Genetics - Chapter 11

Since frameshift mutations change the reading frame of the mRNA codons the wrong amino acids get inserted into the resultant protein product.

True

Spontaneous mutations result from errors in DNA replication.

True

millirems

a measure of radiation dosage

The rubella virus causes a permanent mutation in the DNA nucleotide sequence.

False

​Halogen-containing organic compounds persist in the environment for approximately five years.

False

Beckwith-Wiedemann syndrome is a cell growth disorder that causes enlarged organs, high birth weight, and predisposition to cancer.

True

DNA mutations can be corrected by DNA repair systems.

True

Excessive DNA damage can cause cells to become cancerous.

True

Frameshift mutations result in a change in the reading frame of mRNA codons.

True

Gene expression can be changed by chemical modifications to DNA that make promoters available for transcription.

True

Induced DNA mutations can be caused by exposure to radiation or chemicals.

True

Often, hemoglobin mutations result in amino acid substitutions in the hemoglobin protein.

True

PBDEs have not been linked directly to cancer in test animals.

True

The maternal copy of some genes is preferentially expressed over the paternal copy; if this pattern is not followed, growth abnormalities can result.

True

The size of the expanded trinucleotide repeat correlates to the earlier age of onset and the severity of the symptoms of a genetic disorder.

True

When the number of trinucleotide repeats in a gene is significantly above normal, it can produce a mutant phenotype.

True

_______ are mutations involving the increase of the number of repeat sequences in genes.

allelic expansions

Mutations in germ cells:

are transmitted to all cells of future generations

​In sickle cell anemia, affected individuals carry ____.

​the same single nucleotide substitution

Sense mutations produce ____.

elongated proteins

​The epigenetic state of a cell is called its

epigenome

epigenetics

field that deals with how gene expression is changed without permanently affecting the nucleotide sequence of DNA

​Insertion or deletion of a nucleotide in a gene causes a type of mutation called a(n) ________ mutation.

frameshift

Since DNA repair rates are close to the levels of DNA damage, _____ the repair systems is quite common

overloading

Mutations in somatic cells are:

passed on only to other body cells

mutagens

physical or chemical agents that cause mutations

​The ability of DNA polymerase to repair its own nucleotide mismatches is called

proofreading

XP is an autosomal recessive disorder caused by mutations in DNA:

repair genes

Chemicals, such as flame retardants, persist in animal and human tissue long after exposure.

True

The human genome contains more than _____genes for DNA repair.

175

All individuals with cystic fibrosis have similar disease phenotypes.

False

All mutations are the result of errors in normal cellular processes such as DNA replication or are the result of natural changes in the molecular structure of the bases in DNA.

False

Allelic expansion mutations always result in shortened protein products.

False

Autosomal recessive disorders are easy to identify in pedigrees because affected individuals need to inherit only one defective allele.

False

Frameshift mutations, a major cause of genetic disorders, account for 25-30% of all known mutations.

False

Identical twins not only have identical genotypes, but also identical phenotypes.

False

It is possible to trace the mutant allele for an autosomal recessive trait through previous generations.

False

Just over 50% of the radiation that US citizens are exposed to is from background radiation.

False

Large genes − such as the two million base-pair muscular dystrophy genes − typically show a lower rate of mutation than shorter genes.

False

Mutation rate refers to the frequency with which mutated alleles are deleted from a genotype.

False

Mutations in somatic cells are always passed onto offspring through the egg and sperm.

False

Nonsense mutations change termination codons into amino acid codons.

False

Nucleotide deletions and insertions can affect one nucleotide within a gene, or hundreds to thousands of nucleotides in a gene, but does not include the duplication or deletion of the entire gene.

False

Allelic expansion converts a normal allele into a mutant allele by expanding the number of trinucleotide repeats within a gene.

True

methylation

a process that adds methyl groups to promoter sites in DNA

epigenetic trait

a stable phenotype that results from changes in gene expression

________ build(s) new DNA molecules and proofreads the new strand to detect and correct any errors. a. DNA polymerase b. DNA repair systems c. RNA polymerase d. DNA ligase e. RNA ligase

a. DNA polymerase

Why is it difficult to identify the source of an autosomal recessive mutation in a family pedigree? a. Heterozygous carriers can remain undetected for generations. b. Autosomal recessive disorders are only observed in females. c. Autosomal recessive disorders are caused by viruses. d. DNA mutation rates are lower in genes that cause autosomal recessive disorders. e. Autosomal recessive disorders are always lethal.

a. Heterozygous carriers can remain undetected for generations.

Mutations that occur in somatic cells ________. a. are not passed onto the offspring b. are not passed onto daughter cells during cell division c. are passed onto the offspring d. are passed onto the germ cells e. always cause cell death

a. are not passed onto the offspring

Because many imprinted genes control the timing and patterns of prenatal growth, abnormal imprinting can cause ________, which is seen in disorders such as Beckwith-Wiedemann syndrome. a. growth disorders b. dwarfism c. DNA mutations d. behavioral disorders e. skin cancer

a. growth disorders

Measuring how DNA methylation patterns on the glucocorticoid receptor gene promoter change in response to environmental signals can reveal ________. a. how epigenetics controls the stress response b. why identical twins have different phenotypes c. how tightly wound nucleosomes turn on the stress response d. the cause of Beckwith-Wiedemann syndrome e. the cause of depression in humans

a. how epigenetics controls the stress response

Mutations that result in the production of a defective CFTR protein inserted into the cell membrane cause ________ disease phenotypes. a. milder b. no c. rare d. severe e. compound

a. milder

DNA methylation in promoter regions of genes ________. a. turns off gene expression b. loosens the nucleosomes to allow transcription c. is irreversible d. occurs only before birth e. changes the nucleotide sequence

a. turns off gene expression

​When ____ is incorporated into DNA or RNA during synthesis, it will create a(n) ____. a.​5-bromouracil; nucleotide substitution mutation b.​5-bromouracil; frameshift mutation c.​carbon; base analog d.​oxygen; nucleotide substitution mutation e.​oxygen; base analog

a.​5-bromouracil; nucleotide substitution mutation

As radiation strikes molecules in cells, it creates ____. a.​charged atoms called ions b.​charged atoms called isotopes c.​excess copies of mRNA d.​excess storage of tRNA e.​excess DNA polymerase

a.​charged atoms called ions

​What is the largest single source of radiation exposure for the average person in the U.S.? a.​radon b.​cosmic c.​nuclear medicine d.​consumer products e.​medical X-rays

a.​radon

​Several genetic disorders, including Fanconi anemia and ataxia telangiectasia, are caused by mutations in ____. a.​the cell wall b.​DNA repair genes c.​ribosome structure d.​mitochondrial DNA e.​DNA polymerase genes

b.​DNA repair genes

​Mutations are changes in the nucleotide sequence of DNA that ____. a.​are always spontaneous b.​can be passed on to daughter cells c.​do not occur in the germ cells d.​do not occur in the somatic cells e.​are always chemically induced

b.​can be passed on to daughter cells

​As DNA polymerase synthesizes a new DNA strand, it can ____. a.​induce senescence when it detects a mistake in DNA synthesis b.​detect an incorrect nucleotide c.​not detect an incorrect nucleotide d.​immediately stop the cell cycle e.​induce apoptosis when it detects a mistake in DNA synthesis

b.​detect an incorrect nucleotide

​Mutagenic chemicals that ____ and are incorporated into DNA or RNA during synthesis are called base analogs. a.​resemble amino acids b.​resemble nucleotides c.​resemble genes d.​cause frameshift mutations e.​cause deletion mutations

b.​resemble nucleotides

​Radiation in the environment that contributes to radiation exposure is called ______radiation.

background

A purine or pyrimidine that differs in chemical structure from those normally found in DNA or RNA is called a(n)

base analog

During prenatal development or early in life epigenetic responses to environmental signals influence ______during adulthood.

behavior

​Mutations in ______ cells will be passed on by cell division, but cannot be transmitted to future generations.

body

In some parts of the United States where PBDEs are not banned, samples of human milk contain ________ PBDEs than in European countries, where this chemical is banned. a. 5 times less b. 2 times less c. 10 to 100 times more d. 5 to 10 times more e. 2 times more

c. 10 to 100 times more

________ allow(s) for noncomplementary base pairing, which results in permanent mutations after DNA replication. a. Base analogs b. Nitrites c. Tautomeric shifts d. X-ray radiation e. DNA polymerase

c. Tautomeric shifts

________ genes tend to have high DNA mutation rates. a. Short b. X chromosomal c. Trinucleotide repeat-containing d. Dominant e. Autosomal

c. Trinucleotide repeat-containing

PBDEs are ____. a.​permitted in only one European country and in only 11 states in the United States b.​banned in many Europeans countries and all states in the United States c.​banned in many European countries but permitted in most states in the United States d.​permitted in many European countries but banned in the United States e.​banned worldwide but are still being used illegally

c.​banned in many European countries but permitted in most states in the United States

Genetic imprinting is caused by ____. a.​insertion of a nucleotide into an exon b.​deletion of an amino acid from the mRNA strand c.​epigenetic changes to DNA d.​a frameshift mutation e.​a change in a termination codon

c.​epigenetic changes to DNA

The flaking of skin after a sunburn is an example of ________. a. dormant cells b. cancerous cells c. the action of DNA repair systems d. cell suicide as a result of too much DNA damage e. mutations in DNA repair genes

d. cell suicide as a result of too much DNA damage

​What occurs in a missense mutation? a.​A nucleotide is added to the DNA. b.​All of the amino acids beyond the mutation point are changed. c.​A nucleotide is deleted from the DNA. d.​A single amino acid is substituted for another in a protein. e.​The protein is always completely nonfunctional.

d.​A single amino acid is substituted for another in a protein.

Mutations can include a single nucleotide change in DNA, an alteration in the structure of a chromosome or the:

deletion or insertion of one or more base pairs

Huntington Disease results from extra copies of trinucleotide repeats in the Huntingtin gene. This is an example of a(n) ________ mutation. a. nucleotide substitution b. frameshift c. nonsense d. induced e. allelic expansion

e. allelic expansion

Chemical mutagens that incorporate into DNA or RNA molecules are called ________. a. mutagens b. base substitutions c. base mimics d. tautomeric shifts e. base analogs

e. base analogs

A two-nucleotide insertion mutation that results in conversion of an amino acid codon to a stop codon is known as a(n) ________. a. sense mutation b. missense mutation c. allelic expansion d. nucleotide substitution e. frameshift mutation

e. frameshift mutation

A mutation in the Factor VIII gene − required for blood clotting − changes a CGT codon to CAT, and changes the amino acid from arginine to histidine. This is an example of a ________ mutation. a. sense b. frameshift c. nonsense d. spontaneous e. missense

e. missense

New ____ mutations can often be detected by examining the inheritance of the trait in males.​ a.​autosomal dominant b.​autosomal recessive c.​imprinting d.​mitochondrial e.​X-linked

e.​X-linked

​If a genetic disorder appears in a family with no prior history, and is fully expressed by everyone carrying that allele, it is most likely a(n) ____ trait. a.​autosomal recessive b.​X-linked recessive c.​Y-linked d.​mitochondrial e.​autosomal dominant

e.​autosomal dominant

​Several lines of research provide strong evidence that ____ to environmental signals influence behavior. a.​epigenetic feedback b.​base analog reconstruction due c.​base analog reactions d.​base analog responses e.​epigenetic responses

e.​epigenetic responses

Mutation rates of human genes are expressed as the number of ____. a.​induced mutations per generation b.​frameshift mutations per genome c.​mutated alleles per genome d.​nucleotides substitutions per gene e.​mutated alleles per gene in each generation

e.​mutated alleles per gene in each generation

Since DNA repair is controlled genetically mutations in repair genes can cause:

genetic disorders

Selective expression of either the maternal or paternal copy of a gene is called

genetic imprinting

The selective activation or silencing of either the maternal or paternal copy of a gene is called:

genetic imprinting

Methylation of promoter regions in DNA loosens the winding of the DNA around _____ making the promoters available for transcription and hence epigenetic changes

histones

​Beckwith-Wiedemann syndrome results from abnormalities of

imprinting

background radiation

natural sources of radiation

trinucleotide repeats

more than the usual number of copies of a nucleotide sequence

base analogs

mutagenic chemicals resembling nucleotides that can be incorporated into DNA or RNA during synthesis

nucleotide substitutions

mutations that alter the sequence, but not the number of nucleotides

sense mutations

mutations that change a stop codon into one that codes for an amino acid resulting in a longer sequence and elongated proteins

nonsense mutations

mutations that substitute one of the stop codons prematurely into the sequencing of an amino acid resulting in a shorter, unfinished protein

Cells that accumulate significant DNA damage may become dormant, this condition is known as:

senescence

tautomeric shift

small atomic changes within molecules that allow chemical groups, such as nucleotides, to exist in alternate geometric forms

rem

the amount of radiation that causes the same amount of damage as the standard X-ray dose

promoter

the control region of a gene indicating the beginning of the sequence

epigenome

the epigenetic state of a cell

frameshift mutations

the insertion/deletion of extra bases other than in multiples of three in DNA leading to a shift in the codon reading frame

mutation rate

the number of mutated alleles per gene in each generation

missense mutations

the substitution of one amino acid for another in a protein caused by a single nucleotide change