Genetic Mutations and Chromosomal Concepts

Oncogenes

Genes that promote cell division and cancer.

Gain of Function Mutation

Mutation enhancing gene activity or function.

Loss of Function Mutation

Mutation reducing or abolishing gene activity.

Wild Type

Most common phenotype in a population.

Tumor Suppressor Mutations

Mutations leading to loss of cell cycle control.

Incomplete Dominance

Phenotype blending of two alleles in heterozygotes.

Human Blood Types

ABO system determined by multiple alleles.

Dominant Lethal Alleles

Alleles causing death when present in one copy.

Recessive Lethal Alleles

Alleles causing death only in homozygous condition.

Epistasis

Interaction where one gene masks another's effect.

Pleiotropy

Single gene affecting multiple traits.

X-Linkage

Genes located on the X chromosome.

Sex Limited Traits

Traits expressed in one sex only.

Sex Influenced Traits

Traits expressed differently based on sex.

Penetrance

Proportion of individuals expressing a genotype.

Expressivity

Degree of phenotype expression among individuals.

Suppressor Mutations

Mutations that counteract effects of another mutation.

Temperature Sensitive Mutations

Mutations that express differently at varying temperatures.

Nutritional Mutations

Mutations affecting organism's nutrient requirements.

Chromosome Maps

Diagrams showing gene locations on chromosomes.

Robertsonian Translocation

Fusion of two acrocentric chromosomes.

Reciprocal Translocation

Exchange of segments between non-homologous chromosomes.

Bacterial Growth Phases

Lag, log, and stationary phases of bacteria.

Conjugation

Direct transfer of DNA between bacteria.

Transformation

Uptake of free DNA by bacteria.

Transduction

DNA transfer via bacteriophages.

F+ and F- Bacteria

F+ has fertility factor; F- does not.

Plaque Assay

Method to quantify viruses using bacterial lawns.

SRY Gene

Gene determining male sex in mammals.

X and Y Chromosome Size

X is larger; Y is smaller chromosome.

Barr Bodies

Inactivated X chromosomes in female cells.

Lyon Hypothesis

Random X-inactivation in female mammals.

X-Inactivation

Process of silencing one X chromosome.

Temperature Dependent Sex Determination

Sex determined by incubation temperature.

Monosomy

Loss of one chromosome from a pair.

Partial Monosomy

Loss of part of a chromosome.

Maternal Age and Down Syndrome

Increased risk of Down syndrome with maternal age.

Autopolyploid

Polyploid organism with multiple sets from one species.

Allopolyploid

Polyploid organism with sets from different species.

Deletion Mutation

Loss of a segment of DNA.

Duplication Mutation

Repetition of a segment of DNA.

Inversion Mutation

Segment of DNA reversed in orientation.

Translocation

Movement of a segment from one chromosome to another.

Fragile Sites

Chromosomal regions prone to breakage.