Deck 23: Developmental Genetics

Question 1

Which general genetic process is believed to account for the variety of cellular structures and functions in eukaryotic cells?

A)negative control exclusively
B)RNA processing
C)maternal environmental activities
D)intron processing
E)variable gene activity

Answer 1

E

Question 2

Which functions earlier in development: maternal- effect genes or zygotic genes?

Answer 2

maternal- effect genes

Question 3

Design an experiment that would allow you to determine if a particular nucleus in a Drosophila embryo is capable of directing development of an entire new fly.

Answer 3

Experiments in support of such genomic equivalence include the following: the observation that chromosome number and structure do not consistently change in different cells of an organism,nuclear transplantation in amphibians,and the presence of genes but no gene products in some tissues hemoglobin,for example).For the Drosophila experiment,one could do nuclear transplantation similar to the classic experiments in amphibians and recent experiments in mammals or transplant a cell from embryos of one genotype to the posterior end of the early embryos of another genotype.The transplanted cells would be reprogrammed into germ cells by the posterior P granules.The transplant can be detected in the next generation by the recognizable different phenotypes due to different genotypes of the donor and recipient.

Question 4

Provide a brief description of the variable gene activity hypothesis as it relates to development.What information is often provided in support of this hypothesis?

Question 5

Describe the difference between a totipotent cell and a pluripotent cell.

Question 6

In what order do the segmentation genes function in Drosophilia?

A)transdeterminal,gap,pair- rule
B)pair- rule,transdeterminal,gap
C)gap,pair- rule,segment- polarity
D)gap,segment- polarity,pair- rule
E)segmentational,helical,spherical

Question 7

In Drosophila,which type of genes are controlled by maternal gene products laid down in gradients in the egg?

A)gap genes
B)segment polarity genes
C)pair- rule genes
D)all genes are controlled by maternal gene products

Question 8

Maternal effects are cases of extrachromosomal inheritance in which the genotype of the mother influences the phenotype of her immediate offspring in a non- Mendelian manner.Provide a rationale for the molecular basis of a maternal effect.

Question 9

Three investigators-Nüsslein- Volhard,Wieschaus,and Lewis-won the Nobel Prize for physiology and medicine in 1995 for work they did in 1970 with Drosophila.Briefly describe their findings.

Question 10

Which of the following is a fundamental characteristic of the Notch pathway?

A)It provides symmetry to plant flowers.
B)It allows mRNAs to accumulate in the posterior portion of the Drosophila embryo.
C)It works through nuclear signals involving the lac operon.
D)It works through direct cell- to- cell contact.
E)It directs mRNAs to antisense systems in the posterior portion of all organisms.

Question 11

In most species the expression of Hox genes is colinear with the anterior to posterior organization of the organism.Describe what this means.

Question 12

Provide an explanation of the differences between differentiation and determination.Provide examples of each process and indicate how each is involved in development.

Question 13

Arabidopsis thaliana has homologous gene clusters to the Hox genes found in Drosophila.What are these master regulatory clusters called?

A)MRCs
B)CURLY LEAF genes
C)Hox genes
D)MADS- box proteins

Question 14

It is often said that development is a two- step process.What two steps are likely to be referred to here?

Question 15

Immediately after fertilization of a Drosophila egg,the zygote nucleus undergoes a series of divisions.Subsequent nuclear migration generates an_______.

A)homeodomain
B)cleavage nucleus
C)zygote
D)syncytium
E)maternal effect

Question 16

How does determination relate temporally to differentiation?

Question 17

Experiments involving nuclear transplantation in amphibians indicate that nuclei derived from blastula are more likely to support development of complete and normal adults compared with those derived from later stages of development.What do these experiments tell us about the process of development?

Question 18

Which term refers to the regulatory events that establish a specific pattern of gene activity and developmental fate for a given cell?

A)differentiation
B)attenuation
C)gradient regulated
D)lysogen
E)determination

Question 19

What kinds of general observations cause one to conclude that development is the result of variable gene activity?

Question 20

Mutations that eliminate a contiguous region in the Drosophila embryo's segmentation pattern are called_______ .

A)gap genes
B)segment genes
C)linkage genes
D)homeodomains
E)compartment genes

Question 21

Which of the following is not a set of master regulatory genes that control homeobox genes during development?

A)Hox
B)CURLY LEAF
C)Polycomb

Question 22

A homeobox gene is one that produces a_______ .

A)transcription factor that strips methylation from the entire genome
B)repetitive nucleotide sequence such as VNTR
C)60 amino acid DNA binding domain
D)maternal transcription factors

Question 23

Development of the anchor cell in the vulva in the nematode C.elegans is the result of _______.

A)specific upregulation of the LIN- 12 protein
B)stochastically increased production of Delta protein
C)specific upregulation of the Delta protein
D)stochastically increased production of the LIN- 12 protein

Question 24

Give a brief definition of a homeobox.

Question 25

It is presently believed that the asymmetric distribution of substances in the egg,positioned by the mother,is responsible for establishing the determined state.Which general term describes such molecular positioning?

Question 26

Mutations in the selector genes sometimes form structures in the wrong segment,transforming the antenna of a fly into a leg,for example.What are such mutations called?

A)homeotic mutations
B)lethal mutations
C)homologous mutations
D)silent mutations

Question 27

A mutation seen in Drosophila is found to cause antennae to grow on the abdomen of the flies.What type of mutation is this likely to represent?

A)evolutionary mutation
B)lethal mutation
C)silent mutation
D)homeotic mutation

Question 28

From a human developmental standpoint,what is the significance of Hox genes?

Question 29

The bicoid gene of Drosophila generates embryos with two posterior regions.What is the likely aspect of embryonic development that the bicoid gene probably controls?

Question 30

What is the significance of the homeodomain?

Question 31

The process whereby a cell's eventual developmental fate is set is called _______.

A)notching
B)embryogenisis
C)differentiation
D)determination

Question 32

Which class of genes controls the developmental identity of segments along the anterior-posterior axis?

Question 33

The process whereby a cell's determined state is expressed is called _______.

A)embryogenisis
B)notching
C)differentiation
D)determination

Question 34

What significant conclusion has the classic work on the eyeless and Pax6 genes provided in terms of developmental mechanisms?

Question 35

During development,many genes act in such a way as to decrease the number of alternative developmental pathways that a cell can follow.Usually there are two alternative developmental paths for a cell to follow.What is the term given to genes that act in this fashion?

Question 36

After fertilization of an egg the totipotent cell divides and the cells begin to specialize.These 30-40 cells are called_______ and are pluripotent.

A)somatic cells
B)germ line cells
C)T cells
D)embryonic stem cells

Question 37

C.elegans is used as a model organism in the study of the Notch signaling pathway.What is the method communication between cells in the Notch signaling pathway?

A)direct cell- to- cell contact through transmembrane proteins
B)cells do not communicate using the Notch signaling pathway
C)release of extracellular signals to be detected by neighboring cells
D)electrical propagation of signals across small gaps

Question 38

Over the course of evolution,humans have obtained four Hox gene clusters due to duplication.The presence of multiple Hox gene clusters suggests what?

A)All four clusters are active and represent the added complexity of vertebrate development.
B)Three of the four clusters are silent and have no effect on development.
C)Only two of the clusters are active and represent the added complexity of vertebrate development.
D)Only one of the clusters is silent since it would result in Drosophila development not vertebrate.

Question 39

Flowers that develop in Arabidopsis originate from concentric rings of cells.What class of genes is responsible for the development of sepals?

A)A genes
B)A and B genes
C)B and C genes
D)C genes

Question 40

A gene that specifies the fate of a particular anatomical segment in Drosophila is called an_______.

A)MADS genes
B)selector gene
C)silent gene
D)determinant genes

Question 41

Caenorhabditis elegans is extremely useful as an experimental model system due to all of the following EXCEPT_______ .

A)its genetics are well known
B)adults contain a small,fixed number of cells
C)it is highly variable in size and shape making it good for evo- devo studies
D)its genome has been sequenced