Bio. 241 Exam 4 Spring 2017

In an assessment of learning in Drosophila, flies may be trained to avoid certain olfactory cues. In one population, a mean of 8.5 trials was required. A subgroup of this parental population that was trained most quickly (mean = 6.0) was interbred and other progeny examined. These flies demonstrated a mean training value of 7.5. What is the narrow-sense heritability for olfactory learning in Drosophila?

0.4

What is seen from segment-polarity genes?

14 stripes

A homozygous plant with 20 cm diameter flowers is crossed with a homozygous plant of the same species that has 40 cm diameter flowers. The F1 plants all have flowers 30 cm in diameter. In the F2 generation of 512 plants, 2 plants have flowers 20 cm in diameter, 2 plants have flowers 40 cm in diameter and the remaining 508 plants have lowers of a range of sizes in between. Assuming that all alleles involved act additively, how many genes control flower size in this plant?

4

What is seen from pair-rule genes?

7 stripes

Which of the following patterns best describes the expression of even-skipped during Drosophila embryogenesis?

7 stripes

Joe is breeding cockroaches in his dorm room (Do not try this). He finds that the average wing length in his population of cockroaches is 4 cm. He chooses six cockroaches that have the largest wings; the average wing length among these selected cockroaches is 10 cm. Joe interbreeds these selected cockroaches. From earlier studies, he knows that the narrow-sense heritability for wing length in his population of cockroaches is 0.6. What should be the average wing length of the progeny of the selected cockroaches?

7.6

The localization of nanos mRNA to the posterior pole is controlled by:

A determinant in the 3'UTR

A soluble molecule capable of specifying more than one cell type by forming a concentration gradient is known as:

A morphogen

The C. elegans let-23 gene encodes:

A receptor tyrosine kinase

Which of the following statements most accurately describes the key event for the formation of terminal structures during Drosophila embryogenesis?

Activation of receptor tyrosine kinase pathway

What description best characterizes the key event in the formation of terminal structures during Drosophila embryogenesis?

Activation of the Torso receptor tyrosine kinase

The maternal-effect mutation torso (tor) is recessive. In the absence of the torso protein product, embryogenesis is not completed (missing both head and tail structures). Consider a cross between a female heterozygous for the torso (tor+/tor-) and a male homozygous for the mutation (tor-/tor-).

All are normal

In snail coiling, dextral (D, right-handed twist) is dominant, whereas sinistral (d, left-handed twist) is recessive. Based on this, predict the progeny phenotypic ratio from a cross between dextral Dd males and sinistral dd females.

All progeny will be sinistral

The coiling of snail shell is controlled by a maternal-effect locus, where D (dextral) is dominant and d (sinistral) is recessive. If a dextral male of DD genotype is mated with a dextral female of dd genotype, the progeny phenotype will be:

All sinistral

B cells are clonal, meaning that each B cell expresses only one successfully rearranged Ig. This is caused by:

Allelic exclusion

A tissue from the leg bud during chick development is transplanted into the wing bud. Later on, the transplanted tissue forms structures of wing origin. Based on this you can conclude that:

At the time of transplantation, the cell fate of cells in the transplanted tissue has not been determined

Regarding the Bax gene, what statement is true?

Bax forms oligomers to promote programmed cell death

In Drosophila, Sevenless (sev) and bride-of-sevenless (boss) are involved in forming the R7 photoreceptor cells in the Drosophila eye. The Boss proteins are expressed on the surface of R8 cells, whereas Sev is expressed in the R7 precursor cells. Which of the following genes act non-cell-autonomously during R7 determination?

Bride of sevenless

What is seen from gap genes?

Broad stripes

Which of the following genes is an example of proto-oncogene?

E2F

Suppose you have the capability to mutate the GAP (GTPase activating protein) genes in the erbB-expressing cells, will this enhance or suppress the ability of erbB to promote tumor progression?

Enhance

Which of the following genes is an example of tumor suppressor gene?

GAP

E2F mutation type:

Gain-of-function

Broad-sense heritability equation:

H^2=Vg/Vp

What statement best describes over-dominance?

Heterozygous individuals have fitness advantages over homozygous individuals

What term best describes the condition that a human cell has mitochondria of only one genotype?

Homoplasmy

Regarding Hox genes, which of the following statements is incorrect?

In Drosophila Hox mutants, the number of segments is affected

At the G1-S transition, the formation of cyclin/CDK complex will:

Increase the level of E2F proteins in the nucleus

In Drosophila, Sevenless (sev) and bride-of-sevenless (boss) are involved in forming the R7 photoreceptor cells in the Drosophila eye. The Boss proteins are expressed on the surface of R8 cells, whereas Sev is expressed in the R7 precursor cells. Which of the following best describes this Boss-Sev pathway in R7 photoreceptor cell development?

Juxtacrine signaling

What scenario is likely to allow S phase to proceed even in the presence of DNA damage?

L.o.f. mutations in both copies of the p53 gene

In C. elegans vulva formation, which of the following genes encodes a small GTPase?

Let-60

Which of the following gene products usually mediates lateral inhibition?

Lin-12

Rb mutation type:

Loss-of-function

Molecule that can specify multiple structures in a concentration-dependent marker

Morphogen

During Drosophila eye development, the R7 photoreceptor is specified by the activation of Sevenless (Sev) receptor tyrosine kinase. Sev is activated by Bride-of-sevenless (Boss) ligand, which is expressed on the surface of R8 photoreceptor cell. Once bound by Boss, Sev activates the Ras/MAP kinase cascade to regulate cell fate. As expected, animals mutant for Sev or Boss lack R7 photoreceptors. In wild type, multiple cells express Sev but only one becomes R7 because only one of these Sev-expressing cells contacts the Boss-expressing R8. However, some of these Sev-expressing cells have the potential to become R7 cells if the Sev cascade is activated. For example, expression of constitutively active Sev receptor tyrosine kinase or RasV12 (GTP-bound form) in these cells will generate multiple R7 cells. Base on these information, predict the phenotype of a fly that is sev- but expresses RasV12 in these R7 precursor cells.

Multiple R7 cells

In Drosophila, Sevenless (sev) and bride-of-sevenless (boss) are involved in forming the R7 photoreceptor cells in the Drosophila eye. The Boss proteins are expressed on the surface of R8 cells, whereas Sev is expressed in the R7 precursor cells. The function of GTPase-activating protein (GAP) is to accelerate the rate of GTP hydrolysis of small GTPases. Based on this, what is the phenotype of a l.o.f. mutation in Drosophila GAP?

Multiple R7 cells

What is the expected phenotype of a double mutant animal, in which the genotype of anchor cell and Pn.p cells is lin-3-, let-60^gof?

Multiple vulva structures

What is the phenotype when C. elegans is mutant for lin-3 (l.o.f.) and the Pn.p cells express a dominant active let-23 allele?

Multiple vulva structures

We have learned about the C. elegans pathways required for proper vulva development in lecture. Based on our discussion, please answer the following questions. What is the expected phenotype if you express a mutant let-60 with a mutation analogous to those of oncogenic Ras (let-60 is the worm ortholog of Ras)?

Multivulva

We have learned about the C. elegans pathways required for proper vulva development in lecture. Based on our discussion, please answer the following questions. What is the expected phenotype if you over-express lin-3?

Multivulva

Muscle fibers exhibit blotchy red patches resulting from the proliferation of aberrant mitochondria. Symptoms: ataxia, deafness, dementia, and epileptic seizures:

Myoclonic epilepsy and ragged red fiber disease (MERRF)

F2 generation of haploid petite cross and haploid normal cross results in all normal:

Neutral

During Drosophila eye development, the R7 photoreceptor is specified by the activation of Sevenless (Sev) receptor tyrosine kinase. Sev is activated by Bride-of-sevenless (Boss) ligand, which is expressed on the surface of R8 photoreceptor cell. Once bound by Boss, Sev activates the Ras/MAP kinase cascade to regulate cell fate. As expected, animals mutant for Sev or Boss lack R7 photoreceptors. In wild type, multiple cells express Sev but only one becomes R7 because only one of these Sev-expressing cells contacts the Boss-expressing R8. However, some of these Sev-expressing cells have the potential to become R7 cells if the Sev cascade is activated. For example, expression of constitutively active Sev receptor tyrosine kinase or RasV12 (GTP-bound form) in these cells will generate multiple R7 cells. Predict the phenotype of a fly that is sev- but expresses Boss ectopically (Boss is expressed everywhere)

No R7 cell

In Drosophila, Sevenless (sev) and bride-of-sevenless (boss) are involved in forming the R7 photoreceptor cells in the Drosophila eye. The Boss proteins are expressed on the surface of R8 cells, whereas Sev is expressed in the R7 precursor cells. If the R8 cell is genotypically sev+ and the R7 precursor cells are genotypically sev-, what will the phenotype be?

No R7 cell

With respect to vulva formation, what is the phenotype of line-3- formation

No vulva structure

In Drosophila, Sevenless (sev) and bride-of-sevenless (boss) are involved in forming the R7 photoreceptor cells in the Drosophila eye. The Boss proteins are expressed on the surface of R8 cells, whereas Sev is expressed in the R7 precursor cells. During development, R8 cells are evenly spaced. This spacing of R8 cells is achieved by lateral inhibition. Based on this info., which of the following molecules likely participates in the specification of R8?

Notch

In Drosophila, Sevenless (sev) and bride-of-sevenless (boss) are involved in forming the R7 photoreceptor cells in the Drosophila eye. The Boss proteins are expressed on the surface of R8 cells, whereas Sev is expressed in the R7 precursor cells. If the R8 cell is genotypically boss+ and the R7 precursor cells are genotypically boss- what will the phenotype be?

One R7 cell

What is the expected phenotype of a mosaic animal, in which the genotype of anchor cell is let-23- and the genotype of Pn.p cells is let-23+?

One vulva structure (wild type)

Which of the following statements accurately describes PUMA function?

PUMA binds to BcI2 and releases BAX

You have isolated a mutant affecting anterior-posterior patterning of the Drosophila embryo, in which every other segment of the developing mutant embryo was missing. Based on this observation, the mutation is likely be in a

Pair-rule gene

As discussed in class, which of the following descriptions best characterizes the event distinguishing germ cells from the somatic cells during C. elegans embryogenesis?

Partitioning cytoplasmic factors in asymmetric cell division

Gene rearrangement requires:

RAG1 and RAG2

Regarding RB and E2F functions, which of the following statements is correct?

RB binds to E2F and prevents E2F from entering the nucleus

F2 generation of haploid petite cross and haploid normal cross results in petites and normals:

Segregational

The oncogene erbB is a constitutively active form of a receptor tyrosine kinase that sends unregulated signals, from the plasma membrane, to stimulate cell proliferation. Suppose you have the capability to mutate all the copies of Ras genes in these erbB-expressing cells, will this enhance or suppress the ability of erbB to promote tumor progression?

Suppress

Speciation in the absence of a geographic barrier:

Sympatric

Regarding synonymous substitutions, what statement is correct?

Synonymous substitutions are typically found in coding sequences

Regarding T cell receptor, what statement is correct?

T cell receptor recognizes antigens presented by MHC molecules

Which of the following statements is true regarding the generation of antibody diversity?

The diversity is generated by gene rearrangement in both the immunoglobulin heavy chain and the light chain loci

In C. elegans let-60 is a target of microRNA let-7. Based on this, what is the effect of let-7- mutation on the phenotype of Pn.p cells expressing let-60^v12?

The let-7- mutation enhances the phenotype associated with let-60^v12 because the let-60^v12 protein level is higher in the absence of let-7.

Regarding cyclin and CDK functions, what statements are true?

The level of cyclin proteins oscillates with the cell cycle, the kinase activity of CDK becomes active when complex with cyclins, the level of different cyclins peak at different stages of the cell cycle, CDKs and cyclins are positive regulators of cell cycle control

Regarding Drosophila bicoid, which of the following statements is incorrect?

The localization determinant for bicoid mRNA is in 5' UTR

In comparing Drosophila and human genomes, which of the following statements is correct?

The number of identified protein motifs is similar

Regarding Drosophila homeotic genes, what statement is correct?

The organization of homeotic genes along the chromosome is co-linear with the structures specified

In Saccharomyces cerevisiae, a cross between a haploid suppressive petite mutant and a haploid wild type results in petite diploid progeny. This is because

The petite mutation contains deletion in mtDNA, which give nonfunctional mutant mitochondria proliferation advantage

The inheritance of hereditary retinoblastoma (Rb) is autosomal dominant. This is because

The probability of the remaining wild type Rb being mutated during heterozygous individuals' lifetime is high

Regarding the generation of immunoglobulins, what statements are correct?

The subunits of immunoglobulins are held together by disulfide bonds, the gene segments at the immunoglobulin loci undergo somatic recombination, the junctions of joined segments often contain mutations, high somatic mutation rates are detected at the immunoglobulin loci

You have isolated a Drosophila mutant defective in A-P patterning. Examination of the mutant cuticle shows that a part of pattern in every other segment is deleted. Based on this, which of the following statements is likely correct?

This mutation disrupts a pair-rule gene, and the expression of this gene will show 7 stripes

Regarding prions, what is incorrect

Transmission of prions is resistant to treatment of protease

To analyze the genes required for C. elegans vulva development, you have made an animal mosaic for lin-3. Please predict the phenotype of the mosaic animal if the anchor cell is lin-3[-] and the vulva precursor cells (e.g. P5.p, P6.p, and P7.p) are wild-type.

Vulvaless

We have learned about the C. elegans pathways required for proper vulva development in lecture. Based on our discussion, please answer the following questions. What is the expected phenotype of loss-of-function lin-3?

Vulvaless

We have learned about the C. elegans pathways required for proper vulva development in lecture. Based on our discussion, please answer the following questions. What will the phenotype be, if the anchor cell is ablated?

Vulvaless

What is the phenotype when C. elegans has the Pn.p cells are double mutant for a dominant active let-23 allele and a let-60 (l.o.f.) allele?

Vulvaless

non-cell autonomous:

X gene product is required in cell A for cell B to become a neuron

Many of oncogenic mutations are dominant. Which of the following general types of mutations have the potential to create dominant oncogenes?

a mutation in E2F that disrupts its ability to bind RB

Features of cancer cells:

abnormal growth, metastasis, genomic instability, immortal, ability to invade

Speciation in the presence of a geographical barrier:

allopatric speciation

Bicoid is required for:

anterior structures and to suppress posterior development

Rb regulates transcription of S phase genes by:

binding E2F

Regulation of cell cycle progress is mediated by:

cyclins and cyclin-dependent kinases (CDKs)

Oncogene examples:

cyclins, CDK, Ras to RasV12

Paracrine:

diffusable ligand, long-range

Synonymous substitutions

from one alternative codon to another, making no change in the amino acid

Narrow-sense heritability equation

h^2 = R/S

Closely related genes are referred to as:

homologs

How viruses contribute to cancer:

integrated near a proto-oncogene, proto-oncogene incorporates into viral genome

To pinpoint determinants for bicoid and nanos mRNA localization, you have generated several chimera constructs (fusions) using the lacZ gene. After transgenic wild type flies expressing these constructs are established, you perform RNA in situ hybridization on the embryos using lacZ as a probe. Which of the following constructs will yield lacZ-positive signal at the posterior pole?

lacZ 5'UTR - lacZ coding region - nanos 3'UTR

Parkinson's is caused by:

loss of dopaminergic neurons

Juxtacrine:

membrane-associated ligand and receptor, short-range, notch pathway, lateral inhibition

Positive regulator of cell growth, activated forms promote malignancy, mutated form is dominant:

oncogenes

Which of the following genes is known as "the guardian of the genome"?

p53

Stops cells from dividing when there is DNA damage:

p53 and Rb

Controls the G1/S cell cycle checkpoint and loss or mutation of it contributes to unregulated progression through the cell cycle

pRB

Mechanisms to make two different daughter cells from one:

partition of intrinsic determinants and cell-cell signaling with surroundings

Ways oncogenes can be activated:

point mutation (Ras^v12), gene amplification (multiply copies), gene rearrangement ( Philadelphia chrm. Ber-Abl), retroviral insection, retroviral incorporation

Regarding prions, what is true

prion proteins are coded by nuclear genes, prions are responsible for bovine spongiform encephalitis, mutant prion proteins can induce normal prions to adopt diseased conformation, mice with PrP genes deleted are resistant to mutant prion infection

The transmission of prion is sensitive to the treatment of

protease

Nonsynonymous substitutions

result in amino acid changes

F2 Generation of haploid petite cross and haploid normal cross results in all petite:

suppressive

Conservation of gene order along chromosomes from different species is referred to as:

synteny

Negative regulator of cell growth, inactivated forms promote malignancy, mutated form is recessive:

tumor suppressor gene

In a different mosaic animal, the anchor cells is wild-type, and the vulva precursor cells are lin-3[-]. What will be the phenotype of this mosaic animal?

wild type

cell autonomous:

y gene product is required in cell B for cell B to become a neuron