Module 5 EXAM PRACTICE Flashcards
High concentration of which which protein stimulates the development of anterior structures?
Bicoid
Conserved developmental genes can lead to _______ evolution.
parallel
The correct sequence in which Drosophila body axis genes act is:
egg-polarity genes—>gap genes —>pair-rule genes—->segment polarity genes—>homeotic genes.
Pair-rule genes loss-of-function mutation phenotype
Deletes every other segment
Gap genes loss-of-function mutation phenotype
Delete adjacent segments
Segment-polarity genes loss-of-function mutation phenotype
Affect polarity of segment; part of segment is replaced by mirror image of part of another segment.
Genes that regulate development are conserved. This means that they
have changed very little over the course of evolution.
When the mammalian Pax6 gene is overexpressed in flies,
flylike eyes develop.
The following are NOT characteristics of maternal effect mutations:
When mutant offspring arise they account for 50% of the offspring.
Mutant offspring arise from homozygous mutant fathers crossed to heterozygous mutant mothers.
Wild-type offspring arise from crosses of heterozygous mutant fathers regardless of the genotype of the mother.
Heterozygous mutant fathers crossed to homozygous normal mothers will not produce normal offspring.
The following are characteristics of maternal effect mutations:
Mutant offspring arise from homozygous mutant mothers irrespective of the genotypes of the father
Deletion of the _______ gene in Drosophila converts the 3rd thoracic segment into the second thoracic segment, resulting in a fly with 2 sets of fully formed wings.
Ubx
The expression of a zygotic gene product is based on the ____________________.
genotype of the zygote
TRUE or FALSE?
In Drosophila homeotic genes are present in 2 gene complexes.
True
A self-contained unit that is made up of other units is called a
module
Establishment of the dorsal-ventral axis of the Drosophila embryo:
Involves the nuclear localization of Dorsal protein in the ventral nuclei.
Many of the genes that control development encode _______ that act on proteins in a cascade of events.
transcription factors
Which of the following statements is true?
- The transcription factors and the extracellular signals that govern pattern formation can be thought of as the molecular “black box.”
- Developmental processes in both Drosophila and vertebrates are controlled by similar sets of genes.
- Many regulatory genes are required to bring about the diversity of organisms that we observe.
Developmental processes in both Drosophila and vertebrates are controlled by similar sets of genes.
TRUE or FALSE?
The human Hox genes are similar in sequence to the homeotic genes found in Drosophila, but are not lined up in the the same order.
FALSE
The ability of an organism to modify its development in response to environmental conditions is called
developmental plasticity.
Which of the following is NOT a way plants differ from animals regarding regulatory genes that affect their development?
a) Plants have tremendous developmental plasticity.
b) Plant cells do not have MADS box genes and homeobox genes.
c) Future reproductive cells are not set aside during early plant development.
d) None of the above
e) Plant cells do not move relative to one another.
Plant cells do not have MADS box genes and homeobox genes.
Which scientist performed experiments with eyeless and Pax6?
Rebecca Quiring
The transcription factors that govern pattern formation in multicellular organisms, and the genes that encode them, are components of what biologists call the molecular _______.
tool kit
Ways that plants differ from animals regarding regulatory genes that affect plant development:
Plants have tremendous developmental plasticity.
Future reproductive cells are not set aside during early plant development.
Plant cells do not move relative to one another.
What is true of homeotic transformations in Drosophila?
they can be passed on from generation to generation
The action of genes controlled by _______ determines where and when they will be expressed or suppressed.
genetic switches
Which of the following is NOT a developmental environmental signal?
a) Temperature
b) Light
c) The presence of predators
d) All of the above are developmental environmental signals.
All of the above ARE developmental environmental signals.
List some developmental environmental signals
Temperature
Light
The presence of predators
What are the role and relationship of egg-polarity genes, segmentation genes, pair-rule genes, gap genes, and homeotic genes in Drosophila development?
??
EXTENDED RESPONSE
Egg polarity genes establish the anterior-posterior axis of the embryo using a concentration gradient of maternal mRNAs and proteins.
This gradient activates the gap genes, which divide the embryo into broad bands of head/thorax/abdomen.
Gap gene products activate pair-rule genes, which divide embryo into segments.
Pair-rule genes activate segment polarity genes in each segment, dividing each into anterior and posterior regions and aligned linearly.
Homeotic genes will determine the identity of each segment by determining which adult structure will be formed by the segment.
Flies have _______ eyes, while mammals have _______ eyes.
Flies have compound eyes, while mammals have _______ eyes.
dorsal
nuclear localization
bicoid and nanos
??!
c, anterior–posterior axis
Bicoid (bcd) is a maternal effect gene required for anterior development in fruit flies. Suppose that a egg from a mutant mother is destined to develop into an embryo with two posterior ends. A scientist does an experiment with this embryo.
The scientist injects wild type bicoid mRNA at the location that in a wildtype would have formed the posterior end of a developing embryo. What will be the phenotype of the injected larva? Justify your answer.
Certified Correct:
(i) The injected DNA will have no effect since bicoid is a maternal effect gene. Thus, the insertion of DNA into the embryo will have no effect. The larva will still develop two posterior ends.
(ii) The injected mRNA will cause the larva to develop normally (1 posterior end and 1 anterior end). It will compensate for the lack of functional bicoid mRNA from the mother.
Morphogens control cell fate at ____________ concentrations.
??!!
3 or more
Which of the following statements is false?
a) All of the above are true.
b) Homologous genes encoding similar transcription factors are expressed in similar patterns along the anterior–posterior axes of both mammals and insects.
c) Ubx is a Hox gene.
d) The full-sized wing in Drosophila is normally produced on just the third thoracic segment.
e) Deletions of the Ubx gene convert the 3rd thoracic segment into the 2nd thoracic segment.
The full-sized wing in Drosophila is normally produced on just the 3rd thoracic segment.
The developmental pathway for sex determination in Drosophilia is best exemplified by which of the following statements:
One developmental state is the default, whereas its alternative requires the activation of a series of regulatory gene products.
One developmental state is the default, whereas its alternative requires the activation of a series of regulatory gene products.
Regulation occurs at more than one level from the gene to the active protein.
An on-off decision for a master switch is made early on in development.
All of the above are true.
What are some of the different signals that can initiate programmed cell death (apoptosis)?
??!!!
EXTENDED RESPONSE
Infection by Virus, DNA damage, damage to the mitochodria
Drosophila passes through ______ larval stages and a ____before developing into an adult fly.
??
3, pupa stage
There are ______ Hox gene cluster in mammals
4
Mutations in homeotic genes often cause
structures to appear in the wrong place
_______ is the ability to express different phenotypes under different environmental conditions.
Developmental plasticity
Master regulatory genes are ___________ and ____________ to determine cell fate.
??!!!
“necessary, sufficient”
ontogeny recapitulates phylogeny
j, Ernst Haeckel
