Genetic Linkage & Mapping in Eukaryotes and Bacteria

These flashcards encompass key vocabulary and concepts related to genetic linkage and mapping, providing definitions and explanations for important terms covered in the lecture.

Genetic Linkage

The phenomenon where genes that are close together on the same chromosome are inherited together.

Linkage Groups

A group of genes linked together on the same chromosome.

Synteny

Two or more genes located on the same chromosome.

Mendel’s Law of Independent Assortment

The principle stating that genes for different traits segregate independently in gamete formation.

Crossing Over

The exchange of genetic material between homologous chromosomes during meiosis.

Recombinant Genotypes

Genetic combinations that arise from crossing over and are not found in the parental genotypes.

Bivalents

A structure formed during meiosis where replicated homologous chromosomes are closely associated.

Gene Mapping

The process of determining the linear order and distances between genes on a chromosome.

Testcross

A genetic cross between a homozygous recessive and a heterozygous individual to determine genotype.

Map Units

The measurement used in gene mapping, equivalent to a 1% recombination frequency.

Autosomal Linkage Groups

Linkage groups consisting of the autosomes, excluding sex chromosomes.

X-linked Genes

Genes that are located on the X chromosome.

Phenotypic Ratio

The ratio of the different phenotypes expressed in the offspring.

Drosophila

A genus of small flies commonly used for genetic experiments, also known as fruit flies.

Nonparental Offspring

Offspring that display a combination of traits not found in the parental generation.

Mitotic Recombination

A rare event during mitosis where homologous chromosomes exchange genetic material.

Plasmid

A small, circular piece of DNA found in bacteria that is independent of chromosomal DNA.

F Factor

A fertility factor that allows the transfer of DNA during bacterial conjugation.

Conjugation

The process by which bacteria transfer genetic material through direct contact.

Transduction

The process where bacterial DNA is transferred from one bacterium to another via a bacteriophage.

Transformation

The uptake of free DNA from the environment into a bacterial cell.

Auxotrophs

Strains of bacteria that require external nutrients for growth.

Prototrophs

Strains of bacteria that can synthesize all necessary nutrients.

Gene Pair

The two alleles located at corresponding loci on homologous chromosomes.

Crossover Event

An occurrence during meiosis where homologous chromosomes exchange segments of DNA.

Positive Interference

A genetic phenomenon where one crossover event decreases the likelihood of another nearby crossover.

Chiasmata

The points where homologous chromosomes exchange genetic information during meiosis.

Homologous Chromosomes

Chromosome pairs that are similar in shape, size, and genetic content.

Testcross Proportions

The predicted ratios of offspring phenotypes resulting from a testcross.

Recombinant Offspring

Offspring that exhibit new combinations of traits not found in either parent.

Crossover Frequency

The rate at which recombination occurs between two genes during meiosis.

Meiotic Recombination

The mixing of parental genes during meiosis, leading to genetic diversity.

F Pili

Filamentous structures used by bacteria to initiate conjugation.

Centrifugation

The process used to separate particles in a solution by spinning them at high speed.

Electrophoresis

A laboratory technique used to separate DNA fragments based on size.

Bacterial Transformation

The process by which bacteria take up foreign DNA from their environment.

Recombination Frequency Calculation

An equation used to determine the percentage of recombinant offspring.

Three-Factor Cross

A genetic cross involving three genes to study gene linkage.

Gene Locus

The specific location of a gene on a chromosome.

Chromosomal Mutations

Alterations to the structure or number of chromosomes in an organism.

Lethal Alleles

Alleles that, when present in an organism, can cause death.

Selection Pressure

Environmental factors that influence which individuals of a species survive and reproduce.

Genetic Mapping Techniques

Methods used to create a genetic map of a species, including crosses and molecular analysis.

Quantitative Trait Loci (QTL)

Genomic regions that contain genes influencing a quantitative trait.

Comparative Genomics

The field of bioinformatics that compares the genomic features of different organisms.

Trait Variation

Differences in phenotype among individuals caused by genetic diversity.

Mutation Rate

The frequency at which changes to the genetic material occur.

Diploid

A cell or organism that has two sets of chromosomes, one from each parent.

Haploid

A cell or organism that has a single set of unpaired chromosomes.

Oncogene

A gene that has the potential to cause cancer when mutated.

Tumor Suppressor Gene

A gene that protects a cell from one step on the path to cancer when functioning normally.