Mendelian Genetics and Gene Interactions
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What does the Law of Segregation state regarding alleles during meiosis?

  • Alleles segregate so that two alleles are present in each gamete.
  • Alleles are duplicated in gametes.
  • One allele is present in each gamete after segregation. (correct)
  • Alleles remain together in gametes.

    • Which type of mutation results in a complete loss of functional gene product?

  • Null mutation (correct)
  • Gain of function mutation
  • Hypomorphic mutation
  • Neomorphic mutation

    • What is the outcome when a dominant lethal allele is present in a homozygous state?

  • Phenotype is always wild-type.
  • Offspring will die before birth. (correct)
  • All offspring will survive.
  • Phenotype is recessive.

    • What is the primary function of the complement test in genetics?

    <p>To assess whether mutations are in the same or different genes.</p> Signup and view all the answers

    Which describes the term 'incomplete penetrance' in genetics?

    <p>Only a fraction of individuals with a genotype show the expected phenotype.</p> Signup and view all the answers

    What happens in co-dominance regarding alleles in a heterozygote?

    <p>Both alleles are expressed simultaneously.</p> Signup and view all the answers

    What is the key characteristic of haplo-insufficient alleles?

    <p>A single wild-type allele is insufficient for a wild-type phenotype.</p> Signup and view all the answers

    What does a hypermorphic mutation indicate?

    <p>Increase in gene activity or function.</p> Signup and view all the answers

    What is the most frequent outcome of recombination in a trihybrid test cross?

    <p>No recombination</p> Signup and view all the answers

    What type of polyploidy occurs when gametes have multiple copies of the same gene due to a failure in the first division of meiosis?

    <p>Autopolyploid</p> Signup and view all the answers

    What is the term for the phenomenon when chromosomes fail to segregate normally during meiosis, potentially leading to trisomic disorders?

    <p>Non-disjunction</p> Signup and view all the answers

    In a trihybrid test cross, how can one determine the gene order?

    <p>By identifying the middle marker from a double crossover</p> Signup and view all the answers

    What chromosomal abnormality occurs when there is one extra chromosome in a pair?

    <p>Trisomy</p> Signup and view all the answers

    What is the primary outcome of cytokinesis during meiosis?

    <p>The cell divides into two daughter cells with a haploid number of chromosomes.</p> Signup and view all the answers

    What indicates that two genes are linked?

    <p>They produce a higher ratio of parental phenotypes compared to recombinant phenotypes.</p> Signup and view all the answers

    What is the maximum recombination frequency between linked genes?

    <p>50%</p> Signup and view all the answers

    How is the recombination frequency calculated?

    <p>r = (number of recombinant offspring)/(total # of offspring) x 100</p> Signup and view all the answers

    What is the purpose of functional genomics?

    <p>To understand the functional relationship between genes and their phenotypes.</p> Signup and view all the answers

    Which technique is used to locate the position of a gene on a chromosome?

    <p>Positional cloning</p> Signup and view all the answers

    What is the main goal of a dihybrid test cross?

    <p>To assess the genotype of a heterozygous individual.</p> Signup and view all the answers

    Which of the following best describes the outcome of crossing over during meiosis?

    <p>It increases genetic variation by creating recombinant gametes.</p> Signup and view all the answers

    Which type of transposable element uses a cut-and-paste mechanism involving a DNA intermediate?

    <p>DNA Transposons</p> Signup and view all the answers

    What is the primary mechanism by which retrotransposons operate?

    <p>Transposition through RNA intermediates</p> Signup and view all the answers

    In genetic analysis, what does the selection process during a mutant screen entail?

    <p>Identifying individuals with desired mutant phenotypes</p> Signup and view all the answers

    What is the purpose of testing intermediates in mutant strains?

    <p>To determine specific metabolic pathway steps affected by mutations</p> Signup and view all the answers

    Which method is used to determine if two mutations affecting the same phenotype are in the same gene or different genes?

    <p>Complementation testing</p> Signup and view all the answers

    What role do complex transposons typically play?

    <p>Carrying genes that confer antibiotic resistance</p> Signup and view all the answers

    Which of the following statements about insertion sequences is correct?

    <p>They encode their own movement mechanism through a transposase enzyme.</p> Signup and view all the answers

    What is a potential effect of retrotransposons on the genome?

    <p>Disrupting gene function and altering expression</p> Signup and view all the answers

    What does semiconductor sequencing primarily detect during DNA synthesis?

    <p>pH changes</p> Signup and view all the answers

    What is the main advantage of third generation sequencing over previous methods?

    <p>Can sequence single molecules without amplification</p> Signup and view all the answers

    In reversible chain-termination sequencing, what role do modified dNTPs play?

    <p>They incorporate a removable chemical block</p> Signup and view all the answers

    What is necessary for effective genome assembly from DNA sequencing reads?

    <p>Identifying overlaps among reads</p> Signup and view all the answers

    How does increasing read depth impact genome coverage?

    <p>It increases the average number of reads covering the same region</p> Signup and view all the answers

    What is the first step in the experimental approach to gene identification?

    <p>Extracting RNA from tissue</p> Signup and view all the answers

    What is indicated by the term 'average genome coverage'?

    <p>The average number of reads covering the same genomic region</p> Signup and view all the answers

    What is the relationship between read length and assembly accuracy?

    <p>Longer reads are preferable for unique placement</p> Signup and view all the answers

    What is a Barr Body in mammals?

    <p>The inactive X chromosome that is condensed</p> Signup and view all the answers

    What role does the X inactivation specific transcript (Xist) gene play in X chromosome inactivation?

    <p>It encodes a long non-coding RNA that silences gene expression.</p> Signup and view all the answers

    In a population genetics context, what does the symbol 'p' represent?

    <p>Frequency of allele IA</p> Signup and view all the answers

    Which of the following assumptions is NOT required for Hardy-Weinberg equilibrium?

    <p>Complete non-random mating</p> Signup and view all the answers

    How does negative assortative mating affect genotype frequencies in a population?

    <p>Heterozygotes increase while homozygotes decrease.</p> Signup and view all the answers

    What does frequency-dependent selection refer to in genetics?

    <p>Selection that maintains two alleles based on their commonality.</p> Signup and view all the answers

    What is the relationship between allele frequencies and time in a randomly mating population?

    <p>Allele frequencies remain constant if completely random mating occurs.</p> Signup and view all the answers

    Which blood type frequencies are indicated by the following values: A = 0.504, B = 0.175, O = 0.185?

    <p>IA = 0.4, IB = 0.17, i = 0.43</p> Signup and view all the answers

    Study Notes

    Mendel's Laws

    • Law of segregation: alleles segregate during meiosis, one allele per gamete
    • Law of independent assortment: different traits assort independently
    • Chi-square (X²) test: used to determine if observed results differ significantly from expected results

    Gene Interactions

    • Co-dominance: heterozygote expresses both alleles
    • Incomplete dominance: heterozygote expresses an intermediate phenotype
    • Loss-of-function mutations: decrease or complete loss of functional gene product, usually recessive
    • Hypomorphic mutations: partial loss of gene function
    • Null mutations: complete loss of gene function
    • Haplo-sufficient: one WT allele produces enough product for WT phenotype
    • Haplo-insufficient: one WT allele does not produce enough product for WT phenotype
    • Gain-of-function mutations: increase in functional gene product or new cellular function, usually dominant
    • Hypermorphic: increase in gene activity
    • Neomorphic: new function
    • Conditional mutants: phenotype only under specific conditions

    Mutants

    • Conditional mutants: phenotype only under specific conditions
      • Restrictive condition: mutant phenotype occurs
      • Permissive condition: wild-type phenotype occurs
    • Incomplete penetrance: not everyone with a mutant genotype shows the phenotype
    • Penetrance: proportion of individuals with a genotype that show the corresponding phenotype
    • Dominant lethal alleles: homozygous mutant is lethal
    • Recessive lethal alleles: F1 intercross of heterozygotes; 1/4 offspring will die
    • Complementation test: determines if mutations are in the same or different genes (if two same phenotype mutants create WT offspring, mutations are in different genes)

    Sex-Linked Inheritance

    • Mitosis: somatic cells, chromosome number maintained
    • Meiosis: germline cells, chromosome number halved
    • Chromosome theory of inheritance: each member of a homologous pair comes from each parent; homologous pairs sort independently
    • Sex chromosomes: X and Y chromosomes differ greatly in size and morphology
    • Heterogametic sex: sex with different sex chromosomes (XY in humans)
    • Homogametic sex: sex with homologous sex chromosomes (XX in humans)
    • Hemizygote: having only one allele of a gene
    • Reciprocal crosses: determining sex linkage; switch genotypes of male and female parents in crosses

    Population Genetics

    • Haplotype: set of DNA variants on a chromosome inherited together
    • Allele frequency: p+q = 1
    • Genotype frequency: p² + 2pq + q² = 1
    • Assumptions for Hardy-Weinberg equilibrium: large population, no genetic drift, random mating, no mutations, no natural selection

    Quantitative Genetics

    • Nilsson-Ehle experiment: inheritance of traits might not be due to one single gene pair but multiple genes
    • Edward East experiment: crossing strains with opposing traits demonstrate phenotypic variance dependent on genetic and environment
    • Phenotypic variance (VP): the variance in a trait among individuals in a population
    • Genetic variance (VG): variance in trait due to genetic differences
    • Environmental variance (VE): variance in trait due to environmental differences
    • Broad-sense heritability (H²): proportion of the phenotypic variance due to total genetic variance
    • Narrow-sense heritability (h²): proportion of phenotypic variance due to additive genetic variance
    • Genetic variation: additive genetic variance, dominance genetic variance, epistatic variance
    • Response to selection: change in average trait from selection
    • Selection differential (S): difference between average trait in selected individuals and overall population
    • Quantitative Trait Loci (QTLs): regions of a chromosome containing genes that influence a quantitative trait
    • Estimated Breeding Values (EBVs): estimates of an individual's genetic merit

    Mutations + Horizontal Gene Transfer

    • DNA repair mechanisms
    • Tautomers and Non-standard base pairing
    • Mismatch repair
    • UV damage
    • Photoreactivation
    • Silent mutations
    • Missense mutations
    • Nonsense mutations
    • Frameshift mutations
    • Consequences of mutation

    Meiosis & Genetic Analysis

    • Recombination frequencies: calculate map distances between linked genes
    • Recombination: separates linked genes, increases genetic variation
    • Dihybrid/Trihybrid test crosses: determine if genes are linked, gene order, map distances; parental and recombinant phenotypes observed
    • Meiotic error: non-disjunction, trisomy/monosomy, translocation, inversion
    • Molecular markers (SNPs, RFLPs, microsatellites)
    • PCR (Polymerase Chain Reaction)
    • Positional cloning: gene "location", identify "suspect" DNA sequencing
    • GWAS (Genome Wide Association Studies)

    Genomics

    • Genome size and structure - differences in life forms
    • mRNA, rRNA, tRNA, miRNA (non-coding RNAs)
    • DNA sequencing methods (Sanger, Next-Generation, Third Generation)
    • Genome assembly - from fragments to whole

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    Gene Inheritance And Interactions PDF

    Description

    Explore Mendel's laws of inheritance, including the law of segregation and independent assortment. Understand various gene interactions, such as co-dominance, incomplete dominance, and different types of mutations. This quiz will enhance your understanding of genetic principles and their applications.

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