the main system used in the repair of
Bulky, helix distorting lesions
In what disease do genetic changes lead to uncontrolled cell growth?
Cancer
Suppose a disease-causing allele shows autosomal inheritance. How could a carrier of this disease causing allele be identified?
Carriers often show reduced activity for the enzyme encoded by the allele
A nucleotide deletion in DNA replication
Causes the amino acids downstream from the deletion to be incorrect
Most cancer cells are descendants of an original cell that acquired genetic changes. Therefore, cancerous growths are considered to be _____________________ in origin
Clonal
Which change from proto-oncogene to oncogene occurred by chromosomal translocation?
Creation of a new transcription factor through the fusion of chromosomal segments from two different chromosomes
Which of the following synthesizes the new DNA strand? -DNA ligase -DNA polymerase -DNA helicase -UvrA-UvrB trimer
DNA polymerase
Nitrous acid is a mutagen that acts via that process of
Deamination
The mutagen nitrous acid changes cytosine to uracil, and adenine to hypoxanthine, through the process of ________________
Deamination
The removal of a purine from DNA is called ___________________
Depurination
Mutations that remove an adenine or guanine from the DNA are known as
Depurinations
An oncogene is typically formed by a _____________ mutation in a normal gene called a ___________________
Gain-of-function; Proto-oncogene
The Ames test assays whether an agent causes
Gene mutations
An individual that has somatic regions that are genotypically different from each other
Genetic mosaic
Cells that give rise to the gametes such as eggs and sperm are called __________ ____________
Germ cells
Cells that give rise to the gametes
Germ line cells
Mutation that can be passed onto offspring
Germ line mutation
A signaling molecule that can promote division of cells throughout the body of a multicellular organism is called a
Growth factor
A cancer cell is a cell that
Has accumulated genetic changes that allow it to grow unconditionally
The two main mechanisms used to repair DNA double-strand breaks are __________________ recombination and ____________________ end joining
Homologous; Nonhomologous
The mutation rate is commonly expressed as the number of new mutations
In a given gene per cell generation
Genetic testing is used to determine whether an _________________ has a disease-causing gene, while genetic screening is used to determine how frequently the gene is found in a ___________________
Individual; Population
What is the effect of a suppressor mutation?
It suppresses the phenotypic effect of another mutation
Which type of growth has cells that can invade other tissues and migrate to other areas of the body to form secondary tumors?
Malignant growth
Match the DNA sequence with the possible consequence of a mutation in that sequence: UTR
May alter the ability of mRNA to be translated; May alter mRNA stability
A silent mutation is a mutation that results in
No change to the amino acid sequence of the polypeptide
If a mutation occurs in the somatic tissue, approximately how many of the gametes will carry the mutation?
None
Some errors create bulky distortions of the double helix. These errors are removed primarily by a DNA repair system called NER, which stands for ______________ _______________ repair
Nucleotide excision
The nucleic acid sequence in mRNA is determined by
Nucleotide sequence in DNA
Products of oxygen metabolism, such as hydrogen peroxide, superoxide, and hydroxyl radical, are collectively called ____________ ___________ species
Reactive Oxygen
A mutation that does not change the amino acid sequence of a polypeptide is known as a ____________ mutation
Silent
All cells of the body excluding the gametes or cells that can give rise to the gametes
Somatic cells
A mutation that cannot be passed onto the offspring
Somatic mutation
Match the life stage to the type of screening that would be used to detect a genetic disease: Adult
Test for carrier status if one belongs to a family with a history of a specific disease
Match the life stage to the type of screening that would be used to detect a genetic disease: Newborn Baby
Test for excess phenylalanine demonstrating phenylketonuria (PKU)
Which of these is a common example of widespread genetic screening of newborns to identify certain disorders?
Test for excess phenylalanine indicating phenylketonuria (PKU)
To study the distribution of disease-causing genes, genetic ______________ refers to determining if an individual carries the faulty gene, while genetic ______________ relates to assessing the presence of the gene throughout a population
Testing; Screening
Mutations that occur in a promoter sequence can be divided into two types: _____________ promoter mutations increase the transcription rate, while ______________ promoter mutations decrease it
Up; Down
A breakpoint refers to the region
Where two chromosome pieces break and rejoin with other chromosome pieces
Trinucleotide repeat expansions are repeated sequences of three bases
Which increase generation after generation
In a natural population, a __________________-_____________ genotype is the most common one
Wild-type
A malignant tumor
-Has cells with cancerous mutations leading to uncontrolled growth -Can form secondary tumors after spreading to other locations -Can invade nearby healthy tissue
Double-strand breaks are typically repaired by which of the following? -Nonhomologous end joining -Nucleotide excision repair -Methyl-directed mismatch repair -Photoreactivation -Homologous recombination repair
-Homologous recombination repair -Nonhomologous end joining
Which of the following can be categorized under spontaneous mutations? -Depurination -Environmental -UV light -Ethyl methanesulfate -Natural processes -Deamination -Can result in point mutations -DNA polymerase errors -Radiation
-Natural processes -DNA polymerase errors -Deamination -Depurination -Can result in point mutations
Alkylating agents may cause mutations by
Disrupting the normal pairing between nucleotides within the DNA
A mutation in a gene may affect the phenotype of the organism in a way that is ____________________ for its survival
Either beneficial, harmful, or neutral
True or False: In nucleotide excision repair, both strands of the DNA are cut and repaired using DNA polymerase and DNA ligase
False
Transletion synthesis refers to
The replication of a template strand that contains DNA damage
If a frameshift mutation causes a stop codon to be inserted into the coding region of a DNA sequence, then ____________________
The resulting protein will be shortened and is often nonfunctional
How does UV light and other nonionizing radiation damage DNA molecules?
They create thymine dimers between adjacent thymines in the DNA chain
Tay-Sachs disease is inherited with an autosomal recessive allele that leads to a defect in the enzyme hexosaminidase A. When cells are collected from patients, cells with different genotypes exhibit different amounts of enzymatic activity. Rank the amount of enzymatic activity that would be detected in a biochemical assay on cells from patients of these genotypes, with the genotype producing the LEAST amount of enzymatic activity on top
1. Homozygous recessive 2. Heterozygous 3. Homozygous dominant
Match the DNA sequence with the possible consequence of a mutation in that sequence: Splice Site
May alter the ability of pre-mRNA to be properly spliced
The process of converting a normal cell into a malignant cancer cell is called
Transformation
The synthesis of DNA over a template strand that harbors some type of DNA damage is called _______________ ________________
Translesion synthesis
True or False: The phenotypic effects of a mutation are either detrimental or neutral
False
Mutations can be caused in two main ways: 1. _______________ mutations are the result of natural biological or chemical processes; and 2. ________________ mutations are produced by environmental agents
1. Spontaneous 2. Induced
What is the inheritance pattern when the trait occurs with the same frequency in both sexes and two unaffected heterozygotes have, on average, 25% affected children?
Autosomal recessive
During the normal course of DNA replication, the addition of a nucleotide that does not obey the AT/CG rule of base pairing creates a
Base pair mismatch
Base analogs induce mutations by
Being incorporated instead of normal bases during replication
During the initial stage of cancer development, cells with a precancerous genetic change form a
Benign growth
The probability that a gene will be altered by a new mutation is referred to as the ___________ ___________
Mutation rate
Which of these tests is used to evaluate the mutagenicity of an agent? -The Pasteur test -The Ames test -The Pheonol coefficient test -The Kirby-Bauer test
The Ames test
The term germ line is used to describe
The cells that produce sperm and egg
True or False: Chemical agents can cause mutations by inducing methylation of guanine residues in DNA
True
The wild type genotype or phenotype is the one that is
Typically found in nature
Amniocentesis is a procedure for
Obtaining fetal cells in a sample from the fluid surrounding the fetus
A gene that promotes cancer is called an
Oncogene
A mutant gene that is overexpressed and contributes to the formation of cancer is termed an ________________
Oncogene
Cancerous growth are clonal in origin because cancer cells
Originate from a single cell that has accumulated genetic changes during cell division
A _____________ is a change in a single base pair within the DNA
Point mutation
Alkylating agents covalently attach ________________ or _______________ groups to DNA bases, and thus dirupt their normal base pairing properties
Methyl; Ethyl
The enzyme that can recognize thymine dimers and split them is called _______________
Photolyase
A ___________ mutation refers to a mutation in which just one base is changed within the DNA sequence
Point
A change in a single base pair in the genetic material is known as a ____________ mutation
Point
Reactive oxygen species (ROS) are
Products of oxygen metabolism in all aerobic organisms
True or False: Most DNA repair systems involve three major steps: detection of the error, removal of the abnormality, and its replacement with normal DNA
True
True or False: The addition of a single nucleotide to the DNA sequence causes a frameshift mutation
True
Which of these represents the correct order of steps during a typical DNA repair system?
Detection-->Removal-->Replication
Match the DNA sequence with the possible consequence of a mutation in that sequence: Operator
May disrupt the ability of the gene to be properly regulated
Match the DNA sequence with the possible consequence of a mutation in that sequence: Promoter
May increase or decrease the rate of transcription
Cancer cells can migrate to other parts of the body and cause secondary tumors. This property is called ________________
Metastasis
The ability of cancer cells to migrate to other parts of the body where they can cause secondary tumors is referred to as
Metastasis
An agent that can cause DNA structure and cause mutations is known as a _______________
Mutagen
An oncogene is formed when a proto-oncogene gains a
Mutation that causes its expression to be abnormally active
Which of the following statements about promoter mutations is true? -Up promoter mutations cause the promoter sequence to be more like the consensus sequence -Down promoter mutations occur in the 3'-UTR of the gene -Down promoter mutations decrease the affinity of transcription factors to the promoter -Up promoter mutations occur in the coding sequence of the gene
-Up promoter mutations cause the promoter sequence to be more like the consensus sequence -Down promoter mutations decrease the affinity of transcription factors to the promoter
Errors in DNA replication are examples of _____________ mutations, while mutations caused by ultraviolet light are _______________ mutations
Spontaneous; Induced
A second mutation that occurs in a different site than the firsts mutation, and which converts the mutant back to the wild-type phenotype, is best referred to as a ___________________ mutation
Suppressor
The phenomenon in which a repeated sequence of three bases increases in number generation after generation is called ______________ __________ __________
Trinucleotide repeat expansion