M6 - Eukaryotic Genetics Flashcards
What is the primary focus of eukaryotic genetics?
Understanding how genes control biological functions, inheritance patterns, and phenotypic traits in eukaryotic organisms.
What happens during meiosis?
Meiosis shuffles genetic material through recombination and reduces chromosome number by half, generating genetically diverse gametes.
Why is Mendel’s legacy important in genetics?
Mendel’s work established the foundational laws of inheritance, including the principles of segregation and independent assortment.
What is genetic recombination?
The exchange of genetic material between homologous chromosomes during meiosis, leading to new genetic combinations.
What is linkage mapping?
A technique used to determine the relative positions of genes on a chromosome based on how frequently they are inherited together.
What is complex genetic variation?
Variations in traits influenced by multiple genes and environmental factors, rather than following simple Mendelian inheritance.
What is pedigree analysis in human genetics?
A method used to study inheritance patterns of traits and diseases across generations in a family.
What is genome-wide association mapping (GWAS)?
A method that scans the genome for genetic variations associated with specific traits or diseases.
What is non-Mendelian inheritance?
Inheritance patterns that do not follow Mendel’s laws, including mitochondrial inheritance, genomic imprinting, and epigenetic modifications.
What is chromosomal (segmental) variation?
Changes in the structure or number of chromosomes, such as deletions, duplications, inversions, or translocations.
What is population genetics?
The study of genetic variation within populations and how evolutionary forces like selection, mutation, and drift shape gene frequencies.
Why are model organisms important in genetics research?
They allow scientists to study gene function and inheritance patterns that are often conserved across species.
What is the concept of the holobiont in genetics?
The idea that the host and its microbiota form an extended genome, influencing the host’s development, health, and evolution.
How do geneticists contribute to understanding human diseases?
By identifying genetic mutations linked to diseases, studying gene-environment interactions, and developing targeted therapies.
What is the role of technology in modern genetics?
Advanced technologies, like genomics and CRISPR, allow for the generation of large datasets and precise genetic manipulation to study gene function.
What is the primary function of meiosis?
To produce four genetically distinct haploid cells for sexual reproduction by halving the chromosome number.
What is independent assortment?
The random distribution of homologous chromosomes during meiosis, contributing to genetic variation.
What is crossing-over, and when does it occur?
The exchange of genetic material between non-sister chromatids during Prophase I of meiosis, increasing genetic diversity.
What is a synaptonemal complex?
A protein structure that forms between homologous chromosomes during Prophase I to facilitate pairing and recombination.
What happens during Leptotene in Prophase I?
Chromosomes condense and become visible, and homologous pairing begins as double-strand breaks form.
What characterizes the Zygotene stage of Prophase I?
The formation of the synaptonemal complex between homologous chromosomes, forming bivalents.
What occurs during Pachytene in meiosis?
Chromosomes condense further, crossing-over completes, and tetrads (groups of four chromatids) form.
What is visible during Diplotene in Prophase I?
Chiasmata, the physical sites of crossing-over, become visible as homologous chromosomes begin to separate.
What happens during Diakinesis?
Chromosomes repel each other but remain connected at chiasmata; the nuclear membrane breaks down.
What is the significance of chiasmata in meiosis?
They ensure proper alignment and separation of homologous chromosomes during Anaphase I.
What occurs in Metaphase I of meiosis?
Homologous chromosome pairs align along the metaphase plate, and their kinetochores attach monopolar to spindle fibers.
What is a Holliday junction?
A DNA structure formed during recombination where strands from homologous chromosomes cross over.
How does meiosis contribute to genetic diversity?
Through independent assortment of chromosomes and crossing-over during Prophase I.
What is a karyotype?
A visual representation of the chromosome set of an organism, used to detect chromosomal abnormalities.
What is the difference between mitosis and meiosis?
Mitosis: Produces two identical diploid cells for growth and repair.
Meiosis: Produces four genetically distinct haploid cells for sexual reproduction.
Who is considered the father of modern genetics?
Gregor Mendel, an Austrian monk who discovered the basic principles of heredity through pea plant experiments.
What are Mendel’s two fundamental laws of inheritance?
Law of Segregation: Each individual has two alleles for each gene, which segregate during gamete formation.
Law of Independent Assortment: Genes for different traits are inherited independently of each other.
What is phenotype dominance?
When one allele masks the expression of another in a heterozygous individual, producing the dominant trait in the phenotype.
What was Mendel’s experimental approach?
He established a robust experimental system, generated large data sets, repeated experiments with different variables, and created predictive models.
What was the significance of Mendel’s test crosses?
Test crosses allowed Mendel to determine whether an organism showing a dominant trait was homozygous or heterozygous.
What is the concept of blending inheritance, and why was it incorrect?
It was an early theory that offspring are a blend of parental traits; Mendel disproved it by showing traits are inherited as discrete units.
What is linkage mapping?
A genetic technique that identifies the relative positions of genes on a chromosome based on how frequently they are inherited together.
Who coined the terms genetics and epistasis?
William Bateson, a British geneticist, who helped establish genetics as a scientific discipline.
What was the significance of the rediscovery of Mendel’s work in 1900?
Scientists like Hugo de Vries, Carl Correns, and Erich von Tschermak independently confirmed Mendel’s findings, leading to the foundation of modern genetics.
What is applied genetics?
The use of genetic principles to improve organisms, demonstrated by Roland Biffen’s development of rust-resistant wheat in 1910.
What contributions did Eric Lander make to genetics?
He was a leader in the Human Genome Project and contributed to applying genomics in medicine.
What role did statistical genetics play in modern genetics?
Scientists like Ronald Fisher and Sewall Wright developed mathematical models to study gene distribution and inheritance in populations.
How does the size of an organism’s genome vary across species?
Genome sizes differ significantly; for example, humans have 3,300 million base pairs, while yeast has only 13 million base pairs.
What is a model organism in genetics?
An organism widely studied to understand biological processes, such as Drosophila melanogaster (fruit fly) and Arabidopsis thaliana (a model plant).
What was Mendel’s contribution to experimental design?
He emphasized quantitative data collection, statistical analysis, and experimental reproducibility, laying the groundwork for modern scientific methods.
What is the Chromosome Theory of Inheritance?
The theory that chromosomes are the physical carriers of genetic material, explaining Mendel’s laws through chromosomal behavior during meiosis.
What does Mendel’s First Law of Inheritance state?
Each organism inherits two alleles for each trait, which segregate during gamete formation so each gamete receives only one allele.
What is Mendel’s Second Law of Independent Assortment?
Genes for different traits segregate independently during gamete formation if they are located on different chromosomes.
How does meiosis explain Mendel’s First Law?
Homologous chromosomes segregate during Anaphase I of meiosis, ensuring that each gamete receives only one allele from each pair.
What was Thomas Hunt Morgan’s major contribution to genetics?
He demonstrated that genes are located on chromosomes and established the concept of linkage, showing that genes close together on a chromosome tend to be inherited together.
What is genetic linkage?
The tendency of genes located close to each other on the same chromosome to be inherited together due to reduced recombination.
What is a recombination frequency, and how is it calculated?
The percentage of offspring showing non-parental combinations of traits; calculated as (Number of recombinant offspring / Total offspring) × 100.
How did Alfred Sturtevant contribute to genetics?
He developed the first genetic linkage maps by calculating recombination frequencies to estimate the physical distance between genes.
What does 1% recombination frequency represent?
It corresponds to one map unit or 1 centiMorgan (cM), a measure of genetic distance between two loci.
What is a molecular marker?
A specific DNA sequence difference (polymorphism) that can be used to track the inheritance of linked genes across generations.
What is map-based cloning?
A method used to identify and isolate genes responsible for specific traits by locating them through linkage to molecular markers.
How do loss-of-function experiments verify gene function?
By disrupting the gene (e.g., via mutagenesis) and observing whether the trait associated with the gene is lost.
What is a gain-of-function experiment?
Introducing a gene into an organism to observe whether it induces a new trait or restores a lost function, confirming its role.
How does gene recombination contribute to genetic diversity?
It shuffles alleles between chromosomes during meiosis, creating new genetic combinations in offspring.
What is genome-wide association mapping (GWAS)?
A technique used to scan entire genomes for genetic variations associated with specific traits or diseases across populations.
What is complex genetic variation?
Variation influenced by multiple genes and environmental factors, leading to diverse phenotypic outcomes that don’t follow simple Mendelian inheritance.
What is quantitative genetics?
The study of traits influenced by multiple genes (polygenic traits) and environmental factors, resulting in continuous variation, such as height or yield.
How did Ronald Fisher contribute to quantitative genetics?
He developed statistical methods to explain how Mendelian genetics could account for continuous traits through the effects of multiple genes.
What is genotype-environment (GxE) interaction?
When the effect of a genotype on a phenotype varies depending on environmental conditions, such as temperature or nutrient availability.
What is polygenic inheritance?
Inheritance controlled by two or more genes, where each gene contributes to a small effect on the overall phenotype.
What is a mapping population in genetics?
A group of individuals derived from specific parental crosses, used to study gene inheritance and create genetic maps.
What is linkage mapping?
A method to determine the order of genes on a chromosome by measuring recombination frequencies between linked loci.
What is a LOD score in genetics?
The Logarithm of the Odds score assesses the likelihood that two loci are linked versus unlinked, helping identify genetic associations.
What is association mapping?
A method that links genetic variations to phenotypic traits by studying natural populations and identifying correlations.
What is genetic redundancy?
The presence of duplicate genes that can perform the same function, ensuring that one gene can compensate if another is lost or mutated.
What does the term “dominance” refer to in genetics?
When one allele masks the phenotypic expression of another allele in a heterozygous organism.
What is the difference between artificial and natural variation?
Artificial variation: Induced mutations used in experimental genetics.
Natural variation: Genetic diversity occurring in populations due to natural evolutionary processes.
How does genetic mapping help in crop improvement?
It identifies genes associated with desirable traits, such as disease resistance or drought tolerance, for selective breeding.
What is a gain-of-function experiment?
Introducing a gene into an organism to observe if it confers a new or enhanced trait, confirming the gene’s role in a phenotype.
What is an example of genotype-environment interaction in plants?
Some dwarf mutants in plants are responsive to gibberellic acid (GA) and grow normally, while others remain dwarf regardless of GA treatment.
What is pedigree analysis?
A method used to track the inheritance of specific traits or genetic disorders across generations within a family.
What is the purpose of pedigree analysis in genetics?
To determine the mode of inheritance (e.g., autosomal vs. sex-linked, dominant vs. recessive) and calculate the probability of disease occurrence in future generations.
What are the limitations of pedigree analysis?
Small family sizes, incomplete or inaccurate data, false parentage, and ethical constraints prevent controlled matings in humans.
What characterizes autosomal recessive inheritance?
Males and females are equally affected.
Disease appears in homozygous recessive individuals (dd).
Unaffected parents can have affected offspring.
Name two examples of autosomal recessive diseases.
Cystic fibrosis and Tay-Sachs disease.
What characterizes autosomal dominant inheritance?
Disease appears in every generation.
Affected individuals are typically heterozygous (Dd).
Males and females are equally affected.
Name three examples of autosomal dominant diseases.
Huntington’s disease, hereditary retinoblastoma, and achondroplasia.
What defines X-linked recessive inheritance?
Males are more frequently affected since they have only one X chromosome.
Female carriers pass the trait to 50% of their sons.
Females are affected only if they inherit two mutant alleles.
Give examples of X-linked recessive disorders.
Hemophilia, Duchenne muscular dystrophy, and red-green color blindness.
What distinguishes X-linked dominant inheritance?
All daughters of an affected male are affected.
No sons of an affected male are affected.
Examples include incontinentia pigmenti and Coffin-Lowry syndrome.
What are Single Nucleotide Polymorphisms (SNPs)?
Single base-pair variations in DNA that can be used as genetic markers for linkage analysis.
What are Simple Sequence Repeats (SSRs)?
Short DNA sequences repeated in tandem (2-4 base pairs) used for genetic mapping and linkage analysis.
How is linkage mapping performed using SSRs?
By analyzing the inheritance pattern of SSR markers in families and calculating recombination frequencies to map gene locations.
What does a recombination frequency of 0.14 (14%) suggest?
The gene and marker are closely linked on the same chromosome.
How is genetic counseling used in recessive disorders?
It estimates the carrier probability and risk of passing on genetic diseases, as shown in examples like Tay-Sachs disease.
What is a LOD score in genetic linkage analysis?
The Logarithm of the Odds (LOD) score is a statistical measure that evaluates whether two loci are likely linked by comparing the likelihood of linkage to the likelihood of no linkage.
How is the LOD score interpreted?
A LOD score greater than 3.0 suggests linkage, while a score below -2.0 indicates no linkage.
What is a recombination frequency (θ)?
The probability that two loci will be separated during meiosis, ranging from 0 (completely linked) to 0.5 (completely unlinked).
What is association mapping?
A method to identify genetic variants linked to traits or diseases by comparing genetic markers across a population.
What are Single Nucleotide Polymorphisms (SNPs)?
Single base-pair substitutions in DNA, which occur frequently and are used as molecular markers in genetic mapping.
Why are SNPs important in genetic studies?
They help identify genetic differences associated with diseases, traits, or responses to treatments.
What is linkage disequilibrium (LD)?
A non-random association of alleles at different loci within a population, often observed in closely linked genetic regions.
What is a haplotype block?
A segment of DNA containing alleles inherited together due to limited recombination, used in association studies to track genetic variation.
What is genome-wide association mapping (GWAS)?
A method that scans entire genomes to find genetic variations associated with specific traits or diseases across large populations.
What are complex inherited disorders?
Diseases influenced by multiple genes and environmental factors, such as diabetes, Alzheimer’s disease, and Crohn’s disease.
What is fine mapping in genetics?
Narrowing down a genomic region containing a disease-related gene using closely linked markers to identify candidate genes.
What is the significance of loss-of-function experiments?
They test whether disrupting a gene eliminates its function, helping confirm the gene’s role in a particular trait or disease.
What is gain-of-function analysis?
Introducing a functional gene into a mutant organism to see if it restores the lost function, confirming the gene’s involvement.
What is the Human Genome Project?
A global scientific effort (1990-2003) aimed at mapping all human genes and understanding their functions.
What are the goals of identifying causal genes in genetic diseases?
Developing diagnostic tests, creating targeted drugs, and advancing gene therapy to treat or cure genetic disorders.
What are transposable elements, or “jumping genes”?
DNA sequences that can change their position within the genome, affecting gene expression and genome structure.
Who discovered transposable elements, and what award did they receive?
Barbara McClintock discovered transposable elements and won the 1983 Nobel Prize in Physiology or Medicine.
When can transposition occur in cells?
During mitosis and in response to environmental factors like temperature and stress.
What is epigenetics?
Heritable changes in gene expression that are not caused by changes in DNA sequence, often regulated by methylation or histone modification.
What is extranuclear inheritance?
The transmission of genetic material through organelles like mitochondria and chloroplasts, typically inherited maternally.
What is the endosymbiotic theory?
The theory that mitochondria and chloroplasts originated from ancestral bacteria engulfed by early eukaryotic cells.
What is the size of the mitochondrial genome in humans?
Approximately 16 kilobases (kb).
What are the characteristics of the chloroplast genome?
It is circular, contains genes for redox proteins involved in photosynthesis, and varies in size from 80-600 kb.
How does chloroplast inheritance work in Mirabilis jalapa (4 o’clock plant)?
It follows maternal inheritance, where the leaf color depends on the type of chloroplasts inherited from the mother.
What is a yeast petite mutation?
A mitochondrial mutation in yeast that results in small (petite) colonies, affecting respiration and energy production.
What is the difference between segregational and vegetative petite mutants in yeast?
Segregational petites follow Mendelian inheritance (nuclear DNA).
Vegetative petites follow non-Mendelian inheritance (mitochondrial DNA).
What is Myoclonic Epilepsy with Ragged-Red Fibers (MERRF)?
A mitochondrial disorder caused by a mutation in lysine tRNA, leading to muscle spasms, lactic acid accumulation, and uncoordinated movement.
Why is mitochondrial DNA (mtDNA) useful for phylogenetic analysis?
It has a high copy number, is maternally inherited, doesn’t recombine, and evolves slowly, making it useful for tracing ancestry.
What is genomic imprinting?
A form of gene regulation where one parental allele is epigenetically marked (e.g., by methylation), affecting gene expression.
How does maternal inheritance affect shell coiling in snails?
The mother’s nuclear genotype determines the offspring’s coiling direction by influencing spindle orientation during early cell division.
What is a chromosomal mutation?
A large-scale change in chromosome structure or number that can affect gene function and lead to genetic disorders or evolutionary changes.
Why study chromosomal mutations?
To gain cytological insights into meiosis, understand the genetic basis of diseases, investigate gene interactions, and study evolutionary processes.
What is monoploidy, and where is it commonly found?
Monoploidy refers to having a single set of chromosomes (n); it’s common in social insects like ants, bees, and wasps, where males develop via parthenogenesis.
What is polyploidy?
A condition where an organism has more than two sets of chromosomes, common in plants and rare in animals.
Provide examples of polyploidy in plants.
Triploid: Banana
Tetraploid: Cotton, Potato
Hexaploid: Wheat
Octaploid: Strawberry
What are the two origins of polyploidy?
Autopolyploid: Arises from the duplication of chromosomes within a single species.
Allopolyploid: Results from the combination of chromosomes from different species.
How did hexaploid wheat originate?
Through hybridization of three ancestral diploid species, each contributing seven chromosomes (n=7), forming a hexaploid with 42 chromosomes.
What chemical induces polyploidy in plants?
Colchicine, which disrupts spindle assembly, preventing chromosome segregation during cell division.
What is aneuploidy?
A condition where the number of chromosomes changes for some but not all chromosomes, leading to monosomy, trisomy, or other abnormalities.
What causes aneuploidy?
Non-disjunction during meiosis, where chromosomes fail to separate properly, resulting in gametes with abnormal chromosome numbers.
What is a segmental inversion?
A chromosomal rearrangement where a segment of a chromosome is reversed end to end, which can be either paracentric (not involving the centromere) or pericentric (involving the centromere).
What happens during a crossover within an inversion loop?
It can produce dicentric chromosomes (two centromeres) and acentric chromosomes (no centromere), often leading to genetic instability.
What is a reciprocal translocation?
The exchange of chromosome segments between non-homologous chromosomes, potentially affecting gene expression and causing genetic disorders.
How can reciprocal translocations cause cancer?
By creating chimeric genes (e.g., the ABL-BCR fusion in leukemia) that lead to uncontrolled cell proliferation.
What is chromosome painting?
A technique using fluorescence in situ hybridization (FISH) to visualize chromosomal translocations and rearrangements under a microscope.
What is population genetics?
The study of genetic variation within populations and how evolutionary forces like mutation, selection, migration, and drift shape genetic structure.
What defines a population in genetics?
A group of individuals from the same species that interbreed and share a common gene pool.
What is the Hardy-Weinberg Principle?
A mathematical model that describes allele and genotype frequencies in a population that is not evolving, assuming no mutation, migration, selection, or genetic drift.]
What is the equation for Hardy-Weinberg equilibrium?
p^2+2pq+q^2=1,
where p and q are the frequencies of two alleles, and the terms represent the expected genotype frequencies.
What factors disrupt Hardy-Weinberg equilibrium?
Mutation, migration, natural selection, genetic drift, and non-random mating.
What is genetic drift?
A random change in allele frequencies due to chance events, affecting small populations more strongly than large ones.
What is a genetic bottleneck?
A sharp reduction in population size due to environmental events, leading to reduced genetic diversity.
What is the founder effect?
The reduced genetic diversity that results when a population is descended from a small number of colonizing ancestors.
What is directional selection?
A form of natural selection that favors individuals at one extreme of the phenotypic range, shifting the population’s traits over time.
What is stabilizing selection?
A form of selection that favors intermediate phenotypes and reduces variation by selecting against extremes.
What is disruptive selection?
A form of selection that favors individuals with extreme traits at both ends of the phenotypic spectrum, potentially leading to speciation.
What is balancing selection?
A type of selection that maintains multiple alleles in a population, such as heterozygote advantage in sickle cell disease.
What is non-random mating?
When individuals choose mates based on phenotype, leading to assortative (similar phenotypes) or disassortative (dissimilar phenotypes) mating.
How does migration affect genetic structure?
Migration introduces new alleles into a population, increasing genetic diversity and altering allele frequencies.
What is genome-wide association mapping (GWAM)?
A technique used to identify genetic variations associated with specific traits across a genome by analyzing population-wide allele frequencies.
