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