Genetics connect quizzes
Select all examples of mutations that are likely to be recessive to wild-type alleles.
- A null allele of Gene X, if Gene X is haploinsufficient. - A hypermorphic allele of Gene Z that encodes a constitutively active protein.
Which of the following are steps in the generation of knockout mice using ES cells?
- Add LTRs to the ends of a cDNA for the gene to be knocked out. - Introduce a gene-targeting construct into host blastocysts. - Mix modified ES cells with ES cells containing a Cre gene. - Introduce a gene-targeting construct into packaging cells. - Replace the viral genes with a therapeutic gene.
Which is the best method to demonstrate the function of a putative enhancer?
- Compare DNA sequences from two or more species and identify conserved regions located outside of coding regions. - Introduce two separate pieces of DNA into a eukaryotic cell; one is a fragment of DNA with the putative enhancer and the other is a plasmid that contains a reporter gene. - Clone the putative enhancer into a reporter construct and measure the level of reporter gene expression in a prokaryotic cell - Crosslink genomic DNA and associated proteins, fragment the DNA, use an antibody to isolate DNA sequences bound to a particular transcription factor, and sequence the DNA.
Select all examples of metagenomic research projects.
- Genome sequencing of multiple strains of a bacterial species differentiates between the core genome and the pangeome. - The existence of germ-free mice demonstrates that microbes are not beneficial for mammals.
Which of the following are limitations of DNA polymerase?
- It can only add bases to the exposed 5' end of a preexisting strand. - It can only replicate the leading strand. - It can only replicate the lagging strand. - It can only replicate circular chromosomes.
Which of these are required for a Sanger sequencing reaction?
- RNA polymerase - Four ribonucleotides (ATP, GTP, CTP, TTP) - Single-stranded RNA template - A random RNA primer
Short-limb dwarfism in humans is caused by a missense mutation in the human FGFR3 gene, resulting in a gain-of-function, constitutively active FGF receptor protein. Select all steps that would occur to produce a mouse model of this form of dwarfism.
- A construct with a nonsense mutation in FGFR3 is created. - The mutant DNA integrates into a random location in genomic DNA in a mouse pronucleus. - LoxP sites undergo recombination to delete the targeted exon of the mouse FGFR3 gene. - A knockin mouse with the human FGFR3 missense mutation is larger than wild-type littermates.
LHON is a mitochondrial disease caused by weak hypomorphic mutations that affect the mitochondrial electron transport chain. Among the first symptoms of the disease is blindness. People with LHON are usually homoplasmic because retinas must be homoplasmic mutant for a person to have disease symptoms. Which is true about a female who is heteroplasmic for the mutation that causes LHON?
- She is likely to develop the disease in other parts of her body. - All of her children will be homoplasmic for the wild-type mitochondria.
What is true about reciprocal translocation heterozygotes and inversions?
- The amount of DNA in the genome remains the same. - The genes at the boundaries may be disrupted, while those in the middle are most likely unaffected. - Up to 50% of gametes may be unbalanced, resulting in semisterility.
A man who had colon cancer has an aunt who also had the same type of colon cancer. The man's son has just been diagnosed with the same type of colon cancer and doctors perform genome sequencing of his cancer cells and normal cells. If this cancer is associated with an inherited mutation, select the expected results of genome sequencing.
- The cancer cells have two loss-of-function alleles of an oncogene. - His normal cells are heterozygous for a gain-of-function allele of an oncogene.
genomic library
- a collection of cellular clones that contains copies of every sequence in an organism's whole genome inserted into a suitable vector - all regions of the genome are represented in a complete library - a single library may contain the whole genome
cDNA library
- a collection of sequences copied into DNA from all the mRNA transcripts present in a particular cell type, tissue, or organ - reveals the fraction of the genome in a specific tissue that is transcribed and teh genes whose primary RNAs are processed into mRNAs - reverse transcriptase copies mRNA into a complementary DNA strand - a unique library can exist for every tissue in an organism - the frequency with which particular sequences appear is proportional to the level of the corresponding mRNA
self-fertilization
- a cross where the pollen of one plant is used to fertilize the ovum of the same plant - this cross is impossible in species where individuals are the same sex
core genome
- consists of about 1000 genes - genes that are common to all E coli strains - provide essential functions
pangenome
- consists of about 15,000 genes - genes that are found in some but not all E coli strains - allow strains to adapt to different environments
opens chromatin and promotes gene expression
- histone acetyl transferase - histone methyltransferase - histone demethylase
closes chromatin and inhibits gene expression
- histone deacetylase - histone methyltransferase - histone demethylase
transposons
- inverted repeats at the ends are recognized by transposase - contains a gene that encodes transposase - a copy of the element may or may not remain at the original location depending on the template - transposase removes the element and inserts it into a new location - gaps that remain after movement are repaired using a sister chromatid or homologous chromosome as template
protein
- polymer of 20 different amino acids - order of monomers is important for function - can catalyze chemical reactions - has most variable chemical structure - can fold into a variety of 3D shapes
RNA
- polymer of four different nucleotides - can store, replicate, and express heritable information - order of monomers is important to function - can fold into a variety of 3D shapes - can catalyze chemical reactions
DNA
- polymer of four different nucleotides - consists of two strands facing opposite directions - has most stable chemical structure - can store, replicate, and express heritable information - order of monomers is important to function
cross-fertilization
- reciprocal crosses are possible - testcrosses are possible - a cross where the pollen of one plant is used to fertilize the ovum of a different plant
Which process(es) can generate recombinant gametes?
- segregation of alleles in a homozygote - crossing-over between two linked homozygous loci
retrotransposons
- transcribed by RNA polymerase to produce an RNA that encodes reverse transcriptase - some of these have long terminal repeats (LTRs) at both ends, in the same orientation - some of these have a poly-A tail at the 3' end of the RNA like DNA strand - reverse transcriptase produces a double stranded cDNA copy that is inserted into a new location
LHON is a rare mitochondrial disease caused by weak hypomorphic mutations that affect the mitochondrial electron transport chain. The first symptoms of the disease include blindness. People with LHON are usually homoplasmic because retinas must be homoplasmic mutant for a person to have disease symptoms. Which is true about a male who is heteroplasmic for the mutation that causes LHON?
-All of his children will most likely be homoplasmic for the wild-type mitochondria. -Some cells in his body are probably homoplasmic.
Which are possible results of an intragenic inversion (an inversion contained within a gene)?
-All of the gene's A, C, G, and T bases remain in the same order as normal. -The order of genes along the chromosome may be different than normal.
In what way can defective transposable elements alter genomes even if they cannot mobilize?
-Crossing-over between transposable elements on the same chromosome can result in a deletion or an inversion. -Crossing-over between transposable elements on nonhomologous chromosomes can result in a reciprocal translocation.
Select all statements that describe the relationship between telomerase and cancer.
-Telomeres in cancer cells are typically shorter than telomeres in the somatic cells of the same individual. -Cells with a deletion of the gene that encodes a telomerase protein are more likely to become cancerous. -Telomerase is a complex of DNA and protein.
A man who had colon cancer has an aunt who also had the same type of colon cancer. The man's son has just been diagnosed with the same type of colon cancer and doctors perform genome sequencing of his cancer cells and normal cells. If this cancer is associated with an inherited mutation, select the expected results of genome sequencing.
-The cancer cells have two loss-of-function alleles of an oncogene. -His normal cells are heterozygous for a gain-of-function allele of an oncogene.
Which is true of enhancer DNA sequences?
-They contain TATA boxes. -They only function to increase gene transcription levels above the basal level.
Which can result in Down syndrome?
-deletions of a segment of chromosome 21 -having the triploid number of chromosomes
Hemophilia is caused by an X-linked recessive mutation in humans. If a woman whose paternal uncle (father's brother) was a hemophiliac marries a man whose brother is also a hemophiliac, what is the probability that their first child will have hemophilia? (Assume that no other cases of hemophilia and no hidden carriers exist in the pedigree.)
0
If a man has one premutation allele for fragile X syndrome, what is the probability that he will pass the premutation allele on to his son?
0%
Genes A and B are on different (nonhomologous) chromosomes. If an individual's genotype is Aa Bb, what is the genotypic ratio of gametes produced?
1 A B : 1 A b : 1 a B : 1 a b
The genetic code includes
1 start codon and 3 stop codons
Arrange these steps in the proper order, from first to last, in which they occur during a single PCR cycle.
1. Heat denaturation of strands of target DNA 2. Hybridization of primers to target DNA 3. Addition of deoxyribonucleotides by DNA polymerase
PCR Cycle
1. Heat denaturation of strands of target DNA 2. Hybridization of primers to target DNA 3. Addition of deoxyribonucleotides by DNA polymerase
Order the steps in the production of a transgenic mouse from first (1) to last (5).
1. Zygotes are harvested from a recently mated female mouse. 2. Linear copies of the transgene DNA are injected into a pronucleus of a fertilized egg. 3. Tandem copies of DNA integrate into a random location on a chromosome. 4. Mice that were injected as embryos are born from a host female. 5. Cells from mouse tails are tested for transgenic DNA.
Calculate the probability of homozygous genotypes for the genes A, B, E, and F in the offspring of the cross Aa Bb cc dd Ee Ff × Aa Bb Cc dd Ee Ff.
1/128
In the dihybrid cross Aa Bb × aa bb, what proportion of heterozygotes for both gene pairs is expected among the F1 offspring?
1/4
Suppose that in plants, smooth seeds (S) is dominant to wrinkled seeds (s) and tall plants (T) is dominant to short plants (t). An F1 tall plant with smooth seeds was crossed to a parent plant that was short and wrinkled. What proportion of the progeny is expected to be heterozygous for tall and smooth?
1/4
If a trait is controlled by two codominant alleles of one gene, what phenotypic ratio is expected in the offspring of a mating of two heterozygotes?
1:2:1
What is a RefSeq?
A RefSeq is a single, complete, annotated version of a species' genomic DNA sequence that can be accessed for bioinformatic studies.
According to Mendel's law of equal segregation, an Aa monohybrid makes two types of gametes with equal frequency. These two gamete types are:
A and a
Which is not an example of euploidy?
A human with Down syndrome has three copies of chromosome 21.
missense mutation
A mutation that results in production of a mutant protein with only one amino acid change (compared to the wild-type protein) can result in a dramatic difference in phenotype.
Which statement describes a primary mutant screen?
A scientist examines a large number of mutagenized zebrafish embryos for abnormalities in blood vessel formation.
transposition
A short DNA segment moves from one position in the genome to another
Which piece of evidence is most likely to indicate a gene within a genome?
A unique sequence within a genome is 80% similar in human, mouse, and zebrafish.
Currently the two main vectors for delivery of therapeutic genes for human gene therapy are
AAV and retroviruses
What are characteristics of the pedigrees of families with mitochondrial diseases?
All children of affected mothers are usually affected regardless of their sex.
Why are organisms with an odd number of chromosome sets usually sterile?
Almost all gametes will have an unbalanced set of chromosomes.
Which statement is true about sex determination in Drosophila?
Alternative splicing of Sxl transcripts in females results in an active protein that directs alternative splicing of tra transcripts in females.
Which statement about SNPs in the human genome is true?
Any two human genome copies will have on average 3 million single nucleotide polymorphisms.
Two strains of S. cerevisae (yeast) are crossed. One has the genotype ABC and the other abc. Five sets of the resultant tetrads are noted below. In which set did a gene conversion event occur?
abc, aBc, AbC, aBC
What is a trans-acting factor that increases transcription above the basal rate called?
activator
What is a transcription factor that associates with an enhancer and causes an increase in initiation of transcription?
activator
Alkylating agents, such as ethylmethane sulfate (EMS), are mutagens because they
add ethyl or methyl groups to bases.
Huntington disease is caused by expansion of the trinucleotide repeat region of the HD gene that results in the production of a Huntingtin protein with an expanded number of glutamines. An animal model with most features of this syndrome could be created by
adding a transgene containing a disease-causing mutant allele of the HD gene to a mouse or primate genome.
When a dideoxynucleotide is incorporated into one new strand by DNA polymerase,
addition of nucleotides only to that strand ceases.
The coding sequence of the green fluorescent protein gene (GFP) is placed under the control of an enhancer active in neurons. When this transgene is introduced into flies, GFP will be expressed in
all neurons or a subset of neurons.
Oocyte nuclear transfer can be used to
allow women with mitochondrial diseases to have normal offspring.
A single eukaryotic gene can produce two different forms of a protein, one that is membrane bound and one that is secreted. Which of these mechanisms allows a single gene to produce two different proteins from one primary transcript?
alternative splicing
Which of these types of gene regulation occurs earliest in the process of gene expression?
alternative splicing
How can one primary mRNA result in several polypeptides with different amino acid sequences?
alternative splicing of exons
CRISPR sequences occur naturally as
an antiviral immune system in bacteria.
duplication
an increase in the number of copies of a chromosomal region
Which experiment would best determine which genes are expressed in a Drosophila embryo?
analysis of a cDNA library from Drosophila embryos
cDNA is
any DNA produced using an RNA template.
A female mouse from a true-breeding wild-type strain was crossed to a male mouse with apricot eyes (ap) and grey body (gy). The F1 mice were wild-type for both traits. When the F1 were interbred, the F2 were distributed as follows: Females all wild type 200 Males wild type 91 apricot 11 grey 9 apricot, grey 89 Which of the following statements is correct?
ap and gy are X-linked and 10 map units apart
Expression of homeotic genes
assigns a unique identity to each segment.
If integration of DNA provided by pronuclear injection occurs after three cell divisions, the resulting mouse will
be a mosaic of cells with some cells containing the transgene and others not.
A trans-acting factor functions by
binding to enhancers or promoters leading to increased or decreased transcription.
The recognition site for a restriction enzyme is 5′ ACC^GGT 3′. The ^ symbol indicates the site of cleavage. After digestion of DNA with this restriction enzyme, how will the ends of the resulting DNA fragments look?
blunt ends
After exposure to Agrobacterium tumefaciens bacteria containing both a recombinant T-DNA vector and a helper plasmid, new plants can be grown from single cells in the presence of herbicide. Without the herbicide,
both transformed and nontransformed plants will grow
nonsense mutation
changes a codon specifying an amino acid into a stop codon
silent mutation
changes a codon without altering the amino acid that is encoded (for ex. GCA to GCC which both code for alanine
One way N. gonorrhoeae became resistant to penicillin was by acquiring a plasmid that carries the penr penicillin resistance gene, which encodes a protein that
cleaves penicillin to an inactive form.
Enhancers can be identified by
cloning a region of DNA with the putative enhancer in a reporter plasmid and demonstrating an increase in gene expression when the construct is introduced into a eukaryotic cell.
Which method of fragmenting DNA would not be useful for sequencing a genome for the first time?
complete digestion with a restriction enzyme
The amino acid carried by a transfer RNA is joined to the 3' end of the transfer RNA by a(n)
covalent bond
UV light damages DNA by causing
covalent bonds to form between thymine bases next to each other on the same DNA strand.
G to S checkpoint
delays DNA replication if damage to DNA has occurred
The type of mutation that results in a loss of material from the genome is called what?
deletion
Inversions may be difficult to detect because they
do not always cause an abnormal phenotype.
Sequencing of DNA from a tumor sample reveals that one allele of RB has been deleted and the other allele contains a missense mutation. The RB protein in the tumor cells most likely
does not bind to E2F, resulting in uncontrolled cell division.
To generate a cDNA library from mouse muscle cells, reverse transcriptase is required to make
double-stranded cDNA from mature mRNA isolated from muscle cells.
What type of mutation adds material to the genome?
duplication
Methylated histone tail amino acids are associated with chromatin that is
either open or closed
What is the term for a cis-acting DNA sequence that may function at a distance from the gene they are regulating?
enhancer
A variation in gene function that does not involve a change in DNA sequence but can be inherited is a(n)
epigenetic phenomenon
If a phenotype is controlled by the genotypes at two different loci, a possible interaction between alleles of these genes can be called
epistasis
The sequences found in a mature eukaryotic mRNAs are
exons
F+ refers to a cell containing
f plasmid
A PCR using a single pair of primers produces many copies of the entire genome.
false
All the genes in a species' core genome are located on the bacterial chromosome, whereas the genes of the pangenome are carried on plasmids.
false
Multidrug resistance is not a major health concern because new antibiotics are easily and frequently identified.
false
Plasmids are created exclusively in research laboratories and do not occur naturally.
false
A DNA sequence 5′ ATGGGGGACACC 3′ encodes the amino acids Met Gly Asp Thr. A mutation changes the sequence to 5′ ATGAGGGGACACC 3′ that encodes the amino acids Met Arg Gly His. What type of mutation has occurred?
frameshift mutation
proto-oncogene
gain of function mutant alleles act dominantly and contribute to cancer
In an Hfr strain, the F episome is integrated between genes A and B. When this Hfr mates with an F− strain, gene B is always transferred first to the F− cell. What is the last bacterial gene that could possibly (at least in theory) be transferred to the F− from the host chromosome?
gene A
What describes a situation in which an allele's expression depends on the parent from which it was inherited?
genomic imprinting
Inversions are most likely to affect an organism's phenotype
if one or both of the inversion's breakpoints lies within the transcribed region of a gene.
Which is a characteristic of retrotransposons, but not of DNA transposons?
include a gene that encodes reverse transcriptase
Penicillin stops bacterial cell wall formation by
inhibition of a transpeptidase.
frameshift mutation
insertion or deletion of a number of nucleotides that is not divisible by three
What are the four major classes of chromosomal rearrangements?
inversions, duplications, translocations, deletions
To produce a mutation in a specific E. coli gene, an engineered fragment of DNA in which sequences from each end of that gene flank an antibiotic resistance gene,
is introduced into cells and undergoes homologous recombination with the bacterial gene.
When a bacteriophage carrying bacterial DNA infects a new bacterium
it transfers bacterial DNA from the donor bacterium to the recipient bacterium.
tumor-suppressor gene
loss of function mutant alleles act recessively and contribute to cancer
A codon is a three-base sequence of
mRNA that codes for an amino acid.
What is the order of action of these classes of genes during Drosophila development?
maternal effect, gap, pair rule, segment polarity
The leucine zipper motif functions to
mediate the physical association of two polypeptides.
The DNA sequence 5′ ATGGGGGACACC 3′ encodes the amino acids Met Gly Asp Thr. A mutation changes the sequence to 5′ ATGGGGAACACC 3′ that encodes the amino acids Met Gly Asn Thr. What type of mutation has occurred?
missense mutation
What feature of a DNA microarray analysis allows the number of copies of a particular sequence in the genome to be inferred?
more copies of a sequence result in a higher intensity signal
reciprocal translocation
non homologous chromosomes exchange parts
A mutation that changes a codon that originally coded for an amino acid into a stop codon is a
nonsense mutation.
Mutations that completely abolish the function of a wild-type allele are
null mutations
During mitosis, if all of the chromosomes in a diploid cell fail to separate and instead segregate into one daughter cell, the result will be what?
only one tetraploid daughter cell
Acetylated histone tail lysines are associated with chromatin that is
open.
The CDK-cyclin D complex phosphorylates RB, which then
releases E2F to activate genes for DNA synthesis.
deletion
removal of a segment of DNA
What is the term for transcription factors that decrease transcriptional activity?
repressors
What is the most significant advantage of using RNAi to study development?
Genetic studies of a single gene can be completed without creating new mutant organisms.
How can microarrays differentiate between a wild-type allele and a disease allele that differ at only one nucleotide?
Oligonucleotides hybridize with the two alleles differently.
Why is the number of X chromosomes crucial for sex determination in Drosophila?
The Sxl promoter is responsive to the concentration of four transcription factors produced from genes on the X chromosomes.
What is the purpose of ethidium bromide in DNA electrophoresis?
To tag DNA fragments so they can be viewed under UV light
A student analyzes a genomic DNA sequence of 100 nucleotides in order to determine if it is part of a gene. When she translates the sequence beginning at the first nucleotide, she finds that the tenth codon is UAA. What should she do next?
Translate the sequence in the other five reading frames.
A mutation that results in production of a mutant protein with only one amino acid change (compared to the wild-type protein) can result in a dramatic difference in phenotype.
True
Sister chromatids are linked together by their centromeres.
True
The amino acid sequence of a protein determines its shape and specific function.
True
Three genes (X, Y, and Z) are in the same region of a bacterial chromosome. To determine the order of these genes, you infect X− Y− Z− cells with a lysate from wild-type cells infected with a generalized transducing phage. When X+ cells are selected, 70% of cells are also Y+ and 5% of cells are Z+. When Y+ cells are selected, 68% of cells are also X+ and 1% are Z+. What is the relative arrangement of the three genes?
X is in the middle, but closer to Y.
Suppose a three-point testcross was conducted involving genes X, Y, and Z. If the most abundant classes of progeny are X Y z and x y Z and the rarest classes are x Y Z and X y z, which gene is in the middle?
Y
Which sex chromosome aneuploidy is not usually seen in live births?
YO
Imagine that DNA is composed of equal proportions of six different types of nucleotide, instead of the normal four. The six nucleotides are A, C, G, T, X, and Y. In this new type of DNA molecule, A pairs with T, C pairs with G, and X pairs with Y. What would be the average size of the DNA fragments produced when this new DNA is cut by a restriction endonuclease with a four-base recognition sequence?
1296 bp
If 35% of the bases in a region of the mouse genome are cytosine, what percentage in that region are adenine?
15%
Drosophila melanogaster has four pairs of chromosomes (including a pair of sex chromosomes). Sperm from this species are formed by a meiotic process in which homologous chromosomes pair and segregate but do not undergo crossing-over. How many genetically different kinds of sperm could be produced by a Drosophila melanogaster male (XY)?
16
When DNA microarrays are used to genotype SNPs, what form of DNA is attached to the silicon chip?
20-40 base allele-specific oligonucleotides
In Drosophila, the recessive allele for forked bristles is sex-linked, and the recessive allele for purple eyes is autosomal. The wild-type alleles are for straight bristles and red eyes, respectively. A female, heterozygous for both pairs of alleles, is mated with a male with forked bristles and purple eyes. What percentage of the daughters will have forked bristles and purple eyes?
25%
Suppose the L and M genes are on the same chromosome but separated by 100 map units. What fraction of the progeny from the cross L M / l m × l m / l m would be L m / l m?
25%
In a certain breed of plants, dark green is determined by the dominant allele G and light green is determined by the recessive allele g. The heterozygote shows 75% penetrance for the dominant phenotype. If the parental cross is GG × gg, how many light green plants would be expected in a population of 400 F2 plants?
250 dark green; 150 light green
Which genotypic ratio indicates a recessive lethal allele when two heterozygotes are mated?
2:1
If an individual has 10 gene pairs, how many different gametes can be formed if three of the gene pairs are homozygous and the remaining seven gene pairs are heterozygous?
2^(number of heterozygous genes) = 128
DNA polymerases use their ________ activity to remove a mismatched base.
3' → 5' exonuclease
A disease is caused by homozygosity for the g allele (G is the corresponding wild-type allele). However, the penetrance of the disease is 75%. Two individuals known to be heterozygotes have a child. What is the probability that the child exhibits the disease?
3/16
If a single DNA molecule is amplified by PCR, how many DNA molecules will exist after FIVE cycles?
32
To estimate the genome size of a newly discovered organism, you digest one copy of its genomic DNA with the restriction enzyme EcoRI, which has a 6 bp recognition site. The genome is cut into about 100,000 fragments. Which is your best estimate of the size of this organism's genome?
400 Mb
The R and S genes are linked and 10 map units apart. In the cross R s / r S × r s / r s what percentage of the progeny will be R s / r s?
45%
Suppose a region of DNA is 100 bp long. How many unique sequences could it potentially represent?
4^100
The polarity of DNA synthesis is
5' to 3'
Allele specific oligonucleotides (ASO) for the normal and disease alleles of a gene are in one section of a microarray. The disease is a recessive trait. If a probe made from an individual's genomic DNA hybridizes with both ASOs, what can be inferred about the individual?
50% of the individual's children are expected to be carriers
According to the wobble rules, a 5′ G in an anticodon can pair with U or C in a codon. Select all codons that a tRNA with anticodon sequence 3′ GCG 5′ could recognize.
5′ CGC 3′ 5′ CGU 3′
One strand of DNA has the sequence 5′ GGTCTA 3′. What is the sequence of the other strand?
5′ TAGACC 3′
A tRNA with the anticodon sequence 5′ IUA 3′ will not normally exist because
5′ UAA 3′ is a stop codon.
The measured distance between genes D and E in a two-point testcross is 50 map units. Where are genes D and E in relation to each other?
D and E are on the same chromosome, exactly 50 map units apart. D and E are on the same chromosome, less than 50 map units apart
How are the structures of DNA and proteins similar?
DNA and proteins are polymers composed of strings of individual subunits.
A protein with a zinc-finger domain most likely has what type of activity?
DNA binding
Histones and DNA have a strong attraction for each other because
DNA is negatively charged and histones are positively charged
Semiconservative replication of DNA means that
DNA is negatively charged and histones are positively charged.
The ends of DNA molecules can be joined together by
DNA ligase
With respect to DNA structure, polarity means that
DNA strands have a 5′ direction and a 3′ direction.
What is a segment of DNA that can use transposase to move from one place in the genome to another called?
DNA transposon
Which sequences are at the end of PCR amplified DNA fragments?
Deoxyribonucleotides that correspond to primer sequences
What is the relationship between methylation and genomic imprinting?
Differential methylation of DNA in males and females results in only one of the parental alleles being transcriptionally active in the offspring.
What is the purpose of the P element in the creation of transgenic Drosophila?
Efficiently transfer DNA into Drosophila chromosomes.
Consider a normal chromosome with the following gene sequence along its length: F G H I J K L. Which of the following sequences represents an inversion?
F K J I H G L
Daughter cells produced in meiosis are identical.
False
What is one way that genes can be predicted in genome sequences?
Identifying the most conserved sequences between different species.
What is a reason that aneuploidy in sex chromosomes is generally better tolerated than aneuploidy in autosomal chromosomes in humans?
In somatic cells, most of the genes on only one X chromosome are transcriptionally active.
In Sanger sequencing, what causes DNA synthesis to terminate at a specific base?
Incorporation of a dideoxynucleotide that lacks a 3′ hydroxyl.
you are studying a histone complex that contains an unusually high level of modification with acetyl groups. What can you conclude about the DNA bound to this histone complex?
It contains actively transcribed genes.
The presence of a homeodomain in a protein suggests what about its function?
It is a transcription factor.
Which statement best describes the limitations of using of humans in genetic studies of developmental biology?
It is impractical and unethical to conduct experimental manipulation or targeted mutagenesis of humans to examine the role of genes in development.
The cross L p q / l P Q × l p q / l p q is carried out. If the L gene is in the middle, between genes P and Q, what would be the genotypes of the double crossover gametes in this cross?
L P Q and l p q
E. coli cells that are sensitive to ampicillin are mixed with many copies of a plasmid that has a gene for ampicillin resistance and then plated on medium containing ampicillin. What will happen next?
Only E. coli cells that have taken up a plasmid will grow and form colonies.
The most common mutant allele of the PAH gene, which is responsible for the metabolic disorder PKU, has a SNP in the splice donor site of one intron. What is the simplest way to detect this allele?
PCR using two primers, one on either side of the SNP, followed by sequencing the PCR products
Although bacteria can be used to produce proteins for therapeutic uses, what can be a disadvantage to using a prokaryotic system?
Proteins may not be posttranslationally processed correctly.
Which of the following best describes translation?
RNA -> protein
Which is part of a DNA sequencing technique that is useful for high-throughput sequencing, but is not part of Sanger DNA sequencing?
Removal of a chemical group that blocks the 3′ end of the new DNA strand
What is one difference between using restriction endonucleases and mechanical shearing of DNA?
Restriction endonucleases cut DNA at known specific sites while shearing occurs at random sites.
A bacterial mismatch repair system is able to correct replication errors that insert an incorrect nucleotide. How is this repair system able to determine which mismatched base is incorrect?
Some bases of the parental strand are methylated, while none of the new strand are.
A researcher is studying the rII locus of phage T4. Three rII− strains are obtained: A, B, and C. E. coli strain K(λ) is coinfected with two rII− strains simultaneously and the results are recorded. Infection with A and B phage = plaques form Infection with A and C phage = plaques form Infection with B and C phage = no plaques form What can be inferred from this complementation test?
Strains B and C have mutations in the same gene, and strain A has a mutation in a different gene.
Which statement supports the theory that all organisms are related?
The genetic code is almost universal.
How does DNA structure relate to its function?
The order of nucleotides in a DNA strand specifies the order of amino acids in a protein.
What would you anticipate would be true about the metabolism of a bacterial species isolated from water samples, one at the surface and another from a hot vent on the ocean floor?
The species from the water surface would be more likely to be able to conduct photosynthesis.
What is a possible disadvantage of using genetically modified crops?
The transgene may make its way into wild plants.
One strain of rII- phage has a deletion in the rII region, another has a point mutation in the rII region. When E. coli K(λ) cells are infected with either rII- phage (not both) no plaques form. When E. coli K(λ) cells are infected with both rII- phage simultaneously plaques do form. Why do plaques form when E. coli K(λ) cells are infected with both types of rII- phage simultaneously?
The two phage have mutations in different rII genes and their genomes complement each other.
Which statement is true about the structure of DNA?
The two strands of a DNA molecule are held together by base pairing.
What is one problem associated with using retroviruses as human gene therapy vectors?
Their random integration into the host chromosome may result in detrimental mutations.
inversion
a 180 degree rotation of a chromosomal segment
The presence of a selectable marker on a plasmid allows the researcher to determine if
a bacterial cell has taken up the plasmid.
loss-of-heterozygosity
a cell with one mutant tumor-suppressor allele acquires a second loss of function mutation in the wild type allele
cyclin-dependent protein kinases
a class of cell cycle enzymes that phosphorylate proteins
Which of these examples represents a gene family?
a genome includes many genes that encode myosin motor proteins.
Which is an example of a recombinant DNA molecule?
a genomic fragment of human DNA ligated into a bacterial plasmid vector
A scientist might create a conditional knockout of a mouse gene when
a homozygous loss-of-function mutation in the gene causes embryonic lethality.
growth factor
a hormone or cell bound signal that stimulates or inhibits cell division upon binding a membrane receptor
In the modification of eukaryotic mRNA, ______ cap and ______ tail are usually added to the transcript.
a methylated-guanine; a poly-adenine
Which are typically used for positional cloning of a disease gene in humans?
a multigenerational selective breeding program
null or amorphic mutation
a mutation inside or outside a coding region that results in the complete loss of a protein's function
neomorphic
a mutation inside or outside the coding region that produces a protein that either has a new function or has a normal function but is produced at an inappropriate time
hypermorphic
a mutation inside or outside the coding region that results in increased production or activity of a protein with the same function as the wild-type protein
dominant-negative or antimorphic mutation
a mutation that produces a protein that cannot perform the wild-type function and also prevents the normal protein from functioning
transcription factor
a protein that activates or represses transcription of specific genes to promote or inhibit cell division
signal transduction
a series of steps by which a signal is transmitted to and within a cell
The primer used in Sanger sequencing
has a nucleotide sequence complementary to the 3' end of the template, just outside the region to be sequenced.
A researcher has a laboratory strain of flies that have loss-of-function mutations in both gene X and white. These flies are used as hosts for P element transformation: Embryos of the double mutant strain are injected with two plasmids, one containing a wild-type copy of the white gene (w+) and a wild-type copy of gene X, side-by-side within P element inverted repeats, and the other plasmid containing only the P element transposase gene. Transgenic offspring of the injected flies will
have red eyes and a wild-type copy of gene X integrated into a random location in the genome.
Without __________ regions of the DNA during recombination, gene conversion could not occur.
heteroduplex
Two identical Jun polypeptides associate with each other via their leucine zippers to form an active transcription factor. What is the transcription factor called?
homodimer
Recombination involves the breakage and reunion of DNA molecules from
homologous nonsister chromatids.
Maternal effect mutations can be identified when
homozygous mutant females can develop normally, but their offspring exhibit a mutant phenotype.
Mutations that result in the production of much less of a protein or a protein that functions less efficiently than wild type are
hypomorphic mutations
If an organism is isolated that has no nuclear membrane and the DNA is condensed into a body in the cytoplasm, this organism would most likely be classified as a
prokaryote
cyclins
proteins that combine with kinases to direct kinase activity to particular substrates during the cell cycle
The pattern or sequence in which a molecule of mRNA is deciphered by a ribosome is the
reading frame
What information cannot be determined from the DNA sequence of a cDNA clone?
sequence of the promoter
FISH analysis is likely to detect which type of change in DNA?
silent point mutations and frameshift mutations
What are sticky ends?
single-stranded DNA sequences that are generated by staggered cuts
In gel electrophoresis, DNA fragments move at different rates because they have different
sizes
Which does a successful PCR require?
some sequence information about the region to be amplified
In Sanger sequencing, the role of the DNA polymerase is to
synthesize new DNA that is complementary to the template strand.
The wobble base of a tRNA is
the 5′ base of the anticodon.
What might be the outcome of repeated duplications of one or a few genes in a species' genome?
the presence of gene families
The mutations found in the CF gene that result in cystic fibrosis are recessive because
the protein produced by the normal allele is sufficient for normal cellular function.
Following conjugation of an Hfr cell with an F− cell,
the recipient remains F−.
A researcher performs FISH with a probe against a known chromosome 3 sequence on cells with a small deletion on the p arm of chromosome 3. If two fluorescent spots are observed in each cell, what is the most likely explanation?
the sequence targeted by the probe is not within the deleted region.
Transgenic animals made by pronuclear injection can be limited for studies of the links between genes and disease because
the transgene allele must be dominant to the normal, endogenous allele and some diseases are caused by recessive mutations.
A BLAST search can be used for which of these applications?
to compare a nucleotide or amino acid sequence to databases from a variety of species
The different tRNAs are produced by
transcription of different tRNA genes in the genome.
Telomeres consist of direct repeat sequences.
true
To sequence DNA by Sanger sequencing, the DNA to be sequenced must first be denatured to form a single-stranded template.
true
Using PCR, over 1 × 106 copies of a DNA target can be made from one double-stranded DNA template.
true
How would you best follow the timing of expression of a given protein during development in a live animal?
using a transgenic organism that expresses a GFP fusion protein
A bacteriophage is a
virus that infects a bacterium.
Deletions are most useful for gene mapping
when you have a mutant allele of a gene that is recessive to normal alleles and amorphic.
Which is a type of DNA-binding domain found in transcription factors?
zinc finger
