Science Olympiad Designer Genes

Mendel's First Law

Law of Segregation (alleles separate during gamete formation).

Mendel's Second Law

Law of Independent Assortment (genes sort independently if unlinked).

Genetic linkage exception

Linked genes violate independent assortment due to proximity on a chromosome.

Incomplete dominance

Heterozygote displays an intermediate phenotype between both homozygous parents.

Codominance

Heterozygote simultaneously expresses phenotypes of both alleles.

Complementation test

Determines if two mutations causing the same phenotype are in the same gene.

Monohybrid cross Punnett square

A 2x2 grid predicting offspring outcomes for a single trait.

Dihybrid cross Punnett square

A 4x4 grid predicting inheritance of two independent traits.

Trihybrid cross complexity

Requires an 8x8 grid or probability rule calculations.

Probability product rule

The probability of independent events occurring together is their individual probabilities multiplied.

Probability sum rule

The probability of mutually exclusive events is the sum of their individual probabilities.

Autosomal dominant pedigree feature

Trait appears in every generation; affected individuals have an affected parent.

Autosomal recessive pedigree feature

Trait often skips generations; affected individuals can have unaffected parents.

Sex-linked recessive pedigree feature

Predominantly affects males; passed from carrier mothers to sons.

Epistasis definition

Masking or modifying effect of one gene's locus on another gene's phenotypic expression.

Recessive epistasis ratio

Typically yields a 9:3:4 phenotypic ratio in a dihybrid cross.

Dominant epistasis ratio

Typically yields a 12:3:1 phenotypic ratio in a dihybrid cross.

Duplicate recessive epistasis ratio

Yields a 9:7 phenotypic ratio (complementary gene action).

State-level gene mapping

Mapping two genes on a chromosome using recombination frequency data.

National-level gene mapping

Mapping three genes on a chromosome using recombination frequencies.

Recombination frequency unit

1 percent recombination equals 1 map unit or centimorgan (CM).

Mendel's laws implication

Provided foundational understanding of heredity before chromosomes were discovered.

Complementary gene action

Two or more genes working together to produce a single phenotype.

Phenotype prediction

Determining observable traits from known genotypes using probability or Punnett squares.

Genotype prediction

Determining genetic makeup of offspring from parental crosses.

Case study pedigree construction

Building family trees using real genetic data to track traits.

Sex-linked dominant pedigree feature

Affected fathers pass trait to all daughters, no sons.

Quantitative reasoning in genetics

Using mathematical models and statistics to analyze genetic data.

Experimental data analysis

Interpreting laboratory results to draw evidence-based genetic conclusions.

Exhaustive topic list

Science Olympiad event rules list specific subtopics without overemphasis.

Mitosis overview

Cell division producing two genetically identical diploid daughter cells.

Meiosis overview

Cell division producing four genetically distinct haploid gametes.

Prophase of mitosis

Chromosomes condense, mitotic spindle starts to form, nuclear envelope breaks down.

Metaphase of mitosis

Chromosomes align individually along the metaphase plate.

Anaphase of mitosis

Sister chromatids separate and move toward opposite poles.

Telophase of mitosis

Nuclear envelopes reform around two new sets of chromosomes.

Prophase I of meiosis

Homologous chromosomes pair up and undergo crossing over.

Metaphase I of meiosis

Pairs of homologous chromosomes align along the metaphase plate.

Anaphase I of meiosis

Homologous chromosomes separate, but sister chromatids remain attached.

Telophase I of meiosis

Two haploid cells form, though chromosomes still consist of two chromatids.

Meiosis II comparison

Closely resembles mitosis, separating sister chromatids in two haploid cells.

Nondisjunction definition

Failure of homologous chromosomes or sister chromatids to separate properly during cell division.

Nondisjunction consequence

Results in aneuploid gametes with abnormal chromosome numbers.

Karyotype definition

An individual's complete set of chromosomes organized by size and shape.

Down syndrome chromosomal cause

Trisomy 21 caused by nondisjunction.

Turner syndrome chromosomal makeup

Monosomy X (45,X0).

Klinefelter syndrome chromosomal makeup

XXY chromosomal abnormality.

Somatic recombination context

Occurs during immune cell development (State/Nationals topic).

V(D)J recombination definition

Site-specific DNA recombination creating diverse antibody and T-cell receptor genes.

Immunoglobulin class switching

Biological mechanism changing a B cell's antibody production class.

Crossing over significance

Generates genetic recombination and diversity during prophase I.

Synapsis definition

Pairing of homologous chromosomes during prophase I of meiosis.

Chiasma structure

X-shaped region where crossing over occurred between non-sister chromatids.

Cytokinesis definition

Division of the cytoplasm following mitosis or meiosis.

Aneuploidy definition

Presence of an abnormal number of chromosomes in a cell.

Hardy-Weinberg equilibrium equation

p^2 + 2pq + q^2 = 1 and p + q = 1.

Hardy-Weinberg allele frequencies

Represented by variables p and q.

Hardy-Weinberg genotype frequencies

Represented by p^2, 2pq, and q^2.

Hardy-Weinberg assumptions

No mutation, random mating, no gene flow, infinite population size, no selection.

Genetic drift definition

Random fluctuations in allele frequencies over generations, especially in small populations.

Founder effect definition

Loss of genetic variation when a new population is established by a very small number of individuals.

Population bottleneck definition

Sharp reduction in population size due to environmental events, reducing genetic diversity.

Gene flow definition

Transfer of genetic material between populations via migration.

Relative fitness definition

Survival and reproductive success of a genotype compared to others in the population.

Additive alleles concept

Alleles that contribute equally and cumulatively to a quantitative phenotype.

Continuous variation

Phenotypes that vary across a continuous range, controlled by multiple genes (polygenic).

Estimating gene number formula

Using phenotypic extremes in crosses to estimate contributing loci (e.g., via Mather's formula).

Gene duplication role

Provides raw genetic material for evolution and the creation of new gene functions.

Homologs definition

Genes related by descent from a common ancestral DNA sequence.

Orthologs definition

Genes in different species that evolved from a common ancestral gene via speciation.

Paralogs definition

Genes related by duplication within a genome.

Phylogenetic tree purpose

Diagram showing evolutionary relationships among various biological species.

Phylogenetic tree nodes

Represent common ancestors of taxonomic groups.

Phylogenetic tree branches

Represent evolutionary lineages over time.

Nuclear phylogenies

Evolutionary trees constructed using nuclear DNA sequences.

Organellar phylogenies

Evolutionary trees based on mitochondrial or chloroplast DNA.

Sequence data input

First basic step in constructing a phylogenetic tree using aligned nucleotide or amino acid sequences.

Broad-sense heritability (H^2)

Ratio of total genetic variance to total phenotypic variance (V_G/V_P).

Narrow-sense heritability (h^2)

Ratio of additive genetic variance to total phenotypic variance (V_A/V_P).

Realized heritability

Estimated from response to selection and selection differential in breeding experiments.

Heritability usage

Exploring phenotypic variation proportions caused by genetic factors in a population (State/Nationals).

Violating Hardy-Weinberg assumptions

Results in microevolution and changing allele frequencies over time.

Infinite population size violation

Leads directly to genetic drift effects.

Random mating violation

Leads to inbreeding depression and altered genotype frequencies.

Selection pressure impact

Alters allele frequencies by favoring advantageous traits.

Polygenic trait examples

Human height, skin color, and weight showing continuous variation.

Extrachromosomal elements phylogeny

Tracking evolutionary history of plasmids or viral genomes.

Outgroup in phylogeny

A more distantly related group used as a baseline to root the phylogenetic tree.

Clade definition

A group consisting of an ancestor and all its descendants.

Monophyletic group

Synonym for a clade representing a single common ancestral lineage.

Paraphyletic group

Includes an ancestor and some, but not all, of its descendants.

Polyphyletic group

Includes taxa with different immediate ancestors, excluding the common ancestor.

Maximum parsimony method

Tree selection principle favoring the evolutionary pathway with the fewest changes.

Bootstrapping in phylogenies

Statistical method assessing confidence levels for phylogenetic tree branches.

Population genetics goal

Studying allele frequency distribution and change under evolutionary forces.

DNA nucleotide components

Deoxyribose sugar, phosphate group, and a nitrogenous base.

DNA nitrogenous bases

Adenine, thymine, cytosine, and guanine.

Purines vs Pyrimidines

Purines (A, G) have two rings; pyrimidines (T, C) have one ring.

DNA backbone structure

Alternating deoxyribose sugars and phosphate groups linked by phosphodiester bonds.

DNA directionality

Strands run antiparallel from 5-prime to 3-prime ends.