Genetics Final Exam (Compilations of Exams)
Assume that you counted 47 plaques on a bacterial lawn where 0.1 ml of a 10-6 dilution of phage was added to bacterial culture. What is the initial concentration of the undiluted phage?
(47 X 10e6)/0.1 = 4.7 X 10e8 pfu/ml
What is the quantitative value of "w" in homozygous recessive lethal individuals?
0
Neurofibromatosis (NF) is a rare autosomal dominant disorder characterized by bone abnormalities, skin hyperpigmentation, and small tumors on nervous tissue. Assume that a heterozygous woman with NF marries a man with no symptoms and no family history of NF disease. What is the probability that... only one of their first three children will have NF?
1/8 + 1/8 + 1/8 = 3/8 One alternative: Child 1 Affected X Child 2 Unaffected X Child 3 Unaffected = 1/2 X 1/2 X 1/2 = 1/8 Second alternative: Child 1 Unaffected X Child 2 Affected X Child 3 Unaffected= 1/2 X 1/2 X 1/2=1/8 Third alternative: Child 1 Unaffected X Child 2 Unaffected X Child 3 Affected=1/2 X 1/2 X 1/2=1/8 Sum Rule to Find Total Probability: 1/8 + 1/8 + 1/8= 3/8
The following two genotypes are crossed: CcSpaspaEe X CcSpaspaEe What will the probability be of having progeny with the C-Spa-ee phenotype?
9/64 (how to figure it out: make three different Punnett squares solving each and then multiply the fractions).
Investigators analyze a representative sample of the population consisting of 10,000 individuals. Their data follows a theoretical normal distribution. What is the probability that a given individual will fall within 3 standard deviations of the mean?
99%
Answer each of the following: A.) Name three different kinds of extranuclear inheritance. B.) Describe each of the three different kinds of extranuclear inheritance you listed in part A.
A) 1) Organelle 2) maternal 3) infectious B.) Organelle: where each part being inherited is an organelle such as the plant experiment we did in lab. Maternal: The mother's genomes effect her offsprings. No matter what the father passes down it will not trump the mother. Won't give you an even ratio. Infectious: These are changes that are due to an infection or a parasitic effector.
Which of the following statements is(are) true?
A. In plants gametophytes are haploid. B. In plants sporophyte and gametophyte stages alternate. C. In plants sporophytes are diploid. (how to remember: everything you learned in plant biology)
Which of the following statements is(are) true?
A. Multiple alleles for a given gene in a population are thought to arise from mutations. C. With the exception of the Bombay allele phenomenon, the human ABO red blood cell surface antigens in a population are controlled by three different alleles at a single locus.
Which of the following statements is(are) true?
A. The one gene-one enzyme hypothesis was initially modified due to findings showing that not all proteins are enzymes. C. Most recent in time, the one gene-one enzyme hypothesis has been modified to account for functional RNA products of some genes. (how to remember: changed from one gene : one enzyme to one gene : one polypeptide chain/functional RNA product)
Genetic diversity arises from which of the following?
A. crossing over of non-sister chromatids (how to remember: diversity comes from things unrelated.)
Which of the following statements is(are) true?
A. miRNAs are micro RNAs. C. miRNAs are short, non-coding RNAs that act as one kind of epigenetic mechanism.
Answer each of the following: A.) What affect would a normal tumor suppressor gene product have on apoptosis (programmed cell death)? B.) How many of the alleles for a tumor suppressor gene need to be mutated or misexpressed (assumes loss of function with the mutation or with the misexpression) to contribute to cancer development? C.) Provide an example of a tumor suppressor gene.
A.) A normal tumor suppressor would be sure to allow for apoptosis. This apoptosis would only be allowed in certain proportions such as if the cell had received too much damage thus causing the suppressor to allow cell death. B.) In the mutated/misexpressed tumor suppressor, both pairs of alleles would need to be affected in order for the tumor suppressor to stop suppressing thus allowing for a growth of tumors. C.) An example of a tumor suppressor gene HNPCC would be one that transcribes for colon cancer when mutated.
Answer each of the following: A.) In general, what is the cellular function of a proto-oncogene product? B.) How many of the alleles for a given proto-oncogene need to be mutated or misexpressed (assuming gain of function from the mutation or misexpression) to contribute to cancer development? C.) Provide an example of a proto-oncogene.
A.) The cellular function of a proto-oncogene the process of cell growth. Proto-oncogenes are responsible to the reproducing and overall growth of certain cells. B.) For a proto-oncogene to be mutated/misexpressed, only one of the pairs would need to be effected. These would then be classified as an oncogene which would then allow for reproduction and growth of tumor/cancer cells. C.) An example of a proto-oncogene would be the RAS 1. Depending on how RAS 1 is affected, the gene could code for positive or negative encoding.
Answer each of the following: A.) Define the acronym CML. B.) What is the chromosomal abnormality cause of CML? C.) What two genes are involved?
A.) chronic myelogenous leukemia B.) There is a translocating of the genes and not equal distribution. C.) C-ABL and BCR
Waxy (w), colorless (c), and shrunken (s) are three recessive traits in corn whose genes are linked on the same chromosome. A corn plant heterozygous for all three traits is used in a testcross and the progeny are given below: a.) Determine the order of these genes on the chromosome. b.) Calculate the map distances between the genes and show the resulting map.
A: Order = wsc B: Map distance = w-s: 33.5mU s-c: 15.5mU Total map distance = 49mU
Consider the following carefully controlled and performed Mirabilis jalapa (four o'clock plant) cross: Pollen from a white branch X ovule from a green branch What are the most likely progeny in terms of branch/leaf color?
All green
Epigenetic traits...
All of the above: 1.) can be passed through mitosis and meiosis. 2.) are stable. 3.) don't involve changes to nucleotide sequences of genes. 4.) include traits that result from the action of non-coding RNAs.
Which of the following epigenetic modifications appear to occur in many cancer cells?
All of the above: A. global hypomethylation B. selective hypomethylation of proto-oncogenes/oncogenes C. hypermethylation of tumor suppressor genes
Imprinting...
All of the above: A.) is reprogrammed during gamete formation. B.) often involves genes that direct aspects of growth during prenatal development. C.) is considered a form of monoallelic gene expression.
Histone acetylation...
All of the above: A.) makes the associated DNA more accessible to transcription factors. B.) opens up chromatin structure. C.) is catalyzed by a transferase that adds acetyl groups to histone proteins.
Methylation of DNA as an epigenetic mechanism...
All of the above: A.) is catalyzed by DNA methyltransferases. B.) involves the addition of methyl groups to cytosines in CpG islands. C.) transcriptionally silences the genes that are methylated.
Describe one of the inherited enzyme deficiencies discussed in chapter 14 (phenylketonuria, alkaptonuria, albinism, Lesch-Nyhan syndrome, Tay-Sachs disease, or sickle-cell anemia). Include each of the following facts in your description: 1.) the defective gene, 2.) the function of the normal protein, 3.) how the defect changes normal function, 4.) the mode of inheritance for the disease trait, and 5.) the clinical manifestations of the trait.
An example of an inherited enzyme deficiency is albinism. The gene that is effected is the tyrosine. In the normal protein, it would allow for tyrosinase to be activated and would go to the DOPA allowing it to create melanin from the melanocytes. However in this defect the albinism inhibits the DOPA by not producing the tyrosinase thus causing no creation of melanin in those cells. This is a autosomal recessive trait and will cause a lack of pigment in the eyes, hair, and skin.
The condition that exists when an organism gains or loses one or more chromosomes but not a complete haploid set is known as _________.
Aneuploidy
Which of the following characteristics is(are) true about an acute transforming retrovirus?
B. It carries a cell-derived oncogene.
Which of the following statements are true of cytokinesis in plant cells?
B. The cell plate consists of the plasma membrane and cell wall that will eventually separate the two daughter cells. D. Vesicles from the Golgi apparatus move along microtubules, coalesce at the plane of cell division, and form a cell plate.
lncRNAs...
B. affect chromatin modification and hence gene expression. C. can act as decoys, guides, adapters, or enhancers.
Which of the following represents a female proband?
Black circle with arrow pointing at it
Which of the following epigenetic alterations would most likely lead to a cancer?
C. hypermethylation of a tumor suppressor gene D. hypomethylation of a proto-oncogene
Which of the following is the evidence that best supports the multistep, multi-mutation nature of cancer?
C. incidence of most cancers increases with age D. delay between carcinogen exposure and development of cancer
Match the following:
Chloroplast genome = Encodes products for photosynthesis Both mitochondrial and chloroplast genomes = Circular Chloroplast genome = Larger Mitochondrial genome = Thought to resemble the chromosome of an aerobic bacterium
Match the following:
Cigarette smoke = Contains at least 60 different mutagenic chemicals Ionizing radiation = X-rays and gamma rays UV = Common cause of skin cancer Aflatoxin = Carcinogenic mold on bread and corn Nitrosamine = Meat preservative known to cause cancer
Match the phenomenon to its descriptor or example:
Codominance = Both alleles of the heterozygote are expressed Complete dominance = ANL relationship to anl Incomplete dominance = Snap dragon flower color is an example Incomplete dominance = Intermediate phenotype between parental phenotypes occurs in the heterozygote
Match the following key terms to the single best definition:
Determination = an irreversible commitment to a specific cell fate Differentiation = process by which a cell achieves its final adult form and function Specification = development of a spatially distinct cellular identity
Match the following:
Discontinuous = Dimples Continuous = Tomato fruit mass Meristic = Seed number
Analysis of the covariance between infant ear size and IQ yields a correlation coefficient of -0.7. Which of the following is the correct interpretation?
Ear size and IQ are inversely correlated.
Which of the following statements is(are) true? Select all that are true.
Essential genes are required for survival. One copy of a dominant lethal allele results in death.
Fragile-X syndrome is a dominant mental retardation trait caused by a terminal deletion of chromosome 5.
False
In Drosophila an X:A ratio of 0.50 indicates a female individual.
False
Describe two different molecular causes of trisomy-21.
Familial is due to a Robertsonian translocation and the other cause is nondisjunction
An individual organism's genetic contribution to the future generation is a term designated as "w." What is the name for this term?
Fitness
During a normal cell cycle, which phase occurs immediately prior to S phase?
G1 (how to remember: Go, stop)
Random change in allelic frequency in a population due to chance is called...
Genetic drift
Which of the following is the study of the structure, function, and evolution of genes and genomes?
Genomics
The following variances were determined for measurements of fruit mass, sugar content, and seed production in a species of baking pumpkin. Which of these characteristics would respond most rapidly to selection and why? Provide a mathematical rationale for your answer and show all work in your explanation.
Highest narrow-sense heritability will respond best to selection as highest narrow-sense heritability has the greatest phenotypic variance due to additive genetic effects. h2= VA/VP. Calculate that for each trait. Sugar content has highest value.
Is individual IV-2 an obligate carrier? Why or why not?
III. 1 and 2 must be heterozygotes and consequently there is a 1/4 chance that IV-2 will be homozygous dominant and hence not an obligate carrier.
The Agouti viable yellow allele...
In pregnant mice fed methylation precursors (like folic acid) demonstrates that diet can epigenetically alter gene expression.
In the pedigree above, name one kind of inheritance that is possible. I. I.1: Black Circle; I.2: White Square II. (1,2,&3 Progeny of I.1 and I.2) II.1: White Square; II.2: White Circle; II.3: White Square; II.4: White Circle III. III.1: White Square; (2&3 Progeny of II.3 and II.4) III.2: White Circle; III.3: White Circle IV. (Progeny of III.1 and III.2): IV.1: Black Square; IV.2: White Square; IV.3: Black Circle; IV.4: White Square
Infected I.1 Female then skips two generations and infected is IV.1 Male and IV.3 Female, A kind of inheritance that is possible in this graphic is autosomal recessive. As the mother has the issue, and the male doesn't and the lineage is able to go about two generations without another case, you can rule out a sex linked inheritance. As the III 1 and 2 end up with half of their kids having this problem of which they are not the same gender, this can be assumed that it is a autosomal recessive trait and that III 1 and 2 are heterozygous for this trait.
Stabilizing selection...
Involves selection for intermediate types.
What specific protein binds to lacO+ to prevent lac operon transcription?
Lac repressor protein
Place the following Drosophila genes in the order in which their products act during development (from earliest to latest).
Map (no) GPS Home 1. maternal effect genes 2. gap genes 3. pair rule genes 4. segment polarity genes 5. homeotic genes
Which one of the following statements is true?
Mitochondrial dysfunction is implicated in neurodegenerative diseases as well as type II diabetes, autism, and others.
Which statement is true?
Model organisms typically have short life cycles.
Briefly explain why monosomy of autosomes in humans essentially always demonstrates embryonic lethality.
Monosomy results in unmasking of recessive lethal alleles (haploinsufficiency)
Neurofibromatosis (NF) is a rare autosomal dominant disorder characterized by bone abnormalities, skin hyperpigmentation, and small tumors on nervous tissue. Assume that a heterozygous woman with NF marries a man with no symptoms and no family history of NF disease. What is the probability that... they will have a girl with NF?
Must also consider probability that simultaneously the NF child will be a girl: 1/2 X 1/2 = 1/4
From the Beadle and Tatum experimental design discussed in lecture, which gene codes for the enzyme that catalyzes the last step of the pathway? E1: + ; E2: - ; E3: + ; E4: - F1: + ; F2: + ; F3: + ; F4: - G1: - ; G2: - ; G3: + ; G4: - H1: + ; H2: + ; H3: + ; H4: +
Pathway G (how to remember: pathway that has the least amount of +)
Given the accompanying table, answer the question that follows. A1: +; A2:-; A3:+; A4: - B1:+; B2:+; B3:+; B4:- C1: +; C2: +; C3: +; C4:+ D1: -; D2: -; D3:+; D4: - Where numbers 1 through 4 indicate four supplements (intermediates) that must be added to sustain growth of the organism. What is the order of the intermediates generated in the metabolic pathway starting from precursor X?
Precursor X -> 4 -> 2 -> 1 -> 3 (how to remember: least amount of + to most)
Neurofibromatosis (NF) is a rare autosomal dominant disorder characterized by bone abnormalities, skin hyperpigmentation, and small tumors on nervous tissue. Assume that a heterozygous woman with NF marries a man with no symptoms and no family history of NF disease. What is the probability that... the first two children will have NF?
Probability that first child will have NF (1/2) X probability that second child will have NF (1/2)= 1/4
Which of the following is the phenotype of the F1 plants we are using for the Mendelian inheritance experiment?
Purple stem
Match the following:
Results from environmental factors that are common to a family. = VEcf Deviation from additive components when epistasis is involved. = VI When phenotypic expression in heterozygotes is not intermediate between homozygotes. = VD Results from environmental factors that produce immediate, and often reversible changes in phenotype. = VEs
Which choice below involves knocking out a gene of known sequence in order to investigate the gene function or associated phenotype?
Reverse genetics (how to remember: knocking out genes in order to find gene function seems a little backwards.)
Which of the following is false regarding sister chromatids...
Separate during anaphase I.
Which type(s) of selection does long-term study of human birth weights often demonstrate?
Stabilizing
The data below is the result of a bacterial interrupted-mating experiment between the bacterial strains listed below: aziR= 10mins: 5% lac+= 17mins: 8% gal+= 21mins: 12% tonS= 13mins: 7.5% What is the distance between the ton and gal gene?
The distance between the ton and gal genes are 8 minutes.
Mitochondrial DNA is more susceptible to mutation than nuclear DNA due to higher local exposure to reactive oxygen species.
True
Myoclonic epilepsy and ragged-red fiber disease is a mitochondrial disorder characterized by a lack of muscle coordination.
True
Part of X-inactivation control is achieved through an X-inactivation center (XIC) on the X chromosome. The XIC contains a gene that codes for a long noncoding RNA.
True
The development pattern in flowering plants is under the control of MADS-box proteins.
True
Which one of the following statements is true?
Typically specific X chromosome inactivation within cells from a tumor reveals that the cells originated from the same source cell or clone.
Which of the following is a purpose of the Punnett square?
Visualize genotypes of all possible progeny in a given cross.
Which of the following represents a male heterozygote carrier?
White square with black dot in the middle.
A specific allele for a given trait behaves dominantly in males but in a recessive fashion in females. The trait can be expressed in both genders. This type of trait is called...
a sex-influenced trait.
Alternative forms of a gene are most accurately called...
alleles
The figure above represents the relationship between (select all that apply): White circle = Black square
an affected male an unaffected female individuals with a shared recent ancestor
The accompanying sketch depicts a cell from an organism in which 2n = 2 and each chromosome is metacentric: Which of the following is the correct stage for this sketch? (Moving away from each other)
anaphase of meiosis II
Klinefelter and Turner syndromes...
can result from X chromosome nondisjunction.
Which of the following best describes the F factor?
can sometimes integrate into the host chromosome to produce an Hfr strain.
The mutator phenotype of cancer cells involves which of the following characteristics (select all that apply)?
chromosome loss DNA amplification chromosomal deletions translocations
Are two mutations that yield similar phenotypes present in the same gene or in two different genes? This question can be answered by which type of analysis?
complementation
Cri-du-chat is the result of...
deletion of part of a chromosome.
Bacterial conjugation involves which of the following?
direct cell-to-cell contact
Expansion of trinucleotide repeat regions within a gene can result in progressively earlier age of disease onset in successive generations. This is best referred to as...
genetic anticipation.
Which term is used to describe cells with a variable mixture of normal and abnormal organelles?
heteroplasmy
Expression of the lac operon structural genes is maximized in the presence of ...
high lactose and low glucose
People with osteogenesis imperfecta (OI) have a dominant mutation in one of the two genes that produce type 1 collagen, COL1A1 or COL1A2. People with OI have weak bones, bluish color in the whites of their eyes, and a variety of afflictions that cause weakness in their joints and teeth. However, some people can carry the mutation but have no symptoms. Thus, families can unknowingly transmit the mutation from one generation to the next through someone who carries the mutation but does not express the OI phenotype. This is an example of which of the following?
incomplete penetrance
Mendel's first postulate (as discussed in the text and Power Point lecture)...
is unit factors exist in pairs.
Pedigree: same sex children on same branch with a line connecting branch.
monozygotic twins
Dosage compensation results (or can result) in which of the following? (Select all that apply.)
mosaicism random Lyonization formation of Barr bodies
In the lac operon, lacY encodes for which of the following?
permease
Gametes...
produced during spermatogenesis include four haploid spermatids.
Fill-in-the blank: The probability of two or more events occurring simultaneously is equal to the _________ of their individual probabilities.
product
The lac I gene...
product is a trans-acting protein.
Which of the following are tools used in human chromosome mapping (both past and present)? (Select all that apply.)
single nucleotide polymorphisms microsatellites restriction fragment length polymorphisms LOD score analysis
Harlequin chromosomes are the result of what phenomenon?
sister-chromatid exchange
Fill-in-the blank: The probability of obtaining any single outcome, where that outcome can be achieved by two or more events, is equal to the_________ of the individual probabilities of all such events
sum
Crossing over occurs during...
the chiasma stage of prophase I. (how to remember: cross over the chasm)
Yellow seed coat color (Y) is dominant to green seed coat color (y) and round seed shape (R) is dominant to wrinkled seed shape (r). In a dihybrid testcross involving these traits...
the parent of unknown genotype has the dominant phenotype for both of the traits.
Which of the following accurately describe(s) the maternal-effect gene products? (select all that apply)
transcription factors deposited during oogenesis distributed in gradients in egg cytoplasm
Duplication mutations of a region of a chromosome are thought to arise from which of the following?
unequal crossing over
Varying degrees of purple in the stems of your purple-stemmed plants of the Mendelian experiment demonstrates which phenomenon?
variable expressivity
The phenotype of the mutant Drosophila parent in the first fly cross that you performed of the chromosome mapping experiment was which of the following?
white-eyed, miniature-winged, forked bristle