Copy of POB 2 Midterm 1 - notes from class

Probability

The likelihood that an event will occur, ranging from 0 to 1.

Independent events

Events where the outcome of one event does not affect the outcome of another; Pr(A and B) = Pr(A) x Pr(B).

Complementary events

Events where one event represents the absence of another; Pr(not A) = 1 - Pr(A).

Mutually exclusive events

Events that cannot occur at the same time; Pr(A or B) = Pr(A) + Pr(B).

Conditional probability

The probability of an event occurring given that another event has occurred; Pr(A given B) = Pr(A and B) / Pr(B).

Lamarck’s model of inheritance

The theory that acquired characteristics can be passed down to offspring, later proven wrong.

Weismann’s Germ-Soma distinction

Only traits present at conception can be inherited; disproven Lamarckism.

True-breeding

Organisms that produce offspring of the same variety over many generations of self-pollination.

P generation

The true-breeding homozygous parental generation in Mendelian genetics.

F1 generation

The first filial generation; hybrid (heterozygous) offspring of the parental generation.

F2 generation

The second filial generation; offspring of the F1 generation.

Homozygous

Having two identical alleles for a gene (e.g., RR or rr).

Heterozygous

Having two different alleles for a given gene (e.g., Rr).

Mendel's Law of Segregation

The two alleles in a pair segregate into different gametes during gamete formation.

Gamete

A haploid reproductive cell (e.g., egg and sperm) formed in meiosis.

Genotype

The genetic makeup of an organism; the genetic description of a locus.

Phenotype

The observable traits or appearance of an organism.

Punnett square

A diagram that represents the probabilities of each genotype occurring from a genetic cross.

Epistasis

When the phenotypic expression of one gene alters that of another independently inherited gene.

Mitosis

Cell division that produces identical cells.

Meiosis

Cell division that produces haploid cells.

Hardy-Weinberg Equilibrium

A condition where allele frequencies remain constant from generation to generation in a population.

Genetic drift

Random fluctuations in allele frequencies in a population from one generation to the next.

Polygenic traits

Traits influenced by multiple genes, often with additive effects.

Genome-Wide Association Studies (GWAS)

Studies that look for associations between SNPs and traits across the genome.

Linkage disequilibrium

Non-independence among loci; indicates correlation between alleles at different loci.

Pleiotropy

When alleles at a single locus affect multiple traits.

Heritability

The proportion of phenotypic variance in a population that is attributable to genetic variance.

Aneuploidy

Abnormal number of chromosomes due to nondisjunction, resulting in conditions like Down Syndrome.

Sex linkage

Genetic traits associated with genes located on sex chromosomes.

Haplo-diploid sex determination

A system where males are haploid and females are diploid.

Mendelian traits

Traits that display clear inheritance patterns governed by single genes.

Null hypothesis

A hypothesis that assumes no effect or no relationship; serves as a baseline for comparison.

Chi-square test

A statistical test to determine the goodness of fit between observed and expected data.

Variants

Differences in genetic sequences that can lead to different genetic traits.

Allele frequency

The proportion of a specific allele among all allele copies in a population.

Nonsynonymous mutation

A mutation that changes an amino acid in a protein.

Synonymous mutation

A mutation that does not change the amino acid sequence of a protein.

Frameshift mutation

A mutation caused by insertion or deletion of nucleotide bases, altering the reading frame.

Germline mutation

A mutation that can be passed on to the next generation.

Somatic mutation

A mutation that occurs in non-germline tissues and is not passed on to offspring.

SNP (Single Nucleotide Polymorphism)

A variation at a single nucleotide position in the DNA sequence among individuals.

Gene pool

The total collection of alleles in a population.