Deck 18: The Genetic Analysis of Development

Question 1

Mutations that result in a new phenotype for a gene through the production of too much protein are best described by the term

A)conditional.
B)permissive.
C)hypomorphic.
D)gain of function.

Answer 1

gain of function.

Question 2

RNAi

A)depletes protein products of genes.
B)uses dsRNA to bind to transcription factors.
C)is used to create a functional knock-in mutants.
D)is not useful for the study of development.

Answer 2

depletes protein products of genes.

Question 3

Gain-of-function alleles are usually

A)null.
B)conditional.
C)recessive.
D)dominant.

Answer 3

dominant.

Question 4

Evolution has had what effect on development in various organisms?

A)varying
B)conservation of many genes and genetic pathways
C)removal of all mutations.
D)none

Question 5

Which of the following is not a type of loss-of-function mutation?

A)conditional
B)hypomorphic
C)null
D)dominant-negative
E)ectopic

Question 6

A partial loss-of-function mutation is

A)null.
B)hypomorphic.
C)conditional.
D)dominant-negative.

Question 7

The Aniridia gene in humans is involved in eye formation.Although eye development is very different in flies, this gene is highly conserved.What is its homolog in Drosophila?

A)eyeless (ey)
B)Pax-6
C)noeye
D)ommatidia

Question 8

The expression of a gene at an abnormal place or time is called

A)epistasis.
B)ectopic.
C)epigenetic.
D)expressivity.

Question 9

Which of the following is not one of the three characteristics of value to geneticists for model organisms?

A)ease of cultivation
B)rapid reproduction
C)small size
D)small genome

Question 10

What technique would be used to best study a phenocopy?

A)RNAi
B)transgene
C)isolation of mutations
D)QTL mapping analysis

Question 11

What type of mutation is particularly useful to researchers who wish to study a gene's effect on development when a natural loss-of function mutation has not yet been isolated?

A)haploinsufficient
B)hypomorphic
C)conditional
D)dominant-negative

Question 12

What is the most significant advantage of using RNAi to study development?

A)Geneticists have only been able to identify a subset of the genes involved in development.
B)Genetic studies on a single gene can be completed without the creation or isolation of new mutant organisms.
C)RNA is easy to isolate.
D)RNAi causes phenotypes not typical of in vivo development.

Question 13

Which of the following model organisms would be easiest to study recessive mutations using complementation analysis?

A)S.cerevisiae
B)M.musculus
C)elegans

Question 14

Gain-of-function mutations might involve which of the following?

A)deletion of a promoter region
B)constitutive activation of an enzyme
C)a synonymous mutation
D)None of the choices is correct.

Question 15

A loss-of-function mutation that depends on special circumstances is called

A)null.
B)hypomorphic.
C)conditional.
D)dominant-negative.

Question 16

An unusual loss-of-function mutation that is not recessive is

A)null.
B)hypomorphic.
C)conditional.
D)dominant-negative.

Question 17

Which of the following is not eithically prohibited for the use of humans in genetics studies?

A)phenotypic analysis
B)experimental manipulation of affected individuals
C)forced matings
D)deliberate production of mutants

Question 18

Results from RNAi studies are most likely to vary due to

A)variation in the amount of RNAi expressing plasmids transfected into cells.
B)its nonheritable characteristic.
C)different levels of starting mRNA.
D)issues related to fertilization.

Question 19

Mutations that disrupt the earliest stages of human development almost always cause

A)no effect.
B)polydactyly.
C)spontaneous abortion.
D)disruption of the segmented body plan.

Question 20

Which model organism would be best suited for studying cellular lineage, ?

A)E.coli
B)S.cerevisiae
C)C.elegans
D)M.musculus

Question 21

How would you best follow the developmental timing of a given protein in vivo?

A)in situ hybridization
B)Western blotting
C)using a GFP-fusion protein transgenic organism
D)microarray analysis

Question 22

The presence of a homeodomain in a protein suggests what about its function?

A)It has kinase activity.
B)It is a membrane bound receptor.
C)It is a secreted protein.
D)It is a transcription factor.

Question 23

What is a major advantage of using a sensitizer screen as opposed to a primary screen?

A)Sensitizer screens can be used to identify redundant genes.
B)Sensitizer screens are eassier to perform.
C)Sensitizer screens are a random selection of flies based on their morphology and therefore should identify all genes invovled in development.
D)Sensitizer screen are performed with chemically mutagenized flies so any and all genes that affect development should be identified more rapidly than screening for spontaneous mutants.

Question 24

In primary mutant screens

A)mutant flies are identifed by morphology and then the genes that are mutated isolated and studied.
B)mutant flies are created by RNAi using random RNA sequences and then the genes affected identified.
C)mutant flies are created by gain-of-function expression of random genes.
D)two mutant flies are mated to determine if their is an affect on morphology.

Question 25

Cells that provide large amounts of mRNA and proteins for deposition into the egg are called

A)doctor cells.
B)nurse cells.
C)helper cells.
D)bicoid cells.

Question 26

What does a homeodomain do?

A)acts as a receptor
B)has kinase activity
C)It binds to specific DNA sequences
D)None of the choices is correct.

Question 27

How are temperature sensitive mutants used to determine when genes act during development?

A)Embryos can be shifted to the non-permissive temperature to inactivate the mutant gene and the effect of inactivation on subsequent stages observed.
B)Embryos can be shifted to the permissive temperature to inactivate the mutant gene and the effect of inactivation on subsequent stages observed.
C)Adults can be shifted to the non-permissive temperature to inactivate the mutant gene and the effect of inactivation on fertilization can be observed.
D)Embryos can be shifted to the permissive temperature to activate the mutant gene and the effect of activation on subsequent stages observed.

Question 28

How do genetic mosaics help determine the focus of action of a gene?

A)Mosaics ae composed of cells with different genotypes so some genes may be active in some cells and not others.
B)Mosaics are created by mating flies are homozygous recessive for two different genes and the effects of the double miutations on the morphololgy of the progeny are studied.
C)Mosaics are created by mating two flies that carry homozygous gain-of-function muttions in different genes and the effects of the mutations on the morphology studied.
D)Mosaics are created by the Cre-loc system which allows for the deletion of specific genes at controlled stages of development.

Question 29

Which of the choices gives the correct sequence of early embryonic development in Drosophila?

A)zygote, syncytial blastoderm, multinucleate syncytium, cellular blastoderm
B)zygote, cellular blastoderm, syncytial blastoderm, multinucleate syncytium.
C)zygote, multinucleate syncytium, syncytial blastoderm, cellular blastoderm.
D)These stages do not occur in Drosophila.

Question 30

Ligands that circulate throughout the body and signal developmental differentiation are called

A)juxtacrine factors.
B)paracrine factors.
C)endocrine factors.
D)autocrine factors.

Question 31

A molecule whose concentration determines the developmental fate of a cell is called

A)monomorphic.
B)a juxtacrine protein.
C)a signaling molecule.
D)a morphogen.

Question 32

Gene order can be inferred from gene expression patterns since

A)proteins that act first in a pathway are ususally expressed before proteins that act later in a pathway.
B)mRNA for proteins in a pathway are produced at the same time but then are translated only when the proteins are needed.
C)proteins in a pathway are produced at the same time but the proteins that are not needed are degraded.
D)mRNAs for proteins in a pathway are produced at the same time and thost that are not needed are destabilized by miRNAs.

Question 33

What is the most common cause of rare spontaneous ectopic gene expression?

A)insertion mutation
B)deletion mutation
C)a mutation that moves the gene next to a new regulatory element
D)None of the choices is correct.

Question 34

Screening for maternal-effect mutations would involve looking for which of the following?

A)unusual phenotypes in female progeny
B)embryos that are all obviously developmentally arrested
C)asymmetric mutations
D)eggs that can not be fertilized

Question 35

Signaling factors that complete cell-to-cell communication in the form of direct contact are called

A)juxtacrine factors.
B)paracrine factors.
C)endocrine factors.
D)autocrine factors.

Question 36

An example of ectopic gene expression is

A)achondroplastic dwarfism.
B)lack of eye development.
C)abnormal vulvar shape.
D)legs instead of antennae.

Question 37

What technique would you use to best determine when and in what cells of a given tissue a specific gene is expressed?

A)Northern analysis
B)in situ hybridization
C)RT-PCR
D)Southern analysis

Question 38

Which of the following is a zygotic gap gene in Drosophila?

A)knirps (kni)
B)even-skipped (eve)
C)caudal (cad)
D)hedgehog (hh)
E)None of the choices is zygotic genes.

Question 39

A ligand secreted from a cell to a nearby cell that signals developmental differentiation is called

A)juxtacrine factor.
B)paracrine factor.
C)endocrine factor.
D)autocrine factor.

Question 40

In Drosophila, two maternal transcripts that are distributed evenly throughout the oocyte prior to fertilization are:

A)caudal and knirps
B)bicoid and nanos
C)caudal and hunchback
D)None of the choices is correct.

Question 41

How can epistatic interactions be used to order genes in a pathway?

A)Organisms that are homozygous recessive for two different genes will have the phenotype of an organism that is homozygous recessive for the gene that is first in the pathway.
B)Organisms that are homozygous recessive for two different genes will have the phenotype of an organism that is homozygous recessive for the gene that is last in the pathway.
C)Organisms that are homozygous dominant for two different genes will have the phenotype of an organism that is homozygous dominant for the gene that is first in the pathway.
D)Organisms that are heterozygous for two different genes will have the phenotype of an organism that is homozygous recessive for the gene that is first in the pathway.

Question 42

What is the order in development for the different types of genes?

A)Maternal effect, gap rule, pair rule, segment polarity
B)Maternal effect, gap rule, segment polarity, pair rule
C)Maternal effect, pair rule, segment polarity, gap rule
D)Maternal effect, segment polarity, gap rule, pair rule

Question 43

Expression of homeotic genes

A)assign a unique identity to each segment.
B)define anterior and psoterior ends of the fly.
C)control the espression of the segment polarity genes.
D)subdivide the embryo into a precise number of segments.