GN 311 EXAM 5 QUESTIONS WITH VERIFIED SOLUTIONS LATEST UPDATE 2026

GN 311 EXAM 5 QUESTIONS WITH VERIFIED SOLUTIONS LATEST UPDATE 2026 A farmer notices that some of his cows produce more milk than others. If the trait is genetic, what can he do? If it is environmental, what can he do? - Answers genetic - use selective breeding environmental - modify environmental factors (feed, etc) Additive + dominance effects = ? - Answers Genotype (G= A+D) where A = average effect of substituting A for a D = dominance effects due to specific combinations of alleles at a locus Angiogenesis - Answers growth of new blood vessels, important to tumor progression Are gene therapy changes heritable? - Answers 1. somatic cells are non-heritable. treats but does not cure disease. all current gene therapies are somatic cell therapies. 2. germline cells are heritable, but require moral and ethical considerations Assume a dominant allele at each locus adds 5 units of risk, but a recessive allele at a locus only adds 2 units of risk. What is the greatest # of risk factors? The lowest number? - Answers Greatest: AABBCC = 6 alleles x 5 risk each = 30 Lowest: aabbcc = 6 alleles x 2 risk factors each = 12 Can we express PSY and CRTI in rice endosperm? - Answers Yes, but only by turning the mRNA into DNA after isolating PSY from a daffodil Cancer cells have? - Answers - uncontrolled cell division (alteration of cell cycle) - ability to metastasize (spread to other locations) - regulation of cell cycle at checkpoints Colonies 1, 2, and 3 grow on Ampicilin. On the replication plate of Tetracycline, only colony 2 grows. What does this indicate? - Answers Colonies 1 and 3 have recombinant DNA. Colony 2 has the pBR322 plasmid. Cells with no DNA did not grow. Comparing sequences between genes and between species allows evaluation of the rates of change. Which of the following have been observed: Select one or more: introns have a higher mutation rate than exons. non-synonymous mutations are found at a higher rate than synonymous mutations. - Answers introns have a higher mutation rate than exons. Concordance compares what? - Answers pairs of monozygotic and dizygotic twins for a trait can be expressed as a % or a ratio, can be used to estimate heritability Contig map - Answers overlapping sets of clones that give a physical map of part of a chromosome (putting fragments together after putting them in sequence) Cytological map - Answers banding patterns based on chromosome staining Defective Double Strand Break Repair - Answers - BRCA1 and BRCA2 Defective Mismatch Repair - Answers - colorectal, endometrial, stomach cancers Defective Nucleotide Excision Repair - Answers - Xeroderma pigmentosum - high risk of skin cancer since many pyrimidine dimers do not get repaired During electrophoresis, small pieces of DNA move... - Answers faster than large pieces Evolution within a single lineage is known as - Answers anagenesis Explain knock-out mice to study gene function. - Answers 1. a normal gene is disabled by inserting the neo+ gene. The tk+ gene is linked to the target gene and the disabled gene is transferred to embryonic mouse stem cells, where the disabled copy recombines with the normal gene on the mouse chromosome 2. the recombinant chromosome is neo+ and tk- 3. cells are grown on a medium that contains the antibiotic for G418 and gancylcovir; only cells that received the neo+ gene, but not the tk+ gene, by homologous recombination survive 4. cells containing a neo+ gene (disabled) are then injected into early mouse embryos, which are implanted into a pseudopregnant mouse 5. variegated progeny contain a mixture of normal cells and cells with the disabled gene 6. variegated mice are then interbred and produce some progeny that are homozygous for knocked-out gene conclusion: mice that contain no functional copy of the gene are produced. the phenotype of the "knockout" (disabled) mice reveals the gene's function Explain transgenic mice-gene function studies. - Answers 1. inject gene of interest into fertilized egg 2. implant in female 3. test progeny for presence of gene 4. mate to obtain mice homozygous for gene 5. study gene function Expression of genes depends on? - Answers The additive effects of a number of genes Expression vectors allow what? - Answers the inserted gene product to be produced Genetic map - Answers constructed from recombination frequencies in units of cM Genotype + environment = ? - Answers Phenotype GWAS - Answers genome-wise association studies h^2 formula - Answers R/S or VA/Vp H^2 formula - Answers VG / Vp H^2 is what kind of variability? - Answers Broad sense h^2 is what kind of variability? - Answers narrow sense How are alleles used for paternity/forensics purposes? - Answers Allele is based on the length of the DNA segment, with different alleles having different lengths because they have different numbers of copies of a short repeated DNA sequence - useful loci for paternity/forensics purposes must be POLYMORPHIC (many forms) How can evolutionary divergence be evaluated? - Answers by measuring: morphology, chromosome structure, protein sequence, DNA sequence How can one use retroviral vectors for gene therapy? - Answers Retroviral vectors integrate into the DNA of the host cell - transgene is transmitted to all progeny cells in the cell lineage - transgene may integrate so that it disrupts function of another gene How can retroviruses cause cancer? - Answers - mutating and rearranging proto-oncogenes - inserting strong promoter near proto-oncogenes How can we get the daffodil PSY gene to be expressed in rice? - Answers - need lots of DNA - need a way to get it into rice genome - need a promoter How do abnormal tumor suppressor genes work? - Answers no inhibition of uncontrolled growth results in tumor if no normal allele is present must disrupt both copies of the gene to lose cell cycle regulation (recessive) How do bacteria convert phytoene to lycopene? - Answers CRTI How do environmental influences cause cancer? - Answers (Carcinogens) - can cause mutations and alter gene expression How do gain of function mutations work? - Answers - cell produces protein that is not usually present - either new gene product or gene product in new location or at an inappropriate time in development - dominant acting mutation How do other plants convert GGPP to phytoene? - Answers PSY How do you find V(F2)? - Answers V(F2) = Vp = VG + VE How does a dominant proto-oncogene mutation work? - Answers only need mutation in 1 copy of proto-oncogene to get tumor How does a Southern Blot work? - Answers single-stranded DNA fragments from a gel are transferred to a nylon membrane using capillary action in the southern blot 1. the nylon membrane is incubated with labeled, single-stranded probe DNA 2. the probe binds to complimentary DNA fragments on the nylon 3. the position of the probe is identified 4. DNA from 12 different possibly transgenic strains are tested to see if the strains had the PSY/CRTL gene incorporated into the genome Wild type: no PSY/CRTL transgenic genes: PSY/CRTL How does angiogenesis affect tumor progression? - Answers - growth factors and other proteins involved in angiogenesis are often overexpressed in tumor cells - angiogenesis inhibitors may be inactivated or underexpressed How does Blue-White Screening work? - Answers 1. Start with functional LacZ 2. Cut vector and ligate insert into Multiple Cloning Site of nonfunctional LacZ 3. Transform ligation mixture into DH5a cells. 4. Plate cells on media containing Amp and X-Gal. 5. If no DNA uptake: no growth If contains pieces/incomplete plasmids: no growth If contains pUC19: blue colony If contains recombinant plasmid: white colony How does gene therapy work in cancer? In immune deficiencies? - Answers - immune deficiencies: blood cells can be removed and targeted by retroviruses to deliver wild type copy of gene - cancer: for leukemia, remove immune cells and modify them to attack cancerous cells How does genetic change in a population occur? - Answers 1. change occurs (must be genetic - can be through mutation or recombination) 2. different alleles/combinations must increase or decrease in frequency in the gene pool (selection/other factors) How does mutation cause genetic change? - Answers creates new alleles How does one make CDNA? - Answers reverse transcriptase reads RNA and makes DNA -- RNA-dependent DNA polymerase How does recombination cause genetic change? - Answers creates new combinations of alleles How does reproductive isolation occur? - Answers 1. prezygotic (they don't choose to mate with each other or cannot mate with each other) 2. postzygotic (their progeny are sterile/inviable) How does selection work on an organism? - Answers selection works on entire organism's phenotype, so many loci and environmental factors are important How does telomerase affect cancer? - Answers - tumor cells often have telomerase expression, which is thought to contribute to the "immortality" of cancer cells - mutations in genes that regulate telomerase activity may be important in cancer How does the Dideoxy Sequencing Reaction work? - Answers 1. 3'-OH required by DNA polymerase to form phosphodiester bond 2. DNA replication reaction proceeds until a dideoxy nucleotide is incorporated 3. No further extension occurs 4. Detect which position the dideoxy nucleotide was incorporated * how far it migrates -- determines where termination occurs, color determines what base How go loss of function mutations work? - Answers - complete or partial absence of protein function - recessive acting mutations How is DNA sequence alignment done? - Answers identification of homologous genes and properly aligning the sequences is critical in determining an accurate tree How is size determined in electrophoresis? - Answers Sizes can be determined based on comparing fragment migration to that of a control of known size How was Golden Rice able to be improved? - Answers after trying to use the PSY gene from other plants, rice with maize PSY gave much higher B-carotene than the daffodil gene (so kilograms would not have to be consumed) If heritability = 0? - Answers all Vp is due to environmental variance If heritability = 1? - Answers all Vp is due to genetic variation If the inheritance of a genetic marker is associated with inheritance of a quantitative trait, then ? - Answers the marker must be linked to a QTL involved in that trait In DNA sequence analysis, a higher number means what? - Answers More likely (less substitution) In DNA sequence analysis, why are there so many synonymous substitutions as opposed to nonsynonymous? - Answers Nothing is selected against synonymous Nonsynonymous is lower because the AA code is changed, which can alter gene function and cause selection initial population mean - Answers μ or x-bar 0 Low MZ, but still higher than DZ indicates? - Answers genetic predisposition, but environmental factors important Mapping, sequencing, and analyzing genomes involves what? - Answers - collecting sequence data - correlating genetic, cytological and physical chromosome maps - identifying DNA sequences that contain genes of interest in the genome and analyzing the function of those gene products mean of next generation - Answers x-bar 1 = μ + R = x-bar 0 + R Mutations in what cell types can cause cancer? - Answers 1. tumor suppressor genes (prevent bad cells from dividing) 2. proto-oncogenes (allow good cells to divide) Mutations inside tumor cells can affect: - Answers cell cycle regulation, signal transduction, DNA repair, telomere length, chromosome segregation, vascularization Nicks in the sugar-phosphate backbone can be sealed with? - Answers DNA ligase Northern Blot - Answers RNA fragments separated based on length One strand of double-stranded DNA is shown below. Assume that the other strand is also present. Is this sequence a palindrome? 5' - CCATGG - 3' - Answers Yes Physical map - Answers molecular distances in base pairs (bp), kilobases (kb), megabases (mb) often show restriction enzyme recognition sites, locations of particular clones or sequence-tagged sites Pleiotropy - Answers one gene affects multiple traits (positively or negatively) a change in value for one traits is accompanied by a change in value for another trait due to genes affecting one trait also affecting the other trait Practice all examples of problems found in homework! - Answers . Prezygotic reproductive isolation mechanisms include what kind of isolation: - Answers temporal isolation, ecological isolation, mechanical isolation, behavioral isolation proportion selected - Answers p QTL - Answers Quantitative Trait Loci identified by linkage analysis between the trait and molecular markers Recombinant DNA - Answers creating new DNA molecules containing DNA from different sources, often uses restriction enzymes to cut DNA strands that can then be ligated together response to selection - Answers R = (x-bar 1) - (x-bar 0) R = h^2 * S Restriction enzyme - Answers endonuclease that recognizes a specific DNA sequence and cleaves dsDNA at that sequence Retinoblastoma - RB gene - Answers - 40% cases are inherited - Knudsons Two Hit Hypothesis (both copies must be defective in same cell in order for tumor to develop) - Normal protein responsible for regulation at G1/S checkpoint (RB normally prevents E2F from activating replication in G1 to S, later releases E2F to begin replication late in G1) selection differential - Answers S = (x-bar s) - (x-bar 0) Smaller branches on a tree indicate what? - Answers More genetically similar SNP - Answers Single Nucleotide Polymorphism (SNP) is a specific site in the genome where the DNA base varies in at least 1% of the population Southern Blot - Answers DNA fragments separated based on length standard deviation - Answers σ Study the rice genome picture in notes! - Answers . Suppose there are 2 genes controlling plant height. The genotype aabb is 10" tall. Each A and B allele adds 5" to the height. How tall is a plant of genotype AABB? Cros AABB x aabb. How tall is F1? - Answers AABB - 30" (10+5+5+5+5) F1 - AaBb - 20" (10+5+5) The normal bell curve is found when variation is due to? - Answers genotype and environment The part of a bacterial cloning vector that contains many restriction enzyme recognition sequences is called a... - Answers multiple cloning site The process of separating DNA fragments based on their migration in an electrical current is called... - Answers electrophoresis True or false: All variation in the parental and F1 generations is VE since each of these generations only has one genotype. - Answers True True or false: Cancer cells often have abnormal karyotypes. - Answers True True or false: Cancer is heritable. - Answers False. Cancer is genetic, but rarely heritable True or false: different parts of the genome evolve at different rates. - Answers True True or false: Environmental plays an important role in the expression of a trait. - Answers True - as the number of loci affecting a trait increases, the number of phenotypic classes increases and smooths curves True or false: Genotypes may produce a range of phenotypes. - Answers True True or false: Heritability says how much genes affect the trait. - Answers False. heritability does not say how much genes affect the trait, it says how much genes affect the variation in the trait. True or false: If variation is not heritable, it can still be passed to progeny. - Answers False True or false: In a tumor suppressor gene, both copies must be mutated to get tumor - Answers True ("recessive mutation") True or false: In DNA sequence analysis, introns are removed. - Answers True True or false: In electrophoresis, distance migrated is directly proportional to the log of the fragment size. - Answers False. It is inversely proportional True or false: In electrophoresis, DNA is loaded at the negative pole and moves to the positive pole - Answers True True or false: In electrophoresis, small fragments migrate faster than large fragments. - Answers True True or false: in forensics, suspect is excluded from leaving the piece of evidence at the crime scene if she/he does not match exactly at all loci. - Answers True True or false: Molecules cut with the same restriction enzyme have complementary sticky ends that pair if fragments are mixed together. - Answers True True or false: Most cancers are due to one gene. - Answers False. Most cancers are not due to one gene, but accumulations of mutations in several genes. True or false: pseudogenes don't code for the protein. - Answers True True or false: Selection response may increase after selecting for a particular characteristic in a population for a long period of time. - Answers FALSE, selection response may DECLINE. Why? - genetic variation is being lost as more favorable homozygous genotypes become fixed in the population - extremely types may not be healthy - two desirable traits may be negatively correlated True or false: Telomerase normally works in germline cells, but not in somatic cells - Answers True. This allows somatic cells to die, be replaced, etc. True or false: the effect of each gene is small. - Answers True True or false: The higher the heritability, the more progress we can expect from a selection/breeding program - Answers True True or false: the Leader and Trailer (UTR) are transcribed and translated in DNA sequence analysis. - Answers False. They are transcribed, but not translated. Many contain signals for RNA processing and ribosome attachment True or false: The value of heritability is specific for a particular population in a particular environment. - Answers True True or false: there are high correlations between the number of stem cell divisions and cancer risk among tissues in different environments. - Answers True, because mutations are due to replication errors True or false: Tumor cells acquire more mutations that allow them to be progressively more aggressive in proliferation. - Answers True True or false: typically telomeres lengthen as a cell ages and this ultimately contributes to the death of the cell - Answers False. Telomeres SHORTEN as a cell ages and this contributes to cell death True or false: Variance is related to the length of the curve. - Answers False. Variance is related to the width of the curve.